blob: 2d05adb984018776610f573de126f14bda4c9d2e [file] [log] [blame]
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
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
Jeff Garzikde488442007-10-25 04:06:13 -040012config ENABLE_WARN_DEPRECATED
13 bool "Enable __deprecated logic"
14 default y
15 help
16 Enable the __deprecated logic in the kernel build.
17 Disable this to suppress the "warning: 'foo' is deprecated
18 (declared at kernel/power/somefile.c:1234)" messages.
19
Andrew Mortoncebc04b2006-08-14 22:43:18 -070020config ENABLE_MUST_CHECK
21 bool "Enable __must_check logic"
22 default y
23 help
24 Enable the __must_check logic in the kernel build. Disable this to
25 suppress the "warning: ignoring return value of 'foo', declared with
26 attribute warn_unused_result" messages.
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
Andi Kleen35bb5b12008-02-22 15:15:03 +010028config FRAME_WARN
29 int "Warn for stack frames larger than (needs gcc 4.4)"
30 range 0 8192
31 default 1024 if !64BIT
32 default 2048 if 64BIT
33 help
34 Tell gcc to warn at build time for stack frames larger than this.
35 Setting this too low will cause a lot of warnings.
36 Setting it to 0 disables the warning.
37 Requires gcc 4.4
38
Linus Torvalds1da177e2005-04-16 15:20:36 -070039config MAGIC_SYSRQ
40 bool "Magic SysRq key"
Adrian Bunkf346f4b2006-01-09 20:54:51 -080041 depends on !UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070042 help
43 If you say Y here, you will have some control over the system even
44 if the system crashes for example during kernel debugging (e.g., you
45 will be able to flush the buffer cache to disk, reboot the system
46 immediately or dump some status information). This is accomplished
47 by pressing various keys while holding SysRq (Alt+PrintScreen). It
48 also works on a serial console (on PC hardware at least), if you
49 send a BREAK and then within 5 seconds a command keypress. The
50 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
51 unless you really know what this hack does.
52
Randy Dunlap99657c72009-09-18 12:49:22 -070053config STRIP_ASM_SYMS
54 bool "Strip assembler-generated symbols during link"
55 default n
56 help
57 Strip internal assembler-generated symbols during a link (symbols
58 that look like '.Lxxx') so they don't pollute the output of
59 get_wchan() and suchlike.
60
Arjan van de Venf71d20e2006-06-28 04:26:45 -070061config UNUSED_SYMBOLS
62 bool "Enable unused/obsolete exported symbols"
63 default y if X86
64 help
65 Unused but exported symbols make the kernel needlessly bigger. For
66 that reason most of these unused exports will soon be removed. This
67 option is provided temporarily to provide a transition period in case
68 some external kernel module needs one of these symbols anyway. If you
69 encounter such a case in your module, consider if you are actually
70 using the right API. (rationale: since nobody in the kernel is using
71 this in a module, there is a pretty good chance it's actually the
72 wrong interface to use). If you really need the symbol, please send a
73 mail to the linux kernel mailing list mentioning the symbol and why
74 you really need it, and what the merge plan to the mainline kernel for
75 your module is.
76
Don Mullisbf4735a2006-12-10 02:18:37 -080077config DEBUG_FS
78 bool "Debug Filesystem"
Don Mullisbf4735a2006-12-10 02:18:37 -080079 help
80 debugfs is a virtual file system that kernel developers use to put
81 debugging files into. Enable this option to be able to read and
82 write to these files.
83
Robert P. J. Dayff543332008-05-20 00:06:00 +020084 For detailed documentation on the debugfs API, see
85 Documentation/DocBook/filesystems.
86
Don Mullisbf4735a2006-12-10 02:18:37 -080087 If unsure, say N.
88
89config HEADERS_CHECK
90 bool "Run 'make headers_check' when building vmlinux"
91 depends on !UML
92 help
93 This option will extract the user-visible kernel headers whenever
94 building the kernel, and will run basic sanity checks on them to
95 ensure that exported files do not attempt to include files which
96 were not exported, etc.
97
98 If you're making modifications to header files which are
99 relevant for userspace, say 'Y', and check the headers
100 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
101 your build tree), to make sure they're suitable.
102
Sam Ravnborg91341d42008-01-21 21:31:44 +0100103config DEBUG_SECTION_MISMATCH
104 bool "Enable full Section mismatch analysis"
Mike Frysinger1d536612010-03-23 13:35:17 -0700105 depends on UNDEFINED || (BLACKFIN)
106 default y
Sam Ravnborgfa2144b2008-02-15 13:53:11 +0100107 # This option is on purpose disabled for now.
André Goddard Rosaaf901ca2009-11-14 13:09:05 -0200108 # It will be enabled when we are down to a reasonable number
Sam Ravnborgfa2144b2008-02-15 13:53:11 +0100109 # of section mismatch warnings (< 10 for an allyesconfig build)
Sam Ravnborg91341d42008-01-21 21:31:44 +0100110 help
111 The section mismatch analysis checks if there are illegal
112 references from one section to another section.
113 Linux will during link or during runtime drop some sections
114 and any use of code/data previously in these sections will
115 most likely result in an oops.
116 In the code functions and variables are annotated with
117 __init, __devinit etc. (see full list in include/linux/init.h)
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100118 which results in the code/data being placed in specific sections.
119 The section mismatch analysis is always done after a full
120 kernel build but enabling this option will in addition
Sam Ravnborg91341d42008-01-21 21:31:44 +0100121 do the following:
122 - Add the option -fno-inline-functions-called-once to gcc
123 When inlining a function annotated __init in a non-init
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100124 function we would lose the section information and thus
Sam Ravnborg91341d42008-01-21 21:31:44 +0100125 the analysis would not catch the illegal reference.
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100126 This option tells gcc to inline less but will also
Sam Ravnborg91341d42008-01-21 21:31:44 +0100127 result in a larger kernel.
128 - Run the section mismatch analysis for each module/built-in.o
129 When we run the section mismatch analysis on vmlinux.o we
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100130 lose valueble information about where the mismatch was
Sam Ravnborg91341d42008-01-21 21:31:44 +0100131 introduced.
132 Running the analysis for each module/built-in.o file
133 will tell where the mismatch happens much closer to the
134 source. The drawback is that we will report the same
135 mismatch at least twice.
Sam Ravnborg588ccd72008-01-24 21:12:37 +0100136 - Enable verbose reporting from modpost to help solving
137 the section mismatches reported.
Sam Ravnborg91341d42008-01-21 21:31:44 +0100138
Adrian Bunkf346f4b2006-01-09 20:54:51 -0800139config DEBUG_KERNEL
140 bool "Kernel debugging"
141 help
142 Say Y here if you are developing drivers or trying to debug and
143 identify kernel problems.
144
David Woodhousea304e1b2007-02-12 00:52:00 -0800145config DEBUG_SHIRQ
146 bool "Debug shared IRQ handlers"
147 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
148 help
149 Enable this to generate a spurious interrupt as soon as a shared
150 interrupt handler is registered, and just before one is deregistered.
151 Drivers ought to be able to handle interrupts coming in at those
152 points; some don't and need to be caught.
