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1da177e4 LT |
1 | |
2 | config PRINTK_TIME | |
3 | bool "Show timing information on printks" | |
4 | help | |
5 | Selecting this option causes timing information to be | |
6 | included in printk output. This allows you to measure | |
7 | the interval between kernel operations, including bootup | |
8 | operations. This is useful for identifying long delays | |
9 | in kernel startup. | |
10 | ||
cebc04ba AM |
11 | config ENABLE_MUST_CHECK |
12 | bool "Enable __must_check logic" | |
13 | default y | |
14 | help | |
15 | Enable the __must_check logic in the kernel build. Disable this to | |
16 | suppress the "warning: ignoring return value of 'foo', declared with | |
17 | attribute warn_unused_result" messages. | |
1da177e4 | 18 | |
1da177e4 LT |
19 | config MAGIC_SYSRQ |
20 | bool "Magic SysRq key" | |
f346f4b3 | 21 | depends on !UML |
1da177e4 LT |
22 | help |
23 | If you say Y here, you will have some control over the system even | |
24 | if the system crashes for example during kernel debugging (e.g., you | |
25 | will be able to flush the buffer cache to disk, reboot the system | |
26 | immediately or dump some status information). This is accomplished | |
27 | by pressing various keys while holding SysRq (Alt+PrintScreen). It | |
28 | also works on a serial console (on PC hardware at least), if you | |
29 | send a BREAK and then within 5 seconds a command keypress. The | |
30 | keys are documented in <file:Documentation/sysrq.txt>. Don't say Y | |
31 | unless you really know what this hack does. | |
32 | ||
f71d20e9 AV |
33 | config UNUSED_SYMBOLS |
34 | bool "Enable unused/obsolete exported symbols" | |
35 | default y if X86 | |
36 | help | |
37 | Unused but exported symbols make the kernel needlessly bigger. For | |
38 | that reason most of these unused exports will soon be removed. This | |
39 | option is provided temporarily to provide a transition period in case | |
40 | some external kernel module needs one of these symbols anyway. If you | |
41 | encounter such a case in your module, consider if you are actually | |
42 | using the right API. (rationale: since nobody in the kernel is using | |
43 | this in a module, there is a pretty good chance it's actually the | |
44 | wrong interface to use). If you really need the symbol, please send a | |
45 | mail to the linux kernel mailing list mentioning the symbol and why | |
46 | you really need it, and what the merge plan to the mainline kernel for | |
47 | your module is. | |
48 | ||
f346f4b3 AB |
49 | config DEBUG_KERNEL |
50 | bool "Kernel debugging" | |
51 | help | |
52 | Say Y here if you are developing drivers or trying to debug and | |
53 | identify kernel problems. | |
54 | ||
1da177e4 LT |
55 | config LOG_BUF_SHIFT |
56 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL | |
57 | range 12 21 | |
fbb9ce95 | 58 | default 17 if S390 || LOCKDEP |
1da177e4 LT |
59 | default 16 if X86_NUMAQ || IA64 |
60 | default 15 if SMP | |
61 | default 14 | |
62 | help | |
63 | Select kernel log buffer size as a power of 2. | |
64 | Defaults and Examples: | |
65 | 17 => 128 KB for S/390 | |
66 | 16 => 64 KB for x86 NUMAQ or IA-64 | |
67 | 15 => 32 KB for SMP | |
68 | 14 => 16 KB for uniprocessor | |
69 | 13 => 8 KB | |
70 | 12 => 4 KB | |
71 | ||
8446f1d3 IM |
72 | config DETECT_SOFTLOCKUP |
73 | bool "Detect Soft Lockups" | |
74 | depends on DEBUG_KERNEL | |
75 | default y | |
76 | help | |
77 | Say Y here to enable the kernel to detect "soft lockups", | |
78 | which are bugs that cause the kernel to loop in kernel | |
79 | mode for more than 10 seconds, without giving other tasks a | |
80 | chance to run. | |
81 | ||
82 | When a soft-lockup is detected, the kernel will print the | |
83 | current stack trace (which you should report), but the | |
84 | system will stay locked up. This feature has negligible | |
85 | overhead. | |
86 | ||
87 | (Note that "hard lockups" are separate type of bugs that | |
88 | can be detected via the NMI-watchdog, on platforms that | |
89 | support it.) | |
90 | ||
1da177e4 LT |
91 | config SCHEDSTATS |
92 | bool "Collect scheduler statistics" | |
93 | depends on DEBUG_KERNEL && PROC_FS | |
