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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 | ||
11 | ||
1da177e4 LT |
12 | config MAGIC_SYSRQ |
13 | bool "Magic SysRq key" | |
f346f4b3 | 14 | depends on !UML |
1da177e4 LT |
15 | help |
16 | If you say Y here, you will have some control over the system even | |
17 | if the system crashes for example during kernel debugging (e.g., you | |
18 | will be able to flush the buffer cache to disk, reboot the system | |
19 | immediately or dump some status information). This is accomplished | |
20 | by pressing various keys while holding SysRq (Alt+PrintScreen). It | |
21 | also works on a serial console (on PC hardware at least), if you | |
22 | send a BREAK and then within 5 seconds a command keypress. The | |
23 | keys are documented in <file:Documentation/sysrq.txt>. Don't say Y | |
24 | unless you really know what this hack does. | |
25 | ||
f71d20e9 AV |
26 | config UNUSED_SYMBOLS |
27 | bool "Enable unused/obsolete exported symbols" | |
28 | default y if X86 | |
29 | help | |
30 | Unused but exported symbols make the kernel needlessly bigger. For | |
31 | that reason most of these unused exports will soon be removed. This | |
32 | option is provided temporarily to provide a transition period in case | |
33 | some external kernel module needs one of these symbols anyway. If you | |
34 | encounter such a case in your module, consider if you are actually | |
35 | using the right API. (rationale: since nobody in the kernel is using | |
36 | this in a module, there is a pretty good chance it's actually the | |
37 | wrong interface to use). If you really need the symbol, please send a | |
38 | mail to the linux kernel mailing list mentioning the symbol and why | |
39 | you really need it, and what the merge plan to the mainline kernel for | |
40 | your module is. | |
41 | ||
f346f4b3 AB |
42 | config DEBUG_KERNEL |
43 | bool "Kernel debugging" | |
44 | help | |
45 | Say Y here if you are developing drivers or trying to debug and | |
46 | identify kernel problems. | |
47 | ||
1da177e4 LT |
48 | config LOG_BUF_SHIFT |
49 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL | |
50 | range 12 21 | |
fbb9ce95 | 51 | default 17 if S390 || LOCKDEP |
1da177e4 LT |
52 | default 16 if X86_NUMAQ || IA64 |
53 | default 15 if SMP | |
54 | default 14 | |
55 | help | |
56 | Select kernel log buffer size as a power of 2. | |
57 | Defaults and Examples: | |
58 | 17 => 128 KB for S/390 | |
59 | 16 => 64 KB for x86 NUMAQ or IA-64 | |
60 | 15 => 32 KB for SMP | |
61 | 14 => 16 KB for uniprocessor | |
62 | 13 => 8 KB | |
63 | 12 => 4 KB | |
64 | ||
8446f1d3 IM |
65 | config DETECT_SOFTLOCKUP |
66 | bool "Detect Soft Lockups" | |
67 | depends on DEBUG_KERNEL | |
68 | default y | |
69 | help | |
70 | Say Y here to enable the kernel to detect "soft lockups", | |
71 | which are bugs that cause the kernel to loop in kernel | |
72 | mode for more than 10 seconds, without giving other tasks a | |
73 | chance to run. | |
74 | ||
75 | When a soft-lockup is detected, the kernel will print the | |
76 | current stack trace (which you should report), but the | |
77 | system will stay locked up. This feature has negligible | |
78 | overhead. | |
79 | ||
80 | (Note that "hard lockups" are separate type of bugs that | |
81 | can be detected via the NMI-watchdog, on platforms that | |
82 | support it.) | |
83 | ||
1da177e4 LT |
84 | config SCHEDSTATS |
85 | bool "Collect scheduler statistics" | |
86 | depends on DEBUG_KERNEL && PROC_FS | |
87 | help | |
88 | If you say Y here, additional code will be inserted into the | |
89 | scheduler and related routines to collect statistics about | |
90 | scheduler behavior and provide them in /proc/schedstat. These | |
91 | stats may be useful for both tuning and debugging the scheduler | |
92 | If you aren't debugging the scheduler or trying to tune a specific | |
93 | application, you can say N to avoid the very slight overhead | |
94 | this adds. | |
95 | ||
96 | config DEBUG_SLAB | |
