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1da177e4 LT |
1 | |
2 | config PRINTK_TIME | |
3 | bool "Show timing information on printks" | |
d3b8b6e5 | 4 | depends on PRINTK |
1da177e4 LT |
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 | ||
de488443 JG |
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 | ||
cebc04ba AM |
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. | |
1da177e4 | 27 | |
35bb5b1e AK |
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 | ||
1da177e4 LT |
39 | config MAGIC_SYSRQ |
40 | bool "Magic SysRq key" | |
f346f4b3 | 41 | depends on !UML |
1da177e4 LT |
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 | ||
99657c78 RD |
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 | ||
f71d20e9 AV |
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 | ||
bf4735a4 DM |
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 | ||
ff543332 RD |
85 | For detailed documentation on the debugfs API, see |
86 | Documentation/DocBook/filesystems. | |
87 | ||
bf4735a4 DM |
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 | ||
91341d4b SR |
104 | config DEBUG_SECTION_MISMATCH |
105 | bool "Enable full Section mismatch analysis" | |
1d53661d MF |
106 | depends on UNDEFINED || (BLACKFIN) |
107 | default y | |
fa2144ba | 108 | # This option is on purpose disabled for now. |
af901ca1 | 109 | # It will be enabled when we are down to a reasonable number |
fa2144ba | 110 | # of section mismatch warnings (< 10 for an allyesconfig build) |
91341d4b SR |
111 | help |
112 | The section mismatch analysis checks if there are illegal | |
113 | references from one section to another section. | |
114 | Linux will during link or during runtime drop some sections | |
115 | and any use of code/data previously in these sections will | |
116 | most likely result in an oops. | |
117 | In the code functions and variables are annotated with | |
118 | __init, __devinit etc. (see full list in include/linux/init.h) | |
d6fbfa4f GU |
119 | which results in the code/data being placed in specific sections. |
120 | The section mismatch analysis is always done after a full | |
121 | kernel build but enabling this option will in addition | |
91341d4b SR |
122 | do the following: |
123 | - Add the option -fno-inline-functions-called-once to gcc | |
124 | When inlining a function annotated __init in a non-init | |
d6fbfa4f | 125 | function we would lose the section information and thus |
91341d4b | 126 | the analysis would not catch the illegal reference. |
d6fbfa4f | 127 | This option tells gcc to inline less but will also |
91341d4b SR |
128 | result in a larger kernel. |
129 | - Run the section mismatch analysis for each module/built-in.o | |
130 | When we run the section mismatch analysis on vmlinux.o we | |
d6fbfa4f | 131 | lose valueble information about where the mismatch was |
91341d4b SR |
132 | introduced. |
133 | Running the analysis for each module/built-in.o file | |
134 | will tell where the mismatch happens much closer to the | |
135 | source. The drawback is that we will report the same | |
136 | mismatch at least twice. | |
588ccd73 SR |
137 | - Enable verbose reporting from modpost to help solving |
138 | the section mismatches reported. | |
91341d4b | 139 | |
f346f4b3 AB |
140 | config DEBUG_KERNEL |
141 | bool "Kernel debugging" | |
142 | help | |
143 | Say Y here if you are developing drivers or trying to debug and | |
144 | identify kernel problems. | |
145 | ||
a304e1b8 DW |
146 | config DEBUG_SHIRQ |
147 | bool "Debug shared IRQ handlers" | |
148 | depends on DEBUG_KERNEL && GENERIC_HARDIRQS | |
149 | help | |
150 | Enable this to generate a spurious interrupt as soon as a shared | |
151 | interrupt handler is registered, and just before one is deregistered. | |
152 | Drivers ought to be able to handle interrupts coming in at those | |
153 | points; some don't and need to be caught. | |
154 | ||
8446f1d3 | 155 | config DETECT_SOFTLOCKUP |
58687acb | 156 | bool |
dea20a3f | 157 | depends on DEBUG_KERNEL && !S390 |
8446f1d3 IM |
158 | default y |
159 | help | |
160 | Say Y here to enable the kernel to detect "soft lockups", | |
161 | which are bugs that cause the kernel to loop in kernel | |
9c44bc03 | 162 | mode for more than 60 seconds, without giving other tasks a |
8446f1d3 IM |
163 | chance to run. |
164 | ||
165 | When a soft-lockup is detected, the kernel will print the | |
166 | current stack trace (which you should report), but the | |
167 | system will stay locked up. This feature has negligible | |
168 | overhead. | |
169 | ||
170 | (Note that "hard lockups" are separate type of bugs that | |
171 | can be detected via the NMI-watchdog, on platforms that | |
172 | support it.) | |
173 | ||
58687acb DZ |
174 | config LOCKUP_DETECTOR |
175 | bool "Detect Hard and Soft Lockups" | |
176 | depends on DEBUG_KERNEL | |
177 | default DETECT_SOFTLOCKUP | |
84e478c6 | 178 | help |
58687acb DZ |
179 | Say Y here to enable the kernel to act as a watchdog to detect |
180 | hard and soft lockups. | |
181 | ||
182 | Softlockups are bugs that cause the kernel to loop in kernel | |
183 | mode for more than 60 seconds, without giving other tasks a | |
184 | chance to run. The current stack trace is displayed upon | |
185 | detection and the system will stay locked up. | |
186 | ||
187 | Hardlockups are bugs that cause the CPU to loop in kernel mode | |
188 | for more than 60 seconds, without letting other interrupts have a | |
189 | chance to run. The current stack trace is displayed upon detection | |
190 | and the system will stay locked up. | |
84e478c6 | 191 | |
58687acb DZ |
192 | The overhead should be minimal. A periodic hrtimer runs to |
193 | generate interrupts and kick the watchdog task every 10-12 seconds. | |
194 | An NMI is generated every 60 seconds or so to check for hardlockups. | |
84e478c6 | 195 | |
9c44bc03 IM |
196 | config BOOTPARAM_SOFTLOCKUP_PANIC |
