xref: /openbmc/linux/lib/Kconfig.debug (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1
2config PRINTK_TIME
3	bool "Show timing information on printks"
4	depends on PRINTK
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
12config 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.
19
20config MAGIC_SYSRQ
21	bool "Magic SysRq key"
22	depends on !UML
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
34config 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
50config 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
60config 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
74config 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
80config 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
89config DETECT_SOFTLOCKUP
90	bool "Detect Soft Lockups"
91	depends on DEBUG_KERNEL && !S390
92	default y
93	help
94	  Say Y here to enable the kernel to detect "soft lockups",
95	  which are bugs that cause the kernel to loop in kernel
96	  mode for more than 10 seconds, without giving other tasks a
97	  chance to run.
98
99	  When a soft-lockup is detected, the kernel will print the
100	  current stack trace (which you should report), but the
101	  system will stay locked up. This feature has negligible
102	  overhead.
103
104	  (Note that "hard lockups" are separate type of bugs that
105	   can be detected via the NMI-watchdog, on platforms that
106	   support it.)
107
108config SCHEDSTATS
109	bool "Collect scheduler statistics"
110	depends on DEBUG_KERNEL && PROC_FS
111	help
112	  If you say Y here, additional code will be inserted into the
113	  scheduler and related routines to collect statistics about
114	  scheduler behavior and provide them in /proc/schedstat.  These
115	  stats may be useful for both tuning and debugging the scheduler
116	  If you aren't debugging the scheduler or trying to tune a specific
117	  application, you can say N to avoid the very slight overhead
118	  this adds.
119
120config TIMER_STATS
121	bool "Collect kernel timers statistics"
122	depends on DEBUG_KERNEL && PROC_FS
123	help
124	  If you say Y here, additional code will be inserted into the
125	  timer routines to collect statistics about kernel timers being
126	  reprogrammed. The statistics can be read from /proc/timer_stats.
127	  The statistics collection is started by writing 1 to /proc/timer_stats,
128	  writing 0 stops it. This feature is useful to collect information
129	  about timer usage patterns in kernel and userspace.
130
131config DEBUG_SLAB
132	bool "Debug slab memory allocations"
133	depends on DEBUG_KERNEL && SLAB
134	help
135	  Say Y here to have the kernel do limited verification on memory
136	  allocation as well as poisoning memory on free to catch use of freed
137	  memory. This can make kmalloc/kfree-intensive workloads much slower.
138
139config DEBUG_SLAB_LEAK
140	bool "Memory leak debugging"
141	depends on DEBUG_SLAB
142
143config DEBUG_PREEMPT
144	bool "Debug preemptible kernel"
145	depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
146	default y
147	help
148	  If you say Y here then the kernel will use a debug variant of the
149	  commonly used smp_processor_id() function and will print warnings
150	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
151	  will detect preemption count underflows.
152
153config DEBUG_RT_MUTEXES
154	bool "RT Mutex debugging, deadlock detection"
155	depends on DEBUG_KERNEL && RT_MUTEXES
156	help
157	 This allows rt mutex semantics violations and rt mutex related
158	 deadlocks (lockups) to be detected and reported automatically.
159
160config DEBUG_PI_LIST
161	bool
162	default y
163	depends on DEBUG_RT_MUTEXES
164
165config RT_MUTEX_TESTER
166	bool "Built-in scriptable tester for rt-mutexes"
167	depends on DEBUG_KERNEL && RT_MUTEXES
168	help
169	  This option enables a rt-mutex tester.
170
171config DEBUG_SPINLOCK
172	bool "Spinlock and rw-lock debugging: basic checks"
173	depends on DEBUG_KERNEL
174	help
175	  Say Y here and build SMP to catch missing spinlock initialization
176	  and certain other kinds of spinlock errors commonly made.  This is
177	  best used in conjunction with the NMI watchdog so that spinlock
178	  deadlocks are also debuggable.
179
180config DEBUG_MUTEXES
181	bool "Mutex debugging: basic checks"
182	depends on DEBUG_KERNEL
183	help
184	 This feature allows mutex semantics violations to be detected and
185	 reported.
186
187config DEBUG_SEMAPHORE
188	bool "Semaphore debugging"
189	depends on DEBUG_KERNEL
190	depends on ALPHA || FRV
191	default n
192	help
193	  If you say Y here then semaphore processing will issue lots of
194	  verbose debugging messages.  If you suspect a semaphore problem or a
195	  kernel hacker asks for this option then say Y.  Otherwise say N.
