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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 | ||
1da177e4 LT |
89 | config LOG_BUF_SHIFT |
90 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL | |
91 | range 12 21 | |
fbb9ce95 | 92 | default 17 if S390 || LOCKDEP |
1da177e4 LT |
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 | ||
8446f1d3 IM |
106 | config DETECT_SOFTLOCKUP |
107 | bool "Detect Soft Lockups" | |
dea20a3f | 108 | depends on DEBUG_KERNEL && !S390 |
8446f1d3 IM |
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 | ||
1da177e4 LT |
125 | config 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 | ||
137 | config DEBUG_SLAB | |
4a2f0acf | 138 | bool "Debug slab memory allocations" |
50dd26ba | 139 | depends on DEBUG_KERNEL && SLAB |
1da177e4 LT |
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 | ||
871751e2 AV |
145 | config DEBUG_SLAB_LEAK |
146 | bool "Memory leak debugging" | |
147 | depends on DEBUG_SLAB | |
148 | ||
1da177e4 LT |
149 | config DEBUG_PREEMPT |
150 | bool "Debug preemptible kernel" | |
8637c099 | 151 | depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT |
1da177e4 LT |
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 | ||
e7eebaf6 IM |
159 | config DEBUG_RT_MUTEXES |
160 | bool "RT Mutex debugging, deadlock detection" | |
e7eebaf6 IM |
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 | ||
166 | config DEBUG_PI_LIST | |
167 | bool | |
168 | default y | |
169 | depends on DEBUG_RT_MUTEXES | |
170 | ||
61a87122 TG |
171 | config RT_MUTEX_TESTER |
172 | bool "Built-in scriptable tester for rt-mutexes" | |
a1583d3e | 173 | depends on DEBUG_KERNEL && RT_MUTEXES |
61a87122 TG |
174 | help |
175 | This option enables a rt-mutex tester. | |
176 | ||
1da177e4 | 177 | config DEBUG_SPINLOCK |
4d9f34ad | 178 | bool "Spinlock and rw-lock debugging: basic checks" |
1da177e4 LT |
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 | ||
4d9f34ad IM |
186 | config 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 | ||
4d9f34ad IM |
193 | config DEBUG_LOCK_ALLOC |
194 | bool "Lock debugging: detect incorrect freeing of live locks" | |
517e7aa5 | 195 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
196 | select DEBUG_SPINLOCK |
197 | select DEBUG_MUTEXES | |
4d9f34ad IM |
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 | ||
207 | config PROVE_LOCKING | |
208 | bool "Lock debugging: prove locking correctness" | |
517e7aa5 | 209 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
210 | select LOCKDEP |
211 | select DEBUG_SPINLOCK | |
212 | select DEBUG_MUTEXES | |
4d9f34ad IM |
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 | ||
249 | config LOCKDEP | |
250 | bool | |
517e7aa5 | 251 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad | 252 | select STACKTRACE |
3b8d1fe0 | 253 | select FRAME_POINTER if !X86 |
4d9f34ad IM |
254 | select KALLSYMS |
255 | select KALLSYMS_ALL | |
256 | ||
257 | config DEBUG_LOCKDEP | |
258 | bool "Lock dependency engine debugging" | |
517e7aa5 | 259 | depends on DEBUG_KERNEL && LOCKDEP |
4d9f34ad IM |
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 | ||
265 | config TRACE_IRQFLAGS | |
517e7aa5 | 266 | depends on DEBUG_KERNEL |
4d9f34ad IM |
267 | bool |
268 | default y | |
269 | depends on TRACE_IRQFLAGS_SUPPORT | |
270 | depends on PROVE_LOCKING | |
271 | ||
1da177e4 | 272 | config DEBUG_SPINLOCK_SLEEP |
4d9f34ad | 273 | bool "Spinlock debugging: sleep-inside-spinlock checking" |
1da177e4 LT |
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 | ||
