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1 | ||
2 | config PRINTK_TIME | |
3 | bool "Show timing information on printks" | |
4 | depends on PRINTK | |
5 | help | |
6 | Selecting this option causes timing information to be | |
7 | included in printk output. This allows you to measure | |
8 | the interval between kernel operations, including bootup | |
9 | operations. This is useful for identifying long delays | |
10 | in kernel startup. | |
11 | ||
12 | config 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 | ||
20 | config 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. | |
27 | ||
28 | config 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 | ||
39 | config MAGIC_SYSRQ | |
40 | bool "Magic SysRq key" | |
41 | depends on !UML | |
42 | 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 | ||
53 | config 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 | ||
61 | config 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 | ||
77 | config DEBUG_FS | |
78 | bool "Debug Filesystem" | |
79 | depends on SYSFS | |
80 | help | |
81 | debugfs is a virtual file system that kernel developers use to put | |
82 | debugging files into. Enable this option to be able to read and | |
83 | write to these files. | |
84 | ||
85 | For detailed documentation on the debugfs API, see | |
86 | Documentation/DocBook/filesystems. | |
87 | ||
88 | If unsure, say N. | |
89 | ||
90 | config HEADERS_CHECK | |
91 | bool "Run 'make headers_check' when building vmlinux" | |
92 | depends on !UML | |
93 | help | |
94 | This option will extract the user-visible kernel headers whenever | |
95 | building the kernel, and will run basic sanity checks on them to | |
96 | ensure that exported files do not attempt to include files which | |
97 | were not exported, etc. | |
98 | ||
99 | If you're making modifications to header files which are | |
100 | relevant for userspace, say 'Y', and check the headers | |
101 | exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in | |
102 | your build tree), to make sure they're suitable. | |
103 | ||
104 | config DEBUG_SECTION_MISMATCH | |
105 | bool "Enable full Section mismatch analysis" | |
106 | depends on UNDEFINED | |
107 | # This option is on purpose disabled for now. | |
108 | # It will be enabled when we are down to a resonable number | |
109 | # of section mismatch warnings (< 10 for an allyesconfig build) | |
110 | 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) | |
118 | 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 | |
121 | 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 | |
124 | function we would lose the section information and thus | |
125 | the analysis would not catch the illegal reference. | |
126 | This option tells gcc to inline less but will also | |
127 | 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 | |
130 | lose valueble information about where the mismatch was | |
131 | 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. | |
136 | - Enable verbose reporting from modpost to help solving | |
137 | the section mismatches reported. | |
138 | ||
139 | config 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 | ||
145 | config 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 | ||
154 | config DETECT_SOFTLOCKUP | |
155 | bool "Detect Soft Lockups" | |
156 | depends on DEBUG_KERNEL && !S390 | |
157 | default y | |
158 | help | |
159 | Say Y here to enable the kernel to detect "soft lockups", | |
160 | which are bugs that cause the kernel to loop in kernel | |
161 | mode for more than 60 seconds, without giving other tasks a | |
162 | chance to run. | |
163 | ||
164 | When a soft-lockup is detected, the kernel will print the | |
165 | current stack trace (which you should report), but the | |
166 | system will stay locked up. This feature has negligible | |
167 | overhead. | |
168 | ||
169 | (Note that "hard lockups" are separate type of bugs that | |
170 | can be detected via the NMI-watchdog, on platforms that | |
171 | support it.) | |
172 | ||
173 | config BOOTPARAM_SOFTLOCKUP_PANIC | |
174 | bool "Panic (Reboot) On Soft Lockups" | |
175 | depends on DETECT_SOFTLOCKUP | |
176 | help | |
177 | Say Y here to enable the kernel to panic on "soft lockups", | |
178 | which are bugs that cause the kernel to loop in kernel | |
179 | mode for more than 60 seconds, without giving other tasks a | |
180 | chance to run. | |
181 | ||
182 | The panic can be used in combination with panic_timeout, | |
183 | to cause the system to reboot automatically after a | |
184 | lockup has been detected. This feature is useful for | |
185 | high-availability systems that have uptime guarantees and | |
186 | where a lockup must be resolved ASAP. | |
187 | ||
188 | Say N if unsure. | |
189 | ||
190 | config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE | |
191 | int | |
192 | depends on DETECT_SOFTLOCKUP | |
193 | range 0 1 | |
194 | default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC | |
195 | default 1 if BOOTPARAM_SOFTLOCKUP_PANIC | |
196 | ||
197 | config DETECT_HUNG_TASK | |
198 | bool "Detect Hung Tasks" | |
199 | depends on DEBUG_KERNEL | |
200 | default DETECT_SOFTLOCKUP | |
