Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1
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
11config 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.
18
19config MAGIC_SYSRQ
20 bool "Magic SysRq key"
21 depends on !UML
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
33config 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
49config 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
55config LOG_BUF_SHIFT
56 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
57 range 12 21
58 default 17 if S390 || LOCKDEP
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
72config DETECT_SOFTLOCKUP
73 bool "Detect Soft Lockups"
74 depends on DEBUG_KERNEL && !S390
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
91config 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
103config DEBUG_SLAB
104 bool "Debug slab memory allocations"
105 depends on DEBUG_KERNEL && SLAB
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
111config DEBUG_SLAB_LEAK
112 bool "Memory leak debugging"
113 depends on DEBUG_SLAB
114
115config DEBUG_PREEMPT
116 bool "Debug preemptible kernel"
117 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
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
125config DEBUG_RT_MUTEXES
126 bool "RT Mutex debugging, deadlock detection"
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
132config DEBUG_PI_LIST
133 bool
134 default y
135 depends on DEBUG_RT_MUTEXES
136
137config RT_MUTEX_TESTER
138 bool "Built-in scriptable tester for rt-mutexes"
139 depends on DEBUG_KERNEL && RT_MUTEXES
140 help
141 This option enables a rt-mutex tester.
142
143config DEBUG_SPINLOCK
144 bool "Spinlock and rw-lock debugging: basic checks"
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
152config 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
159config 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
166config DEBUG_LOCK_ALLOC
167 bool "Lock debugging: detect incorrect freeing of live locks"
168 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
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
181config PROVE_LOCKING
182 bool "Lock debugging: prove locking correctness"
183 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
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
224config LOCKDEP
225 bool
226 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
227 select STACKTRACE
228 select FRAME_POINTER if !X86
229 select KALLSYMS
230 select KALLSYMS_ALL
231
232config DEBUG_LOCKDEP
233 bool "Lock dependency engine debugging"
234 depends on DEBUG_KERNEL && LOCKDEP
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
240config TRACE_IRQFLAGS
241 depends on DEBUG_KERNEL
242 bool
243 default y
244 depends on TRACE_IRQFLAGS_SUPPORT
245 depends on PROVE_LOCKING
246
247config DEBUG_SPINLOCK_SLEEP
248 bool "Spinlock debugging: sleep-inside-spinlock checking"
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
254config 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
265config STACKTRACE
266 bool
267 depends on DEBUG_KERNEL
268 depends on STACKTRACE_SUPPORT
269
270config 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
277config 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
284config DEBUG_BUGVERBOSE
285 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
286 depends on BUG
287 depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV || SUPERH
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
294config 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
304config DEBUG_FS
305 bool "Debug Filesystem"
306 depends on SYSFS
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
314config DEBUG_VM
315 bool "Debug VM"
316 depends on DEBUG_KERNEL
317 help
318 Enable this to turn on extended checks in the virtual-memory system
319 that may impact performance.
320
321 If unsure, say N.
322
323config DEBUG_LIST
324 bool "Debug linked list manipulation"
325 depends on DEBUG_KERNEL
326 help
327 Enable this to turn on extended checks in the linked-list
328 walking routines.
329
330 If unsure, say N.
331
332config FRAME_POINTER
333 bool "Compile the kernel with frame pointers"
334 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH)
335 default y if DEBUG_INFO && UML
336 help
337 If you say Y here the resulting kernel image will be slightly larger
338 and slower, but it might give very useful debugging information on
339 some architectures or if you use external debuggers.
340 If you don't debug the kernel, you can say N.
341
342config UNWIND_INFO
343 bool "Compile the kernel with frame unwind information"
344 depends on !IA64 && !PARISC && !ARM
345 depends on !MODULES || !(MIPS || PPC || SUPERH || V850)
346 help
347 If you say Y here the resulting kernel image will be slightly larger
348 but not slower, and it will give very useful debugging information.
349 If you don't debug the kernel, you can say N, but we may not be able
350 to solve problems without frame unwind information or frame pointers.
351
352config STACK_UNWIND
353 bool "Stack unwind support"
354 depends on UNWIND_INFO
355 depends on X86
356 help
357 This enables more precise stack traces, omitting all unrelated
358 occurrences of pointers into kernel code from the dump.
359
360config FORCED_INLINING
361 bool "Force gcc to inline functions marked 'inline'"
362 depends on DEBUG_KERNEL
363 default y
364 help
365 This option determines if the kernel forces gcc to inline the functions
366 developers have marked 'inline'. Doing so takes away freedom from gcc to
367 do what it thinks is best, which is desirable for the gcc 3.x series of
368 compilers. The gcc 4.x series have a rewritten inlining algorithm and
369 disabling this option will generate a smaller kernel there. Hopefully
370 this algorithm is so good that allowing gcc4 to make the decision can
371 become the default in the future, until then this option is there to
372 test gcc for this.
373
374config HEADERS_CHECK
375 bool "Run 'make headers_check' when building vmlinux"
376 depends on !UML
377 help
378 This option will extract the user-visible kernel headers whenever
379 building the kernel, and will run basic sanity checks on them to
380 ensure that exported files do not attempt to include files which
381 were not exported, etc.
382
383 If you're making modifications to header files which are
384 relevant for userspace, say 'Y', and check the headers
385 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
386 your build tree), to make sure they're suitable.
387
388config RCU_TORTURE_TEST
389 tristate "torture tests for RCU"
390 depends on DEBUG_KERNEL
391 default n
392 help
393 This option provides a kernel module that runs torture tests
394 on the RCU infrastructure. The kernel module may be built
395 after the fact on the running kernel to be tested, if desired.
396
397 Say Y here if you want RCU torture tests to start automatically
398 at boot time (you probably don't).
399 Say M if you want the RCU torture tests to build as a module.
400 Say N if you are unsure.
401
402config LKDTM
403 tristate "Linux Kernel Dump Test Tool Module"
404 depends on KPROBES
405 default n
406 help
407 This module enables testing of the different dumping mechanisms by
408 inducing system failures at predefined crash points.
409 If you don't need it: say N
410 Choose M here to compile this code as a module. The module will be
411 called lkdtm.
412
413 Documentation on how to use the module can be found in
414 drivers/misc/lkdtm.c