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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 | |
99172a2f JC |
10 | in kernel startup. Or add printk.time=1 at boot-time. |
11 | See Documentation/kernel-parameters.txt | |
1da177e4 | 12 | |
5af5bcb8 MSB |
13 | config DEFAULT_MESSAGE_LOGLEVEL |
14 | int "Default message log level (1-7)" | |
15 | range 1 7 | |
16 | default "4" | |
17 | help | |
18 | Default log level for printk statements with no specified priority. | |
19 | ||
20 | This was hard-coded to KERN_WARNING since at least 2.6.10 but folks | |
21 | that are auditing their logs closely may want to set it to a lower | |
22 | priority. | |
23 | ||
de488443 JG |
24 | config ENABLE_WARN_DEPRECATED |
25 | bool "Enable __deprecated logic" | |
26 | default y | |
27 | help | |
28 | Enable the __deprecated logic in the kernel build. | |
29 | Disable this to suppress the "warning: 'foo' is deprecated | |
30 | (declared at kernel/power/somefile.c:1234)" messages. | |
31 | ||
cebc04ba AM |
32 | config ENABLE_MUST_CHECK |
33 | bool "Enable __must_check logic" | |
34 | default y | |
35 | help | |
36 | Enable the __must_check logic in the kernel build. Disable this to | |
37 | suppress the "warning: ignoring return value of 'foo', declared with | |
38 | attribute warn_unused_result" messages. | |
1da177e4 | 39 | |
35bb5b1e AK |
40 | config FRAME_WARN |
41 | int "Warn for stack frames larger than (needs gcc 4.4)" | |
42 | range 0 8192 | |
43 | default 1024 if !64BIT | |
44 | default 2048 if 64BIT | |
45 | help | |
46 | Tell gcc to warn at build time for stack frames larger than this. | |
47 | Setting this too low will cause a lot of warnings. | |
48 | Setting it to 0 disables the warning. | |
49 | Requires gcc 4.4 | |
50 | ||
1da177e4 LT |
51 | config MAGIC_SYSRQ |
52 | bool "Magic SysRq key" | |
f346f4b3 | 53 | depends on !UML |
1da177e4 LT |
54 | help |
55 | If you say Y here, you will have some control over the system even | |
56 | if the system crashes for example during kernel debugging (e.g., you | |
57 | will be able to flush the buffer cache to disk, reboot the system | |
58 | immediately or dump some status information). This is accomplished | |
59 | by pressing various keys while holding SysRq (Alt+PrintScreen). It | |
60 | also works on a serial console (on PC hardware at least), if you | |
61 | send a BREAK and then within 5 seconds a command keypress. The | |
62 | keys are documented in <file:Documentation/sysrq.txt>. Don't say Y | |
63 | unless you really know what this hack does. | |
64 | ||
99657c78 RD |
65 | config STRIP_ASM_SYMS |
66 | bool "Strip assembler-generated symbols during link" | |
67 | default n | |
68 | help | |
69 | Strip internal assembler-generated symbols during a link (symbols | |
70 | that look like '.Lxxx') so they don't pollute the output of | |
71 | get_wchan() and suchlike. | |
72 | ||
f71d20e9 AV |
73 | config UNUSED_SYMBOLS |
74 | bool "Enable unused/obsolete exported symbols" | |
75 | default y if X86 | |
76 | help | |
77 | Unused but exported symbols make the kernel needlessly bigger. For | |
78 | that reason most of these unused exports will soon be removed. This | |
79 | option is provided temporarily to provide a transition period in case | |
80 | some external kernel module needs one of these symbols anyway. If you | |
81 | encounter such a case in your module, consider if you are actually | |
82 | using the right API. (rationale: since nobody in the kernel is using | |
83 | this in a module, there is a pretty good chance it's actually the | |
84 | wrong interface to use). If you really need the symbol, please send a | |
85 | mail to the linux kernel mailing list mentioning the symbol and why | |
86 | you really need it, and what the merge plan to the mainline kernel for | |
87 | your module is. | |
88 | ||
bf4735a4 DM |
89 | config DEBUG_FS |
90 | bool "Debug Filesystem" | |
bf4735a4 DM |
91 | help |
92 | debugfs is a virtual file system that kernel developers use to put | |
93 | debugging files into. Enable this option to be able to read and | |
94 | write to these files. | |
95 | ||
ff543332 RD |
96 | For detailed documentation on the debugfs API, see |
97 | Documentation/DocBook/filesystems. | |
98 | ||
bf4735a4 DM |
99 | If unsure, say N. |
100 | ||
101 | config HEADERS_CHECK | |
102 | bool "Run 'make headers_check' when building vmlinux" | |
103 | depends on !UML | |
104 | help | |
105 | This option will extract the user-visible kernel headers whenever | |
106 | building the kernel, and will run basic sanity checks on them to | |
107 | ensure that exported files do not attempt to include files which | |
108 | were not exported, etc. | |
109 | ||
110 | If you're making modifications to header files which are | |
111 | relevant for userspace, say 'Y', and check the headers | |
112 | exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in | |
113 | your build tree), to make sure they're suitable. | |
114 | ||
91341d4b SR |
115 | config DEBUG_SECTION_MISMATCH |
116 | bool "Enable full Section mismatch analysis" | |
91341d4b SR |
117 | help |
118 | The section mismatch analysis checks if there are illegal | |
119 | references from one section to another section. | |
e809ab01 MW |
120 | During linktime or runtime, some sections are dropped; |
121 | any use of code/data previously in these sections would | |
91341d4b | 122 | most likely result in an oops. |
e809ab01 MW |
123 | In the code, functions and variables are annotated with |
124 | __init, __devinit, etc. (see the full list in include/linux/init.h), | |
d6fbfa4f | 125 | which results in the code/data being placed in specific sections. |
e809ab01 MW |
126 | The section mismatch analysis is always performed after a full |
127 | kernel build, and enabling this option causes the following | |
128 | additional steps to occur: | |
129 | - Add the option -fno-inline-functions-called-once to gcc commands. | |
130 | When inlining a function annotated with __init in a non-init | |
131 | function, we would lose the section information and thus | |
91341d4b | 132 | the analysis would not catch the illegal reference. |
e809ab01 MW |
133 | This option tells gcc to inline less (but it does result in |
134 | a larger kernel). | |
135 | - Run the section mismatch analysis for each module/built-in.o file. | |
136 | When we run the section mismatch analysis on vmlinux.o, we | |
d6fbfa4f | 137 | lose valueble information about where the mismatch was |
91341d4b SR |
138 | introduced. |
139 | Running the analysis for each module/built-in.o file | |
e809ab01 MW |
140 | tells where the mismatch happens much closer to the |
141 | source. The drawback is that the same mismatch is | |
142 | reported at least twice. | |
143 | - Enable verbose reporting from modpost in order to help resolve | |
144 | the section mismatches that are reported. | |
91341d4b | 145 | |
f346f4b3 AB |
146 | config DEBUG_KERNEL |
147 | bool "Kernel debugging" | |
148 | help | |
149 | Say Y here if you are developing drivers or trying to debug and | |
150 | identify kernel problems. | |
151 | ||
a304e1b8 DW |
152 | config DEBUG_SHIRQ |
153 | bool "Debug shared IRQ handlers" | |
154 | depends on DEBUG_KERNEL && GENERIC_HARDIRQS | |
155 | help | |
156 | Enable this to generate a spurious interrupt as soon as a shared | |
157 | interrupt handler is registered, and just before one is deregistered. | |