201 | help | |
202 | Say Y here to enable the kernel to detect "hung tasks", | |
203 | which are bugs that cause the task to be stuck in | |
204 | uninterruptible "D" state indefinitiley. | |
205 | ||
206 | When a hung task is detected, the kernel will print the | |
207 | current stack trace (which you should report), but the | |
208 | task will stay in uninterruptible state. If lockdep is | |
209 | enabled then all held locks will also be reported. This | |
210 | feature has negligible overhead. | |
211 | ||
212 | config BOOTPARAM_HUNG_TASK_PANIC | |
213 | bool "Panic (Reboot) On Hung Tasks" | |
214 | depends on DETECT_HUNG_TASK | |
215 | help | |
216 | Say Y here to enable the kernel to panic on "hung tasks", | |
217 | which are bugs that cause the kernel to leave a task stuck | |
218 | in uninterruptible "D" state. | |
219 | ||
220 | The panic can be used in combination with panic_timeout, | |
221 | to cause the system to reboot automatically after a | |
222 | hung task has been detected. This feature is useful for | |
223 | high-availability systems that have uptime guarantees and | |
224 | where a hung tasks must be resolved ASAP. | |
225 | ||
226 | Say N if unsure. | |
227 | ||
228 | config BOOTPARAM_HUNG_TASK_PANIC_VALUE | |
229 | int | |
230 | depends on DETECT_HUNG_TASK | |
231 | range 0 1 | |
232 | default 0 if !BOOTPARAM_HUNG_TASK_PANIC | |
233 | default 1 if BOOTPARAM_HUNG_TASK_PANIC | |
234 | ||
235 | config SCHED_DEBUG | |
236 | bool "Collect scheduler debugging info" | |
237 | depends on DEBUG_KERNEL && PROC_FS | |
238 | default y | |
239 | help | |
240 | If you say Y here, the /proc/sched_debug file will be provided | |
241 | that can help debug the scheduler. The runtime overhead of this | |
242 | option is minimal. | |
243 | ||
244 | config SCHEDSTATS | |
245 | bool "Collect scheduler statistics" | |
246 | depends on DEBUG_KERNEL && PROC_FS | |
247 | help | |
248 | If you say Y here, additional code will be inserted into the | |
249 | scheduler and related routines to collect statistics about | |
250 | scheduler behavior and provide them in /proc/schedstat. These | |
251 | stats may be useful for both tuning and debugging the scheduler | |
252 | If you aren't debugging the scheduler or trying to tune a specific | |
253 | application, you can say N to avoid the very slight overhead | |
254 | this adds. | |
255 | ||
256 | config TIMER_STATS | |
257 | bool "Collect kernel timers statistics" | |
258 | depends on DEBUG_KERNEL && PROC_FS | |
259 | help | |
260 | If you say Y here, additional code will be inserted into the | |
261 | timer routines to collect statistics about kernel timers being | |
262 | reprogrammed. The statistics can be read from /proc/timer_stats. | |
263 | The statistics collection is started by writing 1 to /proc/timer_stats, | |
264 | writing 0 stops it. This feature is useful to collect information | |
265 | about timer usage patterns in kernel and userspace. This feature | |
266 | is lightweight if enabled in the kernel config but not activated | |
267 | (it defaults to deactivated on bootup and will only be activated | |
268 | if some application like powertop activates it explicitly). | |
269 | ||
270 | config DEBUG_OBJECTS | |
271 | bool "Debug object operations" | |
272 | depends on DEBUG_KERNEL | |
273 | help | |
274 | If you say Y here, additional code will be inserted into the | |
275 | kernel to track the life time of various objects and validate | |
276 | the operations on those objects. | |
277 | ||
278 | config DEBUG_OBJECTS_SELFTEST | |
279 | bool "Debug objects selftest" | |
280 | depends on DEBUG_OBJECTS | |
281 | help | |
282 | This enables the selftest of the object debug code. | |
283 | ||
284 | config DEBUG_OBJECTS_FREE | |
285 | bool "Debug objects in freed memory" | |
286 | depends on DEBUG_OBJECTS | |
287 | help | |
288 | This enables checks whether a k/v free operation frees an area | |
289 | which contains an object which has not been deactivated | |
290 | properly. This can make kmalloc/kfree-intensive workloads | |
291 | much slower. | |
292 | ||
293 | config DEBUG_OBJECTS_TIMERS | |
294 | bool "Debug timer objects" | |
295 | depends on DEBUG_OBJECTS | |
296 | help | |
297 | If you say Y here, additional code will be inserted into the | |
298 | timer routines to track the life time of timer objects and | |
299 | validate the timer operations. | |
300 | ||
301 | config DEBUG_OBJECTS_ENABLE_DEFAULT | |
302 | int "debug_objects bootup default value (0-1)" | |
303 | range 0 1 | |
304 | default "1" | |
305 | depends on DEBUG_OBJECTS | |
306 | help | |
307 | Debug objects boot parameter default value | |
308 | ||
309 | config DEBUG_SLAB | |
310 | bool "Debug slab memory allocations" | |
311 | depends on DEBUG_KERNEL && SLAB && !KMEMCHECK | |
312 | help | |
313 | Say Y here to have the kernel do limited verification on memory | |
314 | allocation as well as poisoning memory on free to catch use of freed | |
315 | memory. This can make kmalloc/kfree-intensive workloads much slower. | |
316 | ||
317 | config DEBUG_SLAB_LEAK | |
318 | bool "Memory leak debugging" | |
319 | depends on DEBUG_SLAB | |
320 | ||
