Commit | Line | Data |
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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 | ||
f346f4b3 AB |
50 | config DEBUG_KERNEL |
51 | bool "Kernel debugging" | |
52 | help | |
53 | Say Y here if you are developing drivers or trying to debug and | |
54 | identify kernel problems. | |
55 | ||
1da177e4 LT |
56 | config LOG_BUF_SHIFT |
57 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL | |
58 | range 12 21 | |
fbb9ce95 | 59 | default 17 if S390 || LOCKDEP |
1da177e4 LT |
60 | default 16 if X86_NUMAQ || IA64 |
61 | default 15 if SMP | |
62 | default 14 | |
63 | help | |
64 | Select kernel log buffer size as a power of 2. | |
65 | Defaults and Examples: | |
66 | 17 => 128 KB for S/390 | |
67 | 16 => 64 KB for x86 NUMAQ or IA-64 | |
68 | 15 => 32 KB for SMP | |
69 | 14 => 16 KB for uniprocessor | |
70 | 13 => 8 KB | |
71 | 12 => 4 KB | |
72 | ||
8446f1d3 IM |
73 | config DETECT_SOFTLOCKUP |
74 | bool "Detect Soft Lockups" | |
dea20a3f | 75 | depends on DEBUG_KERNEL && !S390 |
8446f1d3 IM |
76 | default y |
77 | help | |
78 | Say Y here to enable the kernel to detect "soft lockups", | |
79 | which are bugs that cause the kernel to loop in kernel | |
80 | mode for more than 10 seconds, without giving other tasks a | |
81 | chance to run. | |
82 | ||
83 | When a soft-lockup is detected, the kernel will print the | |
84 | current stack trace (which you should report), but the | |
85 | system will stay locked up. This feature has negligible | |
86 | overhead. | |
87 | ||
88 | (Note that "hard lockups" are separate type of bugs that | |
89 | can be detected via the NMI-watchdog, on platforms that | |
90 | support it.) | |
91 | ||
1da177e4 LT |
92 | config SCHEDSTATS |
93 | bool "Collect scheduler statistics" | |
94 | depends on DEBUG_KERNEL && PROC_FS | |
95 | help | |
96 | If you say Y here, additional code will be inserted into the | |
97 | scheduler and related routines to collect statistics about | |
98 | scheduler behavior and provide them in /proc/schedstat. These | |
99 | stats may be useful for both tuning and debugging the scheduler | |
100 | If you aren't debugging the scheduler or trying to tune a specific | |
101 | application, you can say N to avoid the very slight overhead | |
102 | this adds. | |
103 | ||
104 | config DEBUG_SLAB | |
4a2f0acf | 105 | bool "Debug slab memory allocations" |
50dd26ba | 106 | depends on DEBUG_KERNEL && SLAB |
1da177e4 LT |
107 | help |
108 | Say Y here to have the kernel do limited verification on memory | |
109 | allocation as well as poisoning memory on free to catch use of freed | |
110 | memory. This can make kmalloc/kfree-intensive workloads much slower. | |
111 | ||
871751e2 AV |
112 | config DEBUG_SLAB_LEAK |
113 | bool "Memory leak debugging" | |
114 | depends on DEBUG_SLAB | |
115 | ||
1da177e4 LT |
116 | config DEBUG_PREEMPT |
117 | bool "Debug preemptible kernel" | |
8637c099 | 118 | depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT |
1da177e4 LT |
119 | default y |
120 | help | |
121 | If you say Y here then the kernel will use a debug variant of the | |
122 | commonly used smp_processor_id() function and will print warnings | |
123 | if kernel code uses it in a preemption-unsafe way. Also, the kernel | |
124 | will detect preemption count underflows. | |
125 | ||
e7eebaf6 IM |
126 | config DEBUG_RT_MUTEXES |
127 | bool "RT Mutex debugging, deadlock detection" | |
e7eebaf6 IM |
128 | depends on DEBUG_KERNEL && RT_MUTEXES |
129 | help | |
130 | This allows rt mutex semantics violations and rt mutex related | |
131 | deadlocks (lockups) to be detected and reported automatically. | |
132 | ||
133 | config DEBUG_PI_LIST | |
134 | bool | |
135 | default y | |
136 | depends on DEBUG_RT_MUTEXES | |
137 | ||
61a87122 TG |
138 | config RT_MUTEX_TESTER |
139 | bool "Built-in scriptable tester for rt-mutexes" | |
a1583d3e | 140 | depends on DEBUG_KERNEL && RT_MUTEXES |
61a87122 TG |
141 | help |
142 | This option enables a rt-mutex tester. | |
143 | ||
1da177e4 | 144 | config DEBUG_SPINLOCK |
4d9f34ad | 145 | bool "Spinlock and rw-lock debugging: basic checks" |
1da177e4 LT |
146 | depends on DEBUG_KERNEL |
147 | help | |
148 | Say Y here and build SMP to catch missing spinlock initialization | |