197 | bool "Panic (Reboot) On Soft Lockups" | |
198 | depends on DETECT_SOFTLOCKUP | |
199 | help | |
200 | Say Y here to enable the kernel to panic on "soft lockups", | |
201 | which are bugs that cause the kernel to loop in kernel | |
202 | mode for more than 60 seconds, without giving other tasks a | |
203 | chance to run. | |
204 | ||
205 | The panic can be used in combination with panic_timeout, | |
206 | to cause the system to reboot automatically after a | |
207 | lockup has been detected. This feature is useful for | |
208 | high-availability systems that have uptime guarantees and | |
209 | where a lockup must be resolved ASAP. | |
210 | ||
211 | Say N if unsure. | |
212 | ||
213 | config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE | |
214 | int | |
215 | depends on DETECT_SOFTLOCKUP | |
216 | range 0 1 | |
217 | default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC | |
218 | default 1 if BOOTPARAM_SOFTLOCKUP_PANIC | |
219 | ||
e162b39a MSB |
220 | config DETECT_HUNG_TASK |
221 | bool "Detect Hung Tasks" | |
222 | depends on DEBUG_KERNEL | |
77d05632 | 223 | default DETECT_SOFTLOCKUP |
e162b39a MSB |
224 | help |
225 | Say Y here to enable the kernel to detect "hung tasks", | |
226 | which are bugs that cause the task to be stuck in | |
227 | uninterruptible "D" state indefinitiley. | |
228 | ||
229 | When a hung task is detected, the kernel will print the | |
230 | current stack trace (which you should report), but the | |
231 | task will stay in uninterruptible state. If lockdep is | |
232 | enabled then all held locks will also be reported. This | |
233 | feature has negligible overhead. | |
234 | ||
235 | config BOOTPARAM_HUNG_TASK_PANIC | |
236 | bool "Panic (Reboot) On Hung Tasks" | |
237 | depends on DETECT_HUNG_TASK | |
238 | help | |
239 | Say Y here to enable the kernel to panic on "hung tasks", | |
240 | which are bugs that cause the kernel to leave a task stuck | |
241 | in uninterruptible "D" state. | |
242 | ||
243 | The panic can be used in combination with panic_timeout, | |
244 | to cause the system to reboot automatically after a | |
245 | hung task has been detected. This feature is useful for | |
246 | high-availability systems that have uptime guarantees and | |
247 | where a hung tasks must be resolved ASAP. | |
248 | ||
249 | Say N if unsure. | |
250 | ||
251 | config BOOTPARAM_HUNG_TASK_PANIC_VALUE | |
252 | int | |
253 | depends on DETECT_HUNG_TASK | |
254 | range 0 1 | |
255 | default 0 if !BOOTPARAM_HUNG_TASK_PANIC | |
256 | default 1 if BOOTPARAM_HUNG_TASK_PANIC | |
257 | ||
b642b6d3 IM |
258 | config SCHED_DEBUG |
259 | bool "Collect scheduler debugging info" | |
260 | depends on DEBUG_KERNEL && PROC_FS | |
261 | default y | |
262 | help | |
263 | If you say Y here, the /proc/sched_debug file will be provided | |
264 | that can help debug the scheduler. The runtime overhead of this | |
265 | option is minimal. | |
266 | ||
1da177e4 LT |
267 | config SCHEDSTATS |
268 | bool "Collect scheduler statistics" | |
269 | depends on DEBUG_KERNEL && PROC_FS | |
270 | help | |
271 | If you say Y here, additional code will be inserted into the | |
272 | scheduler and related routines to collect statistics about | |
273 | scheduler behavior and provide them in /proc/schedstat. These | |
274 | stats may be useful for both tuning and debugging the scheduler | |
275 | If you aren't debugging the scheduler or trying to tune a specific | |
276 | application, you can say N to avoid the very slight overhead | |
277 | this adds. | |
278 | ||
82f67cd9 IM |
279 | config TIMER_STATS |
280 | bool "Collect kernel timers statistics" | |
281 | depends on DEBUG_KERNEL && PROC_FS | |
282 | help | |
283 | If you say Y here, additional code will be inserted into the | |
284 | timer routines to collect statistics about kernel timers being | |
285 | reprogrammed. The statistics can be read from /proc/timer_stats. | |
286 | The statistics collection is started by writing 1 to /proc/timer_stats, | |
287 | writing 0 stops it. This feature is useful to collect information | |
c1a834dc IM |
288 | about timer usage patterns in kernel and userspace. This feature |
289 | is lightweight if enabled in the kernel config but not activated | |
290 | (it defaults to deactivated on bootup and will only be activated | |
291 | if some application like powertop activates it explicitly). | |
82f67cd9 | 292 | |
3ac7fe5a TG |
293 | config DEBUG_OBJECTS |
294 | bool "Debug object operations" | |
295 | depends on DEBUG_KERNEL | |
296 | help | |
297 | If you say Y here, additional code will be inserted into the | |
298 | kernel to track the life time of various objects and validate | |
299 | the operations on those objects. | |
300 | ||
301 | config DEBUG_OBJECTS_SELFTEST | |
302 | bool "Debug objects selftest" | |
303 | depends on DEBUG_OBJECTS | |
304 | help | |
305 | This enables the selftest of the object debug code. | |
306 | ||
307 | config DEBUG_OBJECTS_FREE | |
308 | bool "Debug objects in freed memory" | |
309 | depends on DEBUG_OBJECTS | |
310 | help | |
311 | This enables checks whether a k/v free operation frees an area | |
312 | which contains an object which has not been deactivated | |
313 | properly. This can make kmalloc/kfree-intensive workloads | |
314 | much slower. | |
315 | ||
c6f3a97f TG |
316 | config DEBUG_OBJECTS_TIMERS |
317 | bool "Debug timer objects" | |
318 | depends on DEBUG_OBJECTS | |
319 | help | |
320 | If you say Y here, additional code will be inserted into the | |
321 | timer routines to track the life time of timer objects and | |
322 | validate the timer operations. | |
323 | ||
dc186ad7 TG |
324 | config DEBUG_OBJECTS_WORK |
325 | bool "Debug work objects" | |
326 | depends on DEBUG_OBJECTS | |
327 | help | |
328 | If you say Y here, additional code will be inserted into the | |
329 | work queue routines to track the life time of work objects and | |