321 | config SLUB_DEBUG_ON | |
322 | bool "SLUB debugging on by default" | |
323 | depends on SLUB && SLUB_DEBUG && !KMEMCHECK | |
324 | default n | |
325 | help | |
326 | Boot with debugging on by default. SLUB boots by default with | |
327 | the runtime debug capabilities switched off. Enabling this is | |
328 | equivalent to specifying the "slub_debug" parameter on boot. | |
329 | There is no support for more fine grained debug control like | |
330 | possible with slub_debug=xxx. SLUB debugging may be switched | |
331 | off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying | |
332 | "slub_debug=-". | |
333 | ||
334 | config SLUB_STATS | |
335 | default n | |
336 | bool "Enable SLUB performance statistics" | |
337 | depends on SLUB && SLUB_DEBUG && SYSFS | |
338 | help | |
339 | SLUB statistics are useful to debug SLUBs allocation behavior in | |
340 | order find ways to optimize the allocator. This should never be | |
341 | enabled for production use since keeping statistics slows down | |
342 | the allocator by a few percentage points. The slabinfo command | |
343 | supports the determination of the most active slabs to figure | |
344 | out which slabs are relevant to a particular load. | |
345 | Try running: slabinfo -DA | |
346 | ||
347 | config DEBUG_KMEMLEAK | |
348 | bool "Kernel memory leak detector" | |
349 | depends on DEBUG_KERNEL && EXPERIMENTAL && (X86 || ARM || PPC) && \ | |
350 | !MEMORY_HOTPLUG | |
351 | select DEBUG_FS if SYSFS | |
352 | select STACKTRACE if STACKTRACE_SUPPORT | |
353 | select KALLSYMS | |
354 | help | |
355 | Say Y here if you want to enable the memory leak | |
356 | detector. The memory allocation/freeing is traced in a way | |
357 | similar to the Boehm's conservative garbage collector, the | |
358 | difference being that the orphan objects are not freed but | |
359 | only shown in /sys/kernel/debug/kmemleak. Enabling this | |
360 | feature will introduce an overhead to memory | |
361 | allocations. See Documentation/kmemleak.txt for more | |
362 | details. | |
363 | ||
364 | Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances | |
365 | of finding leaks due to the slab objects poisoning. | |
366 | ||
367 | In order to access the kmemleak file, debugfs needs to be | |
368 | mounted (usually at /sys/kernel/debug). | |
369 | ||
370 | config DEBUG_KMEMLEAK_EARLY_LOG_SIZE | |
371 | int "Maximum kmemleak early log entries" | |
372 | depends on DEBUG_KMEMLEAK | |
373 | range 200 2000 | |
374 | default 400 | |
375 | help | |
376 | Kmemleak must track all the memory allocations to avoid | |
377 | reporting false positives. Since memory may be allocated or | |
378 | freed before kmemleak is initialised, an early log buffer is | |
379 | used to store these actions. If kmemleak reports "early log | |
380 | buffer exceeded", please increase this value. | |
381 | ||
382 | config DEBUG_KMEMLEAK_TEST | |
383 | tristate "Simple test for the kernel memory leak detector" | |
384 | depends on DEBUG_KMEMLEAK | |
385 | help | |
386 | Say Y or M here to build a test for the kernel memory leak | |
387 | detector. This option enables a module that explicitly leaks | |
388 | memory. | |
389 | ||
390 | If unsure, say N. | |
391 | ||
392 | config DEBUG_PREEMPT | |
393 | bool "Debug preemptible kernel" | |
394 | depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64) | |
395 | default y | |
396 | help | |
397 | If you say Y here then the kernel will use a debug variant of the | |
398 | commonly used smp_processor_id() function and will print warnings | |
399 | if kernel code uses it in a preemption-unsafe way. Also, the kernel | |
400 | will detect preemption count underflows. | |
401 | ||
402 | config DEBUG_RT_MUTEXES | |
403 | bool "RT Mutex debugging, deadlock detection" | |
404 | depends on DEBUG_KERNEL && RT_MUTEXES | |
405 | help | |
406 | This allows rt mutex semantics violations and rt mutex related | |
407 | deadlocks (lockups) to be detected and reported automatically. | |
408 | ||
409 | config DEBUG_PI_LIST | |
410 | bool | |
411 | default y | |
412 | depends on DEBUG_RT_MUTEXES | |
413 | ||
414 | config RT_MUTEX_TESTER | |
415 | bool "Built-in scriptable tester for rt-mutexes" | |
416 | depends on DEBUG_KERNEL && RT_MUTEXES | |
417 | help | |
418 | This option enables a rt-mutex tester. | |
419 | ||
420 | config DEBUG_SPINLOCK | |
421 | bool "Spinlock and rw-lock debugging: basic checks" | |
422 | depends on DEBUG_KERNEL | |
423 | help | |
424 | Say Y here and build SMP to catch missing spinlock initialization | |
425 | and certain other kinds of spinlock errors commonly made. This is | |
426 | best used in conjunction with the NMI watchdog so that spinlock | |
427 | deadlocks are also debuggable. | |
428 | ||
429 | config DEBUG_MUTEXES | |
430 | bool "Mutex debugging: basic checks" | |
431 | depends on DEBUG_KERNEL | |
432 | help | |
433 | This feature allows mutex semantics violations to be detected and | |
434 | reported. | |
435 | ||
436 | config DEBUG_LOCK_ALLOC | |
437 | bool "Lock debugging: detect incorrect freeing of live locks" | |
438 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT | |
439 | select DEBUG_SPINLOCK | |