94 | help | |
95 | If you say Y here, additional code will be inserted into the | |
96 | scheduler and related routines to collect statistics about | |
97 | scheduler behavior and provide them in /proc/schedstat. These | |
98 | stats may be useful for both tuning and debugging the scheduler | |
99 | If you aren't debugging the scheduler or trying to tune a specific | |
100 | application, you can say N to avoid the very slight overhead | |
101 | this adds. | |
102 | ||
103 | config DEBUG_SLAB | |
4a2f0acf | 104 | bool "Debug slab memory allocations" |
50dd26ba | 105 | depends on DEBUG_KERNEL && SLAB |
1da177e4 LT |
106 | help |
107 | Say Y here to have the kernel do limited verification on memory | |
108 | allocation as well as poisoning memory on free to catch use of freed | |
109 | memory. This can make kmalloc/kfree-intensive workloads much slower. | |
110 | ||
871751e2 AV |
111 | config DEBUG_SLAB_LEAK |
112 | bool "Memory leak debugging" | |
113 | depends on DEBUG_SLAB | |
114 | ||
1da177e4 LT |
115 | config DEBUG_PREEMPT |
116 | bool "Debug preemptible kernel" | |
8637c099 | 117 | depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT |
1da177e4 LT |
118 | default y |
119 | help | |
120 | If you say Y here then the kernel will use a debug variant of the | |
121 | commonly used smp_processor_id() function and will print warnings | |
122 | if kernel code uses it in a preemption-unsafe way. Also, the kernel | |
123 | will detect preemption count underflows. | |
124 | ||
e7eebaf6 IM |
125 | config DEBUG_RT_MUTEXES |
126 | bool "RT Mutex debugging, deadlock detection" | |
e7eebaf6 IM |
127 | depends on DEBUG_KERNEL && RT_MUTEXES |
128 | help | |
129 | This allows rt mutex semantics violations and rt mutex related | |
130 | deadlocks (lockups) to be detected and reported automatically. | |
131 | ||
132 | config DEBUG_PI_LIST | |
133 | bool | |
134 | default y | |
135 | depends on DEBUG_RT_MUTEXES | |
136 | ||
61a87122 TG |
137 | config RT_MUTEX_TESTER |
138 | bool "Built-in scriptable tester for rt-mutexes" | |
a1583d3e | 139 | depends on DEBUG_KERNEL && RT_MUTEXES |
61a87122 TG |
140 | help |
141 | This option enables a rt-mutex tester. | |
142 | ||
1da177e4 | 143 | config DEBUG_SPINLOCK |
4d9f34ad | 144 | bool "Spinlock and rw-lock debugging: basic checks" |
1da177e4 LT |
145 | depends on DEBUG_KERNEL |
146 | help | |
147 | Say Y here and build SMP to catch missing spinlock initialization | |
148 | and certain other kinds of spinlock errors commonly made. This is | |
149 | best used in conjunction with the NMI watchdog so that spinlock | |
150 | deadlocks are also debuggable. | |
151 | ||
4d9f34ad IM |
152 | config DEBUG_MUTEXES |
153 | bool "Mutex debugging: basic checks" | |
154 | depends on DEBUG_KERNEL | |
155 | help | |
156 | This feature allows mutex semantics violations to be detected and | |
157 | reported. | |
158 | ||
159 | config DEBUG_RWSEMS | |
160 | bool "RW-sem debugging: basic checks" | |
161 | depends on DEBUG_KERNEL | |
162 | help | |
163 | This feature allows read-write semaphore semantics violations to | |
164 | be detected and reported. | |
165 | ||
166 | config DEBUG_LOCK_ALLOC | |
167 | bool "Lock debugging: detect incorrect freeing of live locks" | |
517e7aa5 | 168 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
169 | select DEBUG_SPINLOCK |
170 | select DEBUG_MUTEXES | |
171 | select DEBUG_RWSEMS | |
172 | select LOCKDEP | |
173 | help | |
174 | This feature will check whether any held lock (spinlock, rwlock, | |
175 | mutex or rwsem) is incorrectly freed by the kernel, via any of the | |
176 | memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), | |
177 | vfree(), etc.), whether a live lock is incorrectly reinitialized via | |
178 | spin_lock_init()/mutex_init()/etc., or whether there is any lock | |
179 | held during task exit. | |
180 | ||
181 | config PROVE_LOCKING | |
182 | bool "Lock debugging: prove locking correctness" | |
517e7aa5 | 183 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
184 | select LOCKDEP |
185 | select DEBUG_SPINLOCK | |
186 | select DEBUG_MUTEXES | |
187 | select DEBUG_RWSEMS | |
188 | select DEBUG_LOCK_ALLOC | |
189 | default n | |