153
Don Zickus58687ac2010-05-07 17:11:44 -0400154config LOCKUP_DETECTOR
155 bool "Detect Hard and Soft Lockups"
Heiko Carstensdea20a32006-10-11 01:20:44 -0700156 depends on DEBUG_KERNEL && !S390
Ingo Molnar8446f1d2005-09-06 15:16:27 -0700157 help
Don Zickus58687ac2010-05-07 17:11:44 -0400158 Say Y here to enable the kernel to act as a watchdog to detect
159 hard and soft lockups.
Don Zickus84e478c2010-02-05 21:47:05 -0500160
Don Zickus58687ac2010-05-07 17:11:44 -0400161 Softlockups are bugs that cause the kernel to loop in kernel
Ingo Molnar9c44bc02008-05-12 21:21:04 +0200162 mode for more than 60 seconds, without giving other tasks a
Don Zickus58687ac2010-05-07 17:11:44 -0400163 chance to run. The current stack trace is displayed upon
164 detection and the system will stay locked up.
Ingo Molnar8446f1d2005-09-06 15:16:27 -0700165
Don Zickus58687ac2010-05-07 17:11:44 -0400166 Hardlockups are bugs that cause the CPU to loop in kernel mode
167 for more than 60 seconds, without letting other interrupts have a
168 chance to run. The current stack trace is displayed upon detection
169 and the system will stay locked up.
Ingo Molnar8446f1d2005-09-06 15:16:27 -0700170
Don Zickus58687ac2010-05-07 17:11:44 -0400171 The overhead should be minimal. A periodic hrtimer runs to
172 generate interrupts and kick the watchdog task every 10-12 seconds.
173 An NMI is generated every 60 seconds or so to check for hardlockups.
Don Zickus84e478c2010-02-05 21:47:05 -0500174
Frederic Weisbecker23637d42010-05-15 23:15:20 +0200175config HARDLOCKUP_DETECTOR
Don Zickus4a7863c2010-12-22 14:00:03 -0500176 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
177 !ARCH_HAS_NMI_WATCHDOG
Ingo Molnar8446f1d2005-09-06 15:16:27 -0700178
Ingo Molnar9c44bc02008-05-12 21:21:04 +0200179config BOOTPARAM_SOFTLOCKUP_PANIC
180 bool "Panic (Reboot) On Soft Lockups"
Frederic Weisbecker89d7ce22010-05-13 00:27:20 +0200181 depends on LOCKUP_DETECTOR
Ingo Molnar9c44bc02008-05-12 21:21:04 +0200182 help
183 Say Y here to enable the kernel to panic on "soft lockups",
184 which are bugs that cause the kernel to loop in kernel
185 mode for more than 60 seconds, without giving other tasks a
186 chance to run.
187
188 The panic can be used in combination with panic_timeout,
189 to cause the system to reboot automatically after a
190 lockup has been detected. This feature is useful for
191 high-availability systems that have uptime guarantees and
192 where a lockup must be resolved ASAP.
193
194 Say N if unsure.
195
196config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
197 int
Frederic Weisbeckere16bb1d2010-05-15 22:30:22 +0200198 depends on LOCKUP_DETECTOR
Ingo Molnar9c44bc02008-05-12 21:21:04 +0200199 range 0 1
200 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
201 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
202
Mandeep Singh Bainese162b392009-01-15 11:08:40 -0800203config DETECT_HUNG_TASK
204 bool "Detect Hung Tasks"
205 depends on DEBUG_KERNEL
Ingo Molnar77d05632009-04-07 08:55:36 +0200206 default DETECT_SOFTLOCKUP
Mandeep Singh Bainese162b392009-01-15 11:08:40 -0800207 help
208 Say Y here to enable the kernel to detect "hung tasks",
209 which are bugs that cause the task to be stuck in
210 uninterruptible "D" state indefinitiley.
211
212 When a hung task is detected, the kernel will print the
213 current stack trace (which you should report), but the
214 task will stay in uninterruptible state. If lockdep is
215 enabled then all held locks will also be reported. This
216 feature has negligible overhead.
217
218config BOOTPARAM_HUNG_TASK_PANIC
219 bool "Panic (Reboot) On Hung Tasks"
220 depends on DETECT_HUNG_TASK
221 help
222 Say Y here to enable the kernel to panic on "hung tasks",
223 which are bugs that cause the kernel to leave a task stuck
224 in uninterruptible "D" state.
225
226 The panic can be used in combination with panic_timeout,
227 to cause the system to reboot automatically after a
228 hung task has been detected. This feature is useful for
229 high-availability systems that have uptime guarantees and
230 where a hung tasks must be resolved ASAP.
231
232 Say N if unsure.
233
234config BOOTPARAM_HUNG_TASK_PANIC_VALUE
235 int
236 depends on DETECT_HUNG_TASK
237 range 0 1
238 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
239 default 1 if BOOTPARAM_HUNG_TASK_PANIC
240
Ingo Molnarb642b6d2007-07-09 18:52:00 +0200241config SCHED_DEBUG
242 bool "Collect scheduler debugging info"
243 depends on DEBUG_KERNEL && PROC_FS
244 default y
245 help
246 If you say Y here, the /proc/sched_debug file will be provided
247 that can help debug the scheduler. The runtime overhead of this
248 option is minimal.
249
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250config SCHEDSTATS
251 bool "Collect scheduler statistics"
252 depends on DEBUG_KERNEL && PROC_FS
253 help
254 If you say Y here, additional code will be inserted into the
255 scheduler and related routines to collect statistics about
256 scheduler behavior and provide them in /proc/schedstat. These
257 stats may be useful for both tuning and debugging the scheduler
258 If you aren't debugging the scheduler or trying to tune a specific
259 application, you can say N to avoid the very slight overhead
260 this adds.
261
Ingo Molnar82f67cd2007-02-16 01:28:13 -0800262config TIMER_STATS
263 bool "Collect kernel timers statistics"
264 depends on DEBUG_KERNEL && PROC_FS
265 help
266 If you say Y here, additional code will be inserted into the
267 timer routines to collect statistics about kernel timers being
268 reprogrammed. The statistics can be read from /proc/timer_stats.
269 The statistics collection is started by writing 1 to /proc/timer_stats,
270 writing 0 stops it. This feature is useful to collect information
Ingo Molnarc1a834d2007-06-01 00:47:16 -0700271 about timer usage patterns in kernel and userspace. This feature
272 is lightweight if enabled in the kernel config but not activated
273 (it defaults to deactivated on bootup and will only be activated
274 if some application like powertop activates it explicitly).
Ingo Molnar82f67cd2007-02-16 01:28:13 -0800275
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700276config DEBUG_OBJECTS
277 bool "Debug object operations"
278 depends on DEBUG_KERNEL
279 help
280 If you say Y here, additional code will be inserted into the
281 kernel to track the life time of various objects and validate
282 the operations on those objects.
283
284config DEBUG_OBJECTS_SELFTEST
285 bool "Debug objects selftest"
286 depends on DEBUG_OBJECTS
287 help
288 This enables the selftest of the object debug code.
289
290config DEBUG_OBJECTS_FREE
291 bool "Debug objects in freed memory"
292 depends on DEBUG_OBJECTS
293 help
294 This enables checks whether a k/v free operation frees an area
295 which contains an object which has not been deactivated
296 properly. This can make kmalloc/kfree-intensive workloads
297 much slower.