4a2f0acf | 97 | bool "Debug slab memory allocations" |
50dd26ba | 98 | depends on DEBUG_KERNEL && SLAB |
1da177e4 LT |
99 | help |
100 | Say Y here to have the kernel do limited verification on memory | |
101 | allocation as well as poisoning memory on free to catch use of freed | |
102 | memory. This can make kmalloc/kfree-intensive workloads much slower. | |
103 | ||
871751e2 AV |
104 | config DEBUG_SLAB_LEAK |
105 | bool "Memory leak debugging" | |
106 | depends on DEBUG_SLAB | |
107 | ||
1da177e4 LT |
108 | config DEBUG_PREEMPT |
109 | bool "Debug preemptible kernel" | |
8637c099 | 110 | depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT |
1da177e4 LT |
111 | default y |
112 | help | |
113 | If you say Y here then the kernel will use a debug variant of the | |
114 | commonly used smp_processor_id() function and will print warnings | |
115 | if kernel code uses it in a preemption-unsafe way. Also, the kernel | |
116 | will detect preemption count underflows. | |
117 | ||
e7eebaf6 IM |
118 | config DEBUG_RT_MUTEXES |
119 | bool "RT Mutex debugging, deadlock detection" | |
e7eebaf6 IM |
120 | depends on DEBUG_KERNEL && RT_MUTEXES |
121 | help | |
122 | This allows rt mutex semantics violations and rt mutex related | |
123 | deadlocks (lockups) to be detected and reported automatically. | |
124 | ||
125 | config DEBUG_PI_LIST | |
126 | bool | |
127 | default y | |
128 | depends on DEBUG_RT_MUTEXES | |
129 | ||
61a87122 TG |
130 | config RT_MUTEX_TESTER |
131 | bool "Built-in scriptable tester for rt-mutexes" | |
a1583d3e | 132 | depends on DEBUG_KERNEL && RT_MUTEXES |
61a87122 TG |
133 | help |
134 | This option enables a rt-mutex tester. | |
135 | ||
1da177e4 | 136 | config DEBUG_SPINLOCK |
4d9f34ad | 137 | bool "Spinlock and rw-lock debugging: basic checks" |
1da177e4 LT |
138 | depends on DEBUG_KERNEL |
139 | help | |
140 | Say Y here and build SMP to catch missing spinlock initialization | |
141 | and certain other kinds of spinlock errors commonly made. This is | |
142 | best used in conjunction with the NMI watchdog so that spinlock | |
143 | deadlocks are also debuggable. | |
144 | ||
4d9f34ad IM |
145 | config DEBUG_MUTEXES |
146 | bool "Mutex debugging: basic checks" | |
147 | depends on DEBUG_KERNEL | |
148 | help | |
149 | This feature allows mutex semantics violations to be detected and | |
150 | reported. | |
151 | ||
152 | config DEBUG_RWSEMS | |
153 | bool "RW-sem debugging: basic checks" | |
154 | depends on DEBUG_KERNEL | |
155 | help | |
156 | This feature allows read-write semaphore semantics violations to | |
157 | be detected and reported. | |
158 | ||
159 | config DEBUG_LOCK_ALLOC | |
160 | bool "Lock debugging: detect incorrect freeing of live locks" | |
517e7aa5 | 161 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
162 | select DEBUG_SPINLOCK |
163 | select DEBUG_MUTEXES | |
164 | select DEBUG_RWSEMS | |
165 | select LOCKDEP | |
166 | help | |
167 | This feature will check whether any held lock (spinlock, rwlock, | |
168 | mutex or rwsem) is incorrectly freed by the kernel, via any of the | |
169 | memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), | |
170 | vfree(), etc.), whether a live lock is incorrectly reinitialized via | |
171 | spin_lock_init()/mutex_init()/etc., or whether there is any lock | |
172 | held during task exit. | |
173 | ||
174 | config PROVE_LOCKING | |
175 | bool "Lock debugging: prove locking correctness" | |
517e7aa5 | 176 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
177 | select LOCKDEP |
178 | select DEBUG_SPINLOCK | |
179 | select DEBUG_MUTEXES | |
180 | select DEBUG_RWSEMS | |
181 | select DEBUG_LOCK_ALLOC | |
182 | default n | |
183 | help | |
184 | This feature enables the kernel to prove that all locking | |
185 | that occurs in the kernel runtime is mathematically | |
186 | correct: that under no circumstance could an arbitrary (and | |
187 | not yet triggered) combination of observed locking | |
188 | sequences (on an arbitrary number of CPUs, running an | |
