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1da177e4 LT |
1 | |
2 | config PRINTK_TIME | |
3 | bool "Show timing information on printks" | |
d3b8b6e5 | 4 | depends on PRINTK |
1da177e4 LT |
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 | ||
cebc04ba AM |
12 | config 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. | |
1da177e4 | 19 | |
1da177e4 LT |
20 | config MAGIC_SYSRQ |
21 | bool "Magic SysRq key" | |
f346f4b3 | 22 | depends on !UML |
1da177e4 LT |
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 | ||
f71d20e9 AV |
34 | config 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 | ||
bf4735a4 DM |
50 | config 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 | ||
60 | config 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 | ||
f346f4b3 AB |
74 | config 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 | ||
a304e1b8 DW |
80 | config 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 | ||
8446f1d3 IM |
89 | config DETECT_SOFTLOCKUP |
90 | bool "Detect Soft Lockups" | |
dea20a3f | 91 | depends on DEBUG_KERNEL && !S390 |
8446f1d3 IM |
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 | ||
b642b6d3 IM |
108 | config SCHED_DEBUG |
109 | bool "Collect scheduler debugging info" | |
110 | depends on DEBUG_KERNEL && PROC_FS | |
111 | default y | |
112 | help | |
113 | If you say Y here, the /proc/sched_debug file will be provided | |
114 | that can help debug the scheduler. The runtime overhead of this | |
115 | option is minimal. | |
116 | ||
1da177e4 LT |
117 | config SCHEDSTATS |
118 | bool "Collect scheduler statistics" | |
119 | depends on DEBUG_KERNEL && PROC_FS | |
120 | help | |
121 | If you say Y here, additional code will be inserted into the | |
122 | scheduler and related routines to collect statistics about | |
123 | scheduler behavior and provide them in /proc/schedstat. These | |
124 | stats may be useful for both tuning and debugging the scheduler | |
125 | If you aren't debugging the scheduler or trying to tune a specific | |
126 | application, you can say N to avoid the very slight overhead | |
127 | this adds. | |
128 | ||
82f67cd9 IM |
129 | config TIMER_STATS |
130 | bool "Collect kernel timers statistics" | |
131 | depends on DEBUG_KERNEL && PROC_FS | |
132 | help | |
133 | If you say Y here, additional code will be inserted into the | |
134 | timer routines to collect statistics about kernel timers being | |
135 | reprogrammed. The statistics can be read from /proc/timer_stats. | |
136 | The statistics collection is started by writing 1 to /proc/timer_stats, | |
137 | writing 0 stops it. This feature is useful to collect information | |
c1a834dc IM |
138 | about timer usage patterns in kernel and userspace. This feature |
139 | is lightweight if enabled in the kernel config but not activated | |
140 | (it defaults to deactivated on bootup and will only be activated | |
141 | if some application like powertop activates it explicitly). | |
82f67cd9 | 142 | |
1da177e4 | 143 | config DEBUG_SLAB |
4a2f0acf | 144 | bool "Debug slab memory allocations" |
50dd26ba | 145 | depends on DEBUG_KERNEL && SLAB |
1da177e4 LT |
146 | help |
147 | Say Y here to have the kernel do limited verification on memory | |
148 | allocation as well as poisoning memory on free to catch use of freed | |
149 | memory. This can make kmalloc/kfree-intensive workloads much slower. | |
150 | ||
871751e2 AV |
151 | config DEBUG_SLAB_LEAK |
152 | bool "Memory leak debugging" | |
153 | depends on DEBUG_SLAB | |
154 | ||
1da177e4 LT |
155 | config DEBUG_PREEMPT |
156 | bool "Debug preemptible kernel" | |
8637c099 | 157 | depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT |
1da177e4 LT |
158 | default y |
159 | help | |
160 | If you say Y here then the kernel will use a debug variant of the | |
161 | commonly used smp_processor_id() function and will print warnings | |
162 | if kernel code uses it in a preemption-unsafe way. Also, the kernel | |
163 | will detect preemption count underflows. | |
164 | ||
e7eebaf6 IM |
165 | config DEBUG_RT_MUTEXES |
166 | bool "RT Mutex debugging, deadlock detection" | |
e7eebaf6 IM |
167 | depends on DEBUG_KERNEL && RT_MUTEXES |
168 | help | |
