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Linus Torvalds1da177e2005-04-16 15:20:36 -07001
2config PRINTK_TIME
3 bool "Show timing information on printks"
Randy Dunlapd3b8b6e2006-12-06 20:36:38 -08004 depends on PRINTK
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 help
Kay Sievers649e6ee2012-05-10 04:30:45 +02006 Selecting this option causes time stamps of the printk()
7 messages to be added to the output of the syslog() system
8 call and at the console.
9
10 The timestamp is always recorded internally, and exported
11 to /dev/kmsg. This flag just specifies if the timestamp should
12 be included, not that the timestamp is recorded.
13
14 The behavior is also controlled by the kernel command line
15 parameter printk.time=1. See Documentation/kernel-parameters.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -070016
Mandeep Singh Baines5af5bcb2011-03-22 16:34:23 -070017config DEFAULT_MESSAGE_LOGLEVEL
18 int "Default message log level (1-7)"
19 range 1 7
20 default "4"
21 help
22 Default log level for printk statements with no specified priority.
23
24 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
25 that are auditing their logs closely may want to set it to a lower
26 priority.
27
Jeff Garzikde488442007-10-25 04:06:13 -040028config ENABLE_WARN_DEPRECATED
29 bool "Enable __deprecated logic"
30 default y
31 help
32 Enable the __deprecated logic in the kernel build.
33 Disable this to suppress the "warning: 'foo' is deprecated
34 (declared at kernel/power/somefile.c:1234)" messages.
35
Andrew Mortoncebc04b2006-08-14 22:43:18 -070036config ENABLE_MUST_CHECK
37 bool "Enable __must_check logic"
38 default y
39 help
40 Enable the __must_check logic in the kernel build. Disable this to
41 suppress the "warning: ignoring return value of 'foo', declared with
42 attribute warn_unused_result" messages.
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
Andi Kleen35bb5b12008-02-22 15:15:03 +010044config FRAME_WARN
45 int "Warn for stack frames larger than (needs gcc 4.4)"
46 range 0 8192
47 default 1024 if !64BIT
48 default 2048 if 64BIT
49 help
50 Tell gcc to warn at build time for stack frames larger than this.
51 Setting this too low will cause a lot of warnings.
52 Setting it to 0 disables the warning.
53 Requires gcc 4.4
54
Linus Torvalds1da177e2005-04-16 15:20:36 -070055config MAGIC_SYSRQ
56 bool "Magic SysRq key"
Adrian Bunkf346f4b2006-01-09 20:54:51 -080057 depends on !UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 help
59 If you say Y here, you will have some control over the system even
60 if the system crashes for example during kernel debugging (e.g., you
61 will be able to flush the buffer cache to disk, reboot the system
62 immediately or dump some status information). This is accomplished
63 by pressing various keys while holding SysRq (Alt+PrintScreen). It
64 also works on a serial console (on PC hardware at least), if you
65 send a BREAK and then within 5 seconds a command keypress. The
66 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
67 unless you really know what this hack does.
68
Randy Dunlap99657c72009-09-18 12:49:22 -070069config STRIP_ASM_SYMS
70 bool "Strip assembler-generated symbols during link"
71 default n
72 help
73 Strip internal assembler-generated symbols during a link (symbols
74 that look like '.Lxxx') so they don't pollute the output of
75 get_wchan() and suchlike.
76
Andi Kleen1873e872012-03-28 11:51:18 -070077config READABLE_ASM
78 bool "Generate readable assembler code"
79 depends on DEBUG_KERNEL
80 help
81 Disable some compiler optimizations that tend to generate human unreadable
82 assembler output. This may make the kernel slightly slower, but it helps
83 to keep kernel developers who have to stare a lot at assembler listings
84 sane.
85
Arjan van de Venf71d20e2006-06-28 04:26:45 -070086config UNUSED_SYMBOLS
87 bool "Enable unused/obsolete exported symbols"
88 default y if X86
89 help
90 Unused but exported symbols make the kernel needlessly bigger. For
91 that reason most of these unused exports will soon be removed. This
92 option is provided temporarily to provide a transition period in case
93 some external kernel module needs one of these symbols anyway. If you
94 encounter such a case in your module, consider if you are actually
95 using the right API. (rationale: since nobody in the kernel is using
96 this in a module, there is a pretty good chance it's actually the
97 wrong interface to use). If you really need the symbol, please send a
98 mail to the linux kernel mailing list mentioning the symbol and why
99 you really need it, and what the merge plan to the mainline kernel for
100 your module is.
101
Don Mullisbf4735a2006-12-10 02:18:37 -0800102config DEBUG_FS
103 bool "Debug Filesystem"
Don Mullisbf4735a2006-12-10 02:18:37 -0800104 help
105 debugfs is a virtual file system that kernel developers use to put
106 debugging files into. Enable this option to be able to read and
107 write to these files.
108
Robert P. J. Dayff543332008-05-20 00:06:00 +0200109 For detailed documentation on the debugfs API, see
110 Documentation/DocBook/filesystems.
111
Don Mullisbf4735a2006-12-10 02:18:37 -0800112 If unsure, say N.
113
114config HEADERS_CHECK
115 bool "Run 'make headers_check' when building vmlinux"
116 depends on !UML
117 help
118 This option will extract the user-visible kernel headers whenever
119 building the kernel, and will run basic sanity checks on them to
120 ensure that exported files do not attempt to include files which
121 were not exported, etc.
122
123 If you're making modifications to header files which are
124 relevant for userspace, say 'Y', and check the headers
125 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
126 your build tree), to make sure they're suitable.
127
Sam Ravnborg91341d42008-01-21 21:31:44 +0100128config DEBUG_SECTION_MISMATCH
129 bool "Enable full Section mismatch analysis"
Sam Ravnborg91341d42008-01-21 21:31:44 +0100130 help
131 The section mismatch analysis checks if there are illegal
132 references from one section to another section.
Michael Wittene809ab02011-04-17 04:08:48 +0000133 During linktime or runtime, some sections are dropped;
134 any use of code/data previously in these sections would
Sam Ravnborg91341d42008-01-21 21:31:44 +0100135 most likely result in an oops.
Michael Wittene809ab02011-04-17 04:08:48 +0000136 In the code, functions and variables are annotated with
137 __init, __devinit, etc. (see the full list in include/linux/init.h),
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100138 which results in the code/data being placed in specific sections.
Michael Wittene809ab02011-04-17 04:08:48 +0000139 The section mismatch analysis is always performed after a full
140 kernel build, and enabling this option causes the following
141 additional steps to occur:
142 - Add the option -fno-inline-functions-called-once to gcc commands.
143 When inlining a function annotated with __init in a non-init
144 function, we would lose the section information and thus
Sam Ravnborg91341d42008-01-21 21:31:44 +0100145 the analysis would not catch the illegal reference.
Michael Wittene809ab02011-04-17 04:08:48 +0000146 This option tells gcc to inline less (but it does result in
147 a larger kernel).
148 - Run the section mismatch analysis for each module/built-in.o file.
149 When we run the section mismatch analysis on vmlinux.o, we
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100150 lose valueble information about where the mismatch was
Sam Ravnborg91341d42008-01-21 21:31:44 +0100151 introduced.
152 Running the analysis for each module/built-in.o file
Michael Wittene809ab02011-04-17 04:08:48 +0000153 tells where the mismatch happens much closer to the
154 source. The drawback is that the same mismatch is
155 reported at least twice.
156 - Enable verbose reporting from modpost in order to help resolve
157 the section mismatches that are reported.
Sam Ravnborg91341d42008-01-21 21:31:44 +0100158
Adrian Bunkf346f4b2006-01-09 20:54:51 -0800159config DEBUG_KERNEL
160 bool "Kernel debugging"
161 help
162 Say Y here if you are developing drivers or trying to debug and
163 identify kernel problems.
164
David Woodhousea304e1b2007-02-12 00:52:00 -0800165config DEBUG_SHIRQ
166 bool "Debug shared IRQ handlers"
167 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
168 help
169 Enable this to generate a spurious interrupt as soon as a shared
170 interrupt handler is registered, and just before one is deregistered.
171 Drivers ought to be able to handle interrupts coming in at those
172 points; some don't and need to be caught.
173
Don Zickus58687ac2010-05-07 17:11:44 -0400174config LOCKUP_DETECTOR
175 bool "Detect Hard and Soft Lockups"
Heiko Carstensdea20a32006-10-11 01:20:44 -0700176 depends on DEBUG_KERNEL && !S390
Ingo Molnar8446f1d2005-09-06 15:16:27 -0700177 help
Don Zickus58687ac2010-05-07 17:11:44 -0400178 Say Y here to enable the kernel to act as a watchdog to detect
179 hard and soft lockups.