158 | Drivers ought to be able to handle interrupts coming in at those | |
159 | points; some don't and need to be caught. | |
160 | ||
58687acb DZ |
161 | config LOCKUP_DETECTOR |
162 | bool "Detect Hard and Soft Lockups" | |
dea20a3f | 163 | depends on DEBUG_KERNEL && !S390 |
8446f1d3 | 164 | help |
58687acb DZ |
165 | Say Y here to enable the kernel to act as a watchdog to detect |
166 | hard and soft lockups. | |
167 | ||
168 | Softlockups are bugs that cause the kernel to loop in kernel | |
5f329089 | 169 | mode for more than 20 seconds, without giving other tasks a |
58687acb DZ |
170 | chance to run. The current stack trace is displayed upon |
171 | detection and the system will stay locked up. | |
8446f1d3 | 172 | |
58687acb | 173 | Hardlockups are bugs that cause the CPU to loop in kernel mode |
5f329089 | 174 | for more than 10 seconds, without letting other interrupts have a |
58687acb DZ |
175 | chance to run. The current stack trace is displayed upon detection |
176 | and the system will stay locked up. | |
8446f1d3 | 177 | |
58687acb | 178 | The overhead should be minimal. A periodic hrtimer runs to |
5f329089 FLVC |
179 | generate interrupts and kick the watchdog task every 4 seconds. |
180 | An NMI is generated every 10 seconds or so to check for hardlockups. | |
181 | ||
182 | The frequency of hrtimer and NMI events and the soft and hard lockup | |
183 | thresholds can be controlled through the sysctl watchdog_thresh. | |
8446f1d3 | 184 | |
23637d47 | 185 | config HARDLOCKUP_DETECTOR |
4a7863cc | 186 | def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \ |
d314d74c | 187 | !HAVE_NMI_WATCHDOG |
8446f1d3 | 188 | |
fef2c9bc DZ |
189 | config BOOTPARAM_HARDLOCKUP_PANIC |
190 | bool "Panic (Reboot) On Hard Lockups" | |
191 | depends on LOCKUP_DETECTOR | |
192 | help | |
193 | Say Y here to enable the kernel to panic on "hard lockups", | |
194 | which are bugs that cause the kernel to loop in kernel | |
5f329089 FLVC |
195 | mode with interrupts disabled for more than 10 seconds (configurable |
196 | using the watchdog_thresh sysctl). | |
fef2c9bc DZ |
197 | |
198 | Say N if unsure. | |
199 | ||
200 | config BOOTPARAM_HARDLOCKUP_PANIC_VALUE | |
201 | int | |
202 | depends on LOCKUP_DETECTOR | |
203 | range 0 1 | |
204 | default 0 if !BOOTPARAM_HARDLOCKUP_PANIC | |
205 | default 1 if BOOTPARAM_HARDLOCKUP_PANIC | |
206 | ||
9c44bc03 IM |
207 | config BOOTPARAM_SOFTLOCKUP_PANIC |
208 | bool "Panic (Reboot) On Soft Lockups" | |
89d7ce2a | 209 | depends on LOCKUP_DETECTOR |
9c44bc03 IM |
210 | help |
211 | Say Y here to enable the kernel to panic on "soft lockups", | |
212 | which are bugs that cause the kernel to loop in kernel | |
5f329089 FLVC |
213 | mode for more than 20 seconds (configurable using the watchdog_thresh |
214 | sysctl), without giving other tasks a chance to run. | |
9c44bc03 IM |
215 | |
216 | The panic can be used in combination with panic_timeout, | |
217 | to cause the system to reboot automatically after a | |
218 | lockup has been detected. This feature is useful for | |
219 | high-availability systems that have uptime guarantees and | |
220 | where a lockup must be resolved ASAP. | |
221 | ||
222 | Say N if unsure. | |
223 | ||
224 | config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE | |
225 | int | |
e16bb1d7 | 226 | depends on LOCKUP_DETECTOR |
9c44bc03 IM |
227 | range 0 1 |
228 | default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC | |
229 | default 1 if BOOTPARAM_SOFTLOCKUP_PANIC | |
230 | ||
e162b39a MSB |
231 | config DETECT_HUNG_TASK |
232 | bool "Detect Hung Tasks" | |
233 | depends on DEBUG_KERNEL | |
8edbb83e | 234 | default LOCKUP_DETECTOR |
e162b39a MSB |
235 | help |
236 | Say Y here to enable the kernel to detect "hung tasks", | |
237 | which are bugs that cause the task to be stuck in | |
238 | uninterruptible "D" state indefinitiley. | |
239 | ||
240 | When a hung task is detected, the kernel will print the | |
241 | current stack trace (which you should report), but the | |
242 | task will stay in uninterruptible state. If lockdep is | |
243 | enabled then all held locks will also be reported. This | |
244 | feature has negligible overhead. | |
245 | ||
e11feaa1 JM |
246 | config DEFAULT_HUNG_TASK_TIMEOUT |
247 | int "Default timeout for hung task detection (in seconds)" | |
248 | depends on DETECT_HUNG_TASK | |
249 | default 120 | |
250 | help | |
251 | This option controls the default timeout (in seconds) used | |
252 | to determine when a task has become non-responsive and should | |
253 | be considered hung. | |
254 | ||
c51eaacc JZ |
255 | It can be adjusted at runtime via the kernel.hung_task_timeout_secs |
256 | sysctl or by writing a value to | |
257 | /proc/sys/kernel/hung_task_timeout_secs. | |
e11feaa1 JM |
258 | |
259 | A timeout of 0 disables the check. The default is two minutes. | |
260 | Keeping the default should be fine in most cases. | |
261 | ||
e162b39a MSB |
262 | config BOOTPARAM_HUNG_TASK_PANIC |
263 | bool "Panic (Reboot) On Hung Tasks" | |
264 | depends on DETECT_HUNG_TASK | |
265 | help | |
266 | Say Y here to enable the kernel to panic on "hung tasks", | |
267 | which are bugs that cause the kernel to leave a task stuck | |
268 | in uninterruptible "D" state. | |
269 | ||
270 | The panic can be used in combination with panic_timeout, | |
271 | to cause the system to reboot automatically after a | |
272 | hung task has been detected. This feature is useful for | |
273 | high-availability systems that have uptime guarantees and | |
274 | where a hung tasks must be resolved ASAP. | |
275 | ||
276 | Say N if unsure. | |
277 | ||
278 | config BOOTPARAM_HUNG_TASK_PANIC_VALUE | |
279 | int | |
280 | depends on DETECT_HUNG_TASK | |
281 | range 0 1 | |
282 | default 0 if !BOOTPARAM_HUNG_TASK_PANIC | |
283 | default 1 if BOOTPARAM_HUNG_TASK_PANIC | |
284 | ||
b642b6d3 IM |
285 | config SCHED_DEBUG |
286 | bool "Collect scheduler debugging info" | |
287 | depends on DEBUG_KERNEL && PROC_FS | |
288 | default y | |
289 | help | |
290 | If you say Y here, the /proc/sched_debug file will be provided | |
291 | that can help debug the scheduler. The runtime overhead of this | |
292 | option is minimal. | |
293 | ||
1da177e4 LT |
294 | config SCHEDSTATS |
295 | bool "Collect scheduler statistics" | |
296 | depends on DEBUG_KERNEL && PROC_FS | |
297 | help | |
298 | If you say Y here, additional code will be inserted into the | |
299 | scheduler and related routines to collect statistics about | |
300 | scheduler behavior and provide them in /proc/schedstat. These | |
301 | stats may be useful for both tuning and debugging the scheduler | |
302 | If you aren't debugging the scheduler or trying to tune a specific | |
303 | application, you can say N to avoid the very slight overhead | |
304 | this adds. | |
305 | ||
82f67cd9 IM |
306 | config TIMER_STATS |
307 | bool "Collect kernel timers statistics" | |
308 | depends on DEBUG_KERNEL && PROC_FS | |
309 | help | |
310 | If you say Y here, additional code will be inserted into the | |
311 | timer routines to collect statistics about kernel timers being | |
312 | reprogrammed. The statistics can be read from /proc/timer_stats. | |
313 | The statistics collection is started by writing 1 to /proc/timer_stats, | |
314 | writing 0 stops it. This feature is useful to collect information | |