149 | and certain other kinds of spinlock errors commonly made. This is | |
150 | best used in conjunction with the NMI watchdog so that spinlock | |
151 | deadlocks are also debuggable. | |
152 | ||
4d9f34ad IM |
153 | config DEBUG_MUTEXES |
154 | bool "Mutex debugging: basic checks" | |
155 | depends on DEBUG_KERNEL | |
156 | help | |
157 | This feature allows mutex semantics violations to be detected and | |
158 | reported. | |
159 | ||
160 | config DEBUG_RWSEMS | |
161 | bool "RW-sem debugging: basic checks" | |
162 | depends on DEBUG_KERNEL | |
163 | help | |
164 | This feature allows read-write semaphore semantics violations to | |
165 | be detected and reported. | |
166 | ||
167 | config DEBUG_LOCK_ALLOC | |
168 | bool "Lock debugging: detect incorrect freeing of live locks" | |
517e7aa5 | 169 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
170 | select DEBUG_SPINLOCK |
171 | select DEBUG_MUTEXES | |
172 | select DEBUG_RWSEMS | |
173 | select LOCKDEP | |
174 | help | |
175 | This feature will check whether any held lock (spinlock, rwlock, | |
176 | mutex or rwsem) is incorrectly freed by the kernel, via any of the | |
177 | memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), | |
178 | vfree(), etc.), whether a live lock is incorrectly reinitialized via | |
179 | spin_lock_init()/mutex_init()/etc., or whether there is any lock | |
180 | held during task exit. | |
181 | ||
182 | config PROVE_LOCKING | |
183 | bool "Lock debugging: prove locking correctness" | |
517e7aa5 | 184 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
185 | select LOCKDEP |
186 | select DEBUG_SPINLOCK | |
187 | select DEBUG_MUTEXES | |
188 | select DEBUG_RWSEMS | |
189 | select DEBUG_LOCK_ALLOC | |
190 | default n | |
191 | help | |
192 | This feature enables the kernel to prove that all locking | |
193 | that occurs in the kernel runtime is mathematically | |
194 | correct: that under no circumstance could an arbitrary (and | |
195 | not yet triggered) combination of observed locking | |
196 | sequences (on an arbitrary number of CPUs, running an | |
197 | arbitrary number of tasks and interrupt contexts) cause a | |
198 | deadlock. | |
199 | ||
200 | In short, this feature enables the kernel to report locking | |
201 | related deadlocks before they actually occur. | |
202 | ||
203 | The proof does not depend on how hard and complex a | |
204 | deadlock scenario would be to trigger: how many | |
205 | participant CPUs, tasks and irq-contexts would be needed | |
206 | for it to trigger. The proof also does not depend on | |
207 | timing: if a race and a resulting deadlock is possible | |
208 | theoretically (no matter how unlikely the race scenario | |
209 | is), it will be proven so and will immediately be | |
210 | reported by the kernel (once the event is observed that | |
211 | makes the deadlock theoretically possible). | |
212 | ||
213 | If a deadlock is impossible (i.e. the locking rules, as | |
214 | observed by the kernel, are mathematically correct), the | |
215 | kernel reports nothing. | |
216 | ||
217 | NOTE: this feature can also be enabled for rwlocks, mutexes | |
218 | and rwsems - in which case all dependencies between these | |
219 | different locking variants are observed and mapped too, and | |
220 | the proof of observed correctness is also maintained for an | |
221 | arbitrary combination of these separate locking variants. | |
222 | ||
223 | For more details, see Documentation/lockdep-design.txt. | |
224 | ||
225 | config LOCKDEP | |
226 | bool | |
517e7aa5 | 227 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad | 228 | select STACKTRACE |
3b8d1fe0 | 229 | select FRAME_POINTER if !X86 |
4d9f34ad IM |
230 | select KALLSYMS |
231 | select KALLSYMS_ALL | |
232 | ||
233 | config DEBUG_LOCKDEP | |
234 | bool "Lock dependency engine debugging" | |
517e7aa5 | 235 | depends on DEBUG_KERNEL && LOCKDEP |
4d9f34ad IM |
236 | help |
237 | If you say Y here, the lock dependency engine will do | |
238 | additional runtime checks to debug itself, at the price | |
239 | of more runtime overhead. | |
240 | ||
241 | config TRACE_IRQFLAGS | |
517e7aa5 | 242 | depends on DEBUG_KERNEL |
4d9f34ad IM |
243 | bool |
244 | default y | |