298
Thomas Gleixnerc6f3a972008-04-30 00:55:03 -0700299config DEBUG_OBJECTS_TIMERS
300 bool "Debug timer objects"
301 depends on DEBUG_OBJECTS
302 help
303 If you say Y here, additional code will be inserted into the
304 timer routines to track the life time of timer objects and
305 validate the timer operations.
306
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900307config DEBUG_OBJECTS_WORK
308 bool "Debug work objects"
309 depends on DEBUG_OBJECTS
310 help
311 If you say Y here, additional code will be inserted into the
312 work queue routines to track the life time of work objects and
313 validate the work operations.
314
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400315config DEBUG_OBJECTS_RCU_HEAD
316 bool "Debug RCU callbacks objects"
317 depends on DEBUG_OBJECTS && PREEMPT
318 help
319 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
320
Tejun Heoe2852ae2010-10-26 14:23:05 -0700321config DEBUG_OBJECTS_PERCPU_COUNTER
322 bool "Debug percpu counter objects"
323 depends on DEBUG_OBJECTS
324 help
325 If you say Y here, additional code will be inserted into the
326 percpu counter routines to track the life time of percpu counter
327 objects and validate the percpu counter operations.
328
Ingo Molnar3ae70202008-11-26 10:02:00 +0100329config DEBUG_OBJECTS_ENABLE_DEFAULT
330 int "debug_objects bootup default value (0-1)"
331 range 0 1
332 default "1"
333 depends on DEBUG_OBJECTS
334 help
335 Debug objects boot parameter default value
336
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337config DEBUG_SLAB
Andrew Morton4a2f0ac2006-03-25 03:07:22 -0800338 bool "Debug slab memory allocations"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200339 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 help
341 Say Y here to have the kernel do limited verification on memory
342 allocation as well as poisoning memory on free to catch use of freed
343 memory. This can make kmalloc/kfree-intensive workloads much slower.
344
Al Viro871751e2006-03-25 03:06:39 -0800345config DEBUG_SLAB_LEAK
346 bool "Memory leak debugging"
347 depends on DEBUG_SLAB
348
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700349config SLUB_DEBUG_ON
350 bool "SLUB debugging on by default"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200351 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700352 default n
353 help
354 Boot with debugging on by default. SLUB boots by default with
355 the runtime debug capabilities switched off. Enabling this is
356 equivalent to specifying the "slub_debug" parameter on boot.
357 There is no support for more fine grained debug control like
358 possible with slub_debug=xxx. SLUB debugging may be switched
359 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
360 "slub_debug=-".
361
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800362config SLUB_STATS
363 default n
364 bool "Enable SLUB performance statistics"
Christoph Lameterab4d5ed2010-10-05 13:57:26 -0500365 depends on SLUB && SYSFS
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800366 help
367 SLUB statistics are useful to debug SLUBs allocation behavior in
368 order find ways to optimize the allocator. This should never be
369 enabled for production use since keeping statistics slows down
370 the allocator by a few percentage points. The slabinfo command
371 supports the determination of the most active slabs to figure
372 out which slabs are relevant to a particular load.
373 Try running: slabinfo -DA
374
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100375config DEBUG_KMEMLEAK
376 bool "Kernel memory leak detector"
Heiko Carstensdfcc3e62009-10-06 10:33:57 +0200377 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
Chris Metcalf6b945df2010-10-14 14:54:47 -0400378 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
Heiko Carstensdfcc3e62009-10-06 10:33:57 +0200379
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100380 select DEBUG_FS if SYSFS
381 select STACKTRACE if STACKTRACE_SUPPORT
382 select KALLSYMS
Randy Dunlapb60e26a2009-11-06 15:33:45 -0800383 select CRC32
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100384 help
385 Say Y here if you want to enable the memory leak
386 detector. The memory allocation/freeing is traced in a way
387 similar to the Boehm's conservative garbage collector, the
388 difference being that the orphan objects are not freed but
389 only shown in /sys/kernel/debug/kmemleak. Enabling this
390 feature will introduce an overhead to memory
391 allocations. See Documentation/kmemleak.txt for more
392 details.
393
Catalin Marinasbf96d1e2009-06-23 14:40:27 +0100394 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
395 of finding leaks due to the slab objects poisoning.
396
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100397 In order to access the kmemleak file, debugfs needs to be
398 mounted (usually at /sys/kernel/debug).
399
Catalin Marinasa9d90582009-06-25 10:16:11 +0100400config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
401 int "Maximum kmemleak early log entries"
402 depends on DEBUG_KMEMLEAK
Heiko Carstensdfcc3e62009-10-06 10:33:57 +0200403 range 200 40000
Catalin Marinasa9d90582009-06-25 10:16:11 +0100404 default 400
405 help
406 Kmemleak must track all the memory allocations to avoid
407 reporting false positives. Since memory may be allocated or
408 freed before kmemleak is initialised, an early log buffer is
409 used to store these actions. If kmemleak reports "early log
410 buffer exceeded", please increase this value.
411
Catalin Marinas0822ee42009-06-11 13:24:14 +0100412config DEBUG_KMEMLEAK_TEST
413 tristate "Simple test for the kernel memory leak detector"
414 depends on DEBUG_KMEMLEAK
415 help
416 Say Y or M here to build a test for the kernel memory leak
417 detector. This option enables a module that explicitly leaks
418 memory.
419
420 If unsure, say N.
421
Jason Baronab0155a2010-07-19 11:54:17 +0100422config DEBUG_KMEMLEAK_DEFAULT_OFF
423 bool "Default kmemleak to off"
424 depends on DEBUG_KMEMLEAK
425 help
426 Say Y here to disable kmemleak by default. It can then be enabled
427 on the command line via kmemleak=on.
428
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429config DEBUG_PREEMPT
430 bool "Debug preemptible kernel"
Kumar Gala01deab92009-10-16 07:21:39 +0000431 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 default y
433 help
434 If you say Y here then the kernel will use a debug variant of the
435 commonly used smp_processor_id() function and will print warnings
436 if kernel code uses it in a preemption-unsafe way. Also, the kernel
437 will detect preemption count underflows.
438
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700439config DEBUG_RT_MUTEXES
440 bool "RT Mutex debugging, deadlock detection"
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700441 depends on DEBUG_KERNEL && RT_MUTEXES
442 help
443 This allows rt mutex semantics violations and rt mutex related
444 deadlocks (lockups) to be detected and reported automatically.
445
446config DEBUG_PI_LIST
447 bool
448 default y
449 depends on DEBUG_RT_MUTEXES
450
Thomas Gleixner61a87122006-06-27 02:54:56 -0700451config RT_MUTEX_TESTER
452 bool "Built-in scriptable tester for rt-mutexes"
Roman Zippela1583d32006-06-27 02:55:00 -0700453 depends on DEBUG_KERNEL && RT_MUTEXES
Thomas Gleixner61a87122006-06-27 02:54:56 -0700454 help
455 This option enables a rt-mutex tester.
456
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457config DEBUG_SPINLOCK
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700458 bool "Spinlock and rw-lock debugging: basic checks"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 depends on DEBUG_KERNEL
460 help
461 Say Y here and build SMP to catch missing spinlock initialization
462 and certain other kinds of spinlock errors commonly made. This is
463 best used in conjunction with the NMI watchdog so that spinlock
464 deadlocks are also debuggable.