c1a834dc IM |
315 | about timer usage patterns in kernel and userspace. This feature |
316 | is lightweight if enabled in the kernel config but not activated | |
317 | (it defaults to deactivated on bootup and will only be activated | |
318 | if some application like powertop activates it explicitly). | |
82f67cd9 | 319 | |
3ac7fe5a TG |
320 | config DEBUG_OBJECTS |
321 | bool "Debug object operations" | |
322 | depends on DEBUG_KERNEL | |
323 | help | |
324 | If you say Y here, additional code will be inserted into the | |
325 | kernel to track the life time of various objects and validate | |
326 | the operations on those objects. | |
327 | ||
328 | config DEBUG_OBJECTS_SELFTEST | |
329 | bool "Debug objects selftest" | |
330 | depends on DEBUG_OBJECTS | |
331 | help | |
332 | This enables the selftest of the object debug code. | |
333 | ||
334 | config DEBUG_OBJECTS_FREE | |
335 | bool "Debug objects in freed memory" | |
336 | depends on DEBUG_OBJECTS | |
337 | help | |
338 | This enables checks whether a k/v free operation frees an area | |
339 | which contains an object which has not been deactivated | |
340 | properly. This can make kmalloc/kfree-intensive workloads | |
341 | much slower. | |
342 | ||
c6f3a97f TG |
343 | config DEBUG_OBJECTS_TIMERS |
344 | bool "Debug timer objects" | |
345 | depends on DEBUG_OBJECTS | |
346 | help | |
347 | If you say Y here, additional code will be inserted into the | |
348 | timer routines to track the life time of timer objects and | |
349 | validate the timer operations. | |
350 | ||
dc186ad7 TG |
351 | config DEBUG_OBJECTS_WORK |
352 | bool "Debug work objects" | |
353 | depends on DEBUG_OBJECTS | |
354 | help | |
355 | If you say Y here, additional code will be inserted into the | |
356 | work queue routines to track the life time of work objects and | |
357 | validate the work operations. | |
358 | ||
551d55a9 MD |
359 | config DEBUG_OBJECTS_RCU_HEAD |
360 | bool "Debug RCU callbacks objects" | |
fc2ecf7e | 361 | depends on DEBUG_OBJECTS |
551d55a9 MD |
362 | help |
363 | Enable this to turn on debugging of RCU list heads (call_rcu() usage). | |
364 | ||
e2852ae8 TH |
365 | config DEBUG_OBJECTS_PERCPU_COUNTER |
366 | bool "Debug percpu counter objects" | |
367 | depends on DEBUG_OBJECTS | |
368 | help | |
369 | If you say Y here, additional code will be inserted into the | |
370 | percpu counter routines to track the life time of percpu counter | |
371 | objects and validate the percpu counter operations. | |
372 | ||
3ae70205 IM |
373 | config DEBUG_OBJECTS_ENABLE_DEFAULT |
374 | int "debug_objects bootup default value (0-1)" | |
375 | range 0 1 | |
376 | default "1" | |
377 | depends on DEBUG_OBJECTS | |
378 | help | |
379 | Debug objects boot parameter default value | |
380 | ||
1da177e4 | 381 | config DEBUG_SLAB |
4a2f0acf | 382 | bool "Debug slab memory allocations" |
7d46d9e6 | 383 | depends on DEBUG_KERNEL && SLAB && !KMEMCHECK |
1da177e4 LT |
384 | help |
385 | Say Y here to have the kernel do limited verification on memory | |
386 | allocation as well as poisoning memory on free to catch use of freed | |
387 | memory. This can make kmalloc/kfree-intensive workloads much slower. | |
388 | ||
871751e2 AV |
389 | config DEBUG_SLAB_LEAK |
390 | bool "Memory leak debugging" | |
391 | depends on DEBUG_SLAB | |
392 | ||
f0630fff CL |
393 | config SLUB_DEBUG_ON |
394 | bool "SLUB debugging on by default" | |
7d46d9e6 | 395 | depends on SLUB && SLUB_DEBUG && !KMEMCHECK |
f0630fff CL |
396 | default n |
397 | help | |
398 | Boot with debugging on by default. SLUB boots by default with | |
399 | the runtime debug capabilities switched off. Enabling this is | |
400 | equivalent to specifying the "slub_debug" parameter on boot. | |
401 | There is no support for more fine grained debug control like | |
402 | possible with slub_debug=xxx. SLUB debugging may be switched | |
403 | off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying | |
404 | "slub_debug=-". | |
405 | ||
8ff12cfc CL |
406 | config SLUB_STATS |
407 | default n | |
408 | bool "Enable SLUB performance statistics" | |
ab4d5ed5 | 409 | depends on SLUB && SYSFS |
8ff12cfc CL |
410 | help |
411 | SLUB statistics are useful to debug SLUBs allocation behavior in | |
412 | order find ways to optimize the allocator. This should never be | |
413 | enabled for production use since keeping statistics slows down | |
414 | the allocator by a few percentage points. The slabinfo command | |
415 | supports the determination of the most active slabs to figure | |
416 | out which slabs are relevant to a particular load. | |
417 | Try running: slabinfo -DA | |
418 | ||
3bba00d7 CM |
419 | config DEBUG_KMEMLEAK |
420 | bool "Kernel memory leak detector" | |
029aeff5 | 421 | depends on DEBUG_KERNEL && EXPERIMENTAL && \ |
c0a5afb9 | 422 | (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE) |
dfcc3e6a | 423 | |
79e0d9bd | 424 | select DEBUG_FS |
3bba00d7 CM |
425 | select STACKTRACE if STACKTRACE_SUPPORT |
426 | select KALLSYMS | |
b60e26a2 | 427 | select CRC32 |
3bba00d7 CM |
428 | help |
429 | Say Y here if you want to enable the memory leak | |
430 | detector. The memory allocation/freeing is traced in a way | |
431 | similar to the Boehm's conservative garbage collector, the | |
432 | difference being that the orphan objects are not freed but | |
433 | only shown in /sys/kernel/debug/kmemleak. Enabling this | |
434 | feature will introduce an overhead to memory | |
435 | allocations. See Documentation/kmemleak.txt for more | |
436 | details. | |
437 | ||
bf96d1e3 CM |
438 | Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances |
439 | of finding leaks due to the slab objects poisoning. | |
440 | ||
3bba00d7 CM |
441 | In order to access the kmemleak file, debugfs needs to be |
442 | mounted (usually at /sys/kernel/debug). | |
443 | ||
a9d9058a CM |
444 | config DEBUG_KMEMLEAK_EARLY_LOG_SIZE |
445 | int "Maximum kmemleak early log entries" | |
446 | depends on DEBUG_KMEMLEAK | |
dfcc3e6a | 447 | range 200 40000 |
a9d9058a CM |
448 | default 400 |
449 | help | |
450 | Kmemleak must track all the memory allocations to avoid | |
451 | reporting false positives. Since memory may be allocated or | |
452 | freed before kmemleak is initialised, an early log buffer is | |
453 | used to store these actions. If kmemleak reports "early log | |
454 | buffer exceeded", please increase this value. | |
455 | ||
0822ee4a CM |
456 | config DEBUG_KMEMLEAK_TEST |
457 | tristate "Simple test for the kernel memory leak detector" | |
9718269a | 458 | depends on DEBUG_KMEMLEAK && m |
0822ee4a | 459 | help |
9718269a | 460 | This option enables a module that explicitly leaks memory. |
0822ee4a CM |
461 | |
462 | If unsure, say N. | |
463 | ||
ab0155a2 JB |
464 | config DEBUG_KMEMLEAK_DEFAULT_OFF |
465 | bool "Default kmemleak to off" | |
466 | depends on DEBUG_KMEMLEAK | |
467 | help | |
468 | Say Y here to disable kmemleak by default. It can then be enabled | |
469 | on the command line via kmemleak=on. | |
470 | ||
1da177e4 LT |
471 | config DEBUG_PREEMPT |
472 | bool "Debug preemptible kernel" | |
01deab98 | 473 | depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT |
1da177e4 LT |
474 | default y |
475 | help | |
476 | If you say Y here then the kernel will use a debug variant of the | |
477 | commonly used smp_processor_id() function and will print warnings | |