Don Zickus84e478c2010-02-05 21:47:05 -0500180
Don Zickus58687ac2010-05-07 17:11:44 -0400181 Softlockups are bugs that cause the kernel to loop in kernel
Fernando Luis Vázquez Cao5f329082012-02-09 17:42:21 -0500182 mode for more than 20 seconds, without giving other tasks a
Don Zickus58687ac2010-05-07 17:11:44 -0400183 chance to run. The current stack trace is displayed upon
184 detection and the system will stay locked up.
Ingo Molnar8446f1d2005-09-06 15:16:27 -0700185
Don Zickus58687ac2010-05-07 17:11:44 -0400186 Hardlockups are bugs that cause the CPU to loop in kernel mode
Fernando Luis Vázquez Cao5f329082012-02-09 17:42:21 -0500187 for more than 10 seconds, without letting other interrupts have a
Don Zickus58687ac2010-05-07 17:11:44 -0400188 chance to run. The current stack trace is displayed upon detection
189 and the system will stay locked up.
Ingo Molnar8446f1d2005-09-06 15:16:27 -0700190
Don Zickus58687ac2010-05-07 17:11:44 -0400191 The overhead should be minimal. A periodic hrtimer runs to
Fernando Luis Vázquez Cao5f329082012-02-09 17:42:21 -0500192 generate interrupts and kick the watchdog task every 4 seconds.
193 An NMI is generated every 10 seconds or so to check for hardlockups.
194
195 The frequency of hrtimer and NMI events and the soft and hard lockup
196 thresholds can be controlled through the sysctl watchdog_thresh.
Don Zickus84e478c2010-02-05 21:47:05 -0500197
Frederic Weisbecker23637d42010-05-15 23:15:20 +0200198config HARDLOCKUP_DETECTOR
Jan Beulich8f1f66e2012-10-04 17:13:17 -0700199 def_bool y
200 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
201 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
Ingo Molnar8446f1d2005-09-06 15:16:27 -0700202
Don Zickusfef2c9b2011-03-22 16:34:16 -0700203config BOOTPARAM_HARDLOCKUP_PANIC
204 bool "Panic (Reboot) On Hard Lockups"
Jan Beulich8f1f66e2012-10-04 17:13:17 -0700205 depends on HARDLOCKUP_DETECTOR
Don Zickusfef2c9b2011-03-22 16:34:16 -0700206 help
207 Say Y here to enable the kernel to panic on "hard lockups",
208 which are bugs that cause the kernel to loop in kernel
Fernando Luis Vázquez Cao5f329082012-02-09 17:42:21 -0500209 mode with interrupts disabled for more than 10 seconds (configurable
210 using the watchdog_thresh sysctl).
Don Zickusfef2c9b2011-03-22 16:34:16 -0700211
212 Say N if unsure.
213
214config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
215 int
Jan Beulich8f1f66e2012-10-04 17:13:17 -0700216 depends on HARDLOCKUP_DETECTOR
Don Zickusfef2c9b2011-03-22 16:34:16 -0700217 range 0 1
218 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
219 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
220
Ingo Molnar9c44bc02008-05-12 21:21:04 +0200221config BOOTPARAM_SOFTLOCKUP_PANIC
222 bool "Panic (Reboot) On Soft Lockups"
Frederic Weisbecker89d7ce22010-05-13 00:27:20 +0200223 depends on LOCKUP_DETECTOR
Ingo Molnar9c44bc02008-05-12 21:21:04 +0200224 help
225 Say Y here to enable the kernel to panic on "soft lockups",
226 which are bugs that cause the kernel to loop in kernel
Fernando Luis Vázquez Cao5f329082012-02-09 17:42:21 -0500227 mode for more than 20 seconds (configurable using the watchdog_thresh
228 sysctl), without giving other tasks a chance to run.
Ingo Molnar9c44bc02008-05-12 21:21:04 +0200229
230 The panic can be used in combination with panic_timeout,
231 to cause the system to reboot automatically after a
232 lockup has been detected. This feature is useful for
233 high-availability systems that have uptime guarantees and
234 where a lockup must be resolved ASAP.
235
236 Say N if unsure.
237
238config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
239 int
Frederic Weisbeckere16bb1d2010-05-15 22:30:22 +0200240 depends on LOCKUP_DETECTOR
Ingo Molnar9c44bc02008-05-12 21:21:04 +0200241 range 0 1
242 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
243 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
244
Kyle McMartin2a01bb32012-04-11 08:15:29 -0400245config PANIC_ON_OOPS
246 bool "Panic on Oops" if EXPERT
247 default n
248 help
249 Say Y here to enable the kernel to panic when it oopses. This
250 has the same effect as setting oops=panic on the kernel command
251 line.
252
253 This feature is useful to ensure that the kernel does not do
254 anything erroneous after an oops which could result in data
255 corruption or other issues.
256
257 Say N if unsure.
258
259config PANIC_ON_OOPS_VALUE
260 int
261 range 0 1
262 default 0 if !PANIC_ON_OOPS
263 default 1 if PANIC_ON_OOPS
264
Mandeep Singh Bainese162b392009-01-15 11:08:40 -0800265config DETECT_HUNG_TASK
266 bool "Detect Hung Tasks"
267 depends on DEBUG_KERNEL
Anton Blanchard8edbb832011-07-05 13:32:40 +1000268 default LOCKUP_DETECTOR
Mandeep Singh Bainese162b392009-01-15 11:08:40 -0800269 help
270 Say Y here to enable the kernel to detect "hung tasks",
271 which are bugs that cause the task to be stuck in
272 uninterruptible "D" state indefinitiley.
273
274 When a hung task is detected, the kernel will print the
275 current stack trace (which you should report), but the
276 task will stay in uninterruptible state. If lockdep is
277 enabled then all held locks will also be reported. This
278 feature has negligible overhead.
279
Jeff Mahoneye11feaa2011-04-27 14:27:24 -0400280config DEFAULT_HUNG_TASK_TIMEOUT
281 int "Default timeout for hung task detection (in seconds)"
282 depends on DETECT_HUNG_TASK
283 default 120
284 help
285 This option controls the default timeout (in seconds) used
286 to determine when a task has become non-responsive and should
287 be considered hung.
288
Jiaju Zhangc51eaac2011-10-31 17:10:07 -0700289 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
290 sysctl or by writing a value to
291 /proc/sys/kernel/hung_task_timeout_secs.
Jeff Mahoneye11feaa2011-04-27 14:27:24 -0400292
293 A timeout of 0 disables the check. The default is two minutes.
294 Keeping the default should be fine in most cases.
295
Mandeep Singh Bainese162b392009-01-15 11:08:40 -0800296config BOOTPARAM_HUNG_TASK_PANIC
297 bool "Panic (Reboot) On Hung Tasks"
298 depends on DETECT_HUNG_TASK
299 help
300 Say Y here to enable the kernel to panic on "hung tasks",
301 which are bugs that cause the kernel to leave a task stuck
302 in uninterruptible "D" state.
303
304 The panic can be used in combination with panic_timeout,
305 to cause the system to reboot automatically after a
306 hung task has been detected. This feature is useful for
307 high-availability systems that have uptime guarantees and
308 where a hung tasks must be resolved ASAP.
309
310 Say N if unsure.
311
312config BOOTPARAM_HUNG_TASK_PANIC_VALUE
313 int
314 depends on DETECT_HUNG_TASK
315 range 0 1
316 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
317 default 1 if BOOTPARAM_HUNG_TASK_PANIC
318
Ingo Molnarb642b6d2007-07-09 18:52:00 +0200319config SCHED_DEBUG
320 bool "Collect scheduler debugging info"
321 depends on DEBUG_KERNEL && PROC_FS
322 default y
323 help
324 If you say Y here, the /proc/sched_debug file will be provided
325 that can help debug the scheduler. The runtime overhead of this
326 option is minimal.
327
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328config SCHEDSTATS
329 bool "Collect scheduler statistics"
330 depends on DEBUG_KERNEL && PROC_FS
331 help
332 If you say Y here, additional code will be inserted into the
333 scheduler and related routines to collect statistics about
334 scheduler behavior and provide them in /proc/schedstat. These
335 stats may be useful for both tuning and debugging the scheduler
336 If you aren't debugging the scheduler or trying to tune a specific
337 application, you can say N to avoid the very slight overhead
338 this adds.
339
Ingo Molnar82f67cd2007-02-16 01:28:13 -0800340config TIMER_STATS
341 bool "Collect kernel timers statistics"
342 depends on DEBUG_KERNEL && PROC_FS
343 help
344 If you say Y here, additional code will be inserted into the
345 timer routines to collect statistics about kernel timers being
346 reprogrammed. The statistics can be read from /proc/timer_stats.