440 | select DEBUG_MUTEXES | |
441 | select LOCKDEP | |
442 | help | |
443 | This feature will check whether any held lock (spinlock, rwlock, | |
444 | mutex or rwsem) is incorrectly freed by the kernel, via any of the | |
445 | memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), | |
446 | vfree(), etc.), whether a live lock is incorrectly reinitialized via | |
447 | spin_lock_init()/mutex_init()/etc., or whether there is any lock | |
448 | held during task exit. | |
449 | ||
450 | config PROVE_LOCKING | |
451 | bool "Lock debugging: prove locking correctness" | |
452 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT | |
453 | select LOCKDEP | |
454 | select DEBUG_SPINLOCK | |
455 | select DEBUG_MUTEXES | |
456 | select DEBUG_LOCK_ALLOC | |
457 | default n | |
458 | help | |
459 | This feature enables the kernel to prove that all locking | |
460 | that occurs in the kernel runtime is mathematically | |
461 | correct: that under no circumstance could an arbitrary (and | |
462 | not yet triggered) combination of observed locking | |
463 | sequences (on an arbitrary number of CPUs, running an | |
464 | arbitrary number of tasks and interrupt contexts) cause a | |
465 | deadlock. | |
466 | ||
467 | In short, this feature enables the kernel to report locking | |
468 | related deadlocks before they actually occur. | |
469 | ||
470 | The proof does not depend on how hard and complex a | |
471 | deadlock scenario would be to trigger: how many | |
472 | participant CPUs, tasks and irq-contexts would be needed | |
473 | for it to trigger. The proof also does not depend on | |
474 | timing: if a race and a resulting deadlock is possible | |
475 | theoretically (no matter how unlikely the race scenario | |
476 | is), it will be proven so and will immediately be | |
477 | reported by the kernel (once the event is observed that | |
478 | makes the deadlock theoretically possible). | |
479 | ||
480 | If a deadlock is impossible (i.e. the locking rules, as | |
481 | observed by the kernel, are mathematically correct), the | |
482 | kernel reports nothing. | |
483 | ||
484 | NOTE: this feature can also be enabled for rwlocks, mutexes | |
485 | and rwsems - in which case all dependencies between these | |
486 | different locking variants are observed and mapped too, and | |
487 | the proof of observed correctness is also maintained for an | |
488 | arbitrary combination of these separate locking variants. | |
489 | ||
490 | For more details, see Documentation/lockdep-design.txt. | |
491 | ||
492 | config LOCKDEP | |
493 | bool | |
494 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT | |
495 | select STACKTRACE | |
496 | select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 | |
497 | select KALLSYMS | |
498 | select KALLSYMS_ALL | |
499 | ||
500 | config LOCK_STAT | |
501 | bool "Lock usage statistics" | |
502 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT | |
503 | select LOCKDEP | |
504 | select DEBUG_SPINLOCK | |
505 | select DEBUG_MUTEXES | |
506 | select DEBUG_LOCK_ALLOC | |
507 | default n | |
508 | help | |
509 | This feature enables tracking lock contention points | |
510 | ||
511 | For more details, see Documentation/lockstat.txt | |
512 | ||
513 | config DEBUG_LOCKDEP | |
514 | bool "Lock dependency engine debugging" | |
515 | depends on DEBUG_KERNEL && LOCKDEP | |
516 | help | |
517 | If you say Y here, the lock dependency engine will do | |
518 | additional runtime checks to debug itself, at the price | |
519 | of more runtime overhead. | |
520 | ||
521 | config TRACE_IRQFLAGS | |
522 | depends on DEBUG_KERNEL | |
523 | bool | |
524 | default y | |
525 | depends on TRACE_IRQFLAGS_SUPPORT | |
526 | depends on PROVE_LOCKING | |
527 | ||
528 | config DEBUG_SPINLOCK_SLEEP | |
529 | bool "Spinlock debugging: sleep-inside-spinlock checking" | |
530 | depends on DEBUG_KERNEL | |
531 | help | |
532 | If you say Y here, various routines which may sleep will become very | |
533 | noisy if they are called with a spinlock held. | |
534 | ||
535 | config DEBUG_LOCKING_API_SELFTESTS | |
536 | bool "Locking API boot-time self-tests" | |
537 | depends on DEBUG_KERNEL | |
538 | help | |
539 | Say Y here if you want the kernel to run a short self-test during | |
540 | bootup. The self-test checks whether common types of locking bugs | |
541 | are detected by debugging mechanisms or not. (if you disable | |
542 | lock debugging then those bugs wont be detected of course.) | |
543 | The following locking APIs are covered: spinlocks, rwlocks, | |
544 | mutexes and rwsems. | |
545 | ||
546 | config STACKTRACE | |
547 | bool | |
548 | depends on STACKTRACE_SUPPORT | |
549 | ||
550 | config DEBUG_KOBJECT | |
551 | bool "kobject debugging" | |
552 | depends on DEBUG_KERNEL | |
553 | help | |
554 | If you say Y here, some extra kobject debugging messages will be sent | |
555 | to the syslog. | |
556 | ||
557 | config DEBUG_HIGHMEM | |
558 | bool "Highmem debugging" | |
559 | depends on DEBUG_KERNEL && HIGHMEM | |
560 | help | |
561 | This options enables addition error checking for high memory systems. | |
562 | Disable for production systems. | |