478 | if kernel code uses it in a preemption-unsafe way. Also, the kernel | |
479 | will detect preemption count underflows. | |
480 | ||
e7eebaf6 IM |
481 | config DEBUG_RT_MUTEXES |
482 | bool "RT Mutex debugging, deadlock detection" | |
e7eebaf6 IM |
483 | depends on DEBUG_KERNEL && RT_MUTEXES |
484 | help | |
485 | This allows rt mutex semantics violations and rt mutex related | |
486 | deadlocks (lockups) to be detected and reported automatically. | |
487 | ||
488 | config DEBUG_PI_LIST | |
489 | bool | |
490 | default y | |
491 | depends on DEBUG_RT_MUTEXES | |
492 | ||
61a87122 TG |
493 | config RT_MUTEX_TESTER |
494 | bool "Built-in scriptable tester for rt-mutexes" | |
a1583d3e | 495 | depends on DEBUG_KERNEL && RT_MUTEXES |
61a87122 TG |
496 | help |
497 | This option enables a rt-mutex tester. | |
498 | ||
1da177e4 | 499 | config DEBUG_SPINLOCK |
4d9f34ad | 500 | bool "Spinlock and rw-lock debugging: basic checks" |
1da177e4 | 501 | depends on DEBUG_KERNEL |
e335e3eb | 502 | select UNINLINE_SPIN_UNLOCK |
1da177e4 LT |
503 | help |
504 | Say Y here and build SMP to catch missing spinlock initialization | |
505 | and certain other kinds of spinlock errors commonly made. This is | |
506 | best used in conjunction with the NMI watchdog so that spinlock | |
507 | deadlocks are also debuggable. | |
508 | ||
4d9f34ad IM |
509 | config DEBUG_MUTEXES |
510 | bool "Mutex debugging: basic checks" | |
511 | depends on DEBUG_KERNEL | |
512 | help | |
513 | This feature allows mutex semantics violations to be detected and | |
514 | reported. | |
515 | ||
4d9f34ad IM |
516 | config DEBUG_LOCK_ALLOC |
517 | bool "Lock debugging: detect incorrect freeing of live locks" | |
517e7aa5 | 518 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
519 | select DEBUG_SPINLOCK |
520 | select DEBUG_MUTEXES | |
4d9f34ad IM |
521 | select LOCKDEP |
522 | help | |
523 | This feature will check whether any held lock (spinlock, rwlock, | |
524 | mutex or rwsem) is incorrectly freed by the kernel, via any of the | |
525 | memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), | |
526 | vfree(), etc.), whether a live lock is incorrectly reinitialized via | |
527 | spin_lock_init()/mutex_init()/etc., or whether there is any lock | |
528 | held during task exit. | |
529 | ||
530 | config PROVE_LOCKING | |
531 | bool "Lock debugging: prove locking correctness" | |
517e7aa5 | 532 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
533 | select LOCKDEP |
534 | select DEBUG_SPINLOCK | |
535 | select DEBUG_MUTEXES | |
4d9f34ad | 536 | select DEBUG_LOCK_ALLOC |
46b93b74 | 537 | select TRACE_IRQFLAGS |
4d9f34ad IM |
538 | default n |
539 | help | |
540 | This feature enables the kernel to prove that all locking | |
541 | that occurs in the kernel runtime is mathematically | |
542 | correct: that under no circumstance could an arbitrary (and | |
543 | not yet triggered) combination of observed locking | |
544 | sequences (on an arbitrary number of CPUs, running an | |
545 | arbitrary number of tasks and interrupt contexts) cause a | |
546 | deadlock. | |
547 | ||
548 | In short, this feature enables the kernel to report locking | |
549 | related deadlocks before they actually occur. | |
550 | ||
551 | The proof does not depend on how hard and complex a | |
552 | deadlock scenario would be to trigger: how many | |
553 | participant CPUs, tasks and irq-contexts would be needed | |
554 | for it to trigger. The proof also does not depend on | |
555 | timing: if a race and a resulting deadlock is possible | |
556 | theoretically (no matter how unlikely the race scenario | |
557 | is), it will be proven so and will immediately be | |
558 | reported by the kernel (once the event is observed that | |
559 | makes the deadlock theoretically possible). | |
560 | ||
561 | If a deadlock is impossible (i.e. the locking rules, as | |
562 | observed by the kernel, are mathematically correct), the | |
563 | kernel reports nothing. | |
564 | ||
565 | NOTE: this feature can also be enabled for rwlocks, mutexes | |
566 | and rwsems - in which case all dependencies between these | |
567 | different locking variants are observed and mapped too, and | |
568 | the proof of observed correctness is also maintained for an | |
569 | arbitrary combination of these separate locking variants. | |
570 | ||
571 | For more details, see Documentation/lockdep-design.txt. | |
572 | ||
632ee200 PM |
573 | config PROVE_RCU |
574 | bool "RCU debugging: prove RCU correctness" | |
575 | depends on PROVE_LOCKING | |
576 | default n | |
577 | help | |
578 | This feature enables lockdep extensions that check for correct | |
579 | use of RCU APIs. This is currently under development. Say Y | |
580 | if you want to debug RCU usage or help work on the PROVE_RCU | |
581 | feature. | |
582 | ||
583 | Say N if you are unsure. | |
584 | ||
2b3fc35f LJ |
585 | config PROVE_RCU_REPEATEDLY |
586 | bool "RCU debugging: don't disable PROVE_RCU on first splat" | |
587 | depends on PROVE_RCU | |
588 | default n | |
589 | help | |
590 | By itself, PROVE_RCU will disable checking upon issuing the | |
591 | first warning (or "splat"). This feature prevents such | |
592 | disabling, allowing multiple RCU-lockdep warnings to be printed | |
593 | on a single reboot. | |
594 | ||
2dfbf4df PM |
595 | Say Y to allow multiple RCU-lockdep warnings per boot. |
596 | ||
597 | Say N if you are unsure. | |
598 | ||
ca5ecddf PM |
599 | config SPARSE_RCU_POINTER |
600 | bool "RCU debugging: sparse-based checks for pointer usage" | |
601 | default n | |
602 | help | |
603 | This feature enables the __rcu sparse annotation for | |
604 | RCU-protected pointers. This annotation will cause sparse | |
605 | to flag any non-RCU used of annotated pointers. This can be | |
606 | helpful when debugging RCU usage. Please note that this feature | |
607 | is not intended to enforce code cleanliness; it is instead merely | |
608 | a debugging aid. | |
609 | ||
610 | Say Y to make sparse flag questionable use of RCU-protected pointers | |
611 | ||
2b3fc35f LJ |
612 | Say N if you are unsure. |
613 | ||
4d9f34ad IM |
614 | config LOCKDEP |
615 | bool | |
517e7aa5 | 616 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad | 617 | select STACKTRACE |
79aac889 | 618 | select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE |
4d9f34ad IM |
619 | select KALLSYMS |
620 | select KALLSYMS_ALL | |
621 | ||
f20786ff | 622 | config LOCK_STAT |
fdfb870f | 623 | bool "Lock usage statistics" |
f20786ff PZ |
624 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
625 | select LOCKDEP | |
626 | select DEBUG_SPINLOCK | |
627 | select DEBUG_MUTEXES | |
628 | select DEBUG_LOCK_ALLOC | |
629 | default n | |
630 | help | |
631 | This feature enables tracking lock contention points | |
632 | ||
a560aa48 PZ |
633 | For more details, see Documentation/lockstat.txt |
634 | ||
dd8b1cf6 FW |
635 | This also enables lock events required by "perf lock", |
636 | subcommand of perf. | |
637 | If you want to use "perf lock", you also need to turn on | |
638 | CONFIG_EVENT_TRACING. | |
84c6f88f HM |
639 | |
640 | CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. | |
dd8b1cf6 | 641 | (CONFIG_LOCKDEP defines "acquire" and "release" events.) |
84c6f88f | 642 | |
4d9f34ad IM |
643 | config DEBUG_LOCKDEP |
644 | bool "Lock dependency engine debugging" | |