347 The statistics collection is started by writing 1 to /proc/timer_stats,
348 writing 0 stops it. This feature is useful to collect information
Ingo Molnarc1a834d2007-06-01 00:47:16 -0700349 about timer usage patterns in kernel and userspace. This feature
350 is lightweight if enabled in the kernel config but not activated
351 (it defaults to deactivated on bootup and will only be activated
352 if some application like powertop activates it explicitly).
Ingo Molnar82f67cd2007-02-16 01:28:13 -0800353
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700354config DEBUG_OBJECTS
355 bool "Debug object operations"
356 depends on DEBUG_KERNEL
357 help
358 If you say Y here, additional code will be inserted into the
359 kernel to track the life time of various objects and validate
360 the operations on those objects.
361
362config DEBUG_OBJECTS_SELFTEST
363 bool "Debug objects selftest"
364 depends on DEBUG_OBJECTS
365 help
366 This enables the selftest of the object debug code.
367
368config DEBUG_OBJECTS_FREE
369 bool "Debug objects in freed memory"
370 depends on DEBUG_OBJECTS
371 help
372 This enables checks whether a k/v free operation frees an area
373 which contains an object which has not been deactivated
374 properly. This can make kmalloc/kfree-intensive workloads
375 much slower.
376
Thomas Gleixnerc6f3a972008-04-30 00:55:03 -0700377config DEBUG_OBJECTS_TIMERS
378 bool "Debug timer objects"
379 depends on DEBUG_OBJECTS
380 help
381 If you say Y here, additional code will be inserted into the
382 timer routines to track the life time of timer objects and
383 validate the timer operations.
384
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900385config DEBUG_OBJECTS_WORK
386 bool "Debug work objects"
387 depends on DEBUG_OBJECTS
388 help
389 If you say Y here, additional code will be inserted into the
390 work queue routines to track the life time of work objects and
391 validate the work operations.
392
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400393config DEBUG_OBJECTS_RCU_HEAD
394 bool "Debug RCU callbacks objects"
Mathieu Desnoyersfc2ecf72011-02-23 09:42:14 -0800395 depends on DEBUG_OBJECTS
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400396 help
397 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
398
Tejun Heoe2852ae2010-10-26 14:23:05 -0700399config DEBUG_OBJECTS_PERCPU_COUNTER
400 bool "Debug percpu counter objects"
401 depends on DEBUG_OBJECTS
402 help
403 If you say Y here, additional code will be inserted into the
404 percpu counter routines to track the life time of percpu counter
405 objects and validate the percpu counter operations.
406
Ingo Molnar3ae70202008-11-26 10:02:00 +0100407config DEBUG_OBJECTS_ENABLE_DEFAULT
408 int "debug_objects bootup default value (0-1)"
409 range 0 1
410 default "1"
411 depends on DEBUG_OBJECTS
412 help
413 Debug objects boot parameter default value
414
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415config DEBUG_SLAB
Andrew Morton4a2f0ac2006-03-25 03:07:22 -0800416 bool "Debug slab memory allocations"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200417 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 help
419 Say Y here to have the kernel do limited verification on memory
420 allocation as well as poisoning memory on free to catch use of freed
421 memory. This can make kmalloc/kfree-intensive workloads much slower.
422
Al Viro871751e2006-03-25 03:06:39 -0800423config DEBUG_SLAB_LEAK
424 bool "Memory leak debugging"
425 depends on DEBUG_SLAB
426
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700427config SLUB_DEBUG_ON
428 bool "SLUB debugging on by default"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200429 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700430 default n
431 help
432 Boot with debugging on by default. SLUB boots by default with
433 the runtime debug capabilities switched off. Enabling this is
434 equivalent to specifying the "slub_debug" parameter on boot.
435 There is no support for more fine grained debug control like
436 possible with slub_debug=xxx. SLUB debugging may be switched
437 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
438 "slub_debug=-".
439
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800440config SLUB_STATS
441 default n
442 bool "Enable SLUB performance statistics"
Christoph Lameterab4d5ed2010-10-05 13:57:26 -0500443 depends on SLUB && SYSFS
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800444 help
445 SLUB statistics are useful to debug SLUBs allocation behavior in
446 order find ways to optimize the allocator. This should never be
447 enabled for production use since keeping statistics slows down
448 the allocator by a few percentage points. The slabinfo command
449 supports the determination of the most active slabs to figure
450 out which slabs are relevant to a particular load.
451 Try running: slabinfo -DA
452
Catalin Marinasb69ec422012-10-08 16:28:11 -0700453config HAVE_DEBUG_KMEMLEAK
454 bool
455
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100456config DEBUG_KMEMLEAK
457 bool "Kernel memory leak detector"
Catalin Marinasb69ec422012-10-08 16:28:11 -0700458 depends on DEBUG_KERNEL && EXPERIMENTAL && HAVE_DEBUG_KMEMLEAK
Catalin Marinas79e0d9b2011-04-27 17:06:19 +0100459 select DEBUG_FS
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100460 select STACKTRACE if STACKTRACE_SUPPORT
461 select KALLSYMS
Randy Dunlapb60e26a2009-11-06 15:33:45 -0800462 select CRC32
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100463 help
464 Say Y here if you want to enable the memory leak
465 detector. The memory allocation/freeing is traced in a way
466 similar to the Boehm's conservative garbage collector, the
467 difference being that the orphan objects are not freed but
468 only shown in /sys/kernel/debug/kmemleak. Enabling this
469 feature will introduce an overhead to memory
470 allocations. See Documentation/kmemleak.txt for more
471 details.
472
Catalin Marinasbf96d1e2009-06-23 14:40:27 +0100473 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
474 of finding leaks due to the slab objects poisoning.
475
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100476 In order to access the kmemleak file, debugfs needs to be
477 mounted (usually at /sys/kernel/debug).
478
Catalin Marinasa9d90582009-06-25 10:16:11 +0100479config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
480 int "Maximum kmemleak early log entries"
481 depends on DEBUG_KMEMLEAK
Heiko Carstensdfcc3e62009-10-06 10:33:57 +0200482 range 200 40000
Catalin Marinasa9d90582009-06-25 10:16:11 +0100483 default 400
484 help
485 Kmemleak must track all the memory allocations to avoid
486 reporting false positives. Since memory may be allocated or
487 freed before kmemleak is initialised, an early log buffer is
488 used to store these actions. If kmemleak reports "early log
489 buffer exceeded", please increase this value.
490
Catalin Marinas0822ee42009-06-11 13:24:14 +0100491config DEBUG_KMEMLEAK_TEST
492 tristate "Simple test for the kernel memory leak detector"
Daniel Baluta97182692011-04-04 15:06:44 -0700493 depends on DEBUG_KMEMLEAK && m
Catalin Marinas0822ee42009-06-11 13:24:14 +0100494 help
Daniel Baluta97182692011-04-04 15:06:44 -0700495 This option enables a module that explicitly leaks memory.
Catalin Marinas0822ee42009-06-11 13:24:14 +0100496
497 If unsure, say N.
498
Jason Baronab0155a2010-07-19 11:54:17 +0100499config DEBUG_KMEMLEAK_DEFAULT_OFF
500 bool "Default kmemleak to off"
501 depends on DEBUG_KMEMLEAK
502 help
503 Say Y here to disable kmemleak by default. It can then be enabled
504 on the command line via kmemleak=on.
505
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506config DEBUG_PREEMPT
507 bool "Debug preemptible kernel"
Kumar Gala01deab92009-10-16 07:21:39 +0000508 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 default y
510 help
511 If you say Y here then the kernel will use a debug variant of the
512 commonly used smp_processor_id() function and will print warnings
513 if kernel code uses it in a preemption-unsafe way. Also, the kernel
514 will detect preemption count underflows.
515
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700516config DEBUG_RT_MUTEXES
517 bool "RT Mutex debugging, deadlock detection"
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700518 depends on DEBUG_KERNEL && RT_MUTEXES
519 help
520 This allows rt mutex semantics violations and rt mutex related
521 deadlocks (lockups) to be detected and reported automatically.
522
523config DEBUG_PI_LIST
524 bool
525 default y
526 depends on DEBUG_RT_MUTEXES
527
Thomas Gleixner61a87122006-06-27 02:54:56 -0700528config RT_MUTEX_TESTER
529 bool "Built-in scriptable tester for rt-mutexes"
Roman Zippela1583d32006-06-27 02:55:00 -0700530 depends on DEBUG_KERNEL && RT_MUTEXES
Thomas Gleixner61a87122006-06-27 02:54:56 -0700531 help
532 This option enables a rt-mutex tester.
533
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534config DEBUG_SPINLOCK
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700535 bool "Spinlock and rw-lock debugging: basic checks"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 depends on DEBUG_KERNEL
Raghavendra K Te335e3e2012-03-22 15:25:08 +0530537 select UNINLINE_SPIN_UNLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 help
539 Say Y here and build SMP to catch missing spinlock initialization
540 and certain other kinds of spinlock errors commonly made. This is
541 best used in conjunction with the NMI watchdog so that spinlock
542 deadlocks are also debuggable.