189 | arbitrary number of tasks and interrupt contexts) cause a | |
190 | deadlock. | |
191 | ||
192 | In short, this feature enables the kernel to report locking | |
193 | related deadlocks before they actually occur. | |
194 | ||
195 | The proof does not depend on how hard and complex a | |
196 | deadlock scenario would be to trigger: how many | |
197 | participant CPUs, tasks and irq-contexts would be needed | |
198 | for it to trigger. The proof also does not depend on | |
199 | timing: if a race and a resulting deadlock is possible | |
200 | theoretically (no matter how unlikely the race scenario | |
201 | is), it will be proven so and will immediately be | |
202 | reported by the kernel (once the event is observed that | |
203 | makes the deadlock theoretically possible). | |
204 | ||
205 | If a deadlock is impossible (i.e. the locking rules, as | |
206 | observed by the kernel, are mathematically correct), the | |
207 | kernel reports nothing. | |
208 | ||
209 | NOTE: this feature can also be enabled for rwlocks, mutexes | |
210 | and rwsems - in which case all dependencies between these | |
211 | different locking variants are observed and mapped too, and | |
212 | the proof of observed correctness is also maintained for an | |
213 | arbitrary combination of these separate locking variants. | |
214 | ||
215 | For more details, see Documentation/lockdep-design.txt. | |
216 | ||
217 | config LOCKDEP | |
218 | bool | |
517e7aa5 | 219 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
220 | select STACKTRACE |
221 | select FRAME_POINTER | |
222 | select KALLSYMS | |
223 | select KALLSYMS_ALL | |
224 | ||
225 | config DEBUG_LOCKDEP | |
226 | bool "Lock dependency engine debugging" | |
517e7aa5 | 227 | depends on DEBUG_KERNEL && LOCKDEP |
4d9f34ad IM |
228 | help |
229 | If you say Y here, the lock dependency engine will do | |
230 | additional runtime checks to debug itself, at the price | |
231 | of more runtime overhead. | |
232 | ||
233 | config TRACE_IRQFLAGS | |
517e7aa5 | 234 | depends on DEBUG_KERNEL |
4d9f34ad IM |
235 | bool |
236 | default y | |
237 | depends on TRACE_IRQFLAGS_SUPPORT | |
238 | depends on PROVE_LOCKING | |
239 | ||
1da177e4 | 240 | config DEBUG_SPINLOCK_SLEEP |
4d9f34ad | 241 | bool "Spinlock debugging: sleep-inside-spinlock checking" |
1da177e4 LT |
242 | depends on DEBUG_KERNEL |
243 | help | |
244 | If you say Y here, various routines which may sleep will become very | |
245 | noisy if they are called with a spinlock held. | |
246 | ||
cae2ed9a IM |
247 | config DEBUG_LOCKING_API_SELFTESTS |
248 | bool "Locking API boot-time self-tests" | |
249 | depends on DEBUG_KERNEL | |
250 | help | |
251 | Say Y here if you want the kernel to run a short self-test during | |
252 | bootup. The self-test checks whether common types of locking bugs | |
253 | are detected by debugging mechanisms or not. (if you disable | |
254 | lock debugging then those bugs wont be detected of course.) | |
255 | The following locking APIs are covered: spinlocks, rwlocks, | |
256 | mutexes and rwsems. | |
257 | ||
8637c099 IM |
258 | config STACKTRACE |
259 | bool | |
517e7aa5 | 260 | depends on DEBUG_KERNEL |
8637c099 IM |
261 | depends on STACKTRACE_SUPPORT |
262 | ||
1da177e4 LT |
263 | config DEBUG_KOBJECT |
264 | bool "kobject debugging" | |
265 | depends on DEBUG_KERNEL | |
266 | help | |
267 | If you say Y here, some extra kobject debugging messages will be sent | |
268 | to the syslog. | |
269 | ||
270 | config DEBUG_HIGHMEM | |
271 | bool "Highmem debugging" | |
272 | depends on DEBUG_KERNEL && HIGHMEM | |
273 | help | |
274 | This options enables addition error checking for high memory systems. | |
275 | Disable for production systems. | |
276 | ||
277 | config DEBUG_BUGVERBOSE | |
278 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED | |
c8538a7a | 279 | depends on BUG |
0d078f6f | 280 | depends on ARM || ARM26 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV |
1da177e4 LT |
281 | default !EMBEDDED |
282 | help | |
