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1da177e4 LT |
1 | |
2 | config PRINTK_TIME | |
3 | bool "Show timing information on printks" | |
d3b8b6e5 | 4 | depends on PRINTK |
1da177e4 | 5 | help |
649e6ee3 KS |
6 | Selecting this option causes time stamps of the printk() |
7 | messages to be added to the output of the syslog() system | |
8 | call and at the console. | |
9 | ||
10 | The timestamp is always recorded internally, and exported | |
11 | to /dev/kmsg. This flag just specifies if the timestamp should | |
12 | be included, not that the timestamp is recorded. | |
13 | ||
14 | The behavior is also controlled by the kernel command line | |
15 | parameter printk.time=1. See Documentation/kernel-parameters.txt | |
1da177e4 | 16 | |
5af5bcb8 MSB |
17 | config DEFAULT_MESSAGE_LOGLEVEL |
18 | int "Default message log level (1-7)" | |
19 | range 1 7 | |
20 | default "4" | |
21 | help | |
22 | Default log level for printk statements with no specified priority. | |
23 | ||
24 | This was hard-coded to KERN_WARNING since at least 2.6.10 but folks | |
25 | that are auditing their logs closely may want to set it to a lower | |
26 | priority. | |
27 | ||
de488443 JG |
28 | config ENABLE_WARN_DEPRECATED |
29 | bool "Enable __deprecated logic" | |
30 | default y | |
31 | help | |
32 | Enable the __deprecated logic in the kernel build. | |
33 | Disable this to suppress the "warning: 'foo' is deprecated | |
34 | (declared at kernel/power/somefile.c:1234)" messages. | |
35 | ||
cebc04ba AM |
36 | config ENABLE_MUST_CHECK |
37 | bool "Enable __must_check logic" | |
38 | default y | |
39 | help | |
40 | Enable the __must_check logic in the kernel build. Disable this to | |
41 | suppress the "warning: ignoring return value of 'foo', declared with | |
42 | attribute warn_unused_result" messages. | |
1da177e4 | 43 | |
35bb5b1e AK |
44 | config FRAME_WARN |
45 | int "Warn for stack frames larger than (needs gcc 4.4)" | |
46 | range 0 8192 | |
47 | default 1024 if !64BIT | |
48 | default 2048 if 64BIT | |
49 | help | |
50 | Tell gcc to warn at build time for stack frames larger than this. | |
51 | Setting this too low will cause a lot of warnings. | |
52 | Setting it to 0 disables the warning. | |
53 | Requires gcc 4.4 | |
54 | ||
1da177e4 LT |
55 | config MAGIC_SYSRQ |
56 | bool "Magic SysRq key" | |
f346f4b3 | 57 | depends on !UML |
1da177e4 LT |
58 | help |
59 | If you say Y here, you will have some control over the system even | |
60 | if the system crashes for example during kernel debugging (e.g., you | |
61 | will be able to flush the buffer cache to disk, reboot the system | |
62 | immediately or dump some status information). This is accomplished | |
63 | by pressing various keys while holding SysRq (Alt+PrintScreen). It | |
64 | also works on a serial console (on PC hardware at least), if you | |
65 | send a BREAK and then within 5 seconds a command keypress. The | |
66 | keys are documented in <file:Documentation/sysrq.txt>. Don't say Y | |
67 | unless you really know what this hack does. | |
68 | ||
99657c78 RD |
69 | config STRIP_ASM_SYMS |
70 | bool "Strip assembler-generated symbols during link" | |
71 | default n | |
72 | help | |
73 | Strip internal assembler-generated symbols during a link (symbols | |
74 | that look like '.Lxxx') so they don't pollute the output of | |
75 | get_wchan() and suchlike. | |
76 | ||
1873e870 AK |
77 | config READABLE_ASM |
78 | bool "Generate readable assembler code" | |
79 | depends on DEBUG_KERNEL | |
80 | help | |
81 | Disable some compiler optimizations that tend to generate human unreadable | |
82 | assembler output. This may make the kernel slightly slower, but it helps | |
83 | to keep kernel developers who have to stare a lot at assembler listings | |
84 | sane. | |
85 | ||
f71d20e9 AV |
86 | config UNUSED_SYMBOLS |
87 | bool "Enable unused/obsolete exported symbols" | |
88 | default y if X86 | |
89 | help | |
90 | Unused but exported symbols make the kernel needlessly bigger. For | |
91 | that reason most of these unused exports will soon be removed. This | |
92 | option is provided temporarily to provide a transition period in case | |
93 | some external kernel module needs one of these symbols anyway. If you | |
94 | encounter such a case in your module, consider if you are actually | |
95 | using the right API. (rationale: since nobody in the kernel is using | |
96 | this in a module, there is a pretty good chance it's actually the | |
97 | wrong interface to use). If you really need the symbol, please send a | |
98 | mail to the linux kernel mailing list mentioning the symbol and why | |
99 | you really need it, and what the merge plan to the mainline kernel for | |
100 | your module is. | |
101 | ||
bf4735a4 DM |
102 | config DEBUG_FS |
103 | bool "Debug Filesystem" | |
bf4735a4 DM |
104 | help |
105 | debugfs is a virtual file system that kernel developers use to put | |
106 | debugging files into. Enable this option to be able to read and | |
107 | write to these files. | |
108 | ||
ff543332 RD |
109 | For detailed documentation on the debugfs API, see |
110 | Documentation/DocBook/filesystems. | |
111 | ||
bf4735a4 DM |
112 | If unsure, say N. |
113 | ||
114 | config HEADERS_CHECK | |
115 | bool "Run 'make headers_check' when building vmlinux" | |
116 | depends on !UML | |
117 | help | |
118 | This option will extract the user-visible kernel headers whenever | |
119 | building the kernel, and will run basic sanity checks on them to | |
120 | ensure that exported files do not attempt to include files which | |
121 | were not exported, etc. | |
122 | ||
123 | If you're making modifications to header files which are | |
124 | relevant for userspace, say 'Y', and check the headers | |
125 | exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in | |
126 | your build tree), to make sure they're suitable. | |
127 | ||
91341d4b SR |
128 | config DEBUG_SECTION_MISMATCH |
129 | bool "Enable full Section mismatch analysis" | |
91341d4b SR |
130 | help |
131 | The section mismatch analysis checks if there are illegal | |
132 | references from one section to another section. | |
e809ab01 MW |
133 | During linktime or runtime, some sections are dropped; |
134 | any use of code/data previously in these sections would | |
91341d4b | 135 | most likely result in an oops. |
e809ab01 MW |
136 | In the code, functions and variables are annotated with |
137 | __init, __devinit, etc. (see the full list in include/linux/init.h), | |
d6fbfa4f | 138 | which results in the code/data being placed in specific sections. |
e809ab01 MW |
139 | The section mismatch analysis is always performed after a full |
140 | kernel build, and enabling this option causes the following | |
141 | additional steps to occur: | |
142 | - Add the option -fno-inline-functions-called-once to gcc commands. | |
143 | When inlining a function annotated with __init in a non-init | |
144 | function, we would lose the section information and thus | |
91341d4b | 145 | the analysis would not catch the illegal reference. |
e809ab01 MW |
146 | This option tells gcc to inline less (but it does result in |
147 | a larger kernel). | |
148 | - Run the section mismatch analysis for each module/built-in.o file. | |
149 | When we run the section mismatch analysis on vmlinux.o, we | |
d6fbfa4f | 150 | lose valueble information about where the mismatch was |
