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Linus Torvalds1da177e2005-04-16 15:20:36 -07001
2config 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070012config MAGIC_SYSRQ
13 bool "Magic SysRq key"
Adrian Bunkf346f4b2006-01-09 20:54:51 -080014 depends on !UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 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
Arjan van de Venf71d20e2006-06-28 04:26:45 -070026config 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
Adrian Bunkf346f4b2006-01-09 20:54:51 -080042config 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070048config LOG_BUF_SHIFT
49 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
50 range 12 21
Ingo Molnarfbb9ce92006-07-03 00:24:50 -070051 default 17 if S390 || LOCKDEP
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 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
Ingo Molnar8446f1d2005-09-06 15:16:27 -070065config 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070084config 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
96config DEBUG_SLAB
Andrew Morton4a2f0ac2006-03-25 03:07:22 -080097 bool "Debug slab memory allocations"
Ingo Molnar50dd26b2006-01-08 01:01:42 -080098 depends on DEBUG_KERNEL && SLAB
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 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
Al Viro871751e2006-03-25 03:06:39 -0800104config DEBUG_SLAB_LEAK
105 bool "Memory leak debugging"
106 depends on DEBUG_SLAB
107
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108config DEBUG_PREEMPT
109 bool "Debug preemptible kernel"
Ingo Molnar8637c092006-07-03 00:24:38 -0700110 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 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
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700118config DEBUG_RT_MUTEXES
119 bool "RT Mutex debugging, deadlock detection"
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700120 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
125config DEBUG_PI_LIST
126 bool
127 default y
128 depends on DEBUG_RT_MUTEXES
129
Thomas Gleixner61a87122006-06-27 02:54:56 -0700130config RT_MUTEX_TESTER
131 bool "Built-in scriptable tester for rt-mutexes"
Roman Zippela1583d32006-06-27 02:55:00 -0700132 depends on DEBUG_KERNEL && RT_MUTEXES
Thomas Gleixner61a87122006-06-27 02:54:56 -0700133 help
134 This option enables a rt-mutex tester.
135
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136config DEBUG_SPINLOCK
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700137 bool "Spinlock and rw-lock debugging: basic checks"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 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
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700145config 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
152config 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
159config DEBUG_LOCK_ALLOC
160 bool "Lock debugging: detect incorrect freeing of live locks"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700161 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700162 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
174config PROVE_LOCKING
175 bool "Lock debugging: prove locking correctness"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700176 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700177 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
217config LOCKDEP
218 bool
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700219 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700220 select STACKTRACE
221 select FRAME_POINTER
222 select KALLSYMS
223 select KALLSYMS_ALL
224
225config DEBUG_LOCKDEP
226 bool "Lock dependency engine debugging"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700227 depends on DEBUG_KERNEL && LOCKDEP
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700228 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
233config TRACE_IRQFLAGS
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700234 depends on DEBUG_KERNEL
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700235 bool
236 default y
237 depends on TRACE_IRQFLAGS_SUPPORT
238 depends on PROVE_LOCKING
239
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240config DEBUG_SPINLOCK_SLEEP
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700241 bool "Spinlock debugging: sleep-inside-spinlock checking"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 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
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700247config 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
Ingo Molnar8637c092006-07-03 00:24:38 -0700258config STACKTRACE
259 bool
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700260 depends on DEBUG_KERNEL
Ingo Molnar8637c092006-07-03 00:24:38 -0700261 depends on STACKTRACE_SUPPORT
262
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263config 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
270config 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
277config DEBUG_BUGVERBOSE
278 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
Matt Mackallc8538a72005-05-01 08:59:01 -0700279 depends on BUG
Brian Gerst0d078f62005-10-30 14:59:20 -0800280 depends on ARM || ARM26 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 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
287config 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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297config DEBUG_FS
298 bool "Debug Filesystem"
Jens Axboeae36b882006-03-26 14:38:54 +0200299 depends on SYSFS
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 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
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800307config DEBUG_VM
308 bool "Debug VM"
309 depends on DEBUG_KERNEL
310 help
Nick Piggin13e74442006-01-06 00:10:58 -0800311 Enable this to turn on extended checks in the virtual-memory system
312 that may impact performance.
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800313
314 If unsure, say N.
315
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316config FRAME_POINTER
317 bool "Compile the kernel with frame pointers"
Heiko Carstenscbbd1fa2006-07-03 00:24:38 -0700318 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390)
Paolo 'Blaisorblade' Giarrusso37fce852005-05-28 15:51:59 -0700319 default y if DEBUG_INFO && UML
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 help
321 If you say Y here the resulting kernel image will be slightly larger
Jesper Juhl2a38bcc2005-10-30 15:02:51 -0800322 and slower, but it might give very useful debugging information on
323 some architectures or if you use external debuggers.
Andi Kleenaeb39982005-09-12 18:49:25 +0200324 If you don't debug the kernel, you can say N.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325
Jan Beulich604bf5a2006-03-24 03:16:19 -0800326config UNWIND_INFO
327 bool "Compile the kernel with frame unwind information"
Jan Beulich4552d5d2006-06-26 13:57:28 +0200328 depends on !IA64 && !PARISC
329 depends on !MODULES || !(MIPS || PPC || SUPERH || V850)
Jan Beulich604bf5a2006-03-24 03:16:19 -0800330 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
Jan Beulich4552d5d2006-06-26 13:57:28 +0200336config STACK_UNWIND
337 bool "Stack unwind support"
338 depends on UNWIND_INFO
Jan Beulich176a2712006-06-26 13:57:41 +0200339 depends on X86
Jan Beulich4552d5d2006-06-26 13:57:28 +0200340 help
341 This enables more precise stack traces, omitting all unrelated
342 occurrences of pointers into kernel code from the dump.
343
Ingo Molnara9df3d02006-01-14 13:21:33 -0800344config 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
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800358config 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.