517e7aa5 | 645 | depends on DEBUG_KERNEL && LOCKDEP |
4d9f34ad IM |
646 | help |
647 | If you say Y here, the lock dependency engine will do | |
648 | additional runtime checks to debug itself, at the price | |
649 | of more runtime overhead. | |
650 | ||
651 | config TRACE_IRQFLAGS | |
652 | bool | |
46b93b74 SR |
653 | help |
654 | Enables hooks to interrupt enabling and disabling for | |
655 | either tracing or lock debugging. | |
4d9f34ad | 656 | |
d902db1e FW |
657 | config DEBUG_ATOMIC_SLEEP |
658 | bool "Sleep inside atomic section checking" | |
e8f7c70f | 659 | select PREEMPT_COUNT |
1da177e4 LT |
660 | depends on DEBUG_KERNEL |
661 | help | |
662 | If you say Y here, various routines which may sleep will become very | |
d902db1e FW |
663 | noisy if they are called inside atomic sections: when a spinlock is |
664 | held, inside an rcu read side critical section, inside preempt disabled | |
665 | sections, inside an interrupt, etc... | |
1da177e4 | 666 | |
cae2ed9a IM |
667 | config DEBUG_LOCKING_API_SELFTESTS |
668 | bool "Locking API boot-time self-tests" | |
669 | depends on DEBUG_KERNEL | |
670 | help | |
671 | Say Y here if you want the kernel to run a short self-test during | |
672 | bootup. The self-test checks whether common types of locking bugs | |
673 | are detected by debugging mechanisms or not. (if you disable | |
674 | lock debugging then those bugs wont be detected of course.) | |
675 | The following locking APIs are covered: spinlocks, rwlocks, | |
676 | mutexes and rwsems. | |
677 | ||
8637c099 IM |
678 | config STACKTRACE |
679 | bool | |
680 | depends on STACKTRACE_SUPPORT | |
681 | ||
5ca43f6c SB |
682 | config DEBUG_STACK_USAGE |
683 | bool "Stack utilization instrumentation" | |
684 | depends on DEBUG_KERNEL | |
685 | help | |
686 | Enables the display of the minimum amount of free stack which each | |
687 | task has ever had available in the sysrq-T and sysrq-P debug output. | |
688 | ||
689 | This option will slow down process creation somewhat. | |
690 | ||
1da177e4 LT |
691 | config DEBUG_KOBJECT |
692 | bool "kobject debugging" | |
693 | depends on DEBUG_KERNEL | |
694 | help | |
695 | If you say Y here, some extra kobject debugging messages will be sent | |
696 | to the syslog. | |
697 | ||
698 | config DEBUG_HIGHMEM | |
699 | bool "Highmem debugging" | |
700 | depends on DEBUG_KERNEL && HIGHMEM | |
701 | help | |
702 | This options enables addition error checking for high memory systems. | |
703 | Disable for production systems. | |
704 | ||
705 | config DEBUG_BUGVERBOSE | |
6a108a14 | 706 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT |
c8538a7a | 707 | depends on BUG |
b920de1b | 708 | depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ |
3cc39b3f | 709 | FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || TILE |
8420e7ef | 710 | default y |
1da177e4 LT |
711 | help |
712 | Say Y here to make BUG() panics output the file name and line number | |
713 | of the BUG call as well as the EIP and oops trace. This aids | |
714 | debugging but costs about 70-100K of memory. | |
715 | ||
716 | config DEBUG_INFO | |
717 | bool "Compile the kernel with debug info" | |
718 | depends on DEBUG_KERNEL | |
719 | help | |
720 | If you say Y here the resulting kernel image will include | |
721 | debugging info resulting in a larger kernel image. | |
b72e53f8 AD |
722 | This adds debug symbols to the kernel and modules (gcc -g), and |
723 | is needed if you intend to use kernel crashdump or binary object | |
724 | tools like crash, kgdb, LKCD, gdb, etc on the kernel. | |
1da177e4 LT |
725 | Say Y here only if you plan to debug the kernel. |
726 | ||
727 | If unsure, say N. | |
728 | ||
d6f4ceb7 AK |
729 | config DEBUG_INFO_REDUCED |
730 | bool "Reduce debugging information" | |
731 | depends on DEBUG_INFO | |
732 | help | |
733 | If you say Y here gcc is instructed to generate less debugging | |
734 | information for structure types. This means that tools that | |
735 | need full debugging information (like kgdb or systemtap) won't | |
736 | be happy. But if you merely need debugging information to | |
737 | resolve line numbers there is no loss. Advantage is that | |
738 | build directory object sizes shrink dramatically over a full | |
739 | DEBUG_INFO build and compile times are reduced too. | |
740 | Only works with newer gcc versions. | |
741 | ||
a241ec65 PM |
742 | config DEBUG_VM |
743 | bool "Debug VM" | |
744 | depends on DEBUG_KERNEL | |
745 | help | |
13e7444b NP |
746 | Enable this to turn on extended checks in the virtual-memory system |
747 | that may impact performance. | |
a241ec65 PM |
748 | |
749 | If unsure, say N. | |
750 | ||
59ea7463 JS |
751 | config DEBUG_VIRTUAL |
752 | bool "Debug VM translations" | |
753 | depends on DEBUG_KERNEL && X86 | |
754 | help | |
755 | Enable some costly sanity checks in virtual to page code. This can | |
756 | catch mistakes with virt_to_page() and friends. | |
757 | ||
758 | If unsure, say N. | |
759 | ||
8feae131 DH |
760 | config DEBUG_NOMMU_REGIONS |
761 | bool "Debug the global anon/private NOMMU mapping region tree" | |
762 | depends on DEBUG_KERNEL && !MMU | |
763 | help | |
764 | This option causes the global tree of anonymous and private mapping | |
765 | regions to be regularly checked for invalid topology. | |
766 | ||
ad775f5a DH |
767 | config DEBUG_WRITECOUNT |
768 | bool "Debug filesystem writers count" | |
769 | depends on DEBUG_KERNEL | |
770 | help | |
771 | Enable this to catch wrong use of the writers count in struct | |
772 | vfsmount. This will increase the size of each file struct by | |
773 | 32 bits. | |
774 | ||
775 | If unsure, say N. | |
776 | ||
6b74ab97 | 777 | config DEBUG_MEMORY_INIT |
6a108a14 DR |
778 | bool "Debug memory initialisation" if EXPERT |
779 | default !EXPERT | |
6b74ab97 MG |
780 | help |
781 | Enable this for additional checks during memory initialisation. | |
782 | The sanity checks verify aspects of the VM such as the memory model | |
783 | and other information provided by the architecture. Verbose | |
784 | information will be printed at KERN_DEBUG loglevel depending | |
785 | on the mminit_loglevel= command-line option. | |
786 | ||
787 | If unsure, say Y | |
788 | ||
199a9afc DJ |
789 | config DEBUG_LIST |
790 | bool "Debug linked list manipulation" | |
791 | depends on DEBUG_KERNEL | |
792 | help | |
793 | Enable this to turn on extended checks in the linked-list | |
794 | walking routines. | |
795 | ||
796 | If unsure, say N. | |
797 | ||
6d411e6c AB |
798 | config TEST_LIST_SORT |
799 | bool "Linked list sorting test" | |
800 | depends on DEBUG_KERNEL | |
801 | help | |
802 | Enable this to turn on 'list_sort()' function test. This test is | |
803 | executed only once during system boot, so affects only boot time. | |
804 | ||
805 | If unsure, say N. | |
806 | ||
d6ec0842 JA |
807 | config DEBUG_SG |
808 | bool "Debug SG table operations" | |
809 | depends on DEBUG_KERNEL | |
810 | help | |
811 | Enable this to turn on checks on scatter-gather tables. This can | |
812 | help find problems with drivers that do not properly initialize | |
813 | their sg tables. | |
814 | ||
815 | If unsure, say N. | |
816 | ||
1b2439db AV |
817 | config DEBUG_NOTIFIERS |
818 | bool "Debug notifier call chains" | |
819 | depends on DEBUG_KERNEL | |
820 | help | |
821 | Enable this to turn on sanity checking for notifier call chains. | |