91341d4b SR |
151 | introduced. |
152 | Running the analysis for each module/built-in.o file | |
e809ab01 MW |
153 | tells where the mismatch happens much closer to the |
154 | source. The drawback is that the same mismatch is | |
155 | reported at least twice. | |
156 | - Enable verbose reporting from modpost in order to help resolve | |
157 | the section mismatches that are reported. | |
91341d4b | 158 | |
f346f4b3 AB |
159 | config DEBUG_KERNEL |
160 | bool "Kernel debugging" | |
161 | help | |
162 | Say Y here if you are developing drivers or trying to debug and | |
163 | identify kernel problems. | |
164 | ||
a304e1b8 DW |
165 | config DEBUG_SHIRQ |
166 | bool "Debug shared IRQ handlers" | |
167 | depends on DEBUG_KERNEL && GENERIC_HARDIRQS | |
168 | help | |
169 | Enable this to generate a spurious interrupt as soon as a shared | |
170 | interrupt handler is registered, and just before one is deregistered. | |
171 | Drivers ought to be able to handle interrupts coming in at those | |
172 | points; some don't and need to be caught. | |
173 | ||
58687acb DZ |
174 | config LOCKUP_DETECTOR |
175 | bool "Detect Hard and Soft Lockups" | |
dea20a3f | 176 | depends on DEBUG_KERNEL && !S390 |
8446f1d3 | 177 | help |
58687acb DZ |
178 | Say Y here to enable the kernel to act as a watchdog to detect |
179 | hard and soft lockups. | |
180 | ||
181 | Softlockups are bugs that cause the kernel to loop in kernel | |
5f329089 | 182 | mode for more than 20 seconds, without giving other tasks a |
58687acb DZ |
183 | chance to run. The current stack trace is displayed upon |
184 | detection and the system will stay locked up. | |
8446f1d3 | 185 | |
58687acb | 186 | Hardlockups are bugs that cause the CPU to loop in kernel mode |
5f329089 | 187 | for more than 10 seconds, without letting other interrupts have a |
58687acb DZ |
188 | chance to run. The current stack trace is displayed upon detection |
189 | and the system will stay locked up. | |
8446f1d3 | 190 | |
58687acb | 191 | The overhead should be minimal. A periodic hrtimer runs to |
5f329089 FLVC |
192 | generate interrupts and kick the watchdog task every 4 seconds. |
193 | An NMI is generated every 10 seconds or so to check for hardlockups. | |
194 | ||
195 | The frequency of hrtimer and NMI events and the soft and hard lockup | |
196 | thresholds can be controlled through the sysctl watchdog_thresh. | |
8446f1d3 | 197 | |
23637d47 | 198 | config HARDLOCKUP_DETECTOR |
8f1f66ed JB |
199 | def_bool y |
200 | depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG | |
201 | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI | |
8446f1d3 | 202 | |
fef2c9bc DZ |
203 | config BOOTPARAM_HARDLOCKUP_PANIC |
204 | bool "Panic (Reboot) On Hard Lockups" | |
8f1f66ed | 205 | depends on HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
206 | help |
207 | Say Y here to enable the kernel to panic on "hard lockups", | |
208 | which are bugs that cause the kernel to loop in kernel | |
5f329089 FLVC |
209 | mode with interrupts disabled for more than 10 seconds (configurable |
210 | using the watchdog_thresh sysctl). | |
fef2c9bc DZ |
211 | |
212 | Say N if unsure. | |
213 | ||
214 | config BOOTPARAM_HARDLOCKUP_PANIC_VALUE | |
215 | int | |
8f1f66ed | 216 | depends on HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
217 | range 0 1 |
218 | default 0 if !BOOTPARAM_HARDLOCKUP_PANIC | |
219 | default 1 if BOOTPARAM_HARDLOCKUP_PANIC | |
220 | ||
9c44bc03 IM |
221 | config BOOTPARAM_SOFTLOCKUP_PANIC |
222 | bool "Panic (Reboot) On Soft Lockups" | |
89d7ce2a | 223 | depends on LOCKUP_DETECTOR |
9c44bc03 IM |
224 | help |
225 | Say Y here to enable the kernel to panic on "soft lockups", | |
226 | which are bugs that cause the kernel to loop in kernel | |
5f329089 FLVC |
227 | mode for more than 20 seconds (configurable using the watchdog_thresh |
228 | sysctl), without giving other tasks a chance to run. | |
9c44bc03 IM |
229 | |
230 | The panic can be used in combination with panic_timeout, | |
231 | to cause the system to reboot automatically after a | |
232 | lockup has been detected. This feature is useful for | |
233 | high-availability systems that have uptime guarantees and | |
234 | where a lockup must be resolved ASAP. | |
235 | ||
236 | Say N if unsure. | |
237 | ||
238 | config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE | |
239 | int | |
e16bb1d7 | 240 | depends on LOCKUP_DETECTOR |
9c44bc03 IM |
241 | range 0 1 |
242 | default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC | |
243 | default 1 if BOOTPARAM_SOFTLOCKUP_PANIC | |
244 | ||
2a01bb38 KM |
245 | config PANIC_ON_OOPS |
246 | bool "Panic on Oops" if EXPERT | |
247 | default n | |
248 | help | |
249 | Say Y here to enable the kernel to panic when it oopses. This | |
250 | has the same effect as setting oops=panic on the kernel command | |
251 | line. | |
252 | ||
253 | This feature is useful to ensure that the kernel does not do | |
254 | anything erroneous after an oops which could result in data | |
255 | corruption or other issues. | |
256 | ||
257 | Say N if unsure. | |
258 | ||
259 | config PANIC_ON_OOPS_VALUE | |
260 | int | |
261 | range 0 1 | |
262 | default 0 if !PANIC_ON_OOPS | |
263 | default 1 if PANIC_ON_OOPS | |
264 | ||
e162b39a MSB |
265 | config DETECT_HUNG_TASK |
266 | bool "Detect Hung Tasks" | |
267 | depends on DEBUG_KERNEL | |
8edbb83e | 268 | default LOCKUP_DETECTOR |
e162b39a MSB |
269 | help |
270 | Say Y here to enable the kernel to detect "hung tasks", | |
271 | which are bugs that cause the task to be stuck in | |
272 | uninterruptible "D" state indefinitiley. | |
273 | ||
274 | When a hung task is detected, the kernel will print the | |
275 | current stack trace (which you should report), but the | |
276 | task will stay in uninterruptible state. If lockdep is | |
277 | enabled then all held locks will also be reported. This | |
278 | feature has negligible overhead. | |
279 | ||
e11feaa1 JM |
280 | config DEFAULT_HUNG_TASK_TIMEOUT |
281 | int "Default timeout for hung task detection (in seconds)" | |
282 | depends on DETECT_HUNG_TASK | |
283 | default 120 | |
284 | help | |
285 | This option controls the default timeout (in seconds) used | |
286 | to determine when a task has become non-responsive and should | |
287 | be considered hung. | |
288 | ||
c51eaacc JZ |
289 | It can be adjusted at runtime via the kernel.hung_task_timeout_secs |
290 | sysctl or by writing a value to | |
291 | /proc/sys/kernel/hung_task_timeout_secs. | |
e11feaa1 JM |
292 | |
293 | A timeout of 0 disables the check. The default is two minutes. | |
294 | Keeping the default should be fine in most cases. | |
295 | ||
e162b39a MSB |
296 | config BOOTPARAM_HUNG_TASK_PANIC |
297 | bool "Panic (Reboot) On Hung Tasks" | |
298 | depends on DETECT_HUNG_TASK | |
299 | help | |
300 | Say Y here to enable the kernel to panic on "hung tasks", | |
301 | which are bugs that cause the kernel to leave a task stuck | |
302 | in uninterruptible "D" state. | |
303 | ||
304 | The panic can be used in combination with panic_timeout, | |
305 | to cause the system to reboot automatically after a | |
306 | hung task has been detected. This feature is useful for | |
307 | high-availability systems that have uptime guarantees and | |
308 | where a hung tasks must be resolved ASAP. | |
309 | ||