330 | validate the work operations. | |
331 | ||
3ae70205 IM |
332 | config DEBUG_OBJECTS_ENABLE_DEFAULT |
333 | int "debug_objects bootup default value (0-1)" | |
334 | range 0 1 | |
335 | default "1" | |
336 | depends on DEBUG_OBJECTS | |
337 | help | |
338 | Debug objects boot parameter default value | |
339 | ||
1da177e4 | 340 | config DEBUG_SLAB |
4a2f0acf | 341 | bool "Debug slab memory allocations" |
7d46d9e6 | 342 | depends on DEBUG_KERNEL && SLAB && !KMEMCHECK |
1da177e4 LT |
343 | help |
344 | Say Y here to have the kernel do limited verification on memory | |
345 | allocation as well as poisoning memory on free to catch use of freed | |
346 | memory. This can make kmalloc/kfree-intensive workloads much slower. | |
347 | ||
871751e2 AV |
348 | config DEBUG_SLAB_LEAK |
349 | bool "Memory leak debugging" | |
350 | depends on DEBUG_SLAB | |
351 | ||
f0630fff CL |
352 | config SLUB_DEBUG_ON |
353 | bool "SLUB debugging on by default" | |
7d46d9e6 | 354 | depends on SLUB && SLUB_DEBUG && !KMEMCHECK |
f0630fff CL |
355 | default n |
356 | help | |
357 | Boot with debugging on by default. SLUB boots by default with | |
358 | the runtime debug capabilities switched off. Enabling this is | |
359 | equivalent to specifying the "slub_debug" parameter on boot. | |
360 | There is no support for more fine grained debug control like | |
361 | possible with slub_debug=xxx. SLUB debugging may be switched | |
362 | off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying | |
363 | "slub_debug=-". | |
364 | ||
8ff12cfc CL |
365 | config SLUB_STATS |
366 | default n | |
367 | bool "Enable SLUB performance statistics" | |
5b06c853 | 368 | depends on SLUB && SLUB_DEBUG && SYSFS |
8ff12cfc CL |
369 | help |
370 | SLUB statistics are useful to debug SLUBs allocation behavior in | |
371 | order find ways to optimize the allocator. This should never be | |
372 | enabled for production use since keeping statistics slows down | |
373 | the allocator by a few percentage points. The slabinfo command | |
374 | supports the determination of the most active slabs to figure | |
375 | out which slabs are relevant to a particular load. | |
376 | Try running: slabinfo -DA | |
377 | ||
3bba00d7 CM |
378 | config DEBUG_KMEMLEAK |
379 | bool "Kernel memory leak detector" | |
dfcc3e6a | 380 | depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \ |
9343af08 | 381 | (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE) |
dfcc3e6a | 382 | |
3bba00d7 CM |
383 | select DEBUG_FS if SYSFS |
384 | select STACKTRACE if STACKTRACE_SUPPORT | |
385 | select KALLSYMS | |
b60e26a2 | 386 | select CRC32 |
3bba00d7 CM |
387 | help |
388 | Say Y here if you want to enable the memory leak | |
389 | detector. The memory allocation/freeing is traced in a way | |
390 | similar to the Boehm's conservative garbage collector, the | |
391 | difference being that the orphan objects are not freed but | |
392 | only shown in /sys/kernel/debug/kmemleak. Enabling this | |
393 | feature will introduce an overhead to memory | |
394 | allocations. See Documentation/kmemleak.txt for more | |
395 | details. | |
396 | ||
bf96d1e3 CM |
397 | Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances |
398 | of finding leaks due to the slab objects poisoning. | |
399 | ||
3bba00d7 CM |
400 | In order to access the kmemleak file, debugfs needs to be |
401 | mounted (usually at /sys/kernel/debug). | |
402 | ||
a9d9058a CM |
403 | config DEBUG_KMEMLEAK_EARLY_LOG_SIZE |
404 | int "Maximum kmemleak early log entries" | |
405 | depends on DEBUG_KMEMLEAK | |
dfcc3e6a | 406 | range 200 40000 |
a9d9058a CM |
407 | default 400 |
408 | help | |
409 | Kmemleak must track all the memory allocations to avoid | |
410 | reporting false positives. Since memory may be allocated or | |
411 | freed before kmemleak is initialised, an early log buffer is | |
412 | used to store these actions. If kmemleak reports "early log | |
413 | buffer exceeded", please increase this value. | |
414 | ||
0822ee4a CM |
415 | config DEBUG_KMEMLEAK_TEST |
416 | tristate "Simple test for the kernel memory leak detector" | |
417 | depends on DEBUG_KMEMLEAK | |
418 | help | |
419 | Say Y or M here to build a test for the kernel memory leak | |
420 | detector. This option enables a module that explicitly leaks | |
421 | memory. | |
422 | ||
423 | If unsure, say N. | |
424 | ||
1da177e4 LT |
425 | config DEBUG_PREEMPT |
426 | bool "Debug preemptible kernel" | |
01deab98 | 427 | depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT |
1da177e4 LT |
428 | default y |
429 | help | |
430 | If you say Y here then the kernel will use a debug variant of the | |
431 | commonly used smp_processor_id() function and will print warnings | |
432 | if kernel code uses it in a preemption-unsafe way. Also, the kernel | |
433 | will detect preemption count underflows. | |
434 | ||
e7eebaf6 IM |
435 | config DEBUG_RT_MUTEXES |
436 | bool "RT Mutex debugging, deadlock detection" | |
e7eebaf6 IM |
437 | depends on DEBUG_KERNEL && RT_MUTEXES |
438 | help | |
439 | This allows rt mutex semantics violations and rt mutex related | |
440 | deadlocks (lockups) to be detected and reported automatically. | |
441 | ||
442 | config DEBUG_PI_LIST | |
443 | bool | |
444 | default y | |
445 | depends on DEBUG_RT_MUTEXES | |
446 | ||
61a87122 TG |
447 | config RT_MUTEX_TESTER |
448 | bool "Built-in scriptable tester for rt-mutexes" | |
a1583d3e | 449 | depends on DEBUG_KERNEL && RT_MUTEXES |
61a87122 TG |
450 | help |
451 | This option enables a rt-mutex tester. | |
452 | ||
1da177e4 | 453 | config DEBUG_SPINLOCK |
4d9f34ad | 454 | bool "Spinlock and rw-lock debugging: basic checks" |
1da177e4 LT |
455 | depends on DEBUG_KERNEL |
456 | help | |
457 | Say Y here and build SMP to catch missing spinlock initialization | |
458 | and certain other kinds of spinlock errors commonly made. This is | |