563 | ||
564 | config DEBUG_BUGVERBOSE | |
565 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED | |
566 | depends on BUG | |
567 | depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ | |
568 | FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 | |
569 | default !EMBEDDED | |
570 | help | |
571 | Say Y here to make BUG() panics output the file name and line number | |
572 | of the BUG call as well as the EIP and oops trace. This aids | |
573 | debugging but costs about 70-100K of memory. | |
574 | ||
575 | config DEBUG_INFO | |
576 | bool "Compile the kernel with debug info" | |
577 | depends on DEBUG_KERNEL | |
578 | help | |
579 | If you say Y here the resulting kernel image will include | |
580 | debugging info resulting in a larger kernel image. | |
581 | This adds debug symbols to the kernel and modules (gcc -g), and | |
582 | is needed if you intend to use kernel crashdump or binary object | |
583 | tools like crash, kgdb, LKCD, gdb, etc on the kernel. | |
584 | Say Y here only if you plan to debug the kernel. | |
585 | ||
586 | If unsure, say N. | |
587 | ||
588 | config DEBUG_VM | |
589 | bool "Debug VM" | |
590 | depends on DEBUG_KERNEL | |
591 | help | |
592 | Enable this to turn on extended checks in the virtual-memory system | |
593 | that may impact performance. | |
594 | ||
595 | If unsure, say N. | |
596 | ||
597 | config DEBUG_VIRTUAL | |
598 | bool "Debug VM translations" | |
599 | depends on DEBUG_KERNEL && X86 | |
600 | help | |
601 | Enable some costly sanity checks in virtual to page code. This can | |
602 | catch mistakes with virt_to_page() and friends. | |
603 | ||
604 | If unsure, say N. | |
605 | ||
606 | config DEBUG_NOMMU_REGIONS | |
607 | bool "Debug the global anon/private NOMMU mapping region tree" | |
608 | depends on DEBUG_KERNEL && !MMU | |
609 | help | |
610 | This option causes the global tree of anonymous and private mapping | |
611 | regions to be regularly checked for invalid topology. | |
612 | ||
613 | config DEBUG_WRITECOUNT | |
614 | bool "Debug filesystem writers count" | |
615 | depends on DEBUG_KERNEL | |
616 | help | |
617 | Enable this to catch wrong use of the writers count in struct | |
618 | vfsmount. This will increase the size of each file struct by | |
619 | 32 bits. | |
620 | ||
621 | If unsure, say N. | |
622 | ||
623 | config DEBUG_MEMORY_INIT | |
624 | bool "Debug memory initialisation" if EMBEDDED | |
625 | default !EMBEDDED | |
626 | help | |
627 | Enable this for additional checks during memory initialisation. | |
628 | The sanity checks verify aspects of the VM such as the memory model | |
629 | and other information provided by the architecture. Verbose | |
630 | information will be printed at KERN_DEBUG loglevel depending | |
631 | on the mminit_loglevel= command-line option. | |
632 | ||
633 | If unsure, say Y | |
634 | ||
635 | config DEBUG_LIST | |
636 | bool "Debug linked list manipulation" | |
637 | depends on DEBUG_KERNEL | |
638 | help | |
639 | Enable this to turn on extended checks in the linked-list | |
640 | walking routines. | |
641 | ||
642 | If unsure, say N. | |
643 | ||
644 | config DEBUG_SG | |
645 | bool "Debug SG table operations" | |
646 | depends on DEBUG_KERNEL | |
647 | help | |
648 | Enable this to turn on checks on scatter-gather tables. This can | |
649 | help find problems with drivers that do not properly initialize | |
650 | their sg tables. | |
651 | ||
652 | If unsure, say N. | |
653 | ||
654 | config DEBUG_NOTIFIERS | |
655 | bool "Debug notifier call chains" | |
656 | depends on DEBUG_KERNEL | |
657 | help | |
658 | Enable this to turn on sanity checking for notifier call chains. | |
659 | This is most useful for kernel developers to make sure that | |
660 | modules properly unregister themselves from notifier chains. | |
661 | This is a relatively cheap check but if you care about maximum | |
662 | performance, say N. | |
663 | ||
664 | config DEBUG_CREDENTIALS | |
665 | bool "Debug credential management" | |
666 | depends on DEBUG_KERNEL | |
667 | help | |
668 | Enable this to turn on some debug checking for credential | |
669 | management. The additional code keeps track of the number of | |
670 | pointers from task_structs to any given cred struct, and checks to | |
671 | see that this number never exceeds the usage count of the cred | |
672 | struct. | |
673 | ||
674 | Furthermore, if SELinux is enabled, this also checks that the | |
675 | security pointer in the cred struct is never seen to be invalid. | |
676 | ||
677 | If unsure, say N. | |
678 | ||
679 | # | |
680 | # Select this config option from the architecture Kconfig, if it | |
681 | # it is preferred to always offer frame pointers as a config | |
682 | # option on the architecture (regardless of KERNEL_DEBUG): | |
683 | # | |
684 | config ARCH_WANT_FRAME_POINTERS | |
685 | bool | |
686 | help | |
687 | ||
688 | config FRAME_POINTER | |
689 | bool "Compile the kernel with frame pointers" | |
690 | depends on DEBUG_KERNEL && \ | |
691 | (CRIS || M68K || M68KNOMMU || FRV || UML || \ | |
692 | AVR32 || SUPERH || BLACKFIN || MN10300) || \ | |
693 | ARCH_WANT_FRAME_POINTERS | |