cae2ed9a IM |
279 | config 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 | ||
8637c099 IM |
290 | config STACKTRACE |
291 | bool | |
517e7aa5 | 292 | depends on DEBUG_KERNEL |
8637c099 IM |
293 | depends on STACKTRACE_SUPPORT |
294 | ||
1da177e4 LT |
295 | config 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 | ||
302 | config 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 | ||
309 | config DEBUG_BUGVERBOSE | |
310 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED | |
c8538a7a | 311 | depends on BUG |
91768d6c | 312 | depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG |
1da177e4 LT |
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 | ||
319 | config 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 | ||
a241ec65 PM |
329 | config DEBUG_VM |
330 | bool "Debug VM" | |
331 | depends on DEBUG_KERNEL | |
332 | help | |
13e7444b NP |
333 | Enable this to turn on extended checks in the virtual-memory system |
334 | that may impact performance. | |
a241ec65 PM |
335 | |
336 | If unsure, say N. | |
337 | ||
199a9afc DJ |
338 | config 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 | ||
1da177e4 LT |
347 | config FRAME_POINTER |
348 | bool "Compile the kernel with frame pointers" | |
2549b322 | 349 | depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH) |
37fce857 | 350 | default y if DEBUG_INFO && UML |
1da177e4 LT |
351 | help |
352 | If you say Y here the resulting kernel image will be slightly larger | |
2a38bccd JJ |
353 | and slower, but it might give very useful debugging information on |
354 | some architectures or if you use external debuggers. | |
aeb39986 | 355 | If you don't debug the kernel, you can say N. |
1da177e4 | 356 | |
a9df3d0f IM |
357 | config 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 | ||
a241ec65 PM |
371 | config 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. | |
8bb31b9d AG |
384 | |
385 | config LKDTM | |
386 | tristate "Linux Kernel Dump Test Tool Module" | |
bf4735a4 | 387 | depends on DEBUG_KERNEL |
8bb31b9d AG |
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 | |
6ff1cb35 AM |
399 | |
400 | config FAULT_INJECTION | |
1ab8509a AM |
401 | bool "Fault-injection framework" |
402 | depends on DEBUG_KERNEL | |
83ba2546 | 403 | depends on STACKTRACE |
329409ae AM |
404 | select FRAME_POINTER |
405 | help | |
406 | Provide fault-injection framework. | |
407 | For more details, see Documentation/fault-injection/. | |
6ff1cb35 | 408 | |
8a8b6502 | 409 | config FAILSLAB |
1ab8509a AM |
410 | bool "Fault-injection capability for kmalloc" |
411 | depends on FAULT_INJECTION | |
8a8b6502 | 412 | help |
1ab8509a | 413 | Provide fault-injection capability for kmalloc. |
8a8b6502 | 414 | |
933e312e AM |
415 | config FAIL_PAGE_ALLOC |
416 | bool "Fault-injection capabilitiy for alloc_pages()" | |
1ab8509a | 417 | depends on FAULT_INJECTION |
933e312e | 418 | help |
1ab8509a | 419 | Provide fault-injection capability for alloc_pages(). |
933e312e | 420 | |
c17bb495 | 421 | config FAIL_MAKE_REQUEST |
86327d19 | 422 | bool "Fault-injection capability for disk IO" |
1ab8509a | 423 | depends on FAULT_INJECTION |
c17bb495 | 424 | help |
1ab8509a | 425 | Provide fault-injection capability for disk IO. |
c17bb495 | 426 | |
6ff1cb35 AM |
427 | config FAULT_INJECTION_DEBUG_FS |
428 | bool "Debugfs entries for fault-injection capabilities" | |
1ab8509a | 429 | depends on FAULT_INJECTION && SYSFS && DEBUG_FS |
6ff1cb35 | 430 | help |
1ab8509a | 431 | Enable configuration of fault-injection capabilities via debugfs. |