543
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700544config DEBUG_MUTEXES
545 bool "Mutex debugging: basic checks"
546 depends on DEBUG_KERNEL
547 help
548 This feature allows mutex semantics violations to be detected and
549 reported.
550
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700551config DEBUG_LOCK_ALLOC
552 bool "Lock debugging: detect incorrect freeing of live locks"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700553 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700554 select DEBUG_SPINLOCK
555 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700556 select LOCKDEP
557 help
558 This feature will check whether any held lock (spinlock, rwlock,
559 mutex or rwsem) is incorrectly freed by the kernel, via any of the
560 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
561 vfree(), etc.), whether a live lock is incorrectly reinitialized via
562 spin_lock_init()/mutex_init()/etc., or whether there is any lock
563 held during task exit.
564
565config PROVE_LOCKING
566 bool "Lock debugging: prove locking correctness"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700567 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700568 select LOCKDEP
569 select DEBUG_SPINLOCK
570 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700571 select DEBUG_LOCK_ALLOC
Steven Rostedt46b93b72010-08-31 16:35:20 -0400572 select TRACE_IRQFLAGS
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700573 default n
574 help
575 This feature enables the kernel to prove that all locking
576 that occurs in the kernel runtime is mathematically
577 correct: that under no circumstance could an arbitrary (and
578 not yet triggered) combination of observed locking
579 sequences (on an arbitrary number of CPUs, running an
580 arbitrary number of tasks and interrupt contexts) cause a
581 deadlock.
582
583 In short, this feature enables the kernel to report locking
584 related deadlocks before they actually occur.
585
586 The proof does not depend on how hard and complex a
587 deadlock scenario would be to trigger: how many
588 participant CPUs, tasks and irq-contexts would be needed
589 for it to trigger. The proof also does not depend on
590 timing: if a race and a resulting deadlock is possible
591 theoretically (no matter how unlikely the race scenario
592 is), it will be proven so and will immediately be
593 reported by the kernel (once the event is observed that
594 makes the deadlock theoretically possible).
595
596 If a deadlock is impossible (i.e. the locking rules, as
597 observed by the kernel, are mathematically correct), the
598 kernel reports nothing.
599
600 NOTE: this feature can also be enabled for rwlocks, mutexes
601 and rwsems - in which case all dependencies between these
602 different locking variants are observed and mapped too, and
603 the proof of observed correctness is also maintained for an
604 arbitrary combination of these separate locking variants.
605
606 For more details, see Documentation/lockdep-design.txt.
607
Paul E. McKenney632ee202010-02-22 17:04:45 -0800608config PROVE_RCU
609 bool "RCU debugging: prove RCU correctness"
610 depends on PROVE_LOCKING
611 default n
612 help
613 This feature enables lockdep extensions that check for correct
614 use of RCU APIs. This is currently under development. Say Y
615 if you want to debug RCU usage or help work on the PROVE_RCU
616 feature.
617
618 Say N if you are unsure.
619
Lai Jiangshan2b3fc352010-04-20 16:23:07 +0800620config PROVE_RCU_REPEATEDLY
621 bool "RCU debugging: don't disable PROVE_RCU on first splat"
622 depends on PROVE_RCU
623 default n
624 help
625 By itself, PROVE_RCU will disable checking upon issuing the
626 first warning (or "splat"). This feature prevents such
627 disabling, allowing multiple RCU-lockdep warnings to be printed
628 on a single reboot.
629
Paul E. McKenney2dfbf4d2010-09-15 23:30:48 -0700630 Say Y to allow multiple RCU-lockdep warnings per boot.
631
632 Say N if you are unsure.
633
Paul E. McKenneye3ebfb92012-07-02 14:42:01 -0700634config PROVE_RCU_DELAY
635 bool "RCU debugging: preemptible RCU race provocation"
636 depends on DEBUG_KERNEL && PREEMPT_RCU
637 default n
638 help
639 There is a class of races that involve an unlikely preemption
640 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
641 been set to INT_MIN. This feature inserts a delay at that
642 point to increase the probability of these races.
643
644 Say Y to increase probability of preemption of __rcu_read_unlock().
645
646 Say N if you are unsure.
647
Paul E. McKenneyca5ecdd2010-04-28 14:39:09 -0700648config SPARSE_RCU_POINTER
649 bool "RCU debugging: sparse-based checks for pointer usage"
650 default n
651 help
652 This feature enables the __rcu sparse annotation for
653 RCU-protected pointers. This annotation will cause sparse
654 to flag any non-RCU used of annotated pointers. This can be
655 helpful when debugging RCU usage. Please note that this feature
656 is not intended to enforce code cleanliness; it is instead merely
657 a debugging aid.
658
659 Say Y to make sparse flag questionable use of RCU-protected pointers
660
Lai Jiangshan2b3fc352010-04-20 16:23:07 +0800661 Say N if you are unsure.
662
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700663config LOCKDEP
664 bool
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700665 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700666 select STACKTRACE
Michal Simek79aac882010-05-25 11:33:26 +0200667 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700668 select KALLSYMS
669 select KALLSYMS_ALL
670
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700671config LOCK_STAT
Danny ter Haarfdfb8702007-09-24 21:24:43 -0700672 bool "Lock usage statistics"
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700673 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
674 select LOCKDEP
675 select DEBUG_SPINLOCK
676 select DEBUG_MUTEXES
677 select DEBUG_LOCK_ALLOC
678 default n
679 help
680 This feature enables tracking lock contention points
681
Peter Zijlstraa560aa42007-10-07 00:24:33 -0700682 For more details, see Documentation/lockstat.txt
683
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +0100684 This also enables lock events required by "perf lock",
685 subcommand of perf.
686 If you want to use "perf lock", you also need to turn on
687 CONFIG_EVENT_TRACING.
Hitoshi Mitake84c6f882010-02-04 16:08:15 +0900688
689 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +0100690 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
Hitoshi Mitake84c6f882010-02-04 16:08:15 +0900691
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700692config DEBUG_LOCKDEP
693 bool "Lock dependency engine debugging"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700694 depends on DEBUG_KERNEL && LOCKDEP
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700695 help
696 If you say Y here, the lock dependency engine will do
697 additional runtime checks to debug itself, at the price
698 of more runtime overhead.
699
700config TRACE_IRQFLAGS
701 bool
Steven Rostedt46b93b72010-08-31 16:35:20 -0400702 help
703 Enables hooks to interrupt enabling and disabling for
704 either tracing or lock debugging.
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700705
Frederic Weisbeckerd902db12011-06-08 19:31:56 +0200706config DEBUG_ATOMIC_SLEEP
707 bool "Sleep inside atomic section checking"
Frederic Weisbeckere8f7c702011-06-08 01:51:02 +0200708 select PREEMPT_COUNT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709 depends on DEBUG_KERNEL
710 help
711 If you say Y here, various routines which may sleep will become very
Frederic Weisbeckerd902db12011-06-08 19:31:56 +0200712 noisy if they are called inside atomic sections: when a spinlock is
713 held, inside an rcu read side critical section, inside preempt disabled
714 sections, inside an interrupt, etc...
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700716config DEBUG_LOCKING_API_SELFTESTS
717 bool "Locking API boot-time self-tests"
718 depends on DEBUG_KERNEL
719 help
720 Say Y here if you want the kernel to run a short self-test during
721 bootup. The self-test checks whether common types of locking bugs
722 are detected by debugging mechanisms or not. (if you disable
723 lock debugging then those bugs wont be detected of course.)
724 The following locking APIs are covered: spinlocks, rwlocks,
725 mutexes and rwsems.
726
Ingo Molnar8637c092006-07-03 00:24:38 -0700727config STACKTRACE
728 bool
729 depends on STACKTRACE_SUPPORT
730
Stephen Boyd5ca43f62011-05-24 17:13:36 -0700731config DEBUG_STACK_USAGE
732 bool "Stack utilization instrumentation"
Tony Lucke9c31b32012-07-18 10:35:05 -0700733 depends on DEBUG_KERNEL && !IA64 && !PARISC
Stephen Boyd5ca43f62011-05-24 17:13:36 -0700734 help
735 Enables the display of the minimum amount of free stack which each
736 task has ever had available in the sysrq-T and sysrq-P debug output.