822 | This is most useful for kernel developers to make sure that | |
823 | modules properly unregister themselves from notifier chains. | |
824 | This is a relatively cheap check but if you care about maximum | |
825 | performance, say N. | |
826 | ||
e0e81739 DH |
827 | config DEBUG_CREDENTIALS |
828 | bool "Debug credential management" | |
829 | depends on DEBUG_KERNEL | |
830 | help | |
831 | Enable this to turn on some debug checking for credential | |
832 | management. The additional code keeps track of the number of | |
833 | pointers from task_structs to any given cred struct, and checks to | |
834 | see that this number never exceeds the usage count of the cred | |
835 | struct. | |
836 | ||
837 | Furthermore, if SELinux is enabled, this also checks that the | |
838 | security pointer in the cred struct is never seen to be invalid. | |
839 | ||
840 | If unsure, say N. | |
841 | ||
64dec40d JM |
842 | # |
843 | # Select this config option from the architecture Kconfig, if it | |
52288b66 | 844 | # is preferred to always offer frame pointers as a config |
64dec40d JM |
845 | # option on the architecture (regardless of KERNEL_DEBUG): |
846 | # | |
847 | config ARCH_WANT_FRAME_POINTERS | |
848 | bool | |
849 | help | |
850 | ||
1da177e4 LT |
851 | config FRAME_POINTER |
852 | bool "Compile the kernel with frame pointers" | |
b920de1b | 853 | depends on DEBUG_KERNEL && \ |
73020415 | 854 | (CRIS || M68K || FRV || UML || \ |
da4276b8 IM |
855 | AVR32 || SUPERH || BLACKFIN || MN10300) || \ |
856 | ARCH_WANT_FRAME_POINTERS | |
857 | default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS | |
858 | help | |
859 | If you say Y here the resulting kernel image will be slightly | |
860 | larger and slower, but it gives very useful debugging information | |
861 | in case of kernel bugs. (precise oopses/stacktraces/warnings) | |
1da177e4 | 862 | |
bfe8df3d RD |
863 | config BOOT_PRINTK_DELAY |
864 | bool "Delay each boot printk message by N milliseconds" | |
865 | depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY | |
866 | help | |
867 | This build option allows you to read kernel boot messages | |
868 | by inserting a short delay after each one. The delay is | |
869 | specified in milliseconds on the kernel command line, | |
870 | using "boot_delay=N". | |
871 | ||
872 | It is likely that you would also need to use "lpj=M" to preset | |
873 | the "loops per jiffie" value. | |
874 | See a previous boot log for the "lpj" value to use for your | |
875 | system, and then set "lpj=M" before setting "boot_delay=N". | |
876 | NOTE: Using this option may adversely affect SMP systems. | |
877 | I.e., processors other than the first one may not boot up. | |
8edbb83e | 878 | BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect |
bfe8df3d RD |
879 | what it believes to be lockup conditions. |
880 | ||
a241ec65 PM |
881 | config RCU_TORTURE_TEST |
882 | tristate "torture tests for RCU" | |
883 | depends on DEBUG_KERNEL | |
884 | default n | |
885 | help | |
886 | This option provides a kernel module that runs torture tests | |
887 | on the RCU infrastructure. The kernel module may be built | |
888 | after the fact on the running kernel to be tested, if desired. | |
889 | ||
31a72bce PM |
890 | Say Y here if you want RCU torture tests to be built into |
891 | the kernel. | |
a241ec65 PM |
892 | Say M if you want the RCU torture tests to build as a module. |
893 | Say N if you are unsure. | |
8bb31b9d | 894 | |
31a72bce PM |
895 | config RCU_TORTURE_TEST_RUNNABLE |
896 | bool "torture tests for RCU runnable by default" | |
897 | depends on RCU_TORTURE_TEST = y | |
898 | default n | |
899 | help | |
900 | This option provides a way to build the RCU torture tests | |
901 | directly into the kernel without them starting up at boot | |
902 | time. You can use /proc/sys/kernel/rcutorture_runnable | |
903 | to manually override this setting. This /proc file is | |
904 | available only when the RCU torture tests have been built | |
905 | into the kernel. | |
906 | ||
907 | Say Y here if you want the RCU torture tests to start during | |
908 | boot (you probably don't). | |
909 | Say N here if you want the RCU torture tests to start only | |
910 | after being manually enabled via /proc. | |
911 | ||
b163760e PM |
912 | config RCU_CPU_STALL_TIMEOUT |
913 | int "RCU CPU stall timeout in seconds" | |
a00e0d71 | 914 | depends on TREE_RCU || TREE_PREEMPT_RCU |
b163760e PM |
915 | range 3 300 |
916 | default 60 | |
917 | help | |
918 | If a given RCU grace period extends more than the specified | |
919 | number of seconds, a CPU stall warning is printed. If the | |
920 | RCU grace period persists, additional CPU stall warnings are | |
921 | printed at more widely spaced intervals. | |
922 | ||
1ed509a2 PM |
923 | config RCU_CPU_STALL_VERBOSE |
924 | bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" | |
a00e0d71 | 925 | depends on TREE_PREEMPT_RCU |
55ec936f | 926 | default y |
1ed509a2 PM |
927 | help |
928 | This option causes RCU to printk detailed per-task information | |
929 | for any tasks that are stalling the current RCU grace period. | |
67182ae1 PM |
930 | |
931 | Say N if you are unsure. | |
932 | ||
1ed509a2 PM |
933 | Say Y if you want to enable such checks. |
934 | ||
a858af28 PM |
935 | config RCU_CPU_STALL_INFO |
936 | bool "Print additional diagnostics on RCU CPU stall" | |
937 | depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL | |
938 | default n | |
939 | help | |
940 | For each stalled CPU that is aware of the current RCU grace | |
941 | period, print out additional per-CPU diagnostic information | |
942 | regarding scheduling-clock ticks, idle state, and, | |
943 | for RCU_FAST_NO_HZ kernels, idle-entry state. | |
944 | ||
945 | Say N if you are unsure. | |
946 | ||
947 | Say Y if you want to enable such diagnostics. | |
948 | ||
5c8806a0 PM |
949 | config RCU_TRACE |
950 | bool "Enable tracing for RCU" | |
951 | depends on DEBUG_KERNEL | |
952 | help | |
953 | This option provides tracing in RCU which presents stats | |
954 | in debugfs for debugging RCU implementation. | |
955 | ||
956 | Say Y here if you want to enable RCU tracing | |
957 | Say N if you are unsure. | |
958 | ||
8c1c9356 AM |
959 | config KPROBES_SANITY_TEST |
960 | bool "Kprobes sanity tests" | |
961 | depends on DEBUG_KERNEL | |
962 | depends on KPROBES | |
963 | default n | |
964 | help | |
965 | This option provides for testing basic kprobes functionality on | |
966 | boot. A sample kprobe, jprobe and kretprobe are inserted and | |
967 | verified for functionality. | |
968 | ||
969 | Say N if you are unsure. | |
970 | ||
6dab2778 AV |
971 | config BACKTRACE_SELF_TEST |
972 | tristate "Self test for the backtrace code" | |
973 | depends on DEBUG_KERNEL | |
974 | default n | |
975 | help | |
976 | This option provides a kernel module that can be used to test | |
977 | the kernel stack backtrace code. This option is not useful | |
978 | for distributions or general kernels, but only for kernel | |
979 | developers working on architecture code. | |
980 | ||
ad118c54 VN |
981 | Note that if you want to also test saved backtraces, you will |
982 | have to enable STACKTRACE as well. | |
983 | ||
6dab2778 AV |
984 | Say N if you are unsure. |
985 | ||
870d6656 TH |
986 | config DEBUG_BLOCK_EXT_DEVT |