169 | This allows rt mutex semantics violations and rt mutex related | |
170 | deadlocks (lockups) to be detected and reported automatically. | |
171 | ||
172 | config DEBUG_PI_LIST | |
173 | bool | |
174 | default y | |
175 | depends on DEBUG_RT_MUTEXES | |
176 | ||
61a87122 TG |
177 | config RT_MUTEX_TESTER |
178 | bool "Built-in scriptable tester for rt-mutexes" | |
a1583d3e | 179 | depends on DEBUG_KERNEL && RT_MUTEXES |
61a87122 TG |
180 | help |
181 | This option enables a rt-mutex tester. | |
182 | ||
1da177e4 | 183 | config DEBUG_SPINLOCK |
4d9f34ad | 184 | bool "Spinlock and rw-lock debugging: basic checks" |
1da177e4 LT |
185 | depends on DEBUG_KERNEL |
186 | help | |
187 | Say Y here and build SMP to catch missing spinlock initialization | |
188 | and certain other kinds of spinlock errors commonly made. This is | |
189 | best used in conjunction with the NMI watchdog so that spinlock | |
190 | deadlocks are also debuggable. | |
191 | ||
4d9f34ad IM |
192 | config DEBUG_MUTEXES |
193 | bool "Mutex debugging: basic checks" | |
194 | depends on DEBUG_KERNEL | |
195 | help | |
196 | This feature allows mutex semantics violations to be detected and | |
197 | reported. | |
198 | ||
c761c841 RD |
199 | config DEBUG_SEMAPHORE |
200 | bool "Semaphore debugging" | |
201 | depends on DEBUG_KERNEL | |
202 | depends on ALPHA || FRV | |
203 | default n | |
204 | help | |
205 | If you say Y here then semaphore processing will issue lots of | |
206 | verbose debugging messages. If you suspect a semaphore problem or a | |
207 | kernel hacker asks for this option then say Y. Otherwise say N. | |
208 | ||
4d9f34ad IM |
209 | config DEBUG_LOCK_ALLOC |
210 | bool "Lock debugging: detect incorrect freeing of live locks" | |
517e7aa5 | 211 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
212 | select DEBUG_SPINLOCK |
213 | select DEBUG_MUTEXES | |
4d9f34ad IM |
214 | select LOCKDEP |
215 | help | |
216 | This feature will check whether any held lock (spinlock, rwlock, | |
217 | mutex or rwsem) is incorrectly freed by the kernel, via any of the | |
218 | memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), | |
219 | vfree(), etc.), whether a live lock is incorrectly reinitialized via | |
220 | spin_lock_init()/mutex_init()/etc., or whether there is any lock | |
221 | held during task exit. | |
222 | ||
223 | config PROVE_LOCKING | |
224 | bool "Lock debugging: prove locking correctness" | |
517e7aa5 | 225 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
226 | select LOCKDEP |
227 | select DEBUG_SPINLOCK | |
228 | select DEBUG_MUTEXES | |
4d9f34ad IM |
229 | select DEBUG_LOCK_ALLOC |
230 | default n | |
231 | help | |
232 | This feature enables the kernel to prove that all locking | |
233 | that occurs in the kernel runtime is mathematically | |
234 | correct: that under no circumstance could an arbitrary (and | |
235 | not yet triggered) combination of observed locking | |
236 | sequences (on an arbitrary number of CPUs, running an | |
237 | arbitrary number of tasks and interrupt contexts) cause a | |
238 | deadlock. | |
239 | ||
240 | In short, this feature enables the kernel to report locking | |
241 | related deadlocks before they actually occur. | |
242 | ||
243 | The proof does not depend on how hard and complex a | |
244 | deadlock scenario would be to trigger: how many | |
245 | participant CPUs, tasks and irq-contexts would be needed | |
246 | for it to trigger. The proof also does not depend on | |
247 | timing: if a race and a resulting deadlock is possible | |
248 | theoretically (no matter how unlikely the race scenario | |
249 | is), it will be proven so and will immediately be | |
250 | reported by the kernel (once the event is observed that | |
251 | makes the deadlock theoretically possible). | |
252 | ||
253 | If a deadlock is impossible (i.e. the locking rules, as | |
254 | observed by the kernel, are mathematically correct), the | |
255 | kernel reports nothing. | |
256 | ||
257 | NOTE: this feature can also be enabled for rwlocks, mutexes | |
258 | and rwsems - in which case all dependencies between these | |
259 | different locking variants are observed and mapped too, and | |
260 | the proof of observed correctness is also maintained for an | |