694 | default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS | |
695 | help | |
696 | If you say Y here the resulting kernel image will be slightly | |
697 | larger and slower, but it gives very useful debugging information | |
698 | in case of kernel bugs. (precise oopses/stacktraces/warnings) | |
699 | ||
700 | config BOOT_PRINTK_DELAY | |
701 | bool "Delay each boot printk message by N milliseconds" | |
702 | depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY | |
703 | help | |
704 | This build option allows you to read kernel boot messages | |
705 | by inserting a short delay after each one. The delay is | |
706 | specified in milliseconds on the kernel command line, | |
707 | using "boot_delay=N". | |
708 | ||
709 | It is likely that you would also need to use "lpj=M" to preset | |
710 | the "loops per jiffie" value. | |
711 | See a previous boot log for the "lpj" value to use for your | |
712 | system, and then set "lpj=M" before setting "boot_delay=N". | |
713 | NOTE: Using this option may adversely affect SMP systems. | |
714 | I.e., processors other than the first one may not boot up. | |
715 | BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect | |
716 | what it believes to be lockup conditions. | |
717 | ||
718 | config RCU_TORTURE_TEST | |
719 | tristate "torture tests for RCU" | |
720 | depends on DEBUG_KERNEL | |
721 | default n | |
722 | help | |
723 | This option provides a kernel module that runs torture tests | |
724 | on the RCU infrastructure. The kernel module may be built | |
725 | after the fact on the running kernel to be tested, if desired. | |
726 | ||
727 | Say Y here if you want RCU torture tests to be built into | |
728 | the kernel. | |
729 | Say M if you want the RCU torture tests to build as a module. | |
730 | Say N if you are unsure. | |
731 | ||
732 | config RCU_TORTURE_TEST_RUNNABLE | |
733 | bool "torture tests for RCU runnable by default" | |
734 | depends on RCU_TORTURE_TEST = y | |
735 | default n | |
736 | help | |
737 | This option provides a way to build the RCU torture tests | |
738 | directly into the kernel without them starting up at boot | |
739 | time. You can use /proc/sys/kernel/rcutorture_runnable | |
740 | to manually override this setting. This /proc file is | |
741 | available only when the RCU torture tests have been built | |
742 | into the kernel. | |
743 | ||
744 | Say Y here if you want the RCU torture tests to start during | |
745 | boot (you probably don't). | |
746 | Say N here if you want the RCU torture tests to start only | |
747 | after being manually enabled via /proc. | |
748 | ||
749 | config RCU_CPU_STALL_DETECTOR | |
750 | bool "Check for stalled CPUs delaying RCU grace periods" | |
751 | depends on TREE_RCU || TREE_PREEMPT_RCU | |
752 | default n | |
753 | help | |
754 | This option causes RCU to printk information on which | |
755 | CPUs are delaying the current grace period, but only when | |
756 | the grace period extends for excessive time periods. | |
757 | ||
758 | Say Y if you want RCU to perform such checks. | |
759 | ||
760 | Say N if you are unsure. | |
761 | ||
762 | config KPROBES_SANITY_TEST | |
763 | bool "Kprobes sanity tests" | |
764 | depends on DEBUG_KERNEL | |
765 | depends on KPROBES | |
766 | default n | |
767 | help | |
768 | This option provides for testing basic kprobes functionality on | |
769 | boot. A sample kprobe, jprobe and kretprobe are inserted and | |
770 | verified for functionality. | |
771 | ||
772 | Say N if you are unsure. | |
773 | ||
774 | config BACKTRACE_SELF_TEST | |
775 | tristate "Self test for the backtrace code" | |
776 | depends on DEBUG_KERNEL | |
777 | default n | |
778 | help | |
779 | This option provides a kernel module that can be used to test | |
780 | the kernel stack backtrace code. This option is not useful | |
781 | for distributions or general kernels, but only for kernel | |
782 | developers working on architecture code. | |
783 | ||
784 | Note that if you want to also test saved backtraces, you will | |
785 | have to enable STACKTRACE as well. | |
786 | ||
787 | Say N if you are unsure. | |
788 | ||
789 | config DEBUG_BLOCK_EXT_DEVT | |
790 | bool "Force extended block device numbers and spread them" | |
791 | depends on DEBUG_KERNEL | |
792 | depends on BLOCK | |
793 | default n | |
794 | help | |
795 | BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON | |
796 | SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT | |
797 | YOU ARE DOING. Distros, please enable this and fix whatever | |
798 | is broken. | |
799 | ||
800 | Conventionally, block device numbers are allocated from | |
801 | predetermined contiguous area. However, extended block area | |
802 | may introduce non-contiguous block device numbers. This | |
803 | option forces most block device numbers to be allocated from | |
804 | the extended space and spreads them to discover kernel or | |
805 | userland code paths which assume predetermined contiguous | |
806 | device number allocation. | |
807 | ||
808 | Note that turning on this debug option shuffles all the | |
809 | device numbers for all IDE and SCSI devices including libata | |