459 | best used in conjunction with the NMI watchdog so that spinlock | |
460 | deadlocks are also debuggable. | |
461 | ||
4d9f34ad IM |
462 | config DEBUG_MUTEXES |
463 | bool "Mutex debugging: basic checks" | |
464 | depends on DEBUG_KERNEL | |
465 | help | |
466 | This feature allows mutex semantics violations to be detected and | |
467 | reported. | |
468 | ||
4d9f34ad IM |
469 | config DEBUG_LOCK_ALLOC |
470 | bool "Lock debugging: detect incorrect freeing of live locks" | |
517e7aa5 | 471 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
472 | select DEBUG_SPINLOCK |
473 | select DEBUG_MUTEXES | |
4d9f34ad IM |
474 | select LOCKDEP |
475 | help | |
476 | This feature will check whether any held lock (spinlock, rwlock, | |
477 | mutex or rwsem) is incorrectly freed by the kernel, via any of the | |
478 | memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), | |
479 | vfree(), etc.), whether a live lock is incorrectly reinitialized via | |
480 | spin_lock_init()/mutex_init()/etc., or whether there is any lock | |
481 | held during task exit. | |
482 | ||
483 | config PROVE_LOCKING | |
484 | bool "Lock debugging: prove locking correctness" | |
517e7aa5 | 485 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
486 | select LOCKDEP |
487 | select DEBUG_SPINLOCK | |
488 | select DEBUG_MUTEXES | |
4d9f34ad IM |
489 | select DEBUG_LOCK_ALLOC |
490 | default n | |
491 | help | |
492 | This feature enables the kernel to prove that all locking | |
493 | that occurs in the kernel runtime is mathematically | |
494 | correct: that under no circumstance could an arbitrary (and | |
495 | not yet triggered) combination of observed locking | |
496 | sequences (on an arbitrary number of CPUs, running an | |
497 | arbitrary number of tasks and interrupt contexts) cause a | |
498 | deadlock. | |
499 | ||
500 | In short, this feature enables the kernel to report locking | |
501 | related deadlocks before they actually occur. | |
502 | ||
503 | The proof does not depend on how hard and complex a | |
504 | deadlock scenario would be to trigger: how many | |
505 | participant CPUs, tasks and irq-contexts would be needed | |
506 | for it to trigger. The proof also does not depend on | |
507 | timing: if a race and a resulting deadlock is possible | |
508 | theoretically (no matter how unlikely the race scenario | |
509 | is), it will be proven so and will immediately be | |
510 | reported by the kernel (once the event is observed that | |
511 | makes the deadlock theoretically possible). | |
512 | ||
513 | If a deadlock is impossible (i.e. the locking rules, as | |
514 | observed by the kernel, are mathematically correct), the | |
515 | kernel reports nothing. | |
516 | ||
517 | NOTE: this feature can also be enabled for rwlocks, mutexes | |
518 | and rwsems - in which case all dependencies between these | |
519 | different locking variants are observed and mapped too, and | |
520 | the proof of observed correctness is also maintained for an | |
521 | arbitrary combination of these separate locking variants. | |
522 | ||
523 | For more details, see Documentation/lockdep-design.txt. | |
524 | ||
632ee200 PM |
525 | config PROVE_RCU |
526 | bool "RCU debugging: prove RCU correctness" | |
527 | depends on PROVE_LOCKING | |
528 | default n | |
529 | help | |
530 | This feature enables lockdep extensions that check for correct | |
531 | use of RCU APIs. This is currently under development. Say Y | |
532 | if you want to debug RCU usage or help work on the PROVE_RCU | |
533 | feature. | |
534 | ||
535 | Say N if you are unsure. | |
536 | ||
4d9f34ad IM |
537 | config LOCKDEP |
538 | bool | |
517e7aa5 | 539 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad | 540 | select STACKTRACE |
00540e5d | 541 | select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 |
4d9f34ad IM |
542 | select KALLSYMS |
543 | select KALLSYMS_ALL | |
544 | ||
f20786ff | 545 | config LOCK_STAT |
fdfb870f | 546 | bool "Lock usage statistics" |
f20786ff PZ |
547 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
548 | select LOCKDEP | |
549 | select DEBUG_SPINLOCK | |
550 | select DEBUG_MUTEXES | |
551 | select DEBUG_LOCK_ALLOC | |
552 | default n | |
553 | help | |
554 | This feature enables tracking lock contention points | |
555 | ||
a560aa48 PZ |
556 | For more details, see Documentation/lockstat.txt |
557 | ||
dd8b1cf6 FW |
558 | This also enables lock events required by "perf lock", |
559 | subcommand of perf. | |
560 | If you want to use "perf lock", you also need to turn on | |
561 | CONFIG_EVENT_TRACING. | |
84c6f88f HM |
562 | |
563 | CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. | |
dd8b1cf6 | 564 | (CONFIG_LOCKDEP defines "acquire" and "release" events.) |
84c6f88f | 565 | |
4d9f34ad IM |
566 | config DEBUG_LOCKDEP |
567 | bool "Lock dependency engine debugging" | |
517e7aa5 | 568 | depends on DEBUG_KERNEL && LOCKDEP |
4d9f34ad IM |
569 | help |
570 | If you say Y here, the lock dependency engine will do | |
571 | additional runtime checks to debug itself, at the price | |
572 | of more runtime overhead. | |
573 | ||
574 | config TRACE_IRQFLAGS | |
517e7aa5 | 575 | depends on DEBUG_KERNEL |
4d9f34ad IM |
576 | bool |
577 | default y | |
578 | depends on TRACE_IRQFLAGS_SUPPORT | |
579 | depends on PROVE_LOCKING | |
580 | ||
1da177e4 | 581 | config DEBUG_SPINLOCK_SLEEP |
4d9f34ad | 582 | bool "Spinlock debugging: sleep-inside-spinlock checking" |
1da177e4 LT |
583 | depends on DEBUG_KERNEL |
584 | help | |
585 | If you say Y here, various routines which may sleep will become very | |
586 | noisy if they are called with a spinlock held. | |
587 | ||
cae2ed9a IM |
588 | config DEBUG_LOCKING_API_SELFTESTS |
589 | bool "Locking API boot-time self-tests" | |
590 | depends on DEBUG_KERNEL | |
591 | help | |
592 | Say Y here if you want the kernel to run a short self-test during | |