310 | Say N if unsure. | |
311 | ||
312 | config BOOTPARAM_HUNG_TASK_PANIC_VALUE | |
313 | int | |
314 | depends on DETECT_HUNG_TASK | |
315 | range 0 1 | |
316 | default 0 if !BOOTPARAM_HUNG_TASK_PANIC | |
317 | default 1 if BOOTPARAM_HUNG_TASK_PANIC | |
318 | ||
b642b6d3 IM |
319 | config SCHED_DEBUG |
320 | bool "Collect scheduler debugging info" | |
321 | depends on DEBUG_KERNEL && PROC_FS | |
322 | default y | |
323 | help | |
324 | If you say Y here, the /proc/sched_debug file will be provided | |
325 | that can help debug the scheduler. The runtime overhead of this | |
326 | option is minimal. | |
327 | ||
1da177e4 LT |
328 | config SCHEDSTATS |
329 | bool "Collect scheduler statistics" | |
330 | depends on DEBUG_KERNEL && PROC_FS | |
331 | help | |
332 | If you say Y here, additional code will be inserted into the | |
333 | scheduler and related routines to collect statistics about | |
334 | scheduler behavior and provide them in /proc/schedstat. These | |
335 | stats may be useful for both tuning and debugging the scheduler | |
336 | If you aren't debugging the scheduler or trying to tune a specific | |
337 | application, you can say N to avoid the very slight overhead | |
338 | this adds. | |
339 | ||
82f67cd9 IM |
340 | config TIMER_STATS |
341 | bool "Collect kernel timers statistics" | |
342 | depends on DEBUG_KERNEL && PROC_FS | |
343 | help | |
344 | If you say Y here, additional code will be inserted into the | |
345 | timer routines to collect statistics about kernel timers being | |
346 | reprogrammed. The statistics can be read from /proc/timer_stats. | |
347 | The statistics collection is started by writing 1 to /proc/timer_stats, | |
348 | writing 0 stops it. This feature is useful to collect information | |
c1a834dc IM |
349 | about timer usage patterns in kernel and userspace. This feature |
350 | is lightweight if enabled in the kernel config but not activated | |
351 | (it defaults to deactivated on bootup and will only be activated | |
352 | if some application like powertop activates it explicitly). | |
82f67cd9 | 353 | |
3ac7fe5a TG |
354 | config DEBUG_OBJECTS |
355 | bool "Debug object operations" | |
356 | depends on DEBUG_KERNEL | |
357 | help | |
358 | If you say Y here, additional code will be inserted into the | |
359 | kernel to track the life time of various objects and validate | |
360 | the operations on those objects. | |
361 | ||
362 | config DEBUG_OBJECTS_SELFTEST | |
363 | bool "Debug objects selftest" | |
364 | depends on DEBUG_OBJECTS | |
365 | help | |
366 | This enables the selftest of the object debug code. | |
367 | ||
368 | config DEBUG_OBJECTS_FREE | |
369 | bool "Debug objects in freed memory" | |
370 | depends on DEBUG_OBJECTS | |
371 | help | |
372 | This enables checks whether a k/v free operation frees an area | |
373 | which contains an object which has not been deactivated | |
374 | properly. This can make kmalloc/kfree-intensive workloads | |
375 | much slower. | |
376 | ||
c6f3a97f TG |
377 | config DEBUG_OBJECTS_TIMERS |
378 | bool "Debug timer objects" | |
379 | depends on DEBUG_OBJECTS | |
380 | help | |
381 | If you say Y here, additional code will be inserted into the | |
382 | timer routines to track the life time of timer objects and | |
383 | validate the timer operations. | |
384 | ||
dc186ad7 TG |
385 | config DEBUG_OBJECTS_WORK |
386 | bool "Debug work objects" | |
387 | depends on DEBUG_OBJECTS | |
388 | help | |
389 | If you say Y here, additional code will be inserted into the | |
390 | work queue routines to track the life time of work objects and | |
391 | validate the work operations. | |
392 | ||
551d55a9 MD |
393 | config DEBUG_OBJECTS_RCU_HEAD |
394 | bool "Debug RCU callbacks objects" | |
fc2ecf7e | 395 | depends on DEBUG_OBJECTS |
551d55a9 MD |
396 | help |
397 | Enable this to turn on debugging of RCU list heads (call_rcu() usage). | |
398 | ||
e2852ae8 TH |
399 | config DEBUG_OBJECTS_PERCPU_COUNTER |
400 | bool "Debug percpu counter objects" | |
401 | depends on DEBUG_OBJECTS | |
402 | help | |
403 | If you say Y here, additional code will be inserted into the | |
404 | percpu counter routines to track the life time of percpu counter | |
405 | objects and validate the percpu counter operations. | |
406 | ||
3ae70205 IM |
407 | config DEBUG_OBJECTS_ENABLE_DEFAULT |
408 | int "debug_objects bootup default value (0-1)" | |
409 | range 0 1 | |
410 | default "1" | |
411 | depends on DEBUG_OBJECTS | |
412 | help | |
413 | Debug objects boot parameter default value | |
414 | ||
1da177e4 | 415 | config DEBUG_SLAB |
4a2f0acf | 416 | bool "Debug slab memory allocations" |
7d46d9e6 | 417 | depends on DEBUG_KERNEL && SLAB && !KMEMCHECK |
1da177e4 LT |
418 | help |
419 | Say Y here to have the kernel do limited verification on memory | |
420 | allocation as well as poisoning memory on free to catch use of freed | |
421 | memory. This can make kmalloc/kfree-intensive workloads much slower. | |
422 | ||
871751e2 AV |
423 | config DEBUG_SLAB_LEAK |
424 | bool "Memory leak debugging" | |
425 | depends on DEBUG_SLAB | |
426 | ||
f0630fff CL |
427 | config SLUB_DEBUG_ON |
428 | bool "SLUB debugging on by default" | |
7d46d9e6 | 429 | depends on SLUB && SLUB_DEBUG && !KMEMCHECK |
f0630fff CL |
430 | default n |
431 | help | |
432 | Boot with debugging on by default. SLUB boots by default with | |
433 | the runtime debug capabilities switched off. Enabling this is | |
434 | equivalent to specifying the "slub_debug" parameter on boot. | |
435 | There is no support for more fine grained debug control like | |
436 | possible with slub_debug=xxx. SLUB debugging may be switched | |
437 | off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying | |
438 | "slub_debug=-". | |
439 | ||
8ff12cfc CL |
440 | config SLUB_STATS |
441 | default n | |
442 | bool "Enable SLUB performance statistics" | |
ab4d5ed5 | 443 | depends on SLUB && SYSFS |
8ff12cfc CL |
444 | help |
445 | SLUB statistics are useful to debug SLUBs allocation behavior in | |
446 | order find ways to optimize the allocator. This should never be | |
447 | enabled for production use since keeping statistics slows down | |
448 | the allocator by a few percentage points. The slabinfo command | |
449 | supports the determination of the most active slabs to figure | |
450 | out which slabs are relevant to a particular load. | |
451 | Try running: slabinfo -DA | |
452 | ||
b69ec42b CM |
453 | config HAVE_DEBUG_KMEMLEAK |
454 | bool | |
455 | ||
3bba00d7 CM |
456 | config DEBUG_KMEMLEAK |
457 | bool "Kernel memory leak detector" | |
b69ec42b | 458 | depends on DEBUG_KERNEL && EXPERIMENTAL && HAVE_DEBUG_KMEMLEAK |
79e0d9bd | 459 | select DEBUG_FS |
3bba00d7 CM |
460 | select STACKTRACE if STACKTRACE_SUPPORT |
461 | select KALLSYMS | |
b60e26a2 | 462 | select CRC32 |
3bba00d7 CM |
463 | help |
464 | Say Y here if you want to enable the memory leak | |
465 | detector. The memory allocation/freeing is traced in a way | |
466 | similar to the Boehm's conservative garbage collector, the | |
467 | difference being that the orphan objects are not freed but | |
468 | only shown in /sys/kernel/debug/kmemleak. Enabling this | |
469 | feature will introduce an overhead to memory | |
470 | allocations. See Documentation/kmemleak.txt for more | |
471 | details. | |
472 | ||
bf96d1e3 CM |
473 | Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances |
474 | of finding leaks due to the slab objects poisoning. | |
475 | ||
3bba00d7 CM |
476 | In order to access the kmemleak file, debugfs needs to be |
477 | mounted (usually at /sys/kernel/debug). | |
478 | ||
a9d9058a CM |
479 | config DEBUG_KMEMLEAK_EARLY_LOG_SIZE |
480 | int "Maximum kmemleak early log entries" | |
481 | depends on DEBUG_KMEMLEAK | |
dfcc3e6a | 482 | range 200 40000 |
a9d9058a CM |
483 | default 400 |
484 | help | |
485 | Kmemleak must track all the memory allocations to avoid | |
486 | reporting false positives. Since memory may be allocated or | |
487 | freed before kmemleak is initialised, an early log buffer is | |
488 | used to store these actions. If kmemleak reports "early log | |
489 | buffer exceeded", please increase this value. | |
490 | ||
0822ee4a CM |
491 | config DEBUG_KMEMLEAK_TEST |
492 | tristate "Simple test for the kernel memory leak detector" | |
9718269a | 493 | depends on DEBUG_KMEMLEAK && m |
0822ee4a | 494 | help |
9718269a | 495 | This option enables a module that explicitly leaks memory. |
0822ee4a CM |
496 | |
497 | If unsure, say N. | |
498 | ||
ab0155a2 JB |
499 | config DEBUG_KMEMLEAK_DEFAULT_OFF |
500 | bool "Default kmemleak to off" | |
501 | depends on DEBUG_KMEMLEAK | |
502 | help | |
503 | Say Y here to disable kmemleak by default. It can then be enabled | |
504 | on the command line via kmemleak=on. | |
505 | ||
1da177e4 LT |
506 | config DEBUG_PREEMPT |
507 | bool "Debug preemptible kernel" | |
01deab98 | 508 | depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT |
1da177e4 LT |
509 | default y |
510 | help | |
511 | If you say Y here then the kernel will use a debug variant of the | |
512 | commonly used smp_processor_id() function and will print warnings | |
513 | if kernel code uses it in a preemption-unsafe way. Also, the kernel | |
514 | will detect preemption count underflows. | |
515 | ||
e7eebaf6 IM |
516 | config DEBUG_RT_MUTEXES |
517 | bool "RT Mutex debugging, deadlock detection" | |
e7eebaf6 IM |
518 | depends on DEBUG_KERNEL && RT_MUTEXES |
519 | help | |
520 | This allows rt mutex semantics violations and rt mutex related | |
521 | deadlocks (lockups) to be detected and reported automatically. | |
522 | ||
523 | config DEBUG_PI_LIST | |
524 | bool | |
525 | default y | |
526 | depends on DEBUG_RT_MUTEXES | |
527 | ||
61a87122 TG |
528 | config RT_MUTEX_TESTER |
529 | bool "Built-in scriptable tester for rt-mutexes" | |
a1583d3e | 530 | depends on DEBUG_KERNEL && RT_MUTEXES |
61a87122 TG |
531 | help |
532 | This option enables a rt-mutex tester. | |
533 | ||
1da177e4 | 534 | config DEBUG_SPINLOCK |
4d9f34ad | 535 | bool "Spinlock and rw-lock debugging: basic checks" |
1da177e4 | 536 | depends on DEBUG_KERNEL |
e335e3eb | 537 | select UNINLINE_SPIN_UNLOCK |
1da177e4 LT |
538 | help |
539 | Say Y here and build SMP to catch missing spinlock initialization | |
540 | and certain other kinds of spinlock errors commonly made. This is | |
541 | best used in conjunction with the NMI watchdog so that spinlock | |
542 | deadlocks are also debuggable. | |
543 | ||
4d9f34ad IM |
544 | config DEBUG_MUTEXES |
545 | bool "Mutex debugging: basic checks" | |
546 | depends on DEBUG_KERNEL | |
547 | help | |
548 | This feature allows mutex semantics violations to be detected and | |
549 | reported. | |
550 | ||
4d9f34ad IM |
551 | config DEBUG_LOCK_ALLOC |
552 | bool "Lock debugging: detect incorrect freeing of live locks" | |
517e7aa5 | 553 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
554 | select DEBUG_SPINLOCK |
555 | select DEBUG_MUTEXES | |
4d9f34ad IM |
556 | select LOCKDEP |
557 | help | |
558 | This feature will check whether any held lock (spinlock, rwlock, | |
559 | mutex or rwsem) is incorrectly freed by the kernel, via any of the | |
560 | memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), | |
561 | vfree(), etc.), whether a live lock is incorrectly reinitialized via | |
562 | spin_lock_init()/mutex_init()/etc., or whether there is any lock | |
563 | held during task exit. | |
564 | ||
565 | config PROVE_LOCKING | |
566 | bool "Lock debugging: prove locking correctness" | |
517e7aa5 | 567 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
568 | select LOCKDEP |
569 | select DEBUG_SPINLOCK | |
570 | select DEBUG_MUTEXES | |
4d9f34ad | 571 | select DEBUG_LOCK_ALLOC |
46b93b74 | 572 | select TRACE_IRQFLAGS |
4d9f34ad IM |
573 | default n |
574 | help | |
575 | This feature enables the kernel to prove that all locking | |
576 | that occurs in the kernel runtime is mathematically | |
577 | correct: that under no circumstance could an arbitrary (and | |
578 | not yet triggered) combination of observed locking | |
579 | sequences (on an arbitrary number of CPUs, running an | |
580 | arbitrary number of tasks and interrupt contexts) cause a | |
581 | deadlock. | |
582 | ||
583 | In short, this feature enables the kernel to report locking | |
584 | related deadlocks before they actually occur. | |
585 | ||
586 | The proof does not depend on how hard and complex a | |
587 | deadlock scenario would be to trigger: how many | |
588 | participant CPUs, tasks and irq-contexts would be needed | |
589 | for it to trigger. The proof also does not depend on | |
590 | timing: if a race and a resulting deadlock is possible | |
591 | theoretically (no matter how unlikely the race scenario | |
592 | is), it will be proven so and will immediately be | |
593 | reported by the kernel (once the event is observed that | |
594 | makes the deadlock theoretically possible). | |
595 | ||
596 | If a deadlock is impossible (i.e. the locking rules, as | |
597 | observed by the kernel, are mathematically correct), the | |
598 | kernel reports nothing. | |
599 | ||
600 | NOTE: this feature can also be enabled for rwlocks, mutexes | |
601 | and rwsems - in which case all dependencies between these | |
602 | different locking variants are observed and mapped too, and | |
603 | the proof of observed correctness is also maintained for an | |
604 | arbitrary combination of these separate locking variants. | |
605 | ||
606 | For more details, see Documentation/lockdep-design.txt. | |
607 | ||
632ee200 PM |
608 | config PROVE_RCU |
609 | bool "RCU debugging: prove RCU correctness" | |
610 | depends on PROVE_LOCKING | |
611 | default n | |
612 | help | |
613 | This feature enables lockdep extensions that check for correct | |
614 | use of RCU APIs. This is currently under development. Say Y | |
615 | if you want to debug RCU usage or help work on the PROVE_RCU | |
616 | feature. | |
617 | ||
618 | Say N if you are unsure. | |
619 | ||
2b3fc35f LJ |
620 | config PROVE_RCU_REPEATEDLY |
621 | bool "RCU debugging: don't disable PROVE_RCU on first splat" | |
622 | depends on PROVE_RCU | |
623 | default n | |
624 | help | |
625 | By itself, PROVE_RCU will disable checking upon issuing the | |
626 | first warning (or "splat"). This feature prevents such | |
627 | disabling, allowing multiple RCU-lockdep warnings to be printed | |
628 | on a single reboot. | |
629 | ||
2dfbf4df PM |
630 | Say Y to allow multiple RCU-lockdep warnings per boot. |
631 | ||
632 | Say N if you are unsure. | |
633 | ||
e3ebfb96 PM |
634 | config PROVE_RCU_DELAY |
635 | bool "RCU debugging: preemptible RCU race provocation" | |
636 | depends on DEBUG_KERNEL && PREEMPT_RCU | |