987 | bool "Force extended block device numbers and spread them" | |
988 | depends on DEBUG_KERNEL | |
989 | depends on BLOCK | |
759f8ca3 | 990 | default n |
870d6656 | 991 | help |
0e11e342 TH |
992 | BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON |
993 | SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT | |
994 | YOU ARE DOING. Distros, please enable this and fix whatever | |
995 | is broken. | |
996 | ||
870d6656 TH |
997 | Conventionally, block device numbers are allocated from |
998 | predetermined contiguous area. However, extended block area | |
999 | may introduce non-contiguous block device numbers. This | |
1000 | option forces most block device numbers to be allocated from | |
1001 | the extended space and spreads them to discover kernel or | |
1002 | userland code paths which assume predetermined contiguous | |
1003 | device number allocation. | |
1004 | ||
55dc7db7 TH |
1005 | Note that turning on this debug option shuffles all the |
1006 | device numbers for all IDE and SCSI devices including libata | |
1007 | ones, so root partition specified using device number | |
1008 | directly (via rdev or root=MAJ:MIN) won't work anymore. | |
1009 | Textual device names (root=/dev/sdXn) will continue to work. | |
1010 | ||
870d6656 TH |
1011 | Say N if you are unsure. |
1012 | ||
7c756e6e TH |
1013 | config DEBUG_FORCE_WEAK_PER_CPU |
1014 | bool "Force weak per-cpu definitions" | |
1015 | depends on DEBUG_KERNEL | |
1016 | help | |
1017 | s390 and alpha require percpu variables in modules to be | |
1018 | defined weak to work around addressing range issue which | |
1019 | puts the following two restrictions on percpu variable | |
1020 | definitions. | |
1021 | ||
1022 | 1. percpu symbols must be unique whether static or not | |
1023 | 2. percpu variables can't be defined inside a function | |
1024 | ||
1025 | To ensure that generic code follows the above rules, this | |
1026 | option forces all percpu variables to be defined as weak. | |
1027 | ||
44ec7abe SB |
1028 | config DEBUG_PER_CPU_MAPS |
1029 | bool "Debug access to per_cpu maps" | |
1030 | depends on DEBUG_KERNEL | |
1031 | depends on SMP | |
1032 | help | |
1033 | Say Y to verify that the per_cpu map being accessed has | |
1034 | been set up. This adds a fair amount of code to kernel memory | |
1035 | and decreases performance. | |
1036 | ||
1037 | Say N if unsure. | |
1038 | ||
8bb31b9d AG |
1039 | config LKDTM |
1040 | tristate "Linux Kernel Dump Test Tool Module" | |
0347af4e | 1041 | depends on DEBUG_FS |
fddd9cf8 | 1042 | depends on BLOCK |
8bb31b9d AG |
1043 | default n |
1044 | help | |
1045 | This module enables testing of the different dumping mechanisms by | |
1046 | inducing system failures at predefined crash points. | |
1047 | If you don't need it: say N | |
1048 | Choose M here to compile this code as a module. The module will be | |
1049 | called lkdtm. | |
1050 | ||
1051 | Documentation on how to use the module can be found in | |
0347af4e | 1052 | Documentation/fault-injection/provoke-crashes.txt |
6ff1cb35 | 1053 | |
c9d221f8 AM |
1054 | config CPU_NOTIFIER_ERROR_INJECT |
1055 | tristate "CPU notifier error injection module" | |
1056 | depends on HOTPLUG_CPU && DEBUG_KERNEL | |
1057 | help | |
1058 | This option provides a kernel module that can be used to test | |
1059 | the error handling of the cpu notifiers | |
1060 | ||
1061 | To compile this code as a module, choose M here: the module will | |
1062 | be called cpu-notifier-error-inject. | |
1063 | ||
1064 | If unsure, say N. | |
1065 | ||
6ff1cb35 | 1066 | config FAULT_INJECTION |
1ab8509a AM |
1067 | bool "Fault-injection framework" |
1068 | depends on DEBUG_KERNEL | |
329409ae AM |
1069 | help |
1070 | Provide fault-injection framework. | |
1071 | For more details, see Documentation/fault-injection/. | |
6ff1cb35 | 1072 | |
8a8b6502 | 1073 | config FAILSLAB |
1ab8509a AM |
1074 | bool "Fault-injection capability for kmalloc" |
1075 | depends on FAULT_INJECTION | |
773ff60e | 1076 | depends on SLAB || SLUB |
8a8b6502 | 1077 | help |
1ab8509a | 1078 | Provide fault-injection capability for kmalloc. |
8a8b6502 | 1079 | |
933e312e AM |
1080 | config FAIL_PAGE_ALLOC |
1081 | bool "Fault-injection capabilitiy for alloc_pages()" | |
1ab8509a | 1082 | depends on FAULT_INJECTION |
933e312e | 1083 | help |
1ab8509a | 1084 | Provide fault-injection capability for alloc_pages(). |
933e312e | 1085 | |
c17bb495 | 1086 | config FAIL_MAKE_REQUEST |
86327d19 | 1087 | bool "Fault-injection capability for disk IO" |
581d4e28 | 1088 | depends on FAULT_INJECTION && BLOCK |
c17bb495 | 1089 | help |
1ab8509a | 1090 | Provide fault-injection capability for disk IO. |
c17bb495 | 1091 | |
581d4e28 | 1092 | config FAIL_IO_TIMEOUT |
f4d01439 | 1093 | bool "Fault-injection capability for faking disk interrupts" |
581d4e28 JA |
1094 | depends on FAULT_INJECTION && BLOCK |
1095 | help | |
1096 | Provide fault-injection capability on end IO handling. This | |
1097 | will make the block layer "forget" an interrupt as configured, | |
1098 | thus exercising the error handling. | |
1099 | ||
1100 | Only works with drivers that use the generic timeout handling, | |
1101 | for others it wont do anything. | |
1102 | ||
1b676f70 PF |
1103 | config FAIL_MMC_REQUEST |
1104 | bool "Fault-injection capability for MMC IO" | |
1105 | select DEBUG_FS | |
1106 | depends on FAULT_INJECTION && MMC | |
1107 | help | |
1108 | Provide fault-injection capability for MMC IO. | |
1109 | This will make the mmc core return data errors. This is | |
1110 | useful to test the error handling in the mmc block device | |
1111 | and to test how the mmc host driver handles retries from | |
1112 | the block device. | |
1113 | ||
6ff1cb35 AM |
1114 | config FAULT_INJECTION_DEBUG_FS |
1115 | bool "Debugfs entries for fault-injection capabilities" | |
1ab8509a | 1116 | depends on FAULT_INJECTION && SYSFS && DEBUG_FS |
6ff1cb35 | 1117 | help |
1ab8509a | 1118 | Enable configuration of fault-injection capabilities via debugfs. |
1df49008 AM |
1119 | |
1120 | config FAULT_INJECTION_STACKTRACE_FILTER | |
1121 | bool "stacktrace filter for fault-injection capabilities" | |
1122 | depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT | |
6d690dca | 1123 | depends on !X86_64 |
1df49008 | 1124 | select STACKTRACE |
89bace65 | 1125 | select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND |
1df49008 AM |
1126 | help |
1127 | Provide stacktrace filter for fault-injection capabilities | |
267c4025 | 1128 | |
9745512c AV |
1129 | config LATENCYTOP |
1130 | bool "Latency measuring infrastructure" | |
625fdcaa RD |
1131 | depends on HAVE_LATENCYTOP_SUPPORT |
1132 | depends on DEBUG_KERNEL | |
1133 | depends on STACKTRACE_SUPPORT | |
1134 | depends on PROC_FS | |
89bace65 | 1135 | select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND |
9745512c AV |
1136 | select KALLSYMS |
1137 | select KALLSYMS_ALL | |
1138 | select STACKTRACE | |
1139 | select SCHEDSTATS | |
1140 | select SCHED_DEBUG | |
9745512c AV |
1141 | help |
1142 | Enable this option if you want to use the LatencyTOP tool | |
1143 | to find out which userspace is blocking on what kernel operations. | |
1144 | ||
6a11f75b | 1145 | source mm/Kconfig.debug |
16444a8a ACM |
1146 | source kernel/trace/Kconfig |
1147 | ||
f212ec4b | 1148 | config PROVIDE_OHCI1394_DMA_INIT |