465
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700466config DEBUG_MUTEXES
467 bool "Mutex debugging: basic checks"
468 depends on DEBUG_KERNEL
469 help
470 This feature allows mutex semantics violations to be detected and
471 reported.
472
Arnd Bergmann6de5bd12010-09-11 18:00:57 +0200473config BKL
474 bool "Big Kernel Lock" if (SMP || PREEMPT)
475 default y
476 help
477 This is the traditional lock that is used in old code instead
478 of proper locking. All drivers that use the BKL should depend
479 on this symbol.
480 Say Y here unless you are working on removing the BKL.
481
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700482config DEBUG_LOCK_ALLOC
483 bool "Lock debugging: detect incorrect freeing of live locks"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700484 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700485 select DEBUG_SPINLOCK
486 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700487 select LOCKDEP
488 help
489 This feature will check whether any held lock (spinlock, rwlock,
490 mutex or rwsem) is incorrectly freed by the kernel, via any of the
491 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
492 vfree(), etc.), whether a live lock is incorrectly reinitialized via
493 spin_lock_init()/mutex_init()/etc., or whether there is any lock
494 held during task exit.
495
496config PROVE_LOCKING
497 bool "Lock debugging: prove locking correctness"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700498 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700499 select LOCKDEP
500 select DEBUG_SPINLOCK
501 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700502 select DEBUG_LOCK_ALLOC
Steven Rostedt46b93b72010-08-31 16:35:20 -0400503 select TRACE_IRQFLAGS
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700504 default n
505 help
506 This feature enables the kernel to prove that all locking
507 that occurs in the kernel runtime is mathematically
508 correct: that under no circumstance could an arbitrary (and
509 not yet triggered) combination of observed locking
510 sequences (on an arbitrary number of CPUs, running an
511 arbitrary number of tasks and interrupt contexts) cause a
512 deadlock.
513
514 In short, this feature enables the kernel to report locking
515 related deadlocks before they actually occur.
516
517 The proof does not depend on how hard and complex a
518 deadlock scenario would be to trigger: how many
519 participant CPUs, tasks and irq-contexts would be needed
520 for it to trigger. The proof also does not depend on
521 timing: if a race and a resulting deadlock is possible
522 theoretically (no matter how unlikely the race scenario
523 is), it will be proven so and will immediately be
524 reported by the kernel (once the event is observed that
525 makes the deadlock theoretically possible).
526
527 If a deadlock is impossible (i.e. the locking rules, as
528 observed by the kernel, are mathematically correct), the
529 kernel reports nothing.
530
531 NOTE: this feature can also be enabled for rwlocks, mutexes
532 and rwsems - in which case all dependencies between these
533 different locking variants are observed and mapped too, and
534 the proof of observed correctness is also maintained for an
535 arbitrary combination of these separate locking variants.
536
537 For more details, see Documentation/lockdep-design.txt.
538
Paul E. McKenney632ee202010-02-22 17:04:45 -0800539config PROVE_RCU
540 bool "RCU debugging: prove RCU correctness"
541 depends on PROVE_LOCKING
542 default n
543 help
544 This feature enables lockdep extensions that check for correct
545 use of RCU APIs. This is currently under development. Say Y
546 if you want to debug RCU usage or help work on the PROVE_RCU
547 feature.
548
549 Say N if you are unsure.
550
Lai Jiangshan2b3fc352010-04-20 16:23:07 +0800551config PROVE_RCU_REPEATEDLY
552 bool "RCU debugging: don't disable PROVE_RCU on first splat"
553 depends on PROVE_RCU
554 default n
555 help
556 By itself, PROVE_RCU will disable checking upon issuing the
557 first warning (or "splat"). This feature prevents such
558 disabling, allowing multiple RCU-lockdep warnings to be printed
559 on a single reboot.
560
Paul E. McKenney2dfbf4d2010-09-15 23:30:48 -0700561 Say Y to allow multiple RCU-lockdep warnings per boot.
562
563 Say N if you are unsure.
564
Paul E. McKenneyca5ecdd2010-04-28 14:39:09 -0700565config SPARSE_RCU_POINTER
566 bool "RCU debugging: sparse-based checks for pointer usage"
567 default n
568 help
569 This feature enables the __rcu sparse annotation for
570 RCU-protected pointers. This annotation will cause sparse
571 to flag any non-RCU used of annotated pointers. This can be
572 helpful when debugging RCU usage. Please note that this feature
573 is not intended to enforce code cleanliness; it is instead merely
574 a debugging aid.
575
576 Say Y to make sparse flag questionable use of RCU-protected pointers
577
Lai Jiangshan2b3fc352010-04-20 16:23:07 +0800578 Say N if you are unsure.
579
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700580config LOCKDEP
581 bool
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700582 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700583 select STACKTRACE
Michal Simek79aac882010-05-25 11:33:26 +0200584 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700585 select KALLSYMS
586 select KALLSYMS_ALL
587
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700588config LOCK_STAT
Danny ter Haarfdfb8702007-09-24 21:24:43 -0700589 bool "Lock usage statistics"
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700590 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
591 select LOCKDEP
592 select DEBUG_SPINLOCK
593 select DEBUG_MUTEXES
594 select DEBUG_LOCK_ALLOC
595 default n
596 help
597 This feature enables tracking lock contention points
598
Peter Zijlstraa560aa42007-10-07 00:24:33 -0700599 For more details, see Documentation/lockstat.txt
600
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +0100601 This also enables lock events required by "perf lock",
602 subcommand of perf.
603 If you want to use "perf lock", you also need to turn on
604 CONFIG_EVENT_TRACING.
Hitoshi Mitake84c6f882010-02-04 16:08:15 +0900605
606 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +0100607 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
Hitoshi Mitake84c6f882010-02-04 16:08:15 +0900608
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700609config DEBUG_LOCKDEP
610 bool "Lock dependency engine debugging"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700611 depends on DEBUG_KERNEL && LOCKDEP
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700612 help
613 If you say Y here, the lock dependency engine will do
614 additional runtime checks to debug itself, at the price
615 of more runtime overhead.
616
617config TRACE_IRQFLAGS
618 bool
Steven Rostedt46b93b72010-08-31 16:35:20 -0400619 help
620 Enables hooks to interrupt enabling and disabling for
621 either tracing or lock debugging.
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700622
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623config DEBUG_SPINLOCK_SLEEP
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700624 bool "Spinlock debugging: sleep-inside-spinlock checking"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 depends on DEBUG_KERNEL
626 help
627 If you say Y here, various routines which may sleep will become very
628 noisy if they are called with a spinlock held.
629
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700630config DEBUG_LOCKING_API_SELFTESTS
631 bool "Locking API boot-time self-tests"
632 depends on DEBUG_KERNEL
633 help
634 Say Y here if you want the kernel to run a short self-test during
635 bootup. The self-test checks whether common types of locking bugs
636 are detected by debugging mechanisms or not. (if you disable
637 lock debugging then those bugs wont be detected of course.)
638 The following locking APIs are covered: spinlocks, rwlocks,
639 mutexes and rwsems.
