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_LOCK_ALLOC 205 bool "Lock debugging: detect incorrect freeing of live locks" 206 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 207 select DEBUG_SPINLOCK 208 select DEBUG_MUTEXES 209 select LOCKDEP 210 help 211 This feature will check whether any held lock (spinlock, rwlock, 212 mutex or rwsem) is incorrectly freed by the kernel, via any of the 213 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 214 vfree(), etc.), whether a live lock is incorrectly reinitialized via 215 spin_lock_init()/mutex_init()/etc., or whether there is any lock 216 held during task exit. 217 218config PROVE_LOCKING 219 bool "Lock debugging: prove locking correctness" 220 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 221 select LOCKDEP 222 select DEBUG_SPINLOCK 223 select DEBUG_MUTEXES 224 select DEBUG_LOCK_ALLOC 225 default n 226 help 227 This feature enables the kernel to prove that all locking 228 that occurs in the kernel runtime is mathematically 229 correct: that under no circumstance could an arbitrary (and 230 not yet triggered) combination of observed locking 231 sequences (on an arbitrary number of CPUs, running an 232 arbitrary number of tasks and interrupt contexts) cause a 233 deadlock. 234 235 In short, this feature enables the kernel to report locking 236 related deadlocks before they actually occur. 237 238 The proof does not depend on how hard and complex a 239 deadlock scenario would be to trigger: how many 240 participant CPUs, tasks and irq-contexts would be needed 241 for it to trigger. The proof also does not depend on 242 timing: if a race and a resulting deadlock is possible 243 theoretically (no matter how unlikely the race scenario 244 is), it will be proven so and will immediately be 245 reported by the kernel (once the event is observed that 246 makes the deadlock theoretically possible). 247 248 If a deadlock is impossible (i.e. the locking rules, as 249 observed by the kernel, are mathematically correct), the 250 kernel reports nothing. 251 252 NOTE: this feature can also be enabled for rwlocks, mutexes 253 and rwsems - in which case all dependencies between these 254 different locking variants are observed and mapped too, and 255 the proof of observed correctness is also maintained for an 256 arbitrary combination of these separate locking variants. 257 258 For more details, see Documentation/lockdep-design.txt. 259 260config LOCKDEP 261 bool 262 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 263 select STACKTRACE 264 select FRAME_POINTER if !X86 && !MIPS 265 select KALLSYMS 266 select KALLSYMS_ALL 267 268config DEBUG_LOCKDEP 269 bool "Lock dependency engine debugging" 270 depends on DEBUG_KERNEL && LOCKDEP 271 help 272 If you say Y here, the lock dependency engine will do 273 additional runtime checks to debug itself, at the price 274 of more runtime overhead. 275 276config TRACE_IRQFLAGS 277 depends on DEBUG_KERNEL 278 bool 279 default y 280 depends on TRACE_IRQFLAGS_SUPPORT 281 depends on PROVE_LOCKING 282 283config DEBUG_SPINLOCK_SLEEP 284 bool "Spinlock debugging: sleep-inside-spinlock checking" 285 depends on DEBUG_KERNEL 286 help 287 If you say Y here, various routines which may sleep will become very 288 noisy if they are called with a spinlock held. 289 290config DEBUG_LOCKING_API_SELFTESTS 291 bool "Locking API boot-time self-tests" 292 depends on DEBUG_KERNEL 293 help 294 Say Y here if you want the kernel to run a short self-test during 295 bootup. The self-test checks whether common types of locking bugs 296 are detected by debugging mechanisms or not. (if you disable 297 lock debugging then those bugs wont be detected of course.) 298 The following locking APIs are covered: spinlocks, rwlocks, 299 mutexes and rwsems. 300 301config STACKTRACE 302 bool 303 depends on DEBUG_KERNEL 304 depends on STACKTRACE_SUPPORT 305 306config DEBUG_KOBJECT 307 bool "kobject debugging" 308 depends on DEBUG_KERNEL 309 help 310 If you say Y here, some extra kobject debugging messages will be sent 311 to the syslog. 312 313config DEBUG_HIGHMEM 314 bool "Highmem debugging" 315 depends on DEBUG_KERNEL && HIGHMEM 316 help 317 This options enables addition error checking for high memory systems. 318 Disable for production systems. 319 320config DEBUG_BUGVERBOSE 321 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 322 depends on BUG 323 depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BFIN 324 default !EMBEDDED 325 help 326 Say Y here to make BUG() panics output the file name and line number 327 of the BUG call as well as the EIP and oops trace. This aids 328 debugging but costs about 70-100K of memory. 