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