640
Ingo Molnar8637c092006-07-03 00:24:38 -0700641config STACKTRACE
642 bool
643 depends on STACKTRACE_SUPPORT
644
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645config DEBUG_KOBJECT
646 bool "kobject debugging"
647 depends on DEBUG_KERNEL
648 help
649 If you say Y here, some extra kobject debugging messages will be sent
650 to the syslog.
651
652config DEBUG_HIGHMEM
653 bool "Highmem debugging"
654 depends on DEBUG_KERNEL && HIGHMEM
655 help
656 This options enables addition error checking for high memory systems.
657 Disable for production systems.
658
659config DEBUG_BUGVERBOSE
660 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
Matt Mackallc8538a72005-05-01 08:59:01 -0700661 depends on BUG
David Howellsb920de12008-02-08 04:19:31 -0800662 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
663 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
Alexey Dobriyan8420e7e2009-12-14 18:00:25 -0800664 default y
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665 help
666 Say Y here to make BUG() panics output the file name and line number
667 of the BUG call as well as the EIP and oops trace. This aids
668 debugging but costs about 70-100K of memory.
669
670config DEBUG_INFO
671 bool "Compile the kernel with debug info"
672 depends on DEBUG_KERNEL
673 help
674 If you say Y here the resulting kernel image will include
675 debugging info resulting in a larger kernel image.
Andreas Dilgerb72e53f2007-03-27 15:21:33 -0600676 This adds debug symbols to the kernel and modules (gcc -g), and
677 is needed if you intend to use kernel crashdump or binary object
678 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 Say Y here only if you plan to debug the kernel.
680
681 If unsure, say N.
682
Andi Kleend6f4ceb2010-07-14 15:43:52 +0200683config DEBUG_INFO_REDUCED
684 bool "Reduce debugging information"
685 depends on DEBUG_INFO
686 help
687 If you say Y here gcc is instructed to generate less debugging
688 information for structure types. This means that tools that
689 need full debugging information (like kgdb or systemtap) won't
690 be happy. But if you merely need debugging information to
691 resolve line numbers there is no loss. Advantage is that
692 build directory object sizes shrink dramatically over a full
693 DEBUG_INFO build and compile times are reduced too.
694 Only works with newer gcc versions.
695
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800696config DEBUG_VM
697 bool "Debug VM"
698 depends on DEBUG_KERNEL
699 help
Nick Piggin13e74442006-01-06 00:10:58 -0800700 Enable this to turn on extended checks in the virtual-memory system
701 that may impact performance.
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800702
703 If unsure, say N.
704
Jiri Slaby59ea7462008-06-12 13:56:40 +0200705config DEBUG_VIRTUAL
706 bool "Debug VM translations"
707 depends on DEBUG_KERNEL && X86
708 help
709 Enable some costly sanity checks in virtual to page code. This can
710 catch mistakes with virt_to_page() and friends.
711
712 If unsure, say N.
713
David Howells8feae132009-01-08 12:04:47 +0000714config DEBUG_NOMMU_REGIONS
715 bool "Debug the global anon/private NOMMU mapping region tree"
716 depends on DEBUG_KERNEL && !MMU
717 help
718 This option causes the global tree of anonymous and private mapping
719 regions to be regularly checked for invalid topology.
720
Dave Hansenad775f52008-02-15 14:38:01 -0800721config DEBUG_WRITECOUNT
722 bool "Debug filesystem writers count"
723 depends on DEBUG_KERNEL
724 help
725 Enable this to catch wrong use of the writers count in struct
726 vfsmount. This will increase the size of each file struct by
727 32 bits.
728
729 If unsure, say N.
730
Mel Gorman6b74ab92008-07-23 21:26:49 -0700731config DEBUG_MEMORY_INIT
732 bool "Debug memory initialisation" if EMBEDDED
733 default !EMBEDDED
734 help
735 Enable this for additional checks during memory initialisation.
736 The sanity checks verify aspects of the VM such as the memory model
737 and other information provided by the architecture. Verbose
738 information will be printed at KERN_DEBUG loglevel depending
739 on the mminit_loglevel= command-line option.
740
741 If unsure, say Y
742
Dave Jones199a9af2006-09-29 01:59:00 -0700743config DEBUG_LIST
744 bool "Debug linked list manipulation"
745 depends on DEBUG_KERNEL
746 help
747 Enable this to turn on extended checks in the linked-list
748 walking routines.
749
750 If unsure, say N.
751
Artem Bityutskiy6d411e62010-10-26 14:23:05 -0700752config TEST_LIST_SORT
753 bool "Linked list sorting test"
754 depends on DEBUG_KERNEL
755 help
756 Enable this to turn on 'list_sort()' function test. This test is
757 executed only once during system boot, so affects only boot time.
758
759 If unsure, say N.
760
Jens Axboed6ec0842007-10-22 20:01:06 +0200761config DEBUG_SG
762 bool "Debug SG table operations"
763 depends on DEBUG_KERNEL
764 help
765 Enable this to turn on checks on scatter-gather tables. This can
766 help find problems with drivers that do not properly initialize
767 their sg tables.
768
769 If unsure, say N.
770
Arjan van de Ven1b2439d2008-08-15 15:29:38 -0700771config DEBUG_NOTIFIERS
772 bool "Debug notifier call chains"
773 depends on DEBUG_KERNEL
774 help
775 Enable this to turn on sanity checking for notifier call chains.
776 This is most useful for kernel developers to make sure that
777 modules properly unregister themselves from notifier chains.
778 This is a relatively cheap check but if you care about maximum
779 performance, say N.
780
David Howellse0e81732009-09-02 09:13:40 +0100781config DEBUG_CREDENTIALS
782 bool "Debug credential management"
783 depends on DEBUG_KERNEL
784 help
785 Enable this to turn on some debug checking for credential
786 management. The additional code keeps track of the number of
787 pointers from task_structs to any given cred struct, and checks to
788 see that this number never exceeds the usage count of the cred
789 struct.
790
791 Furthermore, if SELinux is enabled, this also checks that the
792 security pointer in the cred struct is never seen to be invalid.
793
794 If unsure, say N.
795
Jeff Mahoney64dec402009-01-16 13:23:35 -0500796#
797# Select this config option from the architecture Kconfig, if it
798# it is preferred to always offer frame pointers as a config
799# option on the architecture (regardless of KERNEL_DEBUG):
800#
801config ARCH_WANT_FRAME_POINTERS
802 bool
803 help
804
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805config FRAME_POINTER
806 bool "Compile the kernel with frame pointers"
David Howellsb920de12008-02-08 04:19:31 -0800807 depends on DEBUG_KERNEL && \
Heiko Carstens75ee0342009-04-23 13:58:10 +0200808 (CRIS || M68K || M68KNOMMU || FRV || UML || \
Ingo Molnarda4276b2009-01-07 11:05:10 +0100809 AVR32 || SUPERH || BLACKFIN || MN10300) || \
810 ARCH_WANT_FRAME_POINTERS
811 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 help
Ingo Molnarda4276b2009-01-07 11:05:10 +0100813 If you say Y here the resulting kernel image will be slightly
814 larger and slower, but it gives very useful debugging information
815 in case of kernel bugs. (precise oopses/stacktraces/warnings)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700817config BOOT_PRINTK_DELAY
818 bool "Delay each boot printk message by N milliseconds"
819 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
820 help
821 This build option allows you to read kernel boot messages
822 by inserting a short delay after each one. The delay is
823 specified in milliseconds on the kernel command line,
824 using "boot_delay=N".