810 | ones, so root partition specified using device number | |
811 | directly (via rdev or root=MAJ:MIN) won't work anymore. | |
812 | Textual device names (root=/dev/sdXn) will continue to work. | |
813 | ||
814 | Say N if you are unsure. | |
815 | ||
816 | config DEBUG_FORCE_WEAK_PER_CPU | |
817 | bool "Force weak per-cpu definitions" | |
818 | depends on DEBUG_KERNEL | |
819 | help | |
820 | s390 and alpha require percpu variables in modules to be | |
821 | defined weak to work around addressing range issue which | |
822 | puts the following two restrictions on percpu variable | |
823 | definitions. | |
824 | ||
825 | 1. percpu symbols must be unique whether static or not | |
826 | 2. percpu variables can't be defined inside a function | |
827 | ||
828 | To ensure that generic code follows the above rules, this | |
829 | option forces all percpu variables to be defined as weak. | |
830 | ||
831 | config LKDTM | |
832 | tristate "Linux Kernel Dump Test Tool Module" | |
833 | depends on DEBUG_KERNEL | |
834 | depends on KPROBES | |
835 | depends on BLOCK | |
836 | default n | |
837 | help | |
838 | This module enables testing of the different dumping mechanisms by | |
839 | inducing system failures at predefined crash points. | |
840 | If you don't need it: say N | |
841 | Choose M here to compile this code as a module. The module will be | |
842 | called lkdtm. | |
843 | ||
844 | Documentation on how to use the module can be found in | |
845 | drivers/misc/lkdtm.c | |
846 | ||
847 | config FAULT_INJECTION | |
848 | bool "Fault-injection framework" | |
849 | depends on DEBUG_KERNEL | |
850 | help | |
851 | Provide fault-injection framework. | |
852 | For more details, see Documentation/fault-injection/. | |
853 | ||
854 | config FAILSLAB | |
855 | bool "Fault-injection capability for kmalloc" | |
856 | depends on FAULT_INJECTION | |
857 | depends on SLAB || SLUB | |
858 | help | |
859 | Provide fault-injection capability for kmalloc. | |
860 | ||
861 | config FAIL_PAGE_ALLOC | |
862 | bool "Fault-injection capabilitiy for alloc_pages()" | |
863 | depends on FAULT_INJECTION | |
864 | help | |
865 | Provide fault-injection capability for alloc_pages(). | |
866 | ||
867 | config FAIL_MAKE_REQUEST | |
868 | bool "Fault-injection capability for disk IO" | |
869 | depends on FAULT_INJECTION && BLOCK | |
870 | help | |
871 | Provide fault-injection capability for disk IO. | |
872 | ||
873 | config FAIL_IO_TIMEOUT | |
874 | bool "Faul-injection capability for faking disk interrupts" | |
875 | depends on FAULT_INJECTION && BLOCK | |
876 | help | |
877 | Provide fault-injection capability on end IO handling. This | |
878 | will make the block layer "forget" an interrupt as configured, | |
879 | thus exercising the error handling. | |
880 | ||
881 | Only works with drivers that use the generic timeout handling, | |
882 | for others it wont do anything. | |
883 | ||
884 | config FAULT_INJECTION_DEBUG_FS | |
885 | bool "Debugfs entries for fault-injection capabilities" | |
886 | depends on FAULT_INJECTION && SYSFS && DEBUG_FS | |
887 | help | |
888 | Enable configuration of fault-injection capabilities via debugfs. | |
889 | ||
890 | config FAULT_INJECTION_STACKTRACE_FILTER | |
891 | bool "stacktrace filter for fault-injection capabilities" | |
892 | depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT | |
893 | depends on !X86_64 | |
894 | select STACKTRACE | |
895 | select FRAME_POINTER if !PPC && !S390 | |
896 | help | |
897 | Provide stacktrace filter for fault-injection capabilities | |
898 | ||
899 | config LATENCYTOP | |
900 | bool "Latency measuring infrastructure" | |
901 | select FRAME_POINTER if !MIPS && !PPC && !S390 | |
902 | select KALLSYMS | |
903 | select KALLSYMS_ALL | |
904 | select STACKTRACE | |
905 | select SCHEDSTATS | |
906 | select SCHED_DEBUG | |
907 | depends on HAVE_LATENCYTOP_SUPPORT | |
908 | help | |
909 | Enable this option if you want to use the LatencyTOP tool | |
910 | to find out which userspace is blocking on what kernel operations. | |
911 | ||
912 | config SYSCTL_SYSCALL_CHECK | |
913 | bool "Sysctl checks" | |
914 | depends on SYSCTL_SYSCALL | |
915 | ---help--- | |
916 | sys_sysctl uses binary paths that have been found challenging | |
917 | to properly maintain and use. This enables checks that help | |
918 | you to keep things correct. | |
919 | ||
920 | source mm/Kconfig.debug | |
921 | source kernel/trace/Kconfig | |
922 | ||
923 | config PROVIDE_OHCI1394_DMA_INIT | |
924 | bool "Remote debugging over FireWire early on boot" | |
925 | depends on PCI && X86 | |
926 | help | |
927 | If you want to debug problems which hang or crash the kernel early | |
928 | on boot and the crashing machine has a FireWire port, you can use | |
929 | this feature to remotely access the memory of the crashed machine | |
930 | over FireWire. This employs remote DMA as part of the OHCI1394 | |
931 | specification which is now the standard for FireWire controllers. | |
932 | ||
933 | With remote DMA, you can monitor the printk buffer remotely using | |
934 | firescope and access all memory below 4GB using fireproxy from gdb. | |
935 | Even controlling a kernel debugger is possible using remote DMA. | |