190 | help | |
191 | This feature enables the kernel to prove that all locking | |
192 | that occurs in the kernel runtime is mathematically | |
193 | correct: that under no circumstance could an arbitrary (and | |
194 | not yet triggered) combination of observed locking | |
195 | sequences (on an arbitrary number of CPUs, running an | |
196 | arbitrary number of tasks and interrupt contexts) cause a | |
197 | deadlock. | |
198 | ||
199 | In short, this feature enables the kernel to report locking | |
200 | related deadlocks before they actually occur. | |
201 | ||
202 | The proof does not depend on how hard and complex a | |
203 | deadlock scenario would be to trigger: how many | |
204 | participant CPUs, tasks and irq-contexts would be needed | |
205 | for it to trigger. The proof also does not depend on | |
206 | timing: if a race and a resulting deadlock is possible | |
207 | theoretically (no matter how unlikely the race scenario | |
208 | is), it will be proven so and will immediately be | |
209 | reported by the kernel (once the event is observed that | |
210 | makes the deadlock theoretically possible). | |
211 | ||
212 | If a deadlock is impossible (i.e. the locking rules, as | |
213 | observed by the kernel, are mathematically correct), the | |
214 | kernel reports nothing. | |
215 | ||
216 | NOTE: this feature can also be enabled for rwlocks, mutexes | |
217 | and rwsems - in which case all dependencies between these | |
218 | different locking variants are observed and mapped too, and | |
219 | the proof of observed correctness is also maintained for an | |
220 | arbitrary combination of these separate locking variants. | |
221 | ||
222 | For more details, see Documentation/lockdep-design.txt. | |
223 | ||
224 | config LOCKDEP | |
225 | bool | |
517e7aa5 | 226 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad | 227 | select STACKTRACE |
3b8d1fe0 | 228 | select FRAME_POINTER if !X86 |
4d9f34ad IM |
229 | select KALLSYMS |
230 | select KALLSYMS_ALL | |
231 | ||
232 | config DEBUG_LOCKDEP | |
233 | bool "Lock dependency engine debugging" | |
517e7aa5 | 234 | depends on DEBUG_KERNEL && LOCKDEP |
4d9f34ad IM |
235 | help |
236 | If you say Y here, the lock dependency engine will do | |
237 | additional runtime checks to debug itself, at the price | |
238 | of more runtime overhead. | |
239 | ||
240 | config TRACE_IRQFLAGS | |
517e7aa5 | 241 | depends on DEBUG_KERNEL |
4d9f34ad IM |
242 | bool |
243 | default y | |
244 | depends on TRACE_IRQFLAGS_SUPPORT | |
245 | depends on PROVE_LOCKING | |
246 | ||
1da177e4 | 247 | config DEBUG_SPINLOCK_SLEEP |
4d9f34ad | 248 | bool "Spinlock debugging: sleep-inside-spinlock checking" |
1da177e4 LT |
249 | depends on DEBUG_KERNEL |
250 | help | |
251 | If you say Y here, various routines which may sleep will become very | |
252 | noisy if they are called with a spinlock held. | |
253 | ||
cae2ed9a IM |
254 | config DEBUG_LOCKING_API_SELFTESTS |
255 | bool "Locking API boot-time self-tests" | |
256 | depends on DEBUG_KERNEL | |
257 | help | |
258 | Say Y here if you want the kernel to run a short self-test during | |
259 | bootup. The self-test checks whether common types of locking bugs | |
260 | are detected by debugging mechanisms or not. (if you disable | |
261 | lock debugging then those bugs wont be detected of course.) | |
262 | The following locking APIs are covered: spinlocks, rwlocks, | |
263 | mutexes and rwsems. | |
264 | ||
8637c099 IM |
265 | config STACKTRACE |
266 | bool | |
517e7aa5 | 267 | depends on DEBUG_KERNEL |
8637c099 IM |
268 | depends on STACKTRACE_SUPPORT |
269 | ||
1da177e4 LT |
270 | config DEBUG_KOBJECT |
271 | bool "kobject debugging" | |
272 | depends on DEBUG_KERNEL | |
273 | help | |
274 | If you say Y here, some extra kobject debugging messages will be sent | |
275 | to the syslog. | |
276 | ||
277 | config DEBUG_HIGHMEM | |
278 | bool "Highmem debugging" | |
279 | depends on DEBUG_KERNEL && HIGHMEM | |
280 | help | |
281 | This options enables addition error checking for high memory systems. | |
282 | Disable for production systems. | |
283 | ||
284 | config DEBUG_BUGVERBOSE | |
285 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED | |
c8538a7a | 286 | depends on BUG |
5f97f7f9 | 287 | depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV |
1da177e4 LT |
288 | default !EMBEDDED |
289 | help | |
290 | Say Y here to make BUG() panics output the file name and line number | |
291 | of the BUG call as well as the EIP and oops trace. This aids | |
292 | debugging but costs about 70-100K of memory. | |
293 | ||
294 | config DEBUG_INFO | |
295 | bool "Compile the kernel with debug info" | |
296 | depends on DEBUG_KERNEL | |
297 | help | |
298 | If you say Y here the resulting kernel image will include | |
299 | debugging info resulting in a larger kernel image. | |
300 | Say Y here only if you plan to debug the kernel. | |
301 | ||
302 | If unsure, say N. | |
303 | ||
1da177e4 LT |
304 | config DEBUG_FS |
305 | bool "Debug Filesystem" | |
ae36b883 | 306 | depends on SYSFS |
1da177e4 LT |
307 | help |
308 | debugfs is a virtual file system that kernel developers use to put | |
309 | debugging files into. Enable this option to be able to read and | |
310 | write to these files. | |
311 | ||
312 | If unsure, say N. | |
313 | ||
a241ec65 PM |
314 | config DEBUG_VM |
315 | bool "Debug VM" | |
316 | depends on DEBUG_KERNEL | |
317 | help | |
13e7444b NP |
318 | Enable this to turn on extended checks in the virtual-memory system |
319 | that may impact performance. | |
a241ec65 PM |
320 | |
321 | If unsure, say N. | |
322 | ||
1da177e4 LT |
323 | config FRAME_POINTER |
324 | bool "Compile the kernel with frame pointers" | |
5f97f7f9 | 325 | depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32) |
37fce857 | 326 | default y if DEBUG_INFO && UML |
1da177e4 LT |
327 | help |
328 | If you say Y here the resulting kernel image will be slightly larger | |
2a38bccd JJ |
329 | and slower, but it might give very useful debugging information on |
330 | some architectures or if you use external debuggers. | |
aeb39986 | 331 | If you don't debug the kernel, you can say N. |
1da177e4 | 332 | |
604bf5a2 JB |
333 | config UNWIND_INFO |
334 | bool "Compile the kernel with frame unwind information" | |
4552d5dc JB |
335 | depends on !IA64 && !PARISC |
336 | depends on !MODULES || !(MIPS || PPC || SUPERH || V850) | |
604bf5a2 JB |
337 | help |
338 | If you say Y here the resulting kernel image will be slightly larger | |
339 | but not slower, and it will give very useful debugging information. | |
340 | If you don't debug the kernel, you can say N, but we may not be able | |
341 | to solve problems without frame unwind information or frame pointers. | |
342 | ||
4552d5dc JB |
343 | config STACK_UNWIND |
344 | bool "Stack unwind support" | |
345 | depends on UNWIND_INFO | |
176a2718 | 346 | depends on X86 |
4552d5dc JB |
347 | help |
348 | This enables more precise stack traces, omitting all unrelated | |
349 | occurrences of pointers into kernel code from the dump. | |
350 | ||
a9df3d0f IM |
351 | config FORCED_INLINING |
352 | bool "Force gcc to inline functions marked 'inline'" | |
353 | depends on DEBUG_KERNEL | |
354 | default y | |
355 | help | |
356 | This option determines if the kernel forces gcc to inline the functions | |
357 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
358 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
359 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
360 | disabling this option will generate a smaller kernel there. Hopefully | |
361 | this algorithm is so good that allowing gcc4 to make the decision can | |
362 | become the default in the future, until then this option is there to | |
363 | test gcc for this. | |
364 | ||
a241ec65 PM |
365 | config RCU_TORTURE_TEST |
366 | tristate "torture tests for RCU" | |
367 | depends on DEBUG_KERNEL | |
368 | default n | |
369 | help | |
370 | This option provides a kernel module that runs torture tests | |
371 | on the RCU infrastructure. The kernel module may be built | |
372 | after the fact on the running kernel to be tested, if desired. | |
373 | ||
374 | Say Y here if you want RCU torture tests to start automatically | |
375 | at boot time (you probably don't). | |
376 | Say M if you want the RCU torture tests to build as a module. | |
377 | Say N if you are unsure. |