825
826 It is likely that you would also need to use "lpj=M" to preset
827 the "loops per jiffie" value.
828 See a previous boot log for the "lpj" value to use for your
829 system, and then set "lpj=M" before setting "boot_delay=N".
830 NOTE: Using this option may adversely affect SMP systems.
831 I.e., processors other than the first one may not boot up.
832 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
833 what it believes to be lockup conditions.
834
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800835config RCU_TORTURE_TEST
836 tristate "torture tests for RCU"
837 depends on DEBUG_KERNEL
838 default n
839 help
840 This option provides a kernel module that runs torture tests
841 on the RCU infrastructure. The kernel module may be built
842 after the fact on the running kernel to be tested, if desired.
843
Paul E. McKenney31a72bc2008-06-18 09:26:49 -0700844 Say Y here if you want RCU torture tests to be built into
845 the kernel.
Paul E. McKenneya241ec62005-10-30 15:03:12 -0800846 Say M if you want the RCU torture tests to build as a module.
847 Say N if you are unsure.
Ankita Garg8bb31b92006-10-02 02:17:36 -0700848
Paul E. McKenney31a72bc2008-06-18 09:26:49 -0700849config RCU_TORTURE_TEST_RUNNABLE
850 bool "torture tests for RCU runnable by default"
851 depends on RCU_TORTURE_TEST = y
852 default n
853 help
854 This option provides a way to build the RCU torture tests
855 directly into the kernel without them starting up at boot
856 time. You can use /proc/sys/kernel/rcutorture_runnable
857 to manually override this setting. This /proc file is
858 available only when the RCU torture tests have been built
859 into the kernel.
860
861 Say Y here if you want the RCU torture tests to start during
862 boot (you probably don't).
863 Say N here if you want the RCU torture tests to start only
864 after being manually enabled via /proc.
865
Paul E. McKenney2133b5d2008-10-02 16:06:39 -0700866config RCU_CPU_STALL_DETECTOR
Paul E. McKenney67182ae2008-08-10 18:35:38 -0700867 bool "Check for stalled CPUs delaying RCU grace periods"
Paul E. McKenney6b3ef482009-08-22 13:56:53 -0700868 depends on TREE_RCU || TREE_PREEMPT_RCU
Paul E. McKenney8bfb2f82009-12-02 12:10:16 -0800869 default y
Paul E. McKenney64db4cf2008-12-18 21:55:32 +0100870 help
871 This option causes RCU to printk information on which
872 CPUs are delaying the current grace period, but only when
873 the grace period extends for excessive time periods.
874
Paul E. McKenney4c540052010-01-14 16:10:57 -0800875 Say N if you want to disable such checks.
Paul E. McKenney64db4cf2008-12-18 21:55:32 +0100876
Paul E. McKenney4c540052010-01-14 16:10:57 -0800877 Say Y if you are unsure.
Paul E. McKenney64db4cf2008-12-18 21:55:32 +0100878
Paul E. McKenneyb1637602010-06-02 16:21:38 -0700879config RCU_CPU_STALL_TIMEOUT
880 int "RCU CPU stall timeout in seconds"
881 depends on RCU_CPU_STALL_DETECTOR
882 range 3 300
883 default 60
884 help
885 If a given RCU grace period extends more than the specified
886 number of seconds, a CPU stall warning is printed. If the
887 RCU grace period persists, additional CPU stall warnings are
888 printed at more widely spaced intervals.
889
Paul E. McKenney910b1b72010-07-21 08:05:56 -0700890config RCU_CPU_STALL_DETECTOR_RUNNABLE
891 bool "RCU CPU stall checking starts automatically at boot"
892 depends on RCU_CPU_STALL_DETECTOR
893 default y
894 help
895 If set, start checking for RCU CPU stalls immediately on
896 boot. Otherwise, RCU CPU stall checking must be manually
897 enabled.
898
899 Say Y if you are unsure.
900
901 Say N if you wish to suppress RCU CPU stall checking during boot.
902
Paul E. McKenney1ed509a2010-02-22 17:05:05 -0800903config RCU_CPU_STALL_VERBOSE
904 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
905 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
Paul E. McKenney55ec9362010-04-13 12:22:33 -0700906 default y
Paul E. McKenney1ed509a2010-02-22 17:05:05 -0800907 help
908 This option causes RCU to printk detailed per-task information
909 for any tasks that are stalling the current RCU grace period.
Arjan van de Ven6dab2772008-01-30 13:33:08 +0100910
911 Say N if you are unsure.
912
Paul E. McKenney1ed509a2010-02-22 17:05:05 -0800913 Say Y if you want to enable such checks.
914
Ananth N Mavinakayanahalli8c1c9352008-01-30 13:32:53 +0100915config KPROBES_SANITY_TEST
916 bool "Kprobes sanity tests"
917 depends on DEBUG_KERNEL
918 depends on KPROBES
919 default n
920 help
921 This option provides for testing basic kprobes functionality on
922 boot. A sample kprobe, jprobe and kretprobe are inserted and
923 verified for functionality.
924
925 Say N if you are unsure.
926
Arjan van de Ven6dab2772008-01-30 13:33:08 +0100927config BACKTRACE_SELF_TEST
928 tristate "Self test for the backtrace code"
929 depends on DEBUG_KERNEL
930 default n
931 help
932 This option provides a kernel module that can be used to test
933 the kernel stack backtrace code. This option is not useful
934 for distributions or general kernels, but only for kernel
935 developers working on architecture code.
936
Vegard Nossumad118c52008-06-27 18:04:48 +0200937 Note that if you want to also test saved backtraces, you will
938 have to enable STACKTRACE as well.
939
Arjan van de Ven6dab2772008-01-30 13:33:08 +0100940 Say N if you are unsure.
941
Tejun Heo870d6652008-08-25 19:47:25 +0900942config DEBUG_BLOCK_EXT_DEVT
943 bool "Force extended block device numbers and spread them"
944 depends on DEBUG_KERNEL
945 depends on BLOCK
Jens Axboe759f8ca2008-08-29 09:06:29 +0200946 default n
Tejun Heo870d6652008-08-25 19:47:25 +0900947 help
Tejun Heo0e11e342008-10-13 10:46:01 +0200948 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
949 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
950 YOU ARE DOING. Distros, please enable this and fix whatever
951 is broken.
952
Tejun Heo870d6652008-08-25 19:47:25 +0900953 Conventionally, block device numbers are allocated from
954 predetermined contiguous area. However, extended block area
955 may introduce non-contiguous block device numbers. This
956 option forces most block device numbers to be allocated from
957 the extended space and spreads them to discover kernel or
958 userland code paths which assume predetermined contiguous
959 device number allocation.
960
Tejun Heo55dc7db2008-09-01 13:44:35 +0200961 Note that turning on this debug option shuffles all the
962 device numbers for all IDE and SCSI devices including libata
963 ones, so root partition specified using device number
964 directly (via rdev or root=MAJ:MIN) won't work anymore.
965 Textual device names (root=/dev/sdXn) will continue to work.
966
Tejun Heo870d6652008-08-25 19:47:25 +0900967 Say N if you are unsure.