637 | default n | |
638 | help | |
639 | There is a class of races that involve an unlikely preemption | |
640 | of __rcu_read_unlock() just after ->rcu_read_lock_nesting has | |
641 | been set to INT_MIN. This feature inserts a delay at that | |
642 | point to increase the probability of these races. | |
643 | ||
644 | Say Y to increase probability of preemption of __rcu_read_unlock(). | |
645 | ||
646 | Say N if you are unsure. | |
647 | ||
ca5ecddf PM |
648 | config SPARSE_RCU_POINTER |
649 | bool "RCU debugging: sparse-based checks for pointer usage" | |
650 | default n | |
651 | help | |
652 | This feature enables the __rcu sparse annotation for | |
653 | RCU-protected pointers. This annotation will cause sparse | |
654 | to flag any non-RCU used of annotated pointers. This can be | |
655 | helpful when debugging RCU usage. Please note that this feature | |
656 | is not intended to enforce code cleanliness; it is instead merely | |
657 | a debugging aid. | |
658 | ||
659 | Say Y to make sparse flag questionable use of RCU-protected pointers | |
660 | ||
2b3fc35f LJ |
661 | Say N if you are unsure. |
662 | ||
4d9f34ad IM |
663 | config LOCKDEP |
664 | bool | |
517e7aa5 | 665 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad | 666 | select STACKTRACE |
79aac889 | 667 | select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE |
4d9f34ad IM |
668 | select KALLSYMS |
669 | select KALLSYMS_ALL | |
670 | ||
f20786ff | 671 | config LOCK_STAT |
fdfb870f | 672 | bool "Lock usage statistics" |
f20786ff PZ |
673 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
674 | select LOCKDEP | |
675 | select DEBUG_SPINLOCK | |
676 | select DEBUG_MUTEXES | |
677 | select DEBUG_LOCK_ALLOC | |
678 | default n | |
679 | help | |
680 | This feature enables tracking lock contention points | |
681 | ||
a560aa48 PZ |
682 | For more details, see Documentation/lockstat.txt |
683 | ||
dd8b1cf6 FW |
684 | This also enables lock events required by "perf lock", |
685 | subcommand of perf. | |
686 | If you want to use "perf lock", you also need to turn on | |
687 | CONFIG_EVENT_TRACING. | |
84c6f88f HM |
688 | |
689 | CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. | |
dd8b1cf6 | 690 | (CONFIG_LOCKDEP defines "acquire" and "release" events.) |
84c6f88f | 691 | |
4d9f34ad IM |
692 | config DEBUG_LOCKDEP |
693 | bool "Lock dependency engine debugging" | |
517e7aa5 | 694 | depends on DEBUG_KERNEL && LOCKDEP |
4d9f34ad IM |
695 | help |
696 | If you say Y here, the lock dependency engine will do | |
697 | additional runtime checks to debug itself, at the price | |
698 | of more runtime overhead. | |
699 | ||
700 | config TRACE_IRQFLAGS | |
701 | bool | |
46b93b74 SR |
702 | help |
703 | Enables hooks to interrupt enabling and disabling for | |
704 | either tracing or lock debugging. | |
4d9f34ad | 705 | |
d902db1e FW |
706 | config DEBUG_ATOMIC_SLEEP |
707 | bool "Sleep inside atomic section checking" | |
e8f7c70f | 708 | select PREEMPT_COUNT |
1da177e4 LT |
709 | depends on DEBUG_KERNEL |
710 | help | |
711 | If you say Y here, various routines which may sleep will become very | |
d902db1e FW |
712 | noisy if they are called inside atomic sections: when a spinlock is |
713 | held, inside an rcu read side critical section, inside preempt disabled | |
714 | sections, inside an interrupt, etc... | |
1da177e4 | 715 | |
cae2ed9a IM |
716 | config DEBUG_LOCKING_API_SELFTESTS |
717 | bool "Locking API boot-time self-tests" | |
718 | depends on DEBUG_KERNEL | |
719 | help | |
720 | Say Y here if you want the kernel to run a short self-test during | |
721 | bootup. The self-test checks whether common types of locking bugs | |
722 | are detected by debugging mechanisms or not. (if you disable | |
723 | lock debugging then those bugs wont be detected of course.) | |
724 | The following locking APIs are covered: spinlocks, rwlocks, | |
725 | mutexes and rwsems. | |
726 | ||
8637c099 IM |
727 | config STACKTRACE |
728 | bool | |
729 | depends on STACKTRACE_SUPPORT | |
730 | ||
5ca43f6c SB |
731 | config DEBUG_STACK_USAGE |
732 | bool "Stack utilization instrumentation" | |
e9c31b32 | 733 | depends on DEBUG_KERNEL && !IA64 && !PARISC |
5ca43f6c SB |
734 | help |
735 | Enables the display of the minimum amount of free stack which each | |
736 | task has ever had available in the sysrq-T and sysrq-P debug output. | |
737 | ||
738 | This option will slow down process creation somewhat. | |
739 | ||
1da177e4 LT |
740 | config DEBUG_KOBJECT |
741 | bool "kobject debugging" | |
742 | depends on DEBUG_KERNEL | |
743 | help | |
744 | If you say Y here, some extra kobject debugging messages will be sent | |
745 | to the syslog. | |
746 | ||
747 | config DEBUG_HIGHMEM | |
748 | bool "Highmem debugging" | |
749 | depends on DEBUG_KERNEL && HIGHMEM | |
750 | help | |
751 | This options enables addition error checking for high memory systems. | |
752 | Disable for production systems. | |
753 | ||
9b2a60c4 CM |
754 | config HAVE_DEBUG_BUGVERBOSE |
755 | bool | |
756 | ||
1da177e4 | 757 | config DEBUG_BUGVERBOSE |
6a108a14 | 758 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT |
9b2a60c4 | 759 | depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) |
8420e7ef | 760 | default y |
1da177e4 LT |
761 | help |
762 | Say Y here to make BUG() panics output the file name and line number | |
763 | of the BUG call as well as the EIP and oops trace. This aids | |
764 | debugging but costs about 70-100K of memory. | |
765 | ||
766 | config DEBUG_INFO | |
767 | bool "Compile the kernel with debug info" | |
768 | depends on DEBUG_KERNEL | |
769 | help | |
770 | If you say Y here the resulting kernel image will include | |
771 | debugging info resulting in a larger kernel image. | |
b72e53f8 AD |
772 | This adds debug symbols to the kernel and modules (gcc -g), and |
773 | is needed if you intend to use kernel crashdump or binary object | |
774 | tools like crash, kgdb, LKCD, gdb, etc on the kernel. | |
1da177e4 LT |
775 | Say Y here only if you plan to debug the kernel. |
776 | ||
777 | If unsure, say N. | |
778 | ||
d6f4ceb7 AK |
779 | config DEBUG_INFO_REDUCED |
780 | bool "Reduce debugging information" | |
781 | depends on DEBUG_INFO | |
782 | help | |
783 | If you say Y here gcc is instructed to generate less debugging | |
784 | information for structure types. This means that tools that | |
785 | need full debugging information (like kgdb or systemtap) won't | |
786 | be happy. But if you merely need debugging information to | |
787 | resolve line numbers there is no loss. Advantage is that | |
788 | build directory object sizes shrink dramatically over a full | |
789 | DEBUG_INFO build and compile times are reduced too. | |
790 | Only works with newer gcc versions. | |
791 | ||
a241ec65 PM |
792 | config DEBUG_VM |
793 | bool "Debug VM" | |
794 | depends on DEBUG_KERNEL | |
795 | help | |
13e7444b NP |
796 | Enable this to turn on extended checks in the virtual-memory system |
797 | that may impact performance. | |
a241ec65 PM |
798 | |
799 | If unsure, say N. | |
800 | ||
59ea7463 JS |
801 | config DEBUG_VIRTUAL |
802 | bool "Debug VM translations" | |
803 | depends on DEBUG_KERNEL && X86 | |
804 | help | |
805 | Enable some costly sanity checks in virtual to page code. This can | |
806 | catch mistakes with virt_to_page() and friends. | |
807 | ||
808 | If unsure, say N. | |