329 330config DEBUG_INFO 331 bool "Compile the kernel with debug info" 332 depends on DEBUG_KERNEL 333 help 334 If you say Y here the resulting kernel image will include 335 debugging info resulting in a larger kernel image. 336 This adds debug symbols to the kernel and modules (gcc -g), and 337 is needed if you intend to use kernel crashdump or binary object 338 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 339 Say Y here only if you plan to debug the kernel. 340 341 If unsure, say N. 342 343config DEBUG_VM 344 bool "Debug VM" 345 depends on DEBUG_KERNEL 346 help 347 Enable this to turn on extended checks in the virtual-memory system 348 that may impact performance. 349 350 If unsure, say N. 351 352config DEBUG_LIST 353 bool "Debug linked list manipulation" 354 depends on DEBUG_KERNEL 355 help 356 Enable this to turn on extended checks in the linked-list 357 walking routines. 358 359 If unsure, say N. 360 361config FRAME_POINTER 362 bool "Compile the kernel with frame pointers" 363 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN) 364 default y if DEBUG_INFO && UML 365 help 366 If you say Y here the resulting kernel image will be slightly larger 367 and slower, but it might give very useful debugging information on 368 some architectures or if you use external debuggers. 369 If you don't debug the kernel, you can say N. 370 371config FORCED_INLINING 372 bool "Force gcc to inline functions marked 'inline'" 373 depends on DEBUG_KERNEL 374 default y 375 help 376 This option determines if the kernel forces gcc to inline the functions 377 developers have marked 'inline'. Doing so takes away freedom from gcc to 378 do what it thinks is best, which is desirable for the gcc 3.x series of 379 compilers. The gcc 4.x series have a rewritten inlining algorithm and 380 disabling this option will generate a smaller kernel there. Hopefully 381 this algorithm is so good that allowing gcc4 to make the decision can 382 become the default in the future, until then this option is there to 383 test gcc for this. 384 385config RCU_TORTURE_TEST 386 tristate "torture tests for RCU" 387 depends on DEBUG_KERNEL 388 default n 389 help 390 This option provides a kernel module that runs torture tests 391 on the RCU infrastructure. The kernel module may be built 392 after the fact on the running kernel to be tested, if desired. 393 394 Say Y here if you want RCU torture tests to start automatically 395 at boot time (you probably don't). 396 Say M if you want the RCU torture tests to build as a module. 397 Say N if you are unsure. 398 399config LKDTM 400 tristate "Linux Kernel Dump Test Tool Module" 401 depends on DEBUG_KERNEL 402 depends on KPROBES 403 default n 404 help 405 This module enables testing of the different dumping mechanisms by 406 inducing system failures at predefined crash points. 407 If you don't need it: say N 408 Choose M here to compile this code as a module. The module will be 409 called lkdtm. 410 411 Documentation on how to use the module can be found in 412 drivers/misc/lkdtm.c 413 414config FAULT_INJECTION 415 bool "Fault-injection framework" 416 depends on DEBUG_KERNEL 417 help 418 Provide fault-injection framework. 419 For more details, see Documentation/fault-injection/. 420 421config FAILSLAB 422 bool "Fault-injection capability for kmalloc" 423 depends on FAULT_INJECTION 424 help 425 Provide fault-injection capability for kmalloc. 426 427config FAIL_PAGE_ALLOC 428 bool "Fault-injection capabilitiy for alloc_pages()" 429 depends on FAULT_INJECTION 430 help 431 Provide fault-injection capability for alloc_pages(). 432 433config FAIL_MAKE_REQUEST 434 bool "Fault-injection capability for disk IO" 435 depends on FAULT_INJECTION 436 help 437 Provide fault-injection capability for disk IO. 438 439config FAULT_INJECTION_DEBUG_FS 440 bool "Debugfs entries for fault-injection capabilities" 441 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 442 help 443 Enable configuration of fault-injection capabilities via debugfs. 444 445config FAULT_INJECTION_STACKTRACE_FILTER 446 bool "stacktrace filter for fault-injection capabilities" 447 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 448 select STACKTRACE 449 select FRAME_POINTER 450 help 451 Provide stacktrace filter for fault-injection capabilities 452