196
197config DEBUG_LOCK_ALLOC
198	bool "Lock debugging: detect incorrect freeing of live locks"
199	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
200	select DEBUG_SPINLOCK
201	select DEBUG_MUTEXES
202	select LOCKDEP
203	help
204	 This feature will check whether any held lock (spinlock, rwlock,
205	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
206	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
207	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
208	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
209	 held during task exit.
210
211config PROVE_LOCKING
212	bool "Lock debugging: prove locking correctness"
213	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
214	select LOCKDEP
215	select DEBUG_SPINLOCK
216	select DEBUG_MUTEXES
217	select DEBUG_LOCK_ALLOC
218	default n
219	help
220	 This feature enables the kernel to prove that all locking
221	 that occurs in the kernel runtime is mathematically
222	 correct: that under no circumstance could an arbitrary (and
223	 not yet triggered) combination of observed locking
224	 sequences (on an arbitrary number of CPUs, running an
225	 arbitrary number of tasks and interrupt contexts) cause a
226	 deadlock.
227
228	 In short, this feature enables the kernel to report locking
229	 related deadlocks before they actually occur.
230
231	 The proof does not depend on how hard and complex a
232	 deadlock scenario would be to trigger: how many
233	 participant CPUs, tasks and irq-contexts would be needed
234	 for it to trigger. The proof also does not depend on
235	 timing: if a race and a resulting deadlock is possible
236	 theoretically (no matter how unlikely the race scenario
237	 is), it will be proven so and will immediately be
238	 reported by the kernel (once the event is observed that
239	 makes the deadlock theoretically possible).
240
241	 If a deadlock is impossible (i.e. the locking rules, as
242	 observed by the kernel, are mathematically correct), the
243	 kernel reports nothing.
244
245	 NOTE: this feature can also be enabled for rwlocks, mutexes
246	 and rwsems - in which case all dependencies between these
247	 different locking variants are observed and mapped too, and
248	 the proof of observed correctness is also maintained for an
249	 arbitrary combination of these separate locking variants.
250
251	 For more details, see Documentation/lockdep-design.txt.
252
253config LOCKDEP
254	bool
255	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
256	select STACKTRACE
257	select FRAME_POINTER if !X86 && !MIPS
258	select KALLSYMS
259	select KALLSYMS_ALL
260
261config DEBUG_LOCKDEP
262	bool "Lock dependency engine debugging"
263	depends on DEBUG_KERNEL && LOCKDEP
264	help
265	  If you say Y here, the lock dependency engine will do
266	  additional runtime checks to debug itself, at the price
267	  of more runtime overhead.
268
269config TRACE_IRQFLAGS
270	depends on DEBUG_KERNEL
271	bool
272	default y
273	depends on TRACE_IRQFLAGS_SUPPORT
274	depends on PROVE_LOCKING
275
276config DEBUG_SPINLOCK_SLEEP
277	bool "Spinlock debugging: sleep-inside-spinlock checking"
278	depends on DEBUG_KERNEL
279	help
280	  If you say Y here, various routines which may sleep will become very
281	  noisy if they are called with a spinlock held.
282
283config DEBUG_LOCKING_API_SELFTESTS
284	bool "Locking API boot-time self-tests"
285	depends on DEBUG_KERNEL
286	help
287	  Say Y here if you want the kernel to run a short self-test during
288	  bootup. The self-test checks whether common types of locking bugs
289	  are detected by debugging mechanisms or not. (if you disable
290	  lock debugging then those bugs wont be detected of course.)
291	  The following locking APIs are covered: spinlocks, rwlocks,
292	  mutexes and rwsems.
293
294config STACKTRACE
295	bool
296	depends on DEBUG_KERNEL
297	depends on STACKTRACE_SUPPORT
298
299config DEBUG_KOBJECT
300	bool "kobject debugging"
301	depends on DEBUG_KERNEL
302	help
303	  If you say Y here, some extra kobject debugging messages will be sent
304	  to the syslog.
305
306config DEBUG_HIGHMEM
307	bool "Highmem debugging"
308	depends on DEBUG_KERNEL && HIGHMEM
309	help
310	  This options enables addition error checking for high memory systems.
311	  Disable for production systems.
312
313config DEBUG_BUGVERBOSE
314	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
315	depends on BUG
316	depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BFIN
317	default !EMBEDDED
318	help
319	  Say Y here to make BUG() panics output the file name and line number
320	  of the BUG call as well as the EIP and oops trace.  This aids
321	  debugging but costs about 70-100K of memory.