809 | ||
8feae131 DH |
810 | config DEBUG_NOMMU_REGIONS |
811 | bool "Debug the global anon/private NOMMU mapping region tree" | |
812 | depends on DEBUG_KERNEL && !MMU | |
813 | help | |
814 | This option causes the global tree of anonymous and private mapping | |
815 | regions to be regularly checked for invalid topology. | |
816 | ||
ad775f5a DH |
817 | config DEBUG_WRITECOUNT |
818 | bool "Debug filesystem writers count" | |
819 | depends on DEBUG_KERNEL | |
820 | help | |
821 | Enable this to catch wrong use of the writers count in struct | |
822 | vfsmount. This will increase the size of each file struct by | |
823 | 32 bits. | |
824 | ||
825 | If unsure, say N. | |
826 | ||
6b74ab97 | 827 | config DEBUG_MEMORY_INIT |
6a108a14 DR |
828 | bool "Debug memory initialisation" if EXPERT |
829 | default !EXPERT | |
6b74ab97 MG |
830 | help |
831 | Enable this for additional checks during memory initialisation. | |
832 | The sanity checks verify aspects of the VM such as the memory model | |
833 | and other information provided by the architecture. Verbose | |
834 | information will be printed at KERN_DEBUG loglevel depending | |
835 | on the mminit_loglevel= command-line option. | |
836 | ||
837 | If unsure, say Y | |
838 | ||
199a9afc DJ |
839 | config DEBUG_LIST |
840 | bool "Debug linked list manipulation" | |
841 | depends on DEBUG_KERNEL | |
842 | help | |
843 | Enable this to turn on extended checks in the linked-list | |
844 | walking routines. | |
845 | ||
846 | If unsure, say N. | |
847 | ||
6d411e6c AB |
848 | config TEST_LIST_SORT |
849 | bool "Linked list sorting test" | |
850 | depends on DEBUG_KERNEL | |
851 | help | |
852 | Enable this to turn on 'list_sort()' function test. This test is | |
853 | executed only once during system boot, so affects only boot time. | |
854 | ||
855 | If unsure, say N. | |
856 | ||
d6ec0842 JA |
857 | config DEBUG_SG |
858 | bool "Debug SG table operations" | |
859 | depends on DEBUG_KERNEL | |
860 | help | |
861 | Enable this to turn on checks on scatter-gather tables. This can | |
862 | help find problems with drivers that do not properly initialize | |
863 | their sg tables. | |
864 | ||
865 | If unsure, say N. | |
866 | ||
1b2439db AV |
867 | config DEBUG_NOTIFIERS |
868 | bool "Debug notifier call chains" | |
869 | depends on DEBUG_KERNEL | |
870 | help | |
871 | Enable this to turn on sanity checking for notifier call chains. | |
872 | This is most useful for kernel developers to make sure that | |
873 | modules properly unregister themselves from notifier chains. | |
874 | This is a relatively cheap check but if you care about maximum | |
875 | performance, say N. | |
876 | ||
e0e81739 DH |
877 | config DEBUG_CREDENTIALS |
878 | bool "Debug credential management" | |
879 | depends on DEBUG_KERNEL | |
880 | help | |
881 | Enable this to turn on some debug checking for credential | |
882 | management. The additional code keeps track of the number of | |
883 | pointers from task_structs to any given cred struct, and checks to | |
884 | see that this number never exceeds the usage count of the cred | |
885 | struct. | |
886 | ||
887 | Furthermore, if SELinux is enabled, this also checks that the | |
888 | security pointer in the cred struct is never seen to be invalid. | |
889 | ||
890 | If unsure, say N. | |
891 | ||
64dec40d JM |
892 | # |
893 | # Select this config option from the architecture Kconfig, if it | |
52288b66 | 894 | # is preferred to always offer frame pointers as a config |
64dec40d JM |
895 | # option on the architecture (regardless of KERNEL_DEBUG): |
896 | # | |
897 | config ARCH_WANT_FRAME_POINTERS | |
898 | bool | |
899 | help | |
900 | ||
1da177e4 LT |
901 | config FRAME_POINTER |
902 | bool "Compile the kernel with frame pointers" | |
b920de1b | 903 | depends on DEBUG_KERNEL && \ |
73020415 | 904 | (CRIS || M68K || FRV || UML || \ |
da4276b8 IM |
905 | AVR32 || SUPERH || BLACKFIN || MN10300) || \ |
906 | ARCH_WANT_FRAME_POINTERS | |
907 | default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS | |
908 | help | |
909 | If you say Y here the resulting kernel image will be slightly | |
910 | larger and slower, but it gives very useful debugging information | |
911 | in case of kernel bugs. (precise oopses/stacktraces/warnings) | |
1da177e4 | 912 | |
bfe8df3d RD |
913 | config BOOT_PRINTK_DELAY |
914 | bool "Delay each boot printk message by N milliseconds" | |
915 | depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY | |
916 | help | |
917 | This build option allows you to read kernel boot messages | |
918 | by inserting a short delay after each one. The delay is | |
919 | specified in milliseconds on the kernel command line, | |
920 | using "boot_delay=N". | |
921 | ||
922 | It is likely that you would also need to use "lpj=M" to preset | |
923 | the "loops per jiffie" value. | |
924 | See a previous boot log for the "lpj" value to use for your | |
925 | system, and then set "lpj=M" before setting "boot_delay=N". | |
926 | NOTE: Using this option may adversely affect SMP systems. | |
927 | I.e., processors other than the first one may not boot up. | |
8edbb83e | 928 | BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect |
bfe8df3d RD |
929 | what it believes to be lockup conditions. |
930 | ||
a241ec65 PM |
931 | config RCU_TORTURE_TEST |
932 | tristate "torture tests for RCU" | |
933 | depends on DEBUG_KERNEL | |
934 | default n | |
935 | help | |
936 | This option provides a kernel module that runs torture tests | |
937 | on the RCU infrastructure. The kernel module may be built | |
938 | after the fact on the running kernel to be tested, if desired. | |
939 | ||
31a72bce PM |
940 | Say Y here if you want RCU torture tests to be built into |
941 | the kernel. | |
a241ec65 PM |
942 | Say M if you want the RCU torture tests to build as a module. |
943 | Say N if you are unsure. | |
8bb31b9d | 944 | |
31a72bce PM |
945 | config RCU_TORTURE_TEST_RUNNABLE |
946 | bool "torture tests for RCU runnable by default" | |
947 | depends on RCU_TORTURE_TEST = y | |
948 | default n | |
949 | help | |
950 | This option provides a way to build the RCU torture tests | |
951 | directly into the kernel without them starting up at boot | |
952 | time. You can use /proc/sys/kernel/rcutorture_runnable | |
953 | to manually override this setting. This /proc file is | |
954 | available only when the RCU torture tests have been built | |
955 | into the kernel. | |
956 | ||
957 | Say Y here if you want the RCU torture tests to start during | |
958 | boot (you probably don't). | |
959 | Say N here if you want the RCU torture tests to start only | |
960 | after being manually enabled via /proc. | |
961 | ||
b163760e PM |
962 | config RCU_CPU_STALL_TIMEOUT |
963 | int "RCU CPU stall timeout in seconds" | |
a00e0d71 | 964 | depends on TREE_RCU || TREE_PREEMPT_RCU |
b163760e PM |
965 | range 3 300 |
966 | default 60 | |
967 | help | |
968 | If a given RCU grace period extends more than the specified | |
969 | number of seconds, a CPU stall warning is printed. If the | |
970 | RCU grace period persists, additional CPU stall warnings are | |
971 | printed at more widely spaced intervals. | |
972 | ||
1ed509a2 PM |
973 | config RCU_CPU_STALL_VERBOSE |
974 | bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR" | |
a00e0d71 | 975 | depends on TREE_PREEMPT_RCU |