968
Tejun Heo7c756e62009-06-24 15:13:50 +0900969config DEBUG_FORCE_WEAK_PER_CPU
970 bool "Force weak per-cpu definitions"
971 depends on DEBUG_KERNEL
972 help
973 s390 and alpha require percpu variables in modules to be
974 defined weak to work around addressing range issue which
975 puts the following two restrictions on percpu variable
976 definitions.
977
978 1. percpu symbols must be unique whether static or not
979 2. percpu variables can't be defined inside a function
980
981 To ensure that generic code follows the above rules, this
982 option forces all percpu variables to be defined as weak.
983
Ankita Garg8bb31b92006-10-02 02:17:36 -0700984config LKDTM
985 tristate "Linux Kernel Dump Test Tool Module"
Simon Kagstrom0347af42010-03-05 13:42:49 -0800986 depends on DEBUG_FS
Chris Snookfddd9cf2008-02-23 15:23:26 -0800987 depends on BLOCK
Ankita Garg8bb31b92006-10-02 02:17:36 -0700988 default n
989 help
990 This module enables testing of the different dumping mechanisms by
991 inducing system failures at predefined crash points.
992 If you don't need it: say N
993 Choose M here to compile this code as a module. The module will be
994 called lkdtm.
995
996 Documentation on how to use the module can be found in
Simon Kagstrom0347af42010-03-05 13:42:49 -0800997 Documentation/fault-injection/provoke-crashes.txt
Akinobu Mita6ff1cb32006-12-08 02:39:43 -0800998
Akinobu Mitac9d221f2010-05-26 14:43:36 -0700999config CPU_NOTIFIER_ERROR_INJECT
1000 tristate "CPU notifier error injection module"
1001 depends on HOTPLUG_CPU && DEBUG_KERNEL
1002 help
1003 This option provides a kernel module that can be used to test
1004 the error handling of the cpu notifiers
1005
1006 To compile this code as a module, choose M here: the module will
1007 be called cpu-notifier-error-inject.
1008
1009 If unsure, say N.
1010
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001011config FAULT_INJECTION
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001012 bool "Fault-injection framework"
1013 depends on DEBUG_KERNEL
Akinobu Mita329409a2006-12-08 02:39:48 -08001014 help
1015 Provide fault-injection framework.
1016 For more details, see Documentation/fault-injection/.
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001017
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001018config FAILSLAB
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001019 bool "Fault-injection capability for kmalloc"
1020 depends on FAULT_INJECTION
Akinobu Mita773ff602008-12-23 19:37:01 +09001021 depends on SLAB || SLUB
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001022 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001023 Provide fault-injection capability for kmalloc.
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001024
Akinobu Mita933e3122006-12-08 02:39:45 -08001025config FAIL_PAGE_ALLOC
1026 bool "Fault-injection capabilitiy for alloc_pages()"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001027 depends on FAULT_INJECTION
Akinobu Mita933e3122006-12-08 02:39:45 -08001028 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001029 Provide fault-injection capability for alloc_pages().
Akinobu Mita933e3122006-12-08 02:39:45 -08001030
Akinobu Mitac17bb492006-12-08 02:39:46 -08001031config FAIL_MAKE_REQUEST
Dave Jones86327d12006-12-12 20:16:36 +01001032 bool "Fault-injection capability for disk IO"
Jens Axboe581d4e22008-09-14 05:56:33 -07001033 depends on FAULT_INJECTION && BLOCK
Akinobu Mitac17bb492006-12-08 02:39:46 -08001034 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001035 Provide fault-injection capability for disk IO.
Akinobu Mitac17bb492006-12-08 02:39:46 -08001036
Jens Axboe581d4e22008-09-14 05:56:33 -07001037config FAIL_IO_TIMEOUT
Takuya Yoshikawaf4d014392010-07-21 16:05:53 +09001038 bool "Fault-injection capability for faking disk interrupts"
Jens Axboe581d4e22008-09-14 05:56:33 -07001039 depends on FAULT_INJECTION && BLOCK
1040 help
1041 Provide fault-injection capability on end IO handling. This
1042 will make the block layer "forget" an interrupt as configured,
1043 thus exercising the error handling.
1044
1045 Only works with drivers that use the generic timeout handling,
1046 for others it wont do anything.
1047
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001048config FAULT_INJECTION_DEBUG_FS
1049 bool "Debugfs entries for fault-injection capabilities"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001050 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001051 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001052 Enable configuration of fault-injection capabilities via debugfs.
Akinobu Mita1df49002007-02-20 13:57:56 -08001053
1054config FAULT_INJECTION_STACKTRACE_FILTER
1055 bool "stacktrace filter for fault-injection capabilities"
1056 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
Akinobu Mita6d690dc2007-05-12 10:36:53 -07001057 depends on !X86_64
Akinobu Mita1df49002007-02-20 13:57:56 -08001058 select STACKTRACE
Michal Simek79aac882010-05-25 11:33:26 +02001059 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
Akinobu Mita1df49002007-02-20 13:57:56 -08001060 help
1061 Provide stacktrace filter for fault-injection capabilities
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001062
Arjan van de Ven97455122008-01-25 21:08:34 +01001063config LATENCYTOP
1064 bool "Latency measuring infrastructure"
Randy Dunlap625fdca2010-08-12 12:31:21 -07001065 depends on HAVE_LATENCYTOP_SUPPORT
1066 depends on DEBUG_KERNEL
1067 depends on STACKTRACE_SUPPORT
1068 depends on PROC_FS
Michal Simek79aac882010-05-25 11:33:26 +02001069 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
Arjan van de Ven97455122008-01-25 21:08:34 +01001070 select KALLSYMS
1071 select KALLSYMS_ALL
1072 select STACKTRACE
1073 select SCHEDSTATS
1074 select SCHED_DEBUG
Arjan van de Ven97455122008-01-25 21:08:34 +01001075 help
1076 Enable this option if you want to use the LatencyTOP tool
1077 to find out which userspace is blocking on what kernel operations.
1078
Andi Kleen9e94cd32008-08-16 07:53:05 +02001079config SYSCTL_SYSCALL_CHECK
1080 bool "Sysctl checks"
Eric W. Biederman83ac2012009-04-03 02:22:26 -07001081 depends on SYSCTL
Andi Kleen9e94cd32008-08-16 07:53:05 +02001082 ---help---
1083 sys_sysctl uses binary paths that have been found challenging
1084 to properly maintain and use. This enables checks that help
1085 you to keep things correct.
1086
Akinobu Mita6a11f752009-03-31 15:23:17 -07001087source mm/Kconfig.debug
Arnaldo Carvalho de Melo16444a82008-05-12 21:20:42 +02001088source kernel/trace/Kconfig
1089
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001090config PROVIDE_OHCI1394_DMA_INIT
Stefan Richter080de8c2008-02-28 20:54:43 +01001091 bool "Remote debugging over FireWire early on boot"
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001092 depends on PCI && X86
1093 help
1094 If you want to debug problems which hang or crash the kernel early
1095 on boot and the crashing machine has a FireWire port, you can use
1096 this feature to remotely access the memory of the crashed machine
1097 over FireWire. This employs remote DMA as part of the OHCI1394
1098 specification which is now the standard for FireWire controllers.
1099
1100 With remote DMA, you can monitor the printk buffer remotely using
1101 firescope and access all memory below 4GB using fireproxy from gdb.