261 | arbitrary combination of these separate locking variants. | |
262 | ||
263 | For more details, see Documentation/lockdep-design.txt. | |
264 | ||
265 | config LOCKDEP | |
266 | bool | |
517e7aa5 | 267 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad | 268 | select STACKTRACE |
14cf232a | 269 | select FRAME_POINTER if !X86 && !MIPS |
4d9f34ad IM |
270 | select KALLSYMS |
271 | select KALLSYMS_ALL | |
272 | ||
273 | config DEBUG_LOCKDEP | |
274 | bool "Lock dependency engine debugging" | |
517e7aa5 | 275 | depends on DEBUG_KERNEL && LOCKDEP |
4d9f34ad IM |
276 | help |
277 | If you say Y here, the lock dependency engine will do | |
278 | additional runtime checks to debug itself, at the price | |
279 | of more runtime overhead. | |
280 | ||
281 | config TRACE_IRQFLAGS | |
517e7aa5 | 282 | depends on DEBUG_KERNEL |
4d9f34ad IM |
283 | bool |
284 | default y | |
285 | depends on TRACE_IRQFLAGS_SUPPORT | |
286 | depends on PROVE_LOCKING | |
287 | ||
1da177e4 | 288 | config DEBUG_SPINLOCK_SLEEP |
4d9f34ad | 289 | bool "Spinlock debugging: sleep-inside-spinlock checking" |
1da177e4 LT |
290 | depends on DEBUG_KERNEL |
291 | help | |
292 | If you say Y here, various routines which may sleep will become very | |
293 | noisy if they are called with a spinlock held. | |
294 | ||
cae2ed9a IM |
295 | config DEBUG_LOCKING_API_SELFTESTS |
296 | bool "Locking API boot-time self-tests" | |
297 | depends on DEBUG_KERNEL | |
298 | help | |
299 | Say Y here if you want the kernel to run a short self-test during | |
300 | bootup. The self-test checks whether common types of locking bugs | |
301 | are detected by debugging mechanisms or not. (if you disable | |
302 | lock debugging then those bugs wont be detected of course.) | |
303 | The following locking APIs are covered: spinlocks, rwlocks, | |
304 | mutexes and rwsems. | |
305 | ||
8637c099 IM |
306 | config STACKTRACE |
307 | bool | |
517e7aa5 | 308 | depends on DEBUG_KERNEL |
8637c099 IM |
309 | depends on STACKTRACE_SUPPORT |
310 | ||
1da177e4 LT |
311 | config DEBUG_KOBJECT |
312 | bool "kobject debugging" | |
313 | depends on DEBUG_KERNEL | |
314 | help | |
315 | If you say Y here, some extra kobject debugging messages will be sent | |
316 | to the syslog. | |
317 | ||
318 | config DEBUG_HIGHMEM | |
319 | bool "Highmem debugging" | |
320 | depends on DEBUG_KERNEL && HIGHMEM | |
321 | help | |
322 | This options enables addition error checking for high memory systems. | |
323 | Disable for production systems. | |
324 | ||
325 | config DEBUG_BUGVERBOSE | |
326 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED | |
c8538a7a | 327 | depends on BUG |
1394f032 | 328 | depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BFIN |
1da177e4 LT |
329 | default !EMBEDDED |
330 | help | |
331 | Say Y here to make BUG() panics output the file name and line number | |
332 | of the BUG call as well as the EIP and oops trace. This aids | |
333 | debugging but costs about 70-100K of memory. | |
334 | ||
335 | config DEBUG_INFO | |
336 | bool "Compile the kernel with debug info" | |
337 | depends on DEBUG_KERNEL | |
338 | help | |
339 | If you say Y here the resulting kernel image will include | |
340 | debugging info resulting in a larger kernel image. | |
b72e53f8 AD |
341 | This adds debug symbols to the kernel and modules (gcc -g), and |
342 | is needed if you intend to use kernel crashdump or binary object | |
343 | tools like crash, kgdb, LKCD, gdb, etc on the kernel. | |
1da177e4 LT |
344 | Say Y here only if you plan to debug the kernel. |
345 | ||
346 | If unsure, say N. | |
347 | ||
a241ec65 PM |
348 | config DEBUG_VM |
349 | bool "Debug VM" | |
350 | depends on DEBUG_KERNEL | |
351 | help | |
13e7444b NP |
352 | Enable this to turn on extended checks in the virtual-memory system |
353 | that may impact performance. | |
a241ec65 PM |
354 | |
355 | If unsure, say N. | |
356 | ||
199a9afc DJ |
357 | config DEBUG_LIST |
358 | bool "Debug linked list manipulation" | |
359 | depends on DEBUG_KERNEL | |
360 | help | |
361 | Enable this to turn on extended checks in the linked-list | |
362 | walking routines. | |
363 | ||
364 | If unsure, say N. | |
365 | ||