080de8c2 | 1149 | bool "Remote debugging over FireWire early on boot" |
f212ec4b BK |
1150 | depends on PCI && X86 |
1151 | help | |
1152 | If you want to debug problems which hang or crash the kernel early | |
1153 | on boot and the crashing machine has a FireWire port, you can use | |
1154 | this feature to remotely access the memory of the crashed machine | |
1155 | over FireWire. This employs remote DMA as part of the OHCI1394 | |
1156 | specification which is now the standard for FireWire controllers. | |
1157 | ||
1158 | With remote DMA, you can monitor the printk buffer remotely using | |
1159 | firescope and access all memory below 4GB using fireproxy from gdb. | |
1160 | Even controlling a kernel debugger is possible using remote DMA. | |
1161 | ||
1162 | Usage: | |
1163 | ||
1164 | If ohci1394_dma=early is used as boot parameter, it will initialize | |
1165 | all OHCI1394 controllers which are found in the PCI config space. | |
1166 | ||
1167 | As all changes to the FireWire bus such as enabling and disabling | |
1168 | devices cause a bus reset and thereby disable remote DMA for all | |
1169 | devices, be sure to have the cable plugged and FireWire enabled on | |
1170 | the debugging host before booting the debug target for debugging. | |
1171 | ||
1172 | This code (~1k) is freed after boot. By then, the firewire stack | |
1173 | in charge of the OHCI-1394 controllers should be used instead. | |
1174 | ||
1175 | See Documentation/debugging-via-ohci1394.txt for more information. | |
9745512c | 1176 | |
080de8c2 SR |
1177 | config FIREWIRE_OHCI_REMOTE_DMA |
1178 | bool "Remote debugging over FireWire with firewire-ohci" | |
1179 | depends on FIREWIRE_OHCI | |
1180 | help | |
1181 | This option lets you use the FireWire bus for remote debugging | |
1182 | with help of the firewire-ohci driver. It enables unfiltered | |
1183 | remote DMA in firewire-ohci. | |
1184 | See Documentation/debugging-via-ohci1394.txt for more information. | |
1185 | ||
1186 | If unsure, say N. | |
1187 | ||
152de30b | 1188 | config BUILD_DOCSRC |
3794f3e8 RD |
1189 | bool "Build targets in Documentation/ tree" |
1190 | depends on HEADERS_CHECK | |
1191 | help | |
1192 | This option attempts to build objects from the source files in the | |
1193 | kernel Documentation/ tree. | |
1194 | ||
1195 | Say N if you are unsure. | |
1196 | ||
e9d376f0 | 1197 | config DYNAMIC_DEBUG |
86151fdf | 1198 | bool "Enable dynamic printk() support" |
346e15be JB |
1199 | default n |
1200 | depends on PRINTK | |
86151fdf | 1201 | depends on DEBUG_FS |
346e15be JB |
1202 | help |
1203 | ||
1204 | Compiles debug level messages into the kernel, which would not | |
1205 | otherwise be available at runtime. These messages can then be | |
86151fdf JB |
1206 | enabled/disabled based on various levels of scope - per source file, |
1207 | function, module, format string, and line number. This mechanism | |
1208 | implicitly enables all pr_debug() and dev_dbg() calls. The impact of | |
1209 | this compile option is a larger kernel text size of about 2%. | |
346e15be JB |
1210 | |
1211 | Usage: | |
1212 | ||
2b2f68b5 | 1213 | Dynamic debugging is controlled via the 'dynamic_debug/control' file, |
86151fdf JB |
1214 | which is contained in the 'debugfs' filesystem. Thus, the debugfs |
1215 | filesystem must first be mounted before making use of this feature. | |
2b2f68b5 | 1216 | We refer the control file as: <debugfs>/dynamic_debug/control. This |
86151fdf JB |
1217 | file contains a list of the debug statements that can be enabled. The |
1218 | format for each line of the file is: | |
346e15be | 1219 | |
86151fdf | 1220 | filename:lineno [module]function flags format |
346e15be | 1221 | |
86151fdf JB |
1222 | filename : source file of the debug statement |
1223 | lineno : line number of the debug statement | |
1224 | module : module that contains the debug statement | |
1225 | function : function that contains the debug statement | |
1226 | flags : 'p' means the line is turned 'on' for printing | |
1227 | format : the format used for the debug statement | |
346e15be JB |
1228 | |
1229 | From a live system: | |
1230 | ||
2b2f68b5 | 1231 | nullarbor:~ # cat <debugfs>/dynamic_debug/control |
86151fdf JB |
1232 | # filename:lineno [module]function flags format |
1233 | fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012" | |
1234 | fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012" | |
1235 | fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012" | |
346e15be | 1236 | |
86151fdf | 1237 | Example usage: |
346e15be | 1238 | |
86151fdf JB |
1239 | // enable the message at line 1603 of file svcsock.c |
1240 | nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > | |
2b2f68b5 | 1241 | <debugfs>/dynamic_debug/control |
346e15be | 1242 | |
86151fdf JB |
1243 | // enable all the messages in file svcsock.c |
1244 | nullarbor:~ # echo -n 'file svcsock.c +p' > | |
2b2f68b5 | 1245 | <debugfs>/dynamic_debug/control |
346e15be | 1246 | |
86151fdf JB |
1247 | // enable all the messages in the NFS server module |
1248 | nullarbor:~ # echo -n 'module nfsd +p' > | |
2b2f68b5 | 1249 | <debugfs>/dynamic_debug/control |
346e15be | 1250 | |
86151fdf JB |
1251 | // enable all 12 messages in the function svc_process() |
1252 | nullarbor:~ # echo -n 'func svc_process +p' > | |
2b2f68b5 | 1253 | <debugfs>/dynamic_debug/control |
346e15be | 1254 | |
86151fdf JB |
1255 | // disable all 12 messages in the function svc_process() |
1256 | nullarbor:~ # echo -n 'func svc_process -p' > | |
2b2f68b5 | 1257 | <debugfs>/dynamic_debug/control |
346e15be | 1258 | |
86151fdf | 1259 | See Documentation/dynamic-debug-howto.txt for additional information. |
346e15be | 1260 | |
5ee00bd4 JR |
1261 | config DMA_API_DEBUG |
1262 | bool "Enable debugging of DMA-API usage" | |
1263 | depends on HAVE_DMA_API_DEBUG | |
1264 | help | |
1265 | Enable this option to debug the use of the DMA API by device drivers. | |
1266 | With this option you will be able to detect common bugs in device | |
1267 | drivers like double-freeing of DMA mappings or freeing mappings that | |
1268 | were never allocated. | |
1269 | This option causes a performance degredation. Use only if you want | |
1270 | to debug device drivers. If unsure, say N. | |
346e15be | 1271 | |
86a89380 LB |
1272 | config ATOMIC64_SELFTEST |
1273 | bool "Perform an atomic64_t self-test at boot" | |
1274 | help | |
1275 | Enable this option to test the atomic64_t functions at boot. | |
1276 | ||
1277 | If unsure, say N. | |
1278 | ||
400fb7f6 DW |
1279 | config ASYNC_RAID6_TEST |
1280 | tristate "Self test for hardware accelerated raid6 recovery" | |
1281 | depends on ASYNC_RAID6_RECOV | |
1282 | select ASYNC_MEMCPY | |
1283 | ---help--- | |
1284 | This is a one-shot self test that permutes through the | |
1285 | recovery of all the possible two disk failure scenarios for a | |
1286 | N-disk array. Recovery is performed with the asynchronous | |
1287 | raid6 recovery routines, and will optionally use an offload | |
1288 | engine if one is available. | |
1289 | ||
1290 | If unsure, say N. | |
1291 | ||
267c4025 | 1292 | source "samples/Kconfig" |
dc7d5527 JW |
1293 | |
1294 | source "lib/Kconfig.kgdb" | |
0a4af3b0 PE |
1295 | |
1296 | source "lib/Kconfig.kmemcheck" | |
33ee3b2e AD |
1297 | |
1298 | config TEST_KSTRTOX | |
1299 | tristate "Test kstrto*() family of functions at runtime" |