283 | Say Y here to make BUG() panics output the file name and line number | |
284 | of the BUG call as well as the EIP and oops trace. This aids | |
285 | debugging but costs about 70-100K of memory. | |
286 | ||
287 | config DEBUG_INFO | |
288 | bool "Compile the kernel with debug info" | |
289 | depends on DEBUG_KERNEL | |
290 | help | |
291 | If you say Y here the resulting kernel image will include | |
292 | debugging info resulting in a larger kernel image. | |
293 | Say Y here only if you plan to debug the kernel. | |
294 | ||
295 | If unsure, say N. | |
296 | ||
1da177e4 LT |
297 | config DEBUG_FS |
298 | bool "Debug Filesystem" | |
ae36b883 | 299 | depends on SYSFS |
1da177e4 LT |
300 | help |
301 | debugfs is a virtual file system that kernel developers use to put | |
302 | debugging files into. Enable this option to be able to read and | |
303 | write to these files. | |
304 | ||
305 | If unsure, say N. | |
306 | ||
a241ec65 PM |
307 | config DEBUG_VM |
308 | bool "Debug VM" | |
309 | depends on DEBUG_KERNEL | |
310 | help | |
13e7444b NP |
311 | Enable this to turn on extended checks in the virtual-memory system |
312 | that may impact performance. | |
a241ec65 PM |
313 | |
314 | If unsure, say N. | |
315 | ||
1da177e4 LT |
316 | config FRAME_POINTER |
317 | bool "Compile the kernel with frame pointers" | |
cbbd1fa7 | 318 | depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390) |
37fce857 | 319 | default y if DEBUG_INFO && UML |
1da177e4 LT |
320 | help |
321 | If you say Y here the resulting kernel image will be slightly larger | |
2a38bccd JJ |
322 | and slower, but it might give very useful debugging information on |
323 | some architectures or if you use external debuggers. | |
aeb39986 | 324 | If you don't debug the kernel, you can say N. |
1da177e4 | 325 | |
604bf5a2 JB |
326 | config UNWIND_INFO |
327 | bool "Compile the kernel with frame unwind information" | |
4552d5dc JB |
328 | depends on !IA64 && !PARISC |
329 | depends on !MODULES || !(MIPS || PPC || SUPERH || V850) | |
604bf5a2 JB |
330 | help |
331 | If you say Y here the resulting kernel image will be slightly larger | |
332 | but not slower, and it will give very useful debugging information. | |
333 | If you don't debug the kernel, you can say N, but we may not be able | |
334 | to solve problems without frame unwind information or frame pointers. | |
335 | ||
4552d5dc JB |
336 | config STACK_UNWIND |
337 | bool "Stack unwind support" | |
338 | depends on UNWIND_INFO | |
176a2718 | 339 | depends on X86 |
4552d5dc JB |
340 | help |
341 | This enables more precise stack traces, omitting all unrelated | |
342 | occurrences of pointers into kernel code from the dump. | |
343 | ||
a9df3d0f IM |
344 | config FORCED_INLINING |
345 | bool "Force gcc to inline functions marked 'inline'" | |
346 | depends on DEBUG_KERNEL | |
347 | default y | |
348 | help | |
349 | This option determines if the kernel forces gcc to inline the functions | |
350 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
351 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
352 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
353 | disabling this option will generate a smaller kernel there. Hopefully | |
354 | this algorithm is so good that allowing gcc4 to make the decision can | |
355 | become the default in the future, until then this option is there to | |
356 | test gcc for this. | |
357 | ||
a241ec65 PM |
358 | config RCU_TORTURE_TEST |
359 | tristate "torture tests for RCU" | |
360 | depends on DEBUG_KERNEL | |
361 | default n | |
362 | help | |
363 | This option provides a kernel module that runs torture tests | |
364 | on the RCU infrastructure. The kernel module may be built | |
365 | after the fact on the running kernel to be tested, if desired. | |
366 | ||
367 | Say Y here if you want RCU torture tests to start automatically | |
368 | at boot time (you probably don't). | |
369 | Say M if you want the RCU torture tests to build as a module. | |
370 | Say N if you are unsure. |