1da177e4 LT |
366 | config FRAME_POINTER |
367 | bool "Compile the kernel with frame pointers" | |
1394f032 | 368 | depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN) |
37fce857 | 369 | default y if DEBUG_INFO && UML |
1da177e4 LT |
370 | help |
371 | If you say Y here the resulting kernel image will be slightly larger | |
2a38bccd JJ |
372 | and slower, but it might give very useful debugging information on |
373 | some architectures or if you use external debuggers. | |
aeb39986 | 374 | If you don't debug the kernel, you can say N. |
1da177e4 | 375 | |
a9df3d0f IM |
376 | config FORCED_INLINING |
377 | bool "Force gcc to inline functions marked 'inline'" | |
378 | depends on DEBUG_KERNEL | |
379 | default y | |
380 | help | |
381 | This option determines if the kernel forces gcc to inline the functions | |
382 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
383 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
384 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
385 | disabling this option will generate a smaller kernel there. Hopefully | |
386 | this algorithm is so good that allowing gcc4 to make the decision can | |
387 | become the default in the future, until then this option is there to | |
388 | test gcc for this. | |
389 | ||
a241ec65 PM |
390 | config RCU_TORTURE_TEST |
391 | tristate "torture tests for RCU" | |
392 | depends on DEBUG_KERNEL | |
9aaffc89 | 393 | depends on m |
a241ec65 PM |
394 | default n |
395 | help | |
396 | This option provides a kernel module that runs torture tests | |
397 | on the RCU infrastructure. The kernel module may be built | |
398 | after the fact on the running kernel to be tested, if desired. | |
399 | ||
a241ec65 PM |
400 | Say M if you want the RCU torture tests to build as a module. |
401 | Say N if you are unsure. | |
8bb31b9d AG |
402 | |
403 | config LKDTM | |
404 | tristate "Linux Kernel Dump Test Tool Module" | |
bf4735a4 | 405 | depends on DEBUG_KERNEL |
8bb31b9d AG |
406 | depends on KPROBES |
407 | default n | |
408 | help | |
409 | This module enables testing of the different dumping mechanisms by | |
410 | inducing system failures at predefined crash points. | |
411 | If you don't need it: say N | |
412 | Choose M here to compile this code as a module. The module will be | |
413 | called lkdtm. | |
414 | ||
415 | Documentation on how to use the module can be found in | |
416 | drivers/misc/lkdtm.c | |
6ff1cb35 AM |
417 | |
418 | config FAULT_INJECTION | |
1ab8509a AM |
419 | bool "Fault-injection framework" |
420 | depends on DEBUG_KERNEL | |
329409ae AM |
421 | help |
422 | Provide fault-injection framework. | |
423 | For more details, see Documentation/fault-injection/. | |
6ff1cb35 | 424 | |
8a8b6502 | 425 | config FAILSLAB |
1ab8509a AM |
426 | bool "Fault-injection capability for kmalloc" |
427 | depends on FAULT_INJECTION | |
8a8b6502 | 428 | help |
1ab8509a | 429 | Provide fault-injection capability for kmalloc. |
8a8b6502 | 430 | |
933e312e AM |
431 | config FAIL_PAGE_ALLOC |
432 | bool "Fault-injection capabilitiy for alloc_pages()" | |
1ab8509a | 433 | depends on FAULT_INJECTION |
933e312e | 434 | help |
1ab8509a | 435 | Provide fault-injection capability for alloc_pages(). |
933e312e | 436 | |
c17bb495 | 437 | config FAIL_MAKE_REQUEST |
86327d19 | 438 | bool "Fault-injection capability for disk IO" |
1ab8509a | 439 | depends on FAULT_INJECTION |
c17bb495 | 440 | help |
1ab8509a | 441 | Provide fault-injection capability for disk IO. |
c17bb495 | 442 | |
6ff1cb35 AM |
443 | config FAULT_INJECTION_DEBUG_FS |
444 | bool "Debugfs entries for fault-injection capabilities" | |
1ab8509a | 445 | depends on FAULT_INJECTION && SYSFS && DEBUG_FS |
6ff1cb35 | 446 | help |
1ab8509a | 447 | Enable configuration of fault-injection capabilities via debugfs. |
1df49008 AM |
448 | |
449 | config FAULT_INJECTION_STACKTRACE_FILTER | |
450 | bool "stacktrace filter for fault-injection capabilities" | |
451 | depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT | |
6d690dca | 452 | depends on !X86_64 |
1df49008 AM |
453 | select STACKTRACE |
454 | select FRAME_POINTER | |
455 | help | |
456 | Provide stacktrace filter for fault-injection capabilities |