245 | depends on TRACE_IRQFLAGS_SUPPORT | |
246 | depends on PROVE_LOCKING | |
247 | ||
1da177e4 | 248 | config DEBUG_SPINLOCK_SLEEP |
4d9f34ad | 249 | bool "Spinlock debugging: sleep-inside-spinlock checking" |
1da177e4 LT |
250 | depends on DEBUG_KERNEL |
251 | help | |
252 | If you say Y here, various routines which may sleep will become very | |
253 | noisy if they are called with a spinlock held. | |
254 | ||
cae2ed9a IM |
255 | config DEBUG_LOCKING_API_SELFTESTS |
256 | bool "Locking API boot-time self-tests" | |
257 | depends on DEBUG_KERNEL | |
258 | help | |
259 | Say Y here if you want the kernel to run a short self-test during | |
260 | bootup. The self-test checks whether common types of locking bugs | |
261 | are detected by debugging mechanisms or not. (if you disable | |
262 | lock debugging then those bugs wont be detected of course.) | |
263 | The following locking APIs are covered: spinlocks, rwlocks, | |
264 | mutexes and rwsems. | |
265 | ||
8637c099 IM |
266 | config STACKTRACE |
267 | bool | |
517e7aa5 | 268 | depends on DEBUG_KERNEL |
8637c099 IM |
269 | depends on STACKTRACE_SUPPORT |
270 | ||
1da177e4 LT |
271 | config DEBUG_KOBJECT |
272 | bool "kobject debugging" | |
273 | depends on DEBUG_KERNEL | |
274 | help | |
275 | If you say Y here, some extra kobject debugging messages will be sent | |
276 | to the syslog. | |
277 | ||
278 | config DEBUG_HIGHMEM | |
279 | bool "Highmem debugging" | |
280 | depends on DEBUG_KERNEL && HIGHMEM | |
281 | help | |
282 | This options enables addition error checking for high memory systems. | |
283 | Disable for production systems. | |
284 | ||
285 | config DEBUG_BUGVERBOSE | |
286 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED | |
c8538a7a | 287 | depends on BUG |
91768d6c | 288 | depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG |
1da177e4 LT |
289 | default !EMBEDDED |
290 | help | |
291 | Say Y here to make BUG() panics output the file name and line number | |
292 | of the BUG call as well as the EIP and oops trace. This aids | |
293 | debugging but costs about 70-100K of memory. | |
294 | ||
295 | config DEBUG_INFO | |
296 | bool "Compile the kernel with debug info" | |
297 | depends on DEBUG_KERNEL | |
298 | help | |
299 | If you say Y here the resulting kernel image will include | |
300 | debugging info resulting in a larger kernel image. | |
301 | Say Y here only if you plan to debug the kernel. | |
302 | ||
303 | If unsure, say N. | |
304 | ||
1da177e4 LT |
305 | config DEBUG_FS |
306 | bool "Debug Filesystem" | |
ae36b883 | 307 | depends on SYSFS |
1da177e4 LT |
308 | help |
309 | debugfs is a virtual file system that kernel developers use to put | |
310 | debugging files into. Enable this option to be able to read and | |
311 | write to these files. | |
312 | ||
313 | If unsure, say N. | |
314 | ||
a241ec65 PM |
315 | config DEBUG_VM |
316 | bool "Debug VM" | |
317 | depends on DEBUG_KERNEL | |
318 | help | |
13e7444b NP |
319 | Enable this to turn on extended checks in the virtual-memory system |
320 | that may impact performance. | |
a241ec65 PM |
321 | |
322 | If unsure, say N. | |
323 | ||
199a9afc DJ |
324 | config DEBUG_LIST |
325 | bool "Debug linked list manipulation" | |
326 | depends on DEBUG_KERNEL | |
327 | help | |
328 | Enable this to turn on extended checks in the linked-list | |
329 | walking routines. | |
330 | ||
331 | If unsure, say N. | |
332 | ||
1da177e4 LT |
333 | config FRAME_POINTER |
334 | bool "Compile the kernel with frame pointers" | |
2549b322 | 335 | depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH) |
37fce857 | 336 | default y if DEBUG_INFO && UML |
1da177e4 LT |
337 | help |
338 | If you say Y here the resulting kernel image will be slightly larger | |
2a38bccd JJ |
339 | and slower, but it might give very useful debugging information on |
340 | some architectures or if you use external debuggers. | |
aeb39986 | 341 | If you don't debug the kernel, you can say N. |
1da177e4 | 342 | |
604bf5a2 JB |
343 | config UNWIND_INFO |
344 | bool "Compile the kernel with frame unwind information" | |
75e31aaa | 345 | depends on !IA64 && !PARISC && !ARM |
4552d5dc | 346 | depends on !MODULES || !(MIPS || PPC || SUPERH || V850) |
604bf5a2 JB |
347 | help |