1102 Even controlling a kernel debugger is possible using remote DMA.
1103
1104 Usage:
1105
1106 If ohci1394_dma=early is used as boot parameter, it will initialize
1107 all OHCI1394 controllers which are found in the PCI config space.
1108
1109 As all changes to the FireWire bus such as enabling and disabling
1110 devices cause a bus reset and thereby disable remote DMA for all
1111 devices, be sure to have the cable plugged and FireWire enabled on
1112 the debugging host before booting the debug target for debugging.
1113
1114 This code (~1k) is freed after boot. By then, the firewire stack
1115 in charge of the OHCI-1394 controllers should be used instead.
1116
1117 See Documentation/debugging-via-ohci1394.txt for more information.
Arjan van de Ven97455122008-01-25 21:08:34 +01001118
Stefan Richter080de8c2008-02-28 20:54:43 +01001119config FIREWIRE_OHCI_REMOTE_DMA
1120 bool "Remote debugging over FireWire with firewire-ohci"
1121 depends on FIREWIRE_OHCI
1122 help
1123 This option lets you use the FireWire bus for remote debugging
1124 with help of the firewire-ohci driver. It enables unfiltered
1125 remote DMA in firewire-ohci.
1126 See Documentation/debugging-via-ohci1394.txt for more information.
1127
1128 If unsure, say N.
1129
Randy Dunlap152de302009-02-20 15:38:47 -08001130config BUILD_DOCSRC
Randy Dunlap3794f3e2008-08-12 15:09:06 -07001131 bool "Build targets in Documentation/ tree"
1132 depends on HEADERS_CHECK
1133 help
1134 This option attempts to build objects from the source files in the
1135 kernel Documentation/ tree.
1136
1137 Say N if you are unsure.
1138
Jason Barone9d376f2009-02-05 11:51:38 -05001139config DYNAMIC_DEBUG
Jason Baron86151fd2009-02-05 11:53:15 -05001140 bool "Enable dynamic printk() support"
Jason Baron346e15b2008-08-12 16:46:19 -04001141 default n
1142 depends on PRINTK
Jason Baron86151fd2009-02-05 11:53:15 -05001143 depends on DEBUG_FS
Jason Baron346e15b2008-08-12 16:46:19 -04001144 help
1145
1146 Compiles debug level messages into the kernel, which would not
1147 otherwise be available at runtime. These messages can then be
Jason Baron86151fd2009-02-05 11:53:15 -05001148 enabled/disabled based on various levels of scope - per source file,
1149 function, module, format string, and line number. This mechanism
1150 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1151 this compile option is a larger kernel text size of about 2%.
Jason Baron346e15b2008-08-12 16:46:19 -04001152
1153 Usage:
1154
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001155 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
Jason Baron86151fd2009-02-05 11:53:15 -05001156 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1157 filesystem must first be mounted before making use of this feature.
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001158 We refer the control file as: <debugfs>/dynamic_debug/control. This
Jason Baron86151fd2009-02-05 11:53:15 -05001159 file contains a list of the debug statements that can be enabled. The
1160 format for each line of the file is:
Jason Baron346e15b2008-08-12 16:46:19 -04001161
Jason Baron86151fd2009-02-05 11:53:15 -05001162 filename:lineno [module]function flags format
Jason Baron346e15b2008-08-12 16:46:19 -04001163
Jason Baron86151fd2009-02-05 11:53:15 -05001164 filename : source file of the debug statement
1165 lineno : line number of the debug statement
1166 module : module that contains the debug statement
1167 function : function that contains the debug statement
1168 flags : 'p' means the line is turned 'on' for printing
1169 format : the format used for the debug statement
Jason Baron346e15b2008-08-12 16:46:19 -04001170
1171 From a live system:
1172
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001173 nullarbor:~ # cat <debugfs>/dynamic_debug/control
Jason Baron86151fd2009-02-05 11:53:15 -05001174 # filename:lineno [module]function flags format
1175 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1176 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1177 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
Jason Baron346e15b2008-08-12 16:46:19 -04001178
Jason Baron86151fd2009-02-05 11:53:15 -05001179 Example usage:
Jason Baron346e15b2008-08-12 16:46:19 -04001180
Jason Baron86151fd2009-02-05 11:53:15 -05001181 // enable the message at line 1603 of file svcsock.c
1182 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001183 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001184
Jason Baron86151fd2009-02-05 11:53:15 -05001185 // enable all the messages in file svcsock.c
1186 nullarbor:~ # echo -n 'file svcsock.c +p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001187 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001188
Jason Baron86151fd2009-02-05 11:53:15 -05001189 // enable all the messages in the NFS server module
1190 nullarbor:~ # echo -n 'module nfsd +p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001191 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001192
Jason Baron86151fd2009-02-05 11:53:15 -05001193 // enable all 12 messages in the function svc_process()
1194 nullarbor:~ # echo -n 'func svc_process +p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001195 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001196
Jason Baron86151fd2009-02-05 11:53:15 -05001197 // disable all 12 messages in the function svc_process()
1198 nullarbor:~ # echo -n 'func svc_process -p' >
Florian Ragwitz2b2f68b2010-05-24 14:33:21 -07001199 <debugfs>/dynamic_debug/control
Jason Baron346e15b2008-08-12 16:46:19 -04001200
Jason Baron86151fd2009-02-05 11:53:15 -05001201 See Documentation/dynamic-debug-howto.txt for additional information.
Jason Baron346e15b2008-08-12 16:46:19 -04001202
Joerg Roedel5ee00bd2009-01-09 12:14:24 +01001203config DMA_API_DEBUG
1204 bool "Enable debugging of DMA-API usage"
1205 depends on HAVE_DMA_API_DEBUG
1206 help
1207 Enable this option to debug the use of the DMA API by device drivers.
1208 With this option you will be able to detect common bugs in device
1209 drivers like double-freeing of DMA mappings or freeing mappings that
1210 were never allocated.
1211 This option causes a performance degredation. Use only if you want
1212 to debug device drivers. If unsure, say N.
Jason Baron346e15b2008-08-12 16:46:19 -04001213
Luca Barbieri86a89382010-02-24 10:54:24 +01001214config ATOMIC64_SELFTEST
1215 bool "Perform an atomic64_t self-test at boot"
1216 help
1217 Enable this option to test the atomic64_t functions at boot.
1218
1219 If unsure, say N.
1220
Dan Williams400fb7f2010-10-07 15:25:04 -07001221config ASYNC_RAID6_TEST
1222 tristate "Self test for hardware accelerated raid6 recovery"
1223 depends on ASYNC_RAID6_RECOV
1224 select ASYNC_MEMCPY
1225 ---help---
1226 This is a one-shot self test that permutes through the
1227 recovery of all the possible two disk failure scenarios for a
1228 N-disk array. Recovery is performed with the asynchronous
1229 raid6 recovery routines, and will optionally use an offload
1230 engine if one is available.
1231
1232 If unsure, say N.
1233
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001234source "samples/Kconfig"
Jason Wesseldc7d5522008-04-17 20:05:37 +02001235
1236source "lib/Kconfig.kgdb"
Pekka Enberg0a4af3b2009-02-26 21:38:56 +02001237
1238source "lib/Kconfig.kmemcheck"