593 | bootup. The self-test checks whether common types of locking bugs | |
594 | are detected by debugging mechanisms or not. (if you disable | |
595 | lock debugging then those bugs wont be detected of course.) | |
596 | The following locking APIs are covered: spinlocks, rwlocks, | |
597 | mutexes and rwsems. | |
598 | ||
8637c099 IM |
599 | config STACKTRACE |
600 | bool | |
601 | depends on STACKTRACE_SUPPORT | |
602 | ||
1da177e4 LT |
603 | config DEBUG_KOBJECT |
604 | bool "kobject debugging" | |
605 | depends on DEBUG_KERNEL | |
606 | help | |
607 | If you say Y here, some extra kobject debugging messages will be sent | |
608 | to the syslog. | |
609 | ||
610 | config DEBUG_HIGHMEM | |
611 | bool "Highmem debugging" | |
612 | depends on DEBUG_KERNEL && HIGHMEM | |
613 | help | |
614 | This options enables addition error checking for high memory systems. | |
615 | Disable for production systems. | |
616 | ||
617 | config DEBUG_BUGVERBOSE | |
618 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED | |
c8538a7a | 619 | depends on BUG |
b920de1b DH |
620 | depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ |
621 | FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 | |
8420e7ef | 622 | default y |
1da177e4 LT |
623 | help |
624 | Say Y here to make BUG() panics output the file name and line number | |
625 | of the BUG call as well as the EIP and oops trace. This aids | |
626 | debugging but costs about 70-100K of memory. | |
627 | ||
628 | config DEBUG_INFO | |
629 | bool "Compile the kernel with debug info" | |
630 | depends on DEBUG_KERNEL | |
631 | help | |
632 | If you say Y here the resulting kernel image will include | |
633 | debugging info resulting in a larger kernel image. | |
b72e53f8 AD |
634 | This adds debug symbols to the kernel and modules (gcc -g), and |
635 | is needed if you intend to use kernel crashdump or binary object | |
636 | tools like crash, kgdb, LKCD, gdb, etc on the kernel. | |
1da177e4 LT |
637 | Say Y here only if you plan to debug the kernel. |
638 | ||
639 | If unsure, say N. | |
640 | ||
a241ec65 PM |
641 | config DEBUG_VM |
642 | bool "Debug VM" | |
643 | depends on DEBUG_KERNEL | |
644 | help | |
13e7444b NP |
645 | Enable this to turn on extended checks in the virtual-memory system |
646 | that may impact performance. | |
a241ec65 PM |
647 | |
648 | If unsure, say N. | |
649 | ||
59ea7463 JS |
650 | config DEBUG_VIRTUAL |
651 | bool "Debug VM translations" | |
652 | depends on DEBUG_KERNEL && X86 | |
653 | help | |
654 | Enable some costly sanity checks in virtual to page code. This can | |
655 | catch mistakes with virt_to_page() and friends. | |
656 | ||
657 | If unsure, say N. | |
658 | ||
8feae131 DH |
659 | config DEBUG_NOMMU_REGIONS |
660 | bool "Debug the global anon/private NOMMU mapping region tree" | |
661 | depends on DEBUG_KERNEL && !MMU | |
662 | help | |
663 | This option causes the global tree of anonymous and private mapping | |
664 | regions to be regularly checked for invalid topology. | |
665 | ||
ad775f5a DH |
666 | config DEBUG_WRITECOUNT |
667 | bool "Debug filesystem writers count" | |
668 | depends on DEBUG_KERNEL | |
669 | help | |
670 | Enable this to catch wrong use of the writers count in struct | |
671 | vfsmount. This will increase the size of each file struct by | |
672 | 32 bits. | |
673 | ||
674 | If unsure, say N. | |
675 | ||
6b74ab97 MG |
676 | config DEBUG_MEMORY_INIT |
677 | bool "Debug memory initialisation" if EMBEDDED | |
678 | default !EMBEDDED | |
679 | help | |
680 | Enable this for additional checks during memory initialisation. | |
681 | The sanity checks verify aspects of the VM such as the memory model | |
682 | and other information provided by the architecture. Verbose | |
683 | information will be printed at KERN_DEBUG loglevel depending | |
684 | on the mminit_loglevel= command-line option. | |
685 | ||
686 | If unsure, say Y | |
687 | ||
199a9afc DJ |
688 | config DEBUG_LIST |
689 | bool "Debug linked list manipulation" | |
690 | depends on DEBUG_KERNEL | |
691 | help | |
692 | Enable this to turn on extended checks in the linked-list | |
693 | walking routines. | |
694 | ||
695 | If unsure, say N. | |
696 | ||
d6ec0842 JA |
697 | config DEBUG_SG |
698 | bool "Debug SG table operations" | |
699 | depends on DEBUG_KERNEL | |
700 | help | |
701 | Enable this to turn on checks on scatter-gather tables. This can | |
702 | help find problems with drivers that do not properly initialize | |
703 | their sg tables. | |
704 | ||
705 | If unsure, say N. | |
706 | ||
1b2439db AV |
707 | config DEBUG_NOTIFIERS |
708 | bool "Debug notifier call chains" | |
709 | depends on DEBUG_KERNEL | |
710 | help | |
711 | Enable this to turn on sanity checking for notifier call chains. | |
712 | This is most useful for kernel developers to make sure that | |
713 | modules properly unregister themselves from notifier chains. | |
714 | This is a relatively cheap check but if you care about maximum | |
715 | performance, say N. | |
716 | ||
e0e81739 DH |
717 | config DEBUG_CREDENTIALS |
718 | bool "Debug credential management" | |
719 | depends on DEBUG_KERNEL | |
720 | help | |
721 | Enable this to turn on some debug checking for credential | |
722 | management. The additional code keeps track of the number of | |
723 | pointers from task_structs to any given cred struct, and checks to | |
724 | see that this number never exceeds the usage count of the cred | |
725 | struct. | |
726 | ||
727 | Furthermore, if SELinux is enabled, this also checks that the | |
728 | security pointer in the cred struct is never seen to be invalid. | |
729 | ||
730 | If unsure, say N. | |
731 | ||
64dec40d JM |
732 | # |
733 | # Select this config option from the architecture Kconfig, if it | |
734 | # it is preferred to always offer frame pointers as a config | |
735 | # option on the architecture (regardless of KERNEL_DEBUG): | |