737
738 This option will slow down process creation somewhat.
739
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740config DEBUG_KOBJECT
741 bool "kobject debugging"
742 depends on DEBUG_KERNEL
743 help
744 If you say Y here, some extra kobject debugging messages will be sent
745 to the syslog.
746
747config DEBUG_HIGHMEM
748 bool "Highmem debugging"
749 depends on DEBUG_KERNEL && HIGHMEM
750 help
751 This options enables addition error checking for high memory systems.
752 Disable for production systems.
753
Catalin Marinas9b2a60c2012-10-08 16:28:13 -0700754config HAVE_DEBUG_BUGVERBOSE
755 bool
756
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757config DEBUG_BUGVERBOSE
David Rientjes6a108a12011-01-20 14:44:16 -0800758 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
Catalin Marinas9b2a60c2012-10-08 16:28:13 -0700759 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
Alexey Dobriyan8420e7e2009-12-14 18:00:25 -0800760 default y
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 help
762 Say Y here to make BUG() panics output the file name and line number
763 of the BUG call as well as the EIP and oops trace. This aids
764 debugging but costs about 70-100K of memory.
765
766config DEBUG_INFO
767 bool "Compile the kernel with debug info"
768 depends on DEBUG_KERNEL
769 help
770 If you say Y here the resulting kernel image will include
771 debugging info resulting in a larger kernel image.
Andreas Dilgerb72e53f2007-03-27 15:21:33 -0600772 This adds debug symbols to the kernel and modules (gcc -g), and
773 is needed if you intend to use kernel crashdump or binary object
774 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 Say Y here only if you plan to debug the kernel.
776
777 If unsure, say N.
778
Andi Kleend6f4ceb2010-07-14 15:43:52 +0200779config DEBUG_INFO_REDUCED
780 bool "Reduce debugging information"
781 depends on DEBUG_INFO
782 help
783 If you say Y here gcc is instructed to generate less debugging
784 information for structure types. This means that tools that
785 need full debugging information (like kgdb or systemtap) won't
786 be happy. But if you merely need debugging information to
787 resolve line numbers there is no loss. Advantage is that
788 build directory object sizes shrink dramatically over a full
789 DEBUG_INFO build and compile times are reduced too.
790 Only works with newer gcc versions.
791
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800792config DEBUG_VM
793 bool "Debug VM"
794 depends on DEBUG_KERNEL
795 help
Nick Piggin13e74442006-01-06 00:10:58 -0800796 Enable this to turn on extended checks in the virtual-memory system
797 that may impact performance.
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800798
799 If unsure, say N.
800
Michel Lespinasseed8ea812012-10-08 16:31:45 -0700801config DEBUG_VM_RB
802 bool "Debug VM red-black trees"
803 depends on DEBUG_VM
804 help
805 Enable this to turn on more extended checks in the virtual-memory
806 system that may impact performance.
807
808 If unsure, say N.
809
Jiri Slaby59ea7462008-06-12 13:56:40 +0200810config DEBUG_VIRTUAL
811 bool "Debug VM translations"
812 depends on DEBUG_KERNEL && X86
813 help
814 Enable some costly sanity checks in virtual to page code. This can
815 catch mistakes with virt_to_page() and friends.
816
817 If unsure, say N.
818
David Howells8feae132009-01-08 12:04:47 +0000819config DEBUG_NOMMU_REGIONS
820 bool "Debug the global anon/private NOMMU mapping region tree"
821 depends on DEBUG_KERNEL && !MMU
822 help
823 This option causes the global tree of anonymous and private mapping
824 regions to be regularly checked for invalid topology.
825
Dave Hansenad775f52008-02-15 14:38:01 -0800826config DEBUG_WRITECOUNT
827 bool "Debug filesystem writers count"
828 depends on DEBUG_KERNEL
829 help
830 Enable this to catch wrong use of the writers count in struct
831 vfsmount. This will increase the size of each file struct by
832 32 bits.
833
834 If unsure, say N.
835
Mel Gorman6b74ab92008-07-23 21:26:49 -0700836config DEBUG_MEMORY_INIT
David Rientjes6a108a12011-01-20 14:44:16 -0800837 bool "Debug memory initialisation" if EXPERT
838 default !EXPERT
Mel Gorman6b74ab92008-07-23 21:26:49 -0700839 help
840 Enable this for additional checks during memory initialisation.
841 The sanity checks verify aspects of the VM such as the memory model
842 and other information provided by the architecture. Verbose
843 information will be printed at KERN_DEBUG loglevel depending
844 on the mminit_loglevel= command-line option.
845
846 If unsure, say Y
847
Dave Jones199a9af2006-09-29 01:59:00 -0700848config DEBUG_LIST
849 bool "Debug linked list manipulation"
850 depends on DEBUG_KERNEL
851 help
852 Enable this to turn on extended checks in the linked-list
853 walking routines.
854
855 If unsure, say N.
856
Artem Bityutskiy6d411e62010-10-26 14:23:05 -0700857config TEST_LIST_SORT
858 bool "Linked list sorting test"
859 depends on DEBUG_KERNEL
860 help
861 Enable this to turn on 'list_sort()' function test. This test is
862 executed only once during system boot, so affects only boot time.
863
864 If unsure, say N.
865
Jens Axboed6ec0842007-10-22 20:01:06 +0200866config DEBUG_SG
867 bool "Debug SG table operations"
868 depends on DEBUG_KERNEL
869 help
870 Enable this to turn on checks on scatter-gather tables. This can
871 help find problems with drivers that do not properly initialize
872 their sg tables.
873
874 If unsure, say N.
875
Arjan van de Ven1b2439d2008-08-15 15:29:38 -0700876config DEBUG_NOTIFIERS
877 bool "Debug notifier call chains"
878 depends on DEBUG_KERNEL
879 help
880 Enable this to turn on sanity checking for notifier call chains.
881 This is most useful for kernel developers to make sure that
882 modules properly unregister themselves from notifier chains.
883 This is a relatively cheap check but if you care about maximum
884 performance, say N.
885
David Howellse0e81732009-09-02 09:13:40 +0100886config DEBUG_CREDENTIALS
887 bool "Debug credential management"
888 depends on DEBUG_KERNEL
889 help
890 Enable this to turn on some debug checking for credential
891 management. The additional code keeps track of the number of
892 pointers from task_structs to any given cred struct, and checks to
893 see that this number never exceeds the usage count of the cred
894 struct.
895
896 Furthermore, if SELinux is enabled, this also checks that the
897 security pointer in the cred struct is never seen to be invalid.
898
899 If unsure, say N.
900
Jeff Mahoney64dec402009-01-16 13:23:35 -0500901#
902# Select this config option from the architecture Kconfig, if it
Justin P. Mattock52288b62011-08-21 20:02:13 -0700903# is preferred to always offer frame pointers as a config
Jeff Mahoney64dec402009-01-16 13:23:35 -0500904# option on the architecture (regardless of KERNEL_DEBUG):
905#
906config ARCH_WANT_FRAME_POINTERS
907 bool
908 help
909
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910config FRAME_POINTER
911 bool "Compile the kernel with frame pointers"
David Howellsb920de12008-02-08 04:19:31 -0800912 depends on DEBUG_KERNEL && \
Geert Uytterhoeven73020412011-01-22 22:35:38 +0100913 (CRIS || M68K || FRV || UML || \
Ingo Molnarda4276b2009-01-07 11:05:10 +0100914 AVR32 || SUPERH || BLACKFIN || MN10300) || \
915 ARCH_WANT_FRAME_POINTERS
916 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 help
Ingo Molnarda4276b2009-01-07 11:05:10 +0100918 If you say Y here the resulting kernel image will be slightly
919 larger and slower, but it gives very useful debugging information
920 in case of kernel bugs. (precise oopses/stacktraces/warnings)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700922config BOOT_PRINTK_DELAY
923 bool "Delay each boot printk message by N milliseconds"
924 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
925 help
926 This build option allows you to read kernel boot messages
927 by inserting a short delay after each one. The delay is
928 specified in milliseconds on the kernel command line,
929 using "boot_delay=N".
930
931 It is likely that you would also need to use "lpj=M" to preset
932 the "loops per jiffie" value.
933 See a previous boot log for the "lpj" value to use for your
934 system, and then set "lpj=M" before setting "boot_delay=N".
935 NOTE: Using this option may adversely affect SMP systems.
936 I.e., processors other than the first one may not boot up.
Anton Blanchard8edbb832011-07-05 13:32:40 +1000937 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700938 what it believes to be lockup conditions.