322
323config DEBUG_INFO
324	bool "Compile the kernel with debug info"
325	depends on DEBUG_KERNEL
326	help
327          If you say Y here the resulting kernel image will include
328	  debugging info resulting in a larger kernel image.
329	  This adds debug symbols to the kernel and modules (gcc -g), and
330	  is needed if you intend to use kernel crashdump or binary object
331	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
332	  Say Y here only if you plan to debug the kernel.
333
334	  If unsure, say N.
335
336config DEBUG_VM
337	bool "Debug VM"
338	depends on DEBUG_KERNEL
339	help
340	  Enable this to turn on extended checks in the virtual-memory system
341          that may impact performance.
342
343	  If unsure, say N.
344
345config DEBUG_LIST
346	bool "Debug linked list manipulation"
347	depends on DEBUG_KERNEL
348	help
349	  Enable this to turn on extended checks in the linked-list
350	  walking routines.
351
352	  If unsure, say N.
353
354config FRAME_POINTER
355	bool "Compile the kernel with frame pointers"
356	depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN)
357	default y if DEBUG_INFO && UML
358	help
359	  If you say Y here the resulting kernel image will be slightly larger
360	  and slower, but it might give very useful debugging information on
361	  some architectures or if you use external debuggers.
362	  If you don't debug the kernel, you can say N.
363
364config FORCED_INLINING
365	bool "Force gcc to inline functions marked 'inline'"
366	depends on DEBUG_KERNEL
367	default y
368	help
369	  This option determines if the kernel forces gcc to inline the functions
370	  developers have marked 'inline'. Doing so takes away freedom from gcc to
371	  do what it thinks is best, which is desirable for the gcc 3.x series of
372	  compilers. The gcc 4.x series have a rewritten inlining algorithm and
373	  disabling this option will generate a smaller kernel there. Hopefully
374	  this algorithm is so good that allowing gcc4 to make the decision can
375	  become the default in the future, until then this option is there to
376	  test gcc for this.
377
378config RCU_TORTURE_TEST
379	tristate "torture tests for RCU"
380	depends on DEBUG_KERNEL
381	default n
382	help
383	  This option provides a kernel module that runs torture tests
384	  on the RCU infrastructure.  The kernel module may be built
385	  after the fact on the running kernel to be tested, if desired.
386
387	  Say Y here if you want RCU torture tests to start automatically
388	  at boot time (you probably don't).
389	  Say M if you want the RCU torture tests to build as a module.
390	  Say N if you are unsure.
391
392config LKDTM
393	tristate "Linux Kernel Dump Test Tool Module"
394	depends on DEBUG_KERNEL
395	depends on KPROBES
396	default n
397	help
398	This module enables testing of the different dumping mechanisms by
399	inducing system failures at predefined crash points.
400	If you don't need it: say N
401	Choose M here to compile this code as a module. The module will be
402	called lkdtm.
403
404	Documentation on how to use the module can be found in
405	drivers/misc/lkdtm.c
406
407config FAULT_INJECTION
408	bool "Fault-injection framework"
409	depends on DEBUG_KERNEL
410	help
411	  Provide fault-injection framework.
412	  For more details, see Documentation/fault-injection/.
413
414config FAILSLAB
415	bool "Fault-injection capability for kmalloc"
416	depends on FAULT_INJECTION
417	help
418	  Provide fault-injection capability for kmalloc.
419
420config FAIL_PAGE_ALLOC
421	bool "Fault-injection capabilitiy for alloc_pages()"
422	depends on FAULT_INJECTION
423	help
424	  Provide fault-injection capability for alloc_pages().
425
426config FAIL_MAKE_REQUEST
427	bool "Fault-injection capability for disk IO"
428	depends on FAULT_INJECTION
429	help
430	  Provide fault-injection capability for disk IO.
431
432config FAULT_INJECTION_DEBUG_FS
433	bool "Debugfs entries for fault-injection capabilities"
434	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
435	help
436	  Enable configuration of fault-injection capabilities via debugfs.
437
438config FAULT_INJECTION_STACKTRACE_FILTER
439	bool "stacktrace filter for fault-injection capabilities"
440	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
441	depends on !X86_64
442	select STACKTRACE
443	select FRAME_POINTER
444	help
445	  Provide stacktrace filter for fault-injection capabilities
446