736 | # | |
737 | config ARCH_WANT_FRAME_POINTERS | |
738 | bool | |
739 | help | |
740 | ||
1da177e4 LT |
741 | config FRAME_POINTER |
742 | bool "Compile the kernel with frame pointers" | |
b920de1b | 743 | depends on DEBUG_KERNEL && \ |
75ee034a | 744 | (CRIS || M68K || M68KNOMMU || FRV || UML || \ |
da4276b8 IM |
745 | AVR32 || SUPERH || BLACKFIN || MN10300) || \ |
746 | ARCH_WANT_FRAME_POINTERS | |
747 | default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS | |
748 | help | |
749 | If you say Y here the resulting kernel image will be slightly | |
750 | larger and slower, but it gives very useful debugging information | |
751 | in case of kernel bugs. (precise oopses/stacktraces/warnings) | |
1da177e4 | 752 | |
bfe8df3d RD |
753 | config BOOT_PRINTK_DELAY |
754 | bool "Delay each boot printk message by N milliseconds" | |
755 | depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY | |
756 | help | |
757 | This build option allows you to read kernel boot messages | |
758 | by inserting a short delay after each one. The delay is | |
759 | specified in milliseconds on the kernel command line, | |
760 | using "boot_delay=N". | |
761 | ||
762 | It is likely that you would also need to use "lpj=M" to preset | |
763 | the "loops per jiffie" value. | |
764 | See a previous boot log for the "lpj" value to use for your | |
765 | system, and then set "lpj=M" before setting "boot_delay=N". | |
766 | NOTE: Using this option may adversely affect SMP systems. | |
767 | I.e., processors other than the first one may not boot up. | |
768 | BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect | |
769 | what it believes to be lockup conditions. | |
770 | ||
a241ec65 PM |
771 | config RCU_TORTURE_TEST |
772 | tristate "torture tests for RCU" | |
773 | depends on DEBUG_KERNEL | |
774 | default n | |
775 | help | |
776 | This option provides a kernel module that runs torture tests | |
777 | on the RCU infrastructure. The kernel module may be built | |
778 | after the fact on the running kernel to be tested, if desired. | |
779 | ||
31a72bce PM |
780 | Say Y here if you want RCU torture tests to be built into |
781 | the kernel. | |
a241ec65 PM |
782 | Say M if you want the RCU torture tests to build as a module. |
783 | Say N if you are unsure. | |
8bb31b9d | 784 | |
31a72bce PM |
785 | config RCU_TORTURE_TEST_RUNNABLE |
786 | bool "torture tests for RCU runnable by default" | |
787 | depends on RCU_TORTURE_TEST = y | |
788 | default n | |
789 | help | |
790 | This option provides a way to build the RCU torture tests | |
791 | directly into the kernel without them starting up at boot | |
792 | time. You can use /proc/sys/kernel/rcutorture_runnable | |
793 | to manually override this setting. This /proc file is | |
794 | available only when the RCU torture tests have been built | |
795 | into the kernel. | |
796 | ||
797 | Say Y here if you want the RCU torture tests to start during | |
798 | boot (you probably don't). | |
799 | Say N here if you want the RCU torture tests to start only | |
800 | after being manually enabled via /proc. | |
801 | ||
64db4cff PM |
802 | config RCU_CPU_STALL_DETECTOR |
803 | bool "Check for stalled CPUs delaying RCU grace periods" | |
6b3ef48a | 804 | depends on TREE_RCU || TREE_PREEMPT_RCU |
8bfb2f8e | 805 | default y |
64db4cff PM |
806 | help |
807 | This option causes RCU to printk information on which | |
808 | CPUs are delaying the current grace period, but only when | |
809 | the grace period extends for excessive time periods. | |
67182ae1 | 810 | |
4c54005c | 811 | Say N if you want to disable such checks. |
67182ae1 | 812 | |
4c54005c | 813 | Say Y if you are unsure. |
67182ae1 | 814 | |
1ed509a2 PM |
815 | config RCU_CPU_STALL_VERBOSE |
816 | bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" | |
817 | depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU | |
818 | default n | |
819 | help | |
820 | This option causes RCU to printk detailed per-task information | |
821 | for any tasks that are stalling the current RCU grace period. | |
67182ae1 PM |
822 | |
823 | Say N if you are unsure. | |
824 | ||
1ed509a2 PM |
825 | Say Y if you want to enable such checks. |
826 | ||
8c1c9356 AM |
827 | config KPROBES_SANITY_TEST |
828 | bool "Kprobes sanity tests" | |
829 | depends on DEBUG_KERNEL | |
830 | depends on KPROBES | |
831 | default n | |
832 | help | |
833 | This option provides for testing basic kprobes functionality on | |
834 | boot. A sample kprobe, jprobe and kretprobe are inserted and | |
835 | verified for functionality. | |
836 | ||
837 | Say N if you are unsure. | |
838 | ||
6dab2778 AV |
839 | config BACKTRACE_SELF_TEST |
840 | tristate "Self test for the backtrace code" | |
841 | depends on DEBUG_KERNEL | |
842 | default n | |
843 | help | |
844 | This option provides a kernel module that can be used to test | |
845 | the kernel stack backtrace code. This option is not useful | |
846 | for distributions or general kernels, but only for kernel | |
847 | developers working on architecture code. | |
848 | ||
ad118c54 VN |
849 | Note that if you want to also test saved backtraces, you will |
850 | have to enable STACKTRACE as well. | |
851 | ||
6dab2778 AV |
852 | Say N if you are unsure. |
853 | ||
870d6656 TH |
854 | config DEBUG_BLOCK_EXT_DEVT |
855 | bool "Force extended block device numbers and spread them" | |
856 | depends on DEBUG_KERNEL | |
857 | depends on BLOCK | |
759f8ca3 | 858 | default n |
870d6656 | 859 | help |
0e11e342 TH |
860 | BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON |
861 | SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT | |
862 | YOU ARE DOING. Distros, please enable this and fix whatever | |
863 | is broken. | |
864 | ||
870d6656 TH |
865 | Conventionally, block device numbers are allocated from |
866 | predetermined contiguous area. However, extended block area | |