939
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800940config RCU_TORTURE_TEST
941 tristate "torture tests for RCU"
942 depends on DEBUG_KERNEL
943 default n
944 help
945 This option provides a kernel module that runs torture tests
946 on the RCU infrastructure. The kernel module may be built
947 after the fact on the running kernel to be tested, if desired.
948
Paul E. McKenney31a72bc2008-06-18 09:26:49 -0700949 Say Y here if you want RCU torture tests to be built into
950 the kernel.
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800951 Say M if you want the RCU torture tests to build as a module.
952 Say N if you are unsure.
Ankita Garg8bb31b92006-10-02 02:17:36 -0700953
Paul E. McKenney31a72bc2008-06-18 09:26:49 -0700954config RCU_TORTURE_TEST_RUNNABLE
955 bool "torture tests for RCU runnable by default"
956 depends on RCU_TORTURE_TEST = y
957 default n
958 help
959 This option provides a way to build the RCU torture tests
960 directly into the kernel without them starting up at boot
961 time. You can use /proc/sys/kernel/rcutorture_runnable
962 to manually override this setting. This /proc file is
963 available only when the RCU torture tests have been built
964 into the kernel.
965
966 Say Y here if you want the RCU torture tests to start during
967 boot (you probably don't).
968 Say N here if you want the RCU torture tests to start only
969 after being manually enabled via /proc.
970
Paul E. McKenneyb1637602010-06-02 16:21:38 -0700971config RCU_CPU_STALL_TIMEOUT
972 int "RCU CPU stall timeout in seconds"
Paul E. McKenneya00e0d712011-02-08 17:14:39 -0800973 depends on TREE_RCU || TREE_PREEMPT_RCU
Paul E. McKenneyb1637602010-06-02 16:21:38 -0700974 range 3 300
Paul E. McKenneyc8960542012-10-25 17:59:23 -0700975 default 21
Paul E. McKenneyb1637602010-06-02 16:21:38 -0700976 help
977 If a given RCU grace period extends more than the specified
978 number of seconds, a CPU stall warning is printed. If the
979 RCU grace period persists, additional CPU stall warnings are
980 printed at more widely spaced intervals.
981
Paul E. McKenney1ed509a2010-02-22 17:05:05 -0800982config RCU_CPU_STALL_VERBOSE
983 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
Paul E. McKenneya00e0d712011-02-08 17:14:39 -0800984 depends on TREE_PREEMPT_RCU
Paul E. McKenney55ec9362010-04-13 12:22:33 -0700985 default y
Paul E. McKenney1ed509a2010-02-22 17:05:05 -0800986 help
987 This option causes RCU to printk detailed per-task information
988 for any tasks that are stalling the current RCU grace period.
Paul E. McKenney64db4cf2008-12-18 21:55:32 +0100989
990 Say N if you are unsure.
991
Paul E. McKenney1ed509a2010-02-22 17:05:05 -0800992 Say Y if you want to enable such checks.
993
Paul E. McKenneya858af22012-01-16 13:29:10 -0800994config RCU_CPU_STALL_INFO
995 bool "Print additional diagnostics on RCU CPU stall"
996 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
997 default n
998 help
999 For each stalled CPU that is aware of the current RCU grace
1000 period, print out additional per-CPU diagnostic information
1001 regarding scheduling-clock ticks, idle state, and,
1002 for RCU_FAST_NO_HZ kernels, idle-entry state.
1003
1004 Say N if you are unsure.
1005
1006 Say Y if you want to enable such diagnostics.
1007
Paul E. McKenney5c8806a2012-01-06 15:10:44 -08001008config RCU_TRACE
1009 bool "Enable tracing for RCU"
1010 depends on DEBUG_KERNEL
1011 help
1012 This option provides tracing in RCU which presents stats
1013 in debugfs for debugging RCU implementation.
1014
1015 Say Y here if you want to enable RCU tracing
1016 Say N if you are unsure.
1017
Ananth N Mavinakayanahalli8c1c9352008-01-30 13:32:53 +01001018config KPROBES_SANITY_TEST
1019 bool "Kprobes sanity tests"
1020 depends on DEBUG_KERNEL
1021 depends on KPROBES
1022 default n
1023 help
1024 This option provides for testing basic kprobes functionality on
1025 boot. A sample kprobe, jprobe and kretprobe are inserted and
1026 verified for functionality.
1027
1028 Say N if you are unsure.
1029
Arjan van de Ven6dab2772008-01-30 13:33:08 +01001030config BACKTRACE_SELF_TEST
1031 tristate "Self test for the backtrace code"
1032 depends on DEBUG_KERNEL
1033 default n
1034 help
1035 This option provides a kernel module that can be used to test
1036 the kernel stack backtrace code. This option is not useful
1037 for distributions or general kernels, but only for kernel
1038 developers working on architecture code.
1039
Vegard Nossumad118c52008-06-27 18:04:48 +02001040 Note that if you want to also test saved backtraces, you will
1041 have to enable STACKTRACE as well.
1042
Arjan van de Ven6dab2772008-01-30 13:33:08 +01001043 Say N if you are unsure.
1044
Tejun Heo870d6652008-08-25 19:47:25 +09001045config DEBUG_BLOCK_EXT_DEVT
1046 bool "Force extended block device numbers and spread them"
1047 depends on DEBUG_KERNEL
1048 depends on BLOCK
Jens Axboe759f8ca2008-08-29 09:06:29 +02001049 default n
Tejun Heo870d6652008-08-25 19:47:25 +09001050 help
Tejun Heo0e11e342008-10-13 10:46:01 +02001051 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1052 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1053 YOU ARE DOING. Distros, please enable this and fix whatever
1054 is broken.
1055
Tejun Heo870d6652008-08-25 19:47:25 +09001056 Conventionally, block device numbers are allocated from
1057 predetermined contiguous area. However, extended block area
1058 may introduce non-contiguous block device numbers. This
1059 option forces most block device numbers to be allocated from
1060 the extended space and spreads them to discover kernel or
1061 userland code paths which assume predetermined contiguous
1062 device number allocation.
1063
Tejun Heo55dc7db2008-09-01 13:44:35 +02001064 Note that turning on this debug option shuffles all the
1065 device numbers for all IDE and SCSI devices including libata
1066 ones, so root partition specified using device number
1067 directly (via rdev or root=MAJ:MIN) won't work anymore.
1068 Textual device names (root=/dev/sdXn) will continue to work.
1069
Tejun Heo870d6652008-08-25 19:47:25 +09001070 Say N if you are unsure.
1071
Tejun Heo7c756e62009-06-24 15:13:50 +09001072config DEBUG_FORCE_WEAK_PER_CPU
1073 bool "Force weak per-cpu definitions"
1074 depends on DEBUG_KERNEL
1075 help
1076 s390 and alpha require percpu variables in modules to be
1077 defined weak to work around addressing range issue which
1078 puts the following two restrictions on percpu variable
1079 definitions.
1080
1081 1. percpu symbols must be unique whether static or not
1082 2. percpu variables can't be defined inside a function
1083
1084 To ensure that generic code follows the above rules, this
1085 option forces all percpu variables to be defined as weak.
1086
Stephen Boyd44ec7ab2011-05-24 17:13:32 -07001087config DEBUG_PER_CPU_MAPS
1088 bool "Debug access to per_cpu maps"
1089 depends on DEBUG_KERNEL
1090 depends on SMP
1091 help
1092 Say Y to verify that the per_cpu map being accessed has
1093 been set up. This adds a fair amount of code to kernel memory
1094 and decreases performance.
1095
1096 Say N if unsure.
1097
Ankita Garg8bb31b92006-10-02 02:17:36 -07001098config LKDTM
1099 tristate "Linux Kernel Dump Test Tool Module"
Simon Kagstrom0347af42010-03-05 13:42:49 -08001100 depends on DEBUG_FS
Chris Snookfddd9cf2008-02-23 15:23:26 -08001101 depends on BLOCK
Ankita Garg8bb31b92006-10-02 02:17:36 -07001102 default n
1103 help
1104 This module enables testing of the different dumping mechanisms by
1105 inducing system failures at predefined crash points.
1106 If you don't need it: say N
1107 Choose M here to compile this code as a module. The module will be
1108 called lkdtm.
1109
1110 Documentation on how to use the module can be found in
Simon Kagstrom0347af42010-03-05 13:42:49 -08001111 Documentation/fault-injection/provoke-crashes.txt
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001112
Akinobu Mita8d438282012-07-30 14:43:02 -07001113config NOTIFIER_ERROR_INJECTION
1114 tristate "Notifier error injection"
1115 depends on DEBUG_KERNEL
1116 select DEBUG_FS
1117 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001118 This option provides the ability to inject artificial errors to
Akinobu Mita8d438282012-07-30 14:43:02 -07001119 specified notifier chain callbacks. It is useful to test the error
1120 handling of notifier call chain failures.