55ec936f | 976 | default y |
1ed509a2 PM |
977 | help |
978 | This option causes RCU to printk detailed per-task information | |
979 | for any tasks that are stalling the current RCU grace period. | |
67182ae1 PM |
980 | |
981 | Say N if you are unsure. | |
982 | ||
1ed509a2 PM |
983 | Say Y if you want to enable such checks. |
984 | ||
a858af28 PM |
985 | config RCU_CPU_STALL_INFO |
986 | bool "Print additional diagnostics on RCU CPU stall" | |
987 | depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL | |
988 | default n | |
989 | help | |
990 | For each stalled CPU that is aware of the current RCU grace | |
991 | period, print out additional per-CPU diagnostic information | |
992 | regarding scheduling-clock ticks, idle state, and, | |
993 | for RCU_FAST_NO_HZ kernels, idle-entry state. | |
994 | ||
995 | Say N if you are unsure. | |
996 | ||
997 | Say Y if you want to enable such diagnostics. | |
998 | ||
5c8806a0 PM |
999 | config RCU_TRACE |
1000 | bool "Enable tracing for RCU" | |
1001 | depends on DEBUG_KERNEL | |
1002 | help | |
1003 | This option provides tracing in RCU which presents stats | |
1004 | in debugfs for debugging RCU implementation. | |
1005 | ||
1006 | Say Y here if you want to enable RCU tracing | |
1007 | Say N if you are unsure. | |
1008 | ||
8c1c9356 AM |
1009 | config KPROBES_SANITY_TEST |
1010 | bool "Kprobes sanity tests" | |
1011 | depends on DEBUG_KERNEL | |
1012 | depends on KPROBES | |
1013 | default n | |
1014 | help | |
1015 | This option provides for testing basic kprobes functionality on | |
1016 | boot. A sample kprobe, jprobe and kretprobe are inserted and | |
1017 | verified for functionality. | |
1018 | ||
1019 | Say N if you are unsure. | |
1020 | ||
6dab2778 AV |
1021 | config BACKTRACE_SELF_TEST |
1022 | tristate "Self test for the backtrace code" | |
1023 | depends on DEBUG_KERNEL | |
1024 | default n | |
1025 | help | |
1026 | This option provides a kernel module that can be used to test | |
1027 | the kernel stack backtrace code. This option is not useful | |
1028 | for distributions or general kernels, but only for kernel | |
1029 | developers working on architecture code. | |
1030 | ||
ad118c54 VN |
1031 | Note that if you want to also test saved backtraces, you will |
1032 | have to enable STACKTRACE as well. | |
1033 | ||
6dab2778 AV |
1034 | Say N if you are unsure. |
1035 | ||
870d6656 TH |
1036 | config DEBUG_BLOCK_EXT_DEVT |
1037 | bool "Force extended block device numbers and spread them" | |
1038 | depends on DEBUG_KERNEL | |
1039 | depends on BLOCK | |
759f8ca3 | 1040 | default n |
870d6656 | 1041 | help |
0e11e342 TH |
1042 | BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON |
1043 | SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT | |
1044 | YOU ARE DOING. Distros, please enable this and fix whatever | |
1045 | is broken. | |
1046 | ||
870d6656 TH |
1047 | Conventionally, block device numbers are allocated from |
1048 | predetermined contiguous area. However, extended block area | |
1049 | may introduce non-contiguous block device numbers. This | |
1050 | option forces most block device numbers to be allocated from | |
1051 | the extended space and spreads them to discover kernel or | |
1052 | userland code paths which assume predetermined contiguous | |
1053 | device number allocation. | |
1054 | ||
55dc7db7 TH |
1055 | Note that turning on this debug option shuffles all the |
1056 | device numbers for all IDE and SCSI devices including libata | |
1057 | ones, so root partition specified using device number | |
1058 | directly (via rdev or root=MAJ:MIN) won't work anymore. | |
1059 | Textual device names (root=/dev/sdXn) will continue to work. | |
1060 | ||
870d6656 TH |
1061 | Say N if you are unsure. |
1062 | ||
7c756e6e TH |
1063 | config DEBUG_FORCE_WEAK_PER_CPU |
1064 | bool "Force weak per-cpu definitions" | |
1065 | depends on DEBUG_KERNEL | |
1066 | help | |
1067 | s390 and alpha require percpu variables in modules to be | |
1068 | defined weak to work around addressing range issue which | |
1069 | puts the following two restrictions on percpu variable | |
1070 | definitions. | |
1071 | ||
1072 | 1. percpu symbols must be unique whether static or not | |
1073 | 2. percpu variables can't be defined inside a function | |
1074 | ||
1075 | To ensure that generic code follows the above rules, this | |
1076 | option forces all percpu variables to be defined as weak. | |
1077 | ||
44ec7abe SB |
1078 | config DEBUG_PER_CPU_MAPS |
1079 | bool "Debug access to per_cpu maps" | |
1080 | depends on DEBUG_KERNEL | |
1081 | depends on SMP | |
1082 | help | |
1083 | Say Y to verify that the per_cpu map being accessed has | |
1084 | been set up. This adds a fair amount of code to kernel memory | |
1085 | and decreases performance. | |
1086 | ||
1087 | Say N if unsure. | |
1088 | ||
8bb31b9d AG |
1089 | config LKDTM |
1090 | tristate "Linux Kernel Dump Test Tool Module" | |
0347af4e | 1091 | depends on DEBUG_FS |
fddd9cf8 | 1092 | depends on BLOCK |
8bb31b9d AG |
1093 | default n |
1094 | help | |
1095 | This module enables testing of the different dumping mechanisms by | |
1096 | inducing system failures at predefined crash points. | |
1097 | If you don't need it: say N | |
1098 | Choose M here to compile this code as a module. The module will be | |
1099 | called lkdtm. | |
1100 | ||
1101 | Documentation on how to use the module can be found in | |
0347af4e | 1102 | Documentation/fault-injection/provoke-crashes.txt |
6ff1cb35 | 1103 | |
8d438288 AM |
1104 | config NOTIFIER_ERROR_INJECTION |
1105 | tristate "Notifier error injection" | |
1106 | depends on DEBUG_KERNEL | |
1107 | select DEBUG_FS | |
1108 | help | |
1109 | This option provides the ability to inject artifical errors to | |
1110 | specified notifier chain callbacks. It is useful to test the error | |
1111 | handling of notifier call chain failures. | |
1112 | ||
1113 | Say N if unsure. | |
1114 | ||
c9d221f8 AM |
1115 | config CPU_NOTIFIER_ERROR_INJECT |
1116 | tristate "CPU notifier error injection module" | |
f5a9f52e | 1117 | depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION |
c9d221f8 AM |
1118 | help |
1119 | This option provides a kernel module that can be used to test | |
f5a9f52e AM |
1120 | the error handling of the cpu notifiers by injecting artifical |
1121 | errors to CPU notifier chain callbacks. It is controlled through | |
1122 | debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu | |
1123 | ||
1124 | If the notifier call chain should be failed with some events | |
1125 | notified, write the error code to "actions/<notifier event>/error". | |
1126 | ||
1127 | Example: Inject CPU offline error (-1 == -EPERM) | |
1128 | ||
1129 | # cd /sys/kernel/debug/notifier-error-inject/cpu | |
1130 | # echo -1 > actions/CPU_DOWN_PREPARE/error | |
1131 | # echo 0 > /sys/devices/system/cpu/cpu1/online | |
1132 | bash: echo: write error: Operation not permitted | |
c9d221f8 AM |
1133 | |
1134 | To compile this code as a module, choose M here: the module will | |
1135 | be called cpu-notifier-error-inject. | |
1136 | ||
1137 | If unsure, say N. | |
1138 | ||
048b9c35 AM |
1139 | config PM_NOTIFIER_ERROR_INJECT |
1140 | tristate "PM notifier error injection module" | |
1141 | depends on PM && NOTIFIER_ERROR_INJECTION | |
1142 | default m if PM_DEBUG | |
1143 | help | |