867 | may introduce non-contiguous block device numbers. This | |
868 | option forces most block device numbers to be allocated from | |
869 | the extended space and spreads them to discover kernel or | |
870 | userland code paths which assume predetermined contiguous | |
871 | device number allocation. | |
872 | ||
55dc7db7 TH |
873 | Note that turning on this debug option shuffles all the |
874 | device numbers for all IDE and SCSI devices including libata | |
875 | ones, so root partition specified using device number | |
876 | directly (via rdev or root=MAJ:MIN) won't work anymore. | |
877 | Textual device names (root=/dev/sdXn) will continue to work. | |
878 | ||
870d6656 TH |
879 | Say N if you are unsure. |
880 | ||
7c756e6e TH |
881 | config DEBUG_FORCE_WEAK_PER_CPU |
882 | bool "Force weak per-cpu definitions" | |
883 | depends on DEBUG_KERNEL | |
884 | help | |
885 | s390 and alpha require percpu variables in modules to be | |
886 | defined weak to work around addressing range issue which | |
887 | puts the following two restrictions on percpu variable | |
888 | definitions. | |
889 | ||
890 | 1. percpu symbols must be unique whether static or not | |
891 | 2. percpu variables can't be defined inside a function | |
892 | ||
893 | To ensure that generic code follows the above rules, this | |
894 | option forces all percpu variables to be defined as weak. | |
895 | ||
8bb31b9d AG |
896 | config LKDTM |
897 | tristate "Linux Kernel Dump Test Tool Module" | |
0347af4e | 898 | depends on DEBUG_FS |
fddd9cf8 | 899 | depends on BLOCK |
8bb31b9d AG |
900 | default n |
901 | help | |
902 | This module enables testing of the different dumping mechanisms by | |
903 | inducing system failures at predefined crash points. | |
904 | If you don't need it: say N | |
905 | Choose M here to compile this code as a module. The module will be | |
906 | called lkdtm. | |
907 | ||
908 | Documentation on how to use the module can be found in | |
0347af4e | 909 | Documentation/fault-injection/provoke-crashes.txt |
6ff1cb35 AM |
910 | |
911 | config FAULT_INJECTION | |
1ab8509a AM |
912 | bool "Fault-injection framework" |
913 | depends on DEBUG_KERNEL | |
329409ae AM |
914 | help |
915 | Provide fault-injection framework. | |
916 | For more details, see Documentation/fault-injection/. | |
6ff1cb35 | 917 | |
8a8b6502 | 918 | config FAILSLAB |
1ab8509a AM |
919 | bool "Fault-injection capability for kmalloc" |
920 | depends on FAULT_INJECTION | |
773ff60e | 921 | depends on SLAB || SLUB |
8a8b6502 | 922 | help |
1ab8509a | 923 | Provide fault-injection capability for kmalloc. |
8a8b6502 | 924 | |
933e312e AM |
925 | config FAIL_PAGE_ALLOC |
926 | bool "Fault-injection capabilitiy for alloc_pages()" | |
1ab8509a | 927 | depends on FAULT_INJECTION |
933e312e | 928 | help |
1ab8509a | 929 | Provide fault-injection capability for alloc_pages(). |
933e312e | 930 | |
c17bb495 | 931 | config FAIL_MAKE_REQUEST |
86327d19 | 932 | bool "Fault-injection capability for disk IO" |
581d4e28 | 933 | depends on FAULT_INJECTION && BLOCK |
c17bb495 | 934 | help |
1ab8509a | 935 | Provide fault-injection capability for disk IO. |
c17bb495 | 936 | |
581d4e28 JA |
937 | config FAIL_IO_TIMEOUT |
938 | bool "Faul-injection capability for faking disk interrupts" | |
939 | depends on FAULT_INJECTION && BLOCK | |
940 | help | |
941 | Provide fault-injection capability on end IO handling. This | |
942 | will make the block layer "forget" an interrupt as configured, | |
943 | thus exercising the error handling. | |
944 | ||
945 | Only works with drivers that use the generic timeout handling, | |
946 | for others it wont do anything. | |
947 | ||
6ff1cb35 AM |
948 | config FAULT_INJECTION_DEBUG_FS |
949 | bool "Debugfs entries for fault-injection capabilities" | |
1ab8509a | 950 | depends on FAULT_INJECTION && SYSFS && DEBUG_FS |
6ff1cb35 | 951 | help |
1ab8509a | 952 | Enable configuration of fault-injection capabilities via debugfs. |
1df49008 AM |
953 | |
954 | config FAULT_INJECTION_STACKTRACE_FILTER | |
955 | bool "stacktrace filter for fault-injection capabilities" | |
956 | depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT | |
6d690dca | 957 | depends on !X86_64 |
1df49008 | 958 | select STACKTRACE |
75ee034a | 959 | select FRAME_POINTER if !PPC && !S390 |
1df49008 AM |
960 | help |
961 | Provide stacktrace filter for fault-injection capabilities | |
267c4025 | 962 | |
9745512c AV |
963 | config LATENCYTOP |
964 | bool "Latency measuring infrastructure" | |
75ee034a | 965 | select FRAME_POINTER if !MIPS && !PPC && !S390 |
9745512c AV |
966 | select KALLSYMS |
967 | select KALLSYMS_ALL | |
968 | select STACKTRACE | |
969 | select SCHEDSTATS | |
970 | select SCHED_DEBUG | |
aa7d9350 | 971 | depends on HAVE_LATENCYTOP_SUPPORT |
9745512c AV |
972 | help |
973 | Enable this option if you want to use the LatencyTOP tool | |
974 | to find out which userspace is blocking on what kernel operations. | |
975 | ||
9e94cd32 AK |
976 | config SYSCTL_SYSCALL_CHECK |
977 | bool "Sysctl checks" | |
83ac201b | 978 | depends on SYSCTL |
9e94cd32 AK |
979 | ---help--- |
980 | sys_sysctl uses binary paths that have been found challenging | |
981 | to properly maintain and use. This enables checks that help | |
982 | you to keep things correct. | |
983 | ||
6a11f75b | 984 | source mm/Kconfig.debug |
16444a8a ACM |
985 | source kernel/trace/Kconfig |
986 | ||
f212ec4b | 987 | config PROVIDE_OHCI1394_DMA_INIT |
080de8c2 | 988 | bool "Remote debugging over FireWire early on boot" |
f212ec4b BK |
989 | depends on PCI && X86 |
990 | help | |
991 | If you want to debug problems which hang or crash the kernel early | |
992 | on boot and the crashing machine has a FireWire port, you can use | |
993 | this feature to remotely access the memory of the crashed machine | |
994 | over FireWire. This employs remote DMA as part of the OHCI1394 | |