1121
1122 Say N if unsure.
1123
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001124config CPU_NOTIFIER_ERROR_INJECT
1125 tristate "CPU notifier error injection module"
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001126 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001127 help
1128 This option provides a kernel module that can be used to test
Masanari Iidae41e85c2012-11-30 16:44:39 +09001129 the error handling of the cpu notifiers by injecting artificial
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001130 errors to CPU notifier chain callbacks. It is controlled through
1131 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1132
1133 If the notifier call chain should be failed with some events
1134 notified, write the error code to "actions/<notifier event>/error".
1135
1136 Example: Inject CPU offline error (-1 == -EPERM)
1137
1138 # cd /sys/kernel/debug/notifier-error-inject/cpu
1139 # echo -1 > actions/CPU_DOWN_PREPARE/error
1140 # echo 0 > /sys/devices/system/cpu/cpu1/online
1141 bash: echo: write error: Operation not permitted
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001142
1143 To compile this code as a module, choose M here: the module will
1144 be called cpu-notifier-error-inject.
1145
1146 If unsure, say N.
1147
Akinobu Mita048b9c32012-07-30 14:43:07 -07001148config PM_NOTIFIER_ERROR_INJECT
1149 tristate "PM notifier error injection module"
1150 depends on PM && NOTIFIER_ERROR_INJECTION
1151 default m if PM_DEBUG
1152 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001153 This option provides the ability to inject artificial errors to
Akinobu Mita048b9c32012-07-30 14:43:07 -07001154 PM notifier chain callbacks. It is controlled through debugfs
1155 interface /sys/kernel/debug/notifier-error-inject/pm
1156
1157 If the notifier call chain should be failed with some events
1158 notified, write the error code to "actions/<notifier event>/error".
1159
1160 Example: Inject PM suspend error (-12 = -ENOMEM)
1161
1162 # cd /sys/kernel/debug/notifier-error-inject/pm/
1163 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1164 # echo mem > /sys/power/state
1165 bash: echo: write error: Cannot allocate memory
1166
1167 To compile this code as a module, choose M here: the module will
1168 be called pm-notifier-error-inject.
1169
1170 If unsure, say N.
1171
Akinobu Mita9579f5b2012-07-30 14:43:10 -07001172config MEMORY_NOTIFIER_ERROR_INJECT
1173 tristate "Memory hotplug notifier error injection module"
1174 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1175 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001176 This option provides the ability to inject artificial errors to
Akinobu Mita9579f5b2012-07-30 14:43:10 -07001177 memory hotplug notifier chain callbacks. It is controlled through
1178 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1179
1180 If the notifier call chain should be failed with some events
1181 notified, write the error code to "actions/<notifier event>/error".
1182
1183 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1184
1185 # cd /sys/kernel/debug/notifier-error-inject/memory
1186 # echo -12 > actions/MEM_GOING_OFFLINE/error
1187 # echo offline > /sys/devices/system/memory/memoryXXX/state
1188 bash: echo: write error: Cannot allocate memory
1189
1190 To compile this code as a module, choose M here: the module will
1191 be called pSeries-reconfig-notifier-error-inject.
1192
1193 If unsure, say N.
1194
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001195config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1196 tristate "OF reconfig notifier error injection module"
1197 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001198 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001199 This option provides the ability to inject artificial errors to
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001200 OF reconfig notifier chain callbacks. It is controlled
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001201 through debugfs interface under
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001202 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001203
1204 If the notifier call chain should be failed with some events
1205 notified, write the error code to "actions/<notifier event>/error".
1206
1207 To compile this code as a module, choose M here: the module will
1208 be called memory-notifier-error-inject.
1209
1210 If unsure, say N.
1211
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001212config FAULT_INJECTION
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001213 bool "Fault-injection framework"
1214 depends on DEBUG_KERNEL
Akinobu Mita329409a2006-12-08 02:39:48 -08001215 help
1216 Provide fault-injection framework.
1217 For more details, see Documentation/fault-injection/.
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001218
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001219config FAILSLAB
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001220 bool "Fault-injection capability for kmalloc"
1221 depends on FAULT_INJECTION
Akinobu Mita773ff602008-12-23 19:37:01 +09001222 depends on SLAB || SLUB
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001223 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001224 Provide fault-injection capability for kmalloc.
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001225
Akinobu Mita933e3122006-12-08 02:39:45 -08001226config FAIL_PAGE_ALLOC
1227 bool "Fault-injection capabilitiy for alloc_pages()"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001228 depends on FAULT_INJECTION
Akinobu Mita933e3122006-12-08 02:39:45 -08001229 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001230 Provide fault-injection capability for alloc_pages().
Akinobu Mita933e3122006-12-08 02:39:45 -08001231
Akinobu Mitac17bb492006-12-08 02:39:46 -08001232config FAIL_MAKE_REQUEST
Dave Jones86327d12006-12-12 20:16:36 +01001233 bool "Fault-injection capability for disk IO"
Jens Axboe581d4e22008-09-14 05:56:33 -07001234 depends on FAULT_INJECTION && BLOCK
Akinobu Mitac17bb492006-12-08 02:39:46 -08001235 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001236 Provide fault-injection capability for disk IO.
Akinobu Mitac17bb492006-12-08 02:39:46 -08001237
Jens Axboe581d4e22008-09-14 05:56:33 -07001238config FAIL_IO_TIMEOUT
Takuya Yoshikawaf4d014392010-07-21 16:05:53 +09001239 bool "Fault-injection capability for faking disk interrupts"
Jens Axboe581d4e22008-09-14 05:56:33 -07001240 depends on FAULT_INJECTION && BLOCK
1241 help
1242 Provide fault-injection capability on end IO handling. This
1243 will make the block layer "forget" an interrupt as configured,
1244 thus exercising the error handling.
1245
1246 Only works with drivers that use the generic timeout handling,
1247 for others it wont do anything.
1248
Per Forlin1b676f72011-08-19 14:52:37 +02001249config FAIL_MMC_REQUEST
1250 bool "Fault-injection capability for MMC IO"
1251 select DEBUG_FS
1252 depends on FAULT_INJECTION && MMC
1253 help
1254 Provide fault-injection capability for MMC IO.
1255 This will make the mmc core return data errors. This is
1256 useful to test the error handling in the mmc block device
1257 and to test how the mmc host driver handles retries from
1258 the block device.
1259
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001260config FAULT_INJECTION_DEBUG_FS
1261 bool "Debugfs entries for fault-injection capabilities"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001262 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001263 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001264 Enable configuration of fault-injection capabilities via debugfs.
Akinobu Mita1df49002007-02-20 13:57:56 -08001265
1266config FAULT_INJECTION_STACKTRACE_FILTER
1267 bool "stacktrace filter for fault-injection capabilities"
1268 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
Akinobu Mita6d690dc2007-05-12 10:36:53 -07001269 depends on !X86_64
Akinobu Mita1df49002007-02-20 13:57:56 -08001270 select STACKTRACE
Arnd Bergmann89bace62011-06-10 14:12:21 +00001271 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
Akinobu Mita1df49002007-02-20 13:57:56 -08001272 help
1273 Provide stacktrace filter for fault-injection capabilities
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001274
Arjan van de Ven97455122008-01-25 21:08:34 +01001275config LATENCYTOP
1276 bool "Latency measuring infrastructure"
Randy Dunlap625fdca2010-08-12 12:31:21 -07001277 depends on HAVE_LATENCYTOP_SUPPORT
1278 depends on DEBUG_KERNEL
1279 depends on STACKTRACE_SUPPORT
1280 depends on PROC_FS
Arnd Bergmann89bace62011-06-10 14:12:21 +00001281 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
Arjan van de Ven97455122008-01-25 21:08:34 +01001282 select KALLSYMS
1283 select KALLSYMS_ALL
1284 select STACKTRACE
1285 select SCHEDSTATS
1286 select SCHED_DEBUG
Arjan van de Ven97455122008-01-25 21:08:34 +01001287 help
1288 Enable this option if you want to use the LatencyTOP tool
1289 to find out which userspace is blocking on what kernel operations.