1144 | This option provides the ability to inject artifical errors to | |
1145 | PM notifier chain callbacks. It is controlled through debugfs | |
1146 | interface /sys/kernel/debug/notifier-error-inject/pm | |
1147 | ||
1148 | If the notifier call chain should be failed with some events | |
1149 | notified, write the error code to "actions/<notifier event>/error". | |
1150 | ||
1151 | Example: Inject PM suspend error (-12 = -ENOMEM) | |
1152 | ||
1153 | # cd /sys/kernel/debug/notifier-error-inject/pm/ | |
1154 | # echo -12 > actions/PM_SUSPEND_PREPARE/error | |
1155 | # echo mem > /sys/power/state | |
1156 | bash: echo: write error: Cannot allocate memory | |
1157 | ||
1158 | To compile this code as a module, choose M here: the module will | |
1159 | be called pm-notifier-error-inject. | |
1160 | ||
1161 | If unsure, say N. | |
1162 | ||
9579f5bd AM |
1163 | config MEMORY_NOTIFIER_ERROR_INJECT |
1164 | tristate "Memory hotplug notifier error injection module" | |
1165 | depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION | |
1166 | help | |
1167 | This option provides the ability to inject artifical errors to | |
1168 | memory hotplug notifier chain callbacks. It is controlled through | |
1169 | debugfs interface under /sys/kernel/debug/notifier-error-inject/memory | |
1170 | ||
1171 | If the notifier call chain should be failed with some events | |
1172 | notified, write the error code to "actions/<notifier event>/error". | |
1173 | ||
1174 | Example: Inject memory hotplug offline error (-12 == -ENOMEM) | |
1175 | ||
1176 | # cd /sys/kernel/debug/notifier-error-inject/memory | |
1177 | # echo -12 > actions/MEM_GOING_OFFLINE/error | |
1178 | # echo offline > /sys/devices/system/memory/memoryXXX/state | |
1179 | bash: echo: write error: Cannot allocate memory | |
1180 | ||
1181 | To compile this code as a module, choose M here: the module will | |
1182 | be called pSeries-reconfig-notifier-error-inject. | |
1183 | ||
1184 | If unsure, say N. | |
1185 | ||
08dfb4dd AM |
1186 | config PSERIES_RECONFIG_NOTIFIER_ERROR_INJECT |
1187 | tristate "pSeries reconfig notifier error injection module" | |
1188 | depends on PPC_PSERIES && NOTIFIER_ERROR_INJECTION | |
1189 | help | |
1190 | This option provides the ability to inject artifical errors to | |
1191 | pSeries reconfig notifier chain callbacks. It is controlled | |
1192 | through debugfs interface under | |
1193 | /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/ | |
1194 | ||
1195 | If the notifier call chain should be failed with some events | |
1196 | notified, write the error code to "actions/<notifier event>/error". | |
1197 | ||
1198 | To compile this code as a module, choose M here: the module will | |
1199 | be called memory-notifier-error-inject. | |
1200 | ||
1201 | If unsure, say N. | |
1202 | ||
6ff1cb35 | 1203 | config FAULT_INJECTION |
1ab8509a AM |
1204 | bool "Fault-injection framework" |
1205 | depends on DEBUG_KERNEL | |
329409ae AM |
1206 | help |
1207 | Provide fault-injection framework. | |
1208 | For more details, see Documentation/fault-injection/. | |
6ff1cb35 | 1209 | |
8a8b6502 | 1210 | config FAILSLAB |
1ab8509a AM |
1211 | bool "Fault-injection capability for kmalloc" |
1212 | depends on FAULT_INJECTION | |
773ff60e | 1213 | depends on SLAB || SLUB |
8a8b6502 | 1214 | help |
1ab8509a | 1215 | Provide fault-injection capability for kmalloc. |
8a8b6502 | 1216 | |
933e312e AM |
1217 | config FAIL_PAGE_ALLOC |
1218 | bool "Fault-injection capabilitiy for alloc_pages()" | |
1ab8509a | 1219 | depends on FAULT_INJECTION |
933e312e | 1220 | help |
1ab8509a | 1221 | Provide fault-injection capability for alloc_pages(). |
933e312e | 1222 | |
c17bb495 | 1223 | config FAIL_MAKE_REQUEST |
86327d19 | 1224 | bool "Fault-injection capability for disk IO" |
581d4e28 | 1225 | depends on FAULT_INJECTION && BLOCK |
c17bb495 | 1226 | help |
1ab8509a | 1227 | Provide fault-injection capability for disk IO. |
c17bb495 | 1228 | |
581d4e28 | 1229 | config FAIL_IO_TIMEOUT |
f4d01439 | 1230 | bool "Fault-injection capability for faking disk interrupts" |
581d4e28 JA |
1231 | depends on FAULT_INJECTION && BLOCK |
1232 | help | |
1233 | Provide fault-injection capability on end IO handling. This | |
1234 | will make the block layer "forget" an interrupt as configured, | |
1235 | thus exercising the error handling. | |
1236 | ||
1237 | Only works with drivers that use the generic timeout handling, | |
1238 | for others it wont do anything. | |
1239 | ||
1b676f70 PF |
1240 | config FAIL_MMC_REQUEST |
1241 | bool "Fault-injection capability for MMC IO" | |
1242 | select DEBUG_FS | |
1243 | depends on FAULT_INJECTION && MMC | |
1244 | help | |
1245 | Provide fault-injection capability for MMC IO. | |
1246 | This will make the mmc core return data errors. This is | |
1247 | useful to test the error handling in the mmc block device | |
1248 | and to test how the mmc host driver handles retries from | |
1249 | the block device. | |
1250 | ||
6ff1cb35 AM |
1251 | config FAULT_INJECTION_DEBUG_FS |
1252 | bool "Debugfs entries for fault-injection capabilities" | |
1ab8509a | 1253 | depends on FAULT_INJECTION && SYSFS && DEBUG_FS |
6ff1cb35 | 1254 | help |
1ab8509a | 1255 | Enable configuration of fault-injection capabilities via debugfs. |
1df49008 AM |
1256 | |
1257 | config FAULT_INJECTION_STACKTRACE_FILTER | |
1258 | bool "stacktrace filter for fault-injection capabilities" | |
1259 | depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT | |
6d690dca | 1260 | depends on !X86_64 |
1df49008 | 1261 | select STACKTRACE |
89bace65 | 1262 | select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND |
1df49008 AM |
1263 | help |
1264 | Provide stacktrace filter for fault-injection capabilities | |
267c4025 | 1265 | |
9745512c AV |
1266 | config LATENCYTOP |
1267 | bool "Latency measuring infrastructure" | |
625fdcaa RD |
1268 | depends on HAVE_LATENCYTOP_SUPPORT |
1269 | depends on DEBUG_KERNEL | |
1270 | depends on STACKTRACE_SUPPORT | |
1271 | depends on PROC_FS | |
89bace65 | 1272 | select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND |
9745512c AV |
1273 | select KALLSYMS |
1274 | select KALLSYMS_ALL | |
1275 | select STACKTRACE | |
1276 | select SCHEDSTATS | |
1277 | select SCHED_DEBUG | |
9745512c AV |
1278 | help |
1279 | Enable this option if you want to use the LatencyTOP tool | |
1280 | to find out which userspace is blocking on what kernel operations. | |
1281 | ||
6a11f75b | 1282 | source mm/Kconfig.debug |
16444a8a ACM |
1283 | source kernel/trace/Kconfig |
1284 | ||
f212ec4b | 1285 | config PROVIDE_OHCI1394_DMA_INIT |
080de8c2 | 1286 | bool "Remote debugging over FireWire early on boot" |
f212ec4b BK |
1287 | depends on PCI && X86 |
1288 | help | |
1289 | If you want to debug problems which hang or crash the kernel early | |
1290 | on boot and the crashing machine has a FireWire port, you can use | |
1291 | this feature to remotely access the memory of the crashed machine | |
1292 | over FireWire. This employs remote DMA as part of the OHCI1394 | |
1293 | specification which is now the standard for FireWire controllers. | |
1294 | ||
1295 | With remote DMA, you can monitor the printk buffer remotely using | |
1296 | firescope and access all memory below 4GB using fireproxy from gdb. | |
1297 | Even controlling a kernel debugger is possible using remote