348 | If you say Y here the resulting kernel image will be slightly larger | |
349 | but not slower, and it will give very useful debugging information. | |
350 | If you don't debug the kernel, you can say N, but we may not be able | |
351 | to solve problems without frame unwind information or frame pointers. | |
352 | ||
4552d5dc JB |
353 | config STACK_UNWIND |
354 | bool "Stack unwind support" | |
355 | depends on UNWIND_INFO | |
176a2718 | 356 | depends on X86 |
4552d5dc JB |
357 | help |
358 | This enables more precise stack traces, omitting all unrelated | |
359 | occurrences of pointers into kernel code from the dump. | |
360 | ||
a9df3d0f IM |
361 | config FORCED_INLINING |
362 | bool "Force gcc to inline functions marked 'inline'" | |
363 | depends on DEBUG_KERNEL | |
364 | default y | |
365 | help | |
366 | This option determines if the kernel forces gcc to inline the functions | |
367 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
368 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
369 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
370 | disabling this option will generate a smaller kernel there. Hopefully | |
371 | this algorithm is so good that allowing gcc4 to make the decision can | |
372 | become the default in the future, until then this option is there to | |
373 | test gcc for this. | |
374 | ||
0f836e5f DW |
375 | config HEADERS_CHECK |
376 | bool "Run 'make headers_check' when building vmlinux" | |
1b95817d | 377 | depends on !UML |
0f836e5f DW |
378 | help |
379 | This option will extract the user-visible kernel headers whenever | |
380 | building the kernel, and will run basic sanity checks on them to | |
381 | ensure that exported files do not attempt to include files which | |
382 | were not exported, etc. | |
383 | ||
384 | If you're making modifications to header files which are | |
385 | relevant for userspace, say 'Y', and check the headers | |
386 | exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in | |
387 | your build tree), to make sure they're suitable. | |
388 | ||
a241ec65 PM |
389 | config RCU_TORTURE_TEST |
390 | tristate "torture tests for RCU" | |
391 | depends on DEBUG_KERNEL | |
392 | default n | |
393 | help | |
394 | This option provides a kernel module that runs torture tests | |
395 | on the RCU infrastructure. The kernel module may be built | |
396 | after the fact on the running kernel to be tested, if desired. | |
397 | ||
398 | Say Y here if you want RCU torture tests to start automatically | |
399 | at boot time (you probably don't). | |
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" | |
405 | depends on KPROBES | |
406 | default n | |
407 | help | |
408 | This module enables testing of the different dumping mechanisms by | |
409 | inducing system failures at predefined crash points. | |
410 | If you don't need it: say N | |
411 | Choose M here to compile this code as a module. The module will be | |
412 | called lkdtm. | |
413 | ||
414 | Documentation on how to use the module can be found in | |
415 | drivers/misc/lkdtm.c | |
6ff1cb35 AM |
416 | |
417 | config FAULT_INJECTION | |
418 | bool | |
419 | ||
8a8b6502 AM |
420 | config FAILSLAB |
421 | bool "Fault-injection capabilitiy for kmalloc" | |
422 | depends on DEBUG_KERNEL | |
423 | select FAULT_INJECTION | |
424 | help | |
425 | This option provides fault-injection capabilitiy for kmalloc. | |
426 | ||
933e312e AM |
427 | config FAIL_PAGE_ALLOC |
428 | bool "Fault-injection capabilitiy for alloc_pages()" | |
429 | depends on DEBUG_KERNEL | |
430 | select FAULT_INJECTION | |
431 | help | |
432 | This option provides fault-injection capabilitiy for alloc_pages(). | |
433 | ||
c17bb495 AM |
434 | config FAIL_MAKE_REQUEST |
435 | bool "Fault-injection capabilitiy for disk IO" | |
436 | depends on DEBUG_KERNEL | |
437 | select FAULT_INJECTION | |
438 | help | |
439 | This option provides fault-injection capabilitiy to disk IO. | |
440 | ||
6ff1cb35 AM |
441 | config FAULT_INJECTION_DEBUG_FS |
442 | bool "Debugfs entries for fault-injection capabilities" | |
443 | depends on FAULT_INJECTION && SYSFS | |
444 | select DEBUG_FS | |
445 | help | |
446 | This option enable configuration of fault-injection capabilities via | |
447 | debugfs. | |
448 |