1290
Akinobu Mita6a11f752009-03-31 15:23:17 -07001291source mm/Kconfig.debug
Arnaldo Carvalho de Melo16444a82008-05-12 21:20:42 +02001292source kernel/trace/Kconfig
1293
Michel Lespinasse910a7422012-10-08 16:30:39 -07001294config RBTREE_TEST
1295 tristate "Red-Black tree test"
1296 depends on m && DEBUG_KERNEL
1297 help
1298 A benchmark measuring the performance of the rbtree library.
1299 Also includes rbtree invariant checks.
1300
Michel Lespinassefff3fd82012-10-08 16:31:23 -07001301config INTERVAL_TREE_TEST
1302 tristate "Interval tree test"
1303 depends on m && DEBUG_KERNEL
1304 help
1305 A benchmark measuring the performance of the interval tree library
1306
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001307config PROVIDE_OHCI1394_DMA_INIT
Stefan Richter080de8c2008-02-28 20:54:43 +01001308 bool "Remote debugging over FireWire early on boot"
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001309 depends on PCI && X86
1310 help
1311 If you want to debug problems which hang or crash the kernel early
1312 on boot and the crashing machine has a FireWire port, you can use
1313 this feature to remotely access the memory of the crashed machine
1314 over FireWire. This employs remote DMA as part of the OHCI1394
1315 specification which is now the standard for FireWire controllers.
1316
1317 With remote DMA, you can monitor the printk buffer remotely using
1318 firescope and access all memory below 4GB using fireproxy from gdb.
1319 Even controlling a kernel debugger is possible using remote DMA.
1320
1321 Usage:
1322
1323 If ohci1394_dma=early is used as boot parameter, it will initialize
1324 all OHCI1394 controllers which are found in the PCI config space.
1325
1326 As all changes to the FireWire bus such as enabling and disabling
1327 devices cause a bus reset and thereby disable remote DMA for all
1328 devices, be sure to have the cable plugged and FireWire enabled on
1329 the debugging host before booting the debug target for debugging.
1330
1331 This code (~1k) is freed after boot. By then, the firewire stack
1332 in charge of the OHCI-1394 controllers should be used instead.
1333
1334 See Documentation/debugging-via-ohci1394.txt for more information.
Arjan van de Ven97455122008-01-25 21:08:34 +01001335
Stefan Richter080de8c2008-02-28 20:54:43 +01001336config FIREWIRE_OHCI_REMOTE_DMA
1337 bool "Remote debugging over FireWire with firewire-ohci"
1338 depends on FIREWIRE_OHCI
1339 help
1340 This option lets you use the FireWire bus for remote debugging
1341 with help of the firewire-ohci driver. It enables unfiltered
1342 remote DMA in firewire-ohci.
1343 See Documentation/debugging-via-ohci1394.txt for more information.
1344
1345 If unsure, say N.
1346
Randy Dunlap152de302009-02-20 15:38:47 -08001347config BUILD_DOCSRC
Randy Dunlap3794f3e2008-08-12 15:09:06 -07001348 bool "Build targets in Documentation/ tree"
1349 depends on HEADERS_CHECK
1350 help
1351 This option attempts to build objects from the source files in the
1352 kernel Documentation/ tree.
1353
1354 Say N if you are unsure.
1355
Jason Barone9d376f2009-02-05 11:51:38 -05001356config DYNAMIC_DEBUG
Jason Baron86151fd2009-02-05 11:53:15 -05001357 bool "Enable dynamic printk() support"
Jason Baron346e15b2008-08-12 16:46:19 -04001358 default n
1359 depends on PRINTK
Jason Baron86151fd2009-02-05 11:53:15 -05001360 depends on DEBUG_FS
Jason Baron346e15b2008-08-12 16:46:19 -04001361 help
1362
1363 Compiles debug level messages into the kernel, which would not
1364 otherwise be available at runtime. These messages can then be
Jason Baron86151fd2009-02-05 11:53:15 -05001365 enabled/disabled based on various levels of scope - per source file,
1366 function, module, format string, and line number. This mechanism
Jim Cromie29e36c92012-04-27 14:30:41 -06001367 implicitly compiles in all pr_debug() and dev_dbg() calls, which
1368 enlarges the kernel text size by about 2%.
1369
1370 If a source file is compiled with DEBUG flag set, any
1371 pr_debug() calls in it are enabled by default, but can be
1372 disabled at runtime as below. Note that DEBUG flag is
1373 turned on by many CONFIG_*DEBUG* options.
Jason Baron346e15b2008-08-12 16:46:19 -04001374
1375 Usage:
1376
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001377 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
Jason Baron86151fd2009-02-05 11:53:15 -05001378 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1379 filesystem must first be mounted before making use of this feature.
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001380 We refer the control file as: <debugfs>/dynamic_debug/control. This
Jason Baron86151fd2009-02-05 11:53:15 -05001381 file contains a list of the debug statements that can be enabled. The
1382 format for each line of the file is:
Jason Baron346e15b2008-08-12 16:46:19 -04001383
Jason Baron86151fd2009-02-05 11:53:15 -05001384 filename:lineno [module]function flags format
Jason Baron346e15b2008-08-12 16:46:19 -04001385
Jason Baron86151fd2009-02-05 11:53:15 -05001386 filename : source file of the debug statement
1387 lineno : line number of the debug statement
1388 module : module that contains the debug statement
1389 function : function that contains the debug statement
Jim Cromie29e36c92012-04-27 14:30:41 -06001390 flags : '=p' means the line is turned 'on' for printing
Jason Baron86151fd2009-02-05 11:53:15 -05001391 format : the format used for the debug statement
Jason Baron346e15b2008-08-12 16:46:19 -04001392
1393 From a live system:
1394
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001395 nullarbor:~ # cat <debugfs>/dynamic_debug/control
Jason Baron86151fd2009-02-05 11:53:15 -05001396 # filename:lineno [module]function flags format
Jim Cromie29e36c92012-04-27 14:30:41 -06001397 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1398 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1399 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
Jason Baron346e15b2008-08-12 16:46:19 -04001400
Jason Baron86151fd2009-02-05 11:53:15 -05001401 Example usage:
Jason Baron346e15b2008-08-12 16:46:19 -04001402
Jason Baron86151fd2009-02-05 11:53:15 -05001403 // enable the message at line 1603 of file svcsock.c
1404 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001405 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001406
Jason Baron86151fd2009-02-05 11:53:15 -05001407 // enable all the messages in file svcsock.c
1408 nullarbor:~ # echo -n 'file svcsock.c +p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001409 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001410
Jason Baron86151fd2009-02-05 11:53:15 -05001411 // enable all the messages in the NFS server module
1412 nullarbor:~ # echo -n 'module nfsd +p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001413 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001414
Jason Baron86151fd2009-02-05 11:53:15 -05001415 // enable all 12 messages in the function svc_process()
1416 nullarbor:~ # echo -n 'func svc_process +p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001417 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001418
Jason Baron86151fd2009-02-05 11:53:15 -05001419 // disable all 12 messages in the function svc_process()
1420 nullarbor:~ # echo -n 'func svc_process -p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001421 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001422
Jason Baron86151fd2009-02-05 11:53:15 -05001423 See Documentation/dynamic-debug-howto.txt for additional information.
Jason Baron346e15b2008-08-12 16:46:19 -04001424
Joerg Roedel5ee00bd2009-01-09 12:14:24 +01001425config DMA_API_DEBUG
1426 bool "Enable debugging of DMA-API usage"
1427 depends on HAVE_DMA_API_DEBUG
1428 help
1429 Enable this option to debug the use of the DMA API by device drivers.
1430 With this option you will be able to detect common bugs in device
1431 drivers like double-freeing of DMA mappings or freeing mappings that
1432 were never allocated.
1433 This option causes a performance degredation. Use only if you want
1434 to debug device drivers. If unsure, say N.
Jason Baron346e15b2008-08-12 16:46:19 -04001435
Luca Barbieri86a89382010-02-24 10:54:24 +01001436config ATOMIC64_SELFTEST
1437 bool "Perform an atomic64_t self-test at boot"
1438 help
1439 Enable this option to test the atomic64_t functions at boot.
1440
1441 If unsure, say N.
1442
Dan Williams400fb7f2010-10-07 15:25:04 -07001443config ASYNC_RAID6_TEST
1444 tristate "Self test for hardware accelerated raid6 recovery"
1445 depends on ASYNC_RAID6_RECOV
1446 select ASYNC_MEMCPY
1447 ---help---
1448 This is a one-shot self test that permutes through the
1449 recovery of all the possible two disk failure scenarios for a
1450 N-disk array. Recovery is performed with the asynchronous
1451 raid6 recovery routines, and will optionally use an offload
1452 engine if one is available.
1453
1454 If unsure, say N.
1455
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001456source "samples/Kconfig"
Jason Wesseldc7d5522008-04-17 20:05:37 +02001457
1458source "lib/Kconfig.kgdb"
Pekka Enberg0a4af3b2009-02-26 21:38:56 +02001459
1460source "lib/Kconfig.kmemcheck"
Alexey Dobriyan33ee3b22011-03-22 16:34:40 -07001461
1462config TEST_KSTRTOX
1463 tristate "Test kstrto*() family of functions at runtime"