936 | ||
937 | Usage: | |
938 | ||
939 | If ohci1394_dma=early is used as boot parameter, it will initialize | |
940 | all OHCI1394 controllers which are found in the PCI config space. | |
941 | ||
942 | As all changes to the FireWire bus such as enabling and disabling | |
943 | devices cause a bus reset and thereby disable remote DMA for all | |
944 | devices, be sure to have the cable plugged and FireWire enabled on | |
945 | the debugging host before booting the debug target for debugging. | |
946 | ||
947 | This code (~1k) is freed after boot. By then, the firewire stack | |
948 | in charge of the OHCI-1394 controllers should be used instead. | |
949 | ||
950 | See Documentation/debugging-via-ohci1394.txt for more information. | |
951 | ||
952 | config FIREWIRE_OHCI_REMOTE_DMA | |
953 | bool "Remote debugging over FireWire with firewire-ohci" | |
954 | depends on FIREWIRE_OHCI | |
955 | help | |
956 | This option lets you use the FireWire bus for remote debugging | |
957 | with help of the firewire-ohci driver. It enables unfiltered | |
958 | remote DMA in firewire-ohci. | |
959 | See Documentation/debugging-via-ohci1394.txt for more information. | |
960 | ||
961 | If unsure, say N. | |
962 | ||
963 | config BUILD_DOCSRC | |
964 | bool "Build targets in Documentation/ tree" | |
965 | depends on HEADERS_CHECK | |
966 | help | |
967 | This option attempts to build objects from the source files in the | |
968 | kernel Documentation/ tree. | |
969 | ||
970 | Say N if you are unsure. | |
971 | ||
972 | config DYNAMIC_DEBUG | |
973 | bool "Enable dynamic printk() support" | |
974 | default n | |
975 | depends on PRINTK | |
976 | depends on DEBUG_FS | |
977 | help | |
978 | ||
979 | Compiles debug level messages into the kernel, which would not | |
980 | otherwise be available at runtime. These messages can then be | |
981 | enabled/disabled based on various levels of scope - per source file, | |
982 | function, module, format string, and line number. This mechanism | |
983 | implicitly enables all pr_debug() and dev_dbg() calls. The impact of | |
984 | this compile option is a larger kernel text size of about 2%. | |
985 | ||
986 | Usage: | |
987 | ||
988 | Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file, | |
989 | which is contained in the 'debugfs' filesystem. Thus, the debugfs | |
990 | filesystem must first be mounted before making use of this feature. | |
991 | We refer the control file as: <debugfs>/dynamic_debug/ddebug. This | |
992 | file contains a list of the debug statements that can be enabled. The | |
993 | format for each line of the file is: | |
994 | ||
995 | filename:lineno [module]function flags format | |
996 | ||
997 | filename : source file of the debug statement | |
998 | lineno : line number of the debug statement | |
999 | module : module that contains the debug statement | |
1000 | function : function that contains the debug statement | |
1001 | flags : 'p' means the line is turned 'on' for printing | |
1002 | format : the format used for the debug statement | |
1003 | ||
1004 | From a live system: | |
1005 | ||
1006 | nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug | |
1007 | # filename:lineno [module]function flags format | |
1008 | fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012" | |
1009 | fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012" | |
1010 | fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012" | |
1011 | ||
1012 | Example usage: | |
1013 | ||
1014 | // enable the message at line 1603 of file svcsock.c | |
1015 | nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > | |
1016 | <debugfs>/dynamic_debug/ddebug | |
1017 | ||
1018 | // enable all the messages in file svcsock.c | |
1019 | nullarbor:~ # echo -n 'file svcsock.c +p' > | |
1020 | <debugfs>/dynamic_debug/ddebug | |
1021 | ||
1022 | // enable all the messages in the NFS server module | |
1023 | nullarbor:~ # echo -n 'module nfsd +p' > | |
1024 | <debugfs>/dynamic_debug/ddebug | |
1025 | ||
1026 | // enable all 12 messages in the function svc_process() | |
1027 | nullarbor:~ # echo -n 'func svc_process +p' > | |
1028 | <debugfs>/dynamic_debug/ddebug | |
1029 | ||
1030 | // disable all 12 messages in the function svc_process() | |
1031 | nullarbor:~ # echo -n 'func svc_process -p' > | |
1032 | <debugfs>/dynamic_debug/ddebug | |
1033 | ||
1034 | See Documentation/dynamic-debug-howto.txt for additional information. | |
1035 | ||
1036 | config DMA_API_DEBUG | |
1037 | bool "Enable debugging of DMA-API usage" | |
1038 | depends on HAVE_DMA_API_DEBUG | |
1039 | help | |
1040 | Enable this option to debug the use of the DMA API by device drivers. | |
1041 | With this option you will be able to detect common bugs in device | |
1042 | drivers like double-freeing of DMA mappings or freeing mappings that | |
1043 | were never allocated. | |
1044 | This option causes a performance degredation. Use only if you want | |
1045 | to debug device drivers. If unsure, say N. | |
1046 | ||
1047 | source "samples/Kconfig" | |
1048 | ||
1049 | source "lib/Kconfig.kgdb" | |
1050 | ||
1051 | source "lib/Kconfig.kmemcheck" |