995 | specification which is now the standard for FireWire controllers. | |
996 | ||
997 | With remote DMA, you can monitor the printk buffer remotely using | |
998 | firescope and access all memory below 4GB using fireproxy from gdb. | |
999 | Even controlling a kernel debugger is possible using remote DMA. | |
1000 | ||
1001 | Usage: | |
1002 | ||
1003 | If ohci1394_dma=early is used as boot parameter, it will initialize | |
1004 | all OHCI1394 controllers which are found in the PCI config space. | |
1005 | ||
1006 | As all changes to the FireWire bus such as enabling and disabling | |
1007 | devices cause a bus reset and thereby disable remote DMA for all | |
1008 | devices, be sure to have the cable plugged and FireWire enabled on | |
1009 | the debugging host before booting the debug target for debugging. | |
1010 | ||
1011 | This code (~1k) is freed after boot. By then, the firewire stack | |
1012 | in charge of the OHCI-1394 controllers should be used instead. | |
1013 | ||
1014 | See Documentation/debugging-via-ohci1394.txt for more information. | |
9745512c | 1015 | |
080de8c2 SR |
1016 | config FIREWIRE_OHCI_REMOTE_DMA |
1017 | bool "Remote debugging over FireWire with firewire-ohci" | |
1018 | depends on FIREWIRE_OHCI | |
1019 | help | |
1020 | This option lets you use the FireWire bus for remote debugging | |
1021 | with help of the firewire-ohci driver. It enables unfiltered | |
1022 | remote DMA in firewire-ohci. | |
1023 | See Documentation/debugging-via-ohci1394.txt for more information. | |
1024 | ||
1025 | If unsure, say N. | |
1026 | ||
152de30b | 1027 | config BUILD_DOCSRC |
3794f3e8 RD |
1028 | bool "Build targets in Documentation/ tree" |
1029 | depends on HEADERS_CHECK | |
1030 | help | |
1031 | This option attempts to build objects from the source files in the | |
1032 | kernel Documentation/ tree. | |
1033 | ||
1034 | Say N if you are unsure. | |
1035 | ||
e9d376f0 | 1036 | config DYNAMIC_DEBUG |
86151fdf | 1037 | bool "Enable dynamic printk() support" |
346e15be JB |
1038 | default n |
1039 | depends on PRINTK | |
86151fdf | 1040 | depends on DEBUG_FS |
346e15be JB |
1041 | help |
1042 | ||
1043 | Compiles debug level messages into the kernel, which would not | |
1044 | otherwise be available at runtime. These messages can then be | |
86151fdf JB |
1045 | enabled/disabled based on various levels of scope - per source file, |
1046 | function, module, format string, and line number. This mechanism | |
1047 | implicitly enables all pr_debug() and dev_dbg() calls. The impact of | |
1048 | this compile option is a larger kernel text size of about 2%. | |
346e15be JB |
1049 | |
1050 | Usage: | |
1051 | ||
86151fdf JB |
1052 | Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file, |
1053 | which is contained in the 'debugfs' filesystem. Thus, the debugfs | |
1054 | filesystem must first be mounted before making use of this feature. | |
1055 | We refer the control file as: <debugfs>/dynamic_debug/ddebug. This | |
1056 | file contains a list of the debug statements that can be enabled. The | |
1057 | format for each line of the file is: | |
346e15be | 1058 | |
86151fdf | 1059 | filename:lineno [module]function flags format |
346e15be | 1060 | |
86151fdf JB |
1061 | filename : source file of the debug statement |
1062 | lineno : line number of the debug statement | |
1063 | module : module that contains the debug statement | |
1064 | function : function that contains the debug statement | |
1065 | flags : 'p' means the line is turned 'on' for printing | |
1066 | format : the format used for the debug statement | |
346e15be JB |
1067 | |
1068 | From a live system: | |
1069 | ||
86151fdf JB |
1070 | nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug |
1071 | # filename:lineno [module]function flags format | |
1072 | fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012" | |
1073 | fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012" | |
1074 | fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012" | |
346e15be | 1075 | |
86151fdf | 1076 | Example usage: |
346e15be | 1077 | |
86151fdf JB |
1078 | // enable the message at line 1603 of file svcsock.c |
1079 | nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > | |
1080 | <debugfs>/dynamic_debug/ddebug | |
346e15be | 1081 | |
86151fdf JB |
1082 | // enable all the messages in file svcsock.c |
1083 | nullarbor:~ # echo -n 'file svcsock.c +p' > | |
1084 | <debugfs>/dynamic_debug/ddebug | |
346e15be | 1085 | |
86151fdf JB |
1086 | // enable all the messages in the NFS server module |
1087 | nullarbor:~ # echo -n 'module nfsd +p' > | |
1088 | <debugfs>/dynamic_debug/ddebug | |
346e15be | 1089 | |
86151fdf JB |
1090 | // enable all 12 messages in the function svc_process() |
1091 | nullarbor:~ # echo -n 'func svc_process +p' > | |
1092 | <debugfs>/dynamic_debug/ddebug | |
346e15be | 1093 | |
86151fdf JB |
1094 | // disable all 12 messages in the function svc_process() |
1095 | nullarbor:~ # echo -n 'func svc_process -p' > | |
1096 | <debugfs>/dynamic_debug/ddebug | |
346e15be | 1097 | |
86151fdf | 1098 | See Documentation/dynamic-debug-howto.txt for additional information. |
346e15be | 1099 | |
5ee00bd4 JR |
1100 | config DMA_API_DEBUG |
1101 | bool "Enable debugging of DMA-API usage" | |
1102 | depends on HAVE_DMA_API_DEBUG | |
1103 | help | |
1104 | Enable this option to debug the use of the DMA API by device drivers. | |
1105 | With this option you will be able to detect common bugs in device | |
1106 | drivers like double-freeing of DMA mappings or freeing mappings that | |
1107 | were never allocated. | |
1108 | This option causes a performance degredation. Use only if you want | |
1109 | to debug device drivers. If unsure, say N. | |
346e15be | 1110 | |
267c4025 | 1111 | source "samples/Kconfig" |
dc7d5527 JW |
1112 | |
1113 | source "lib/Kconfig.kgdb" | |
0a4af3b0 PE |
1114 | |
1115 | source "lib/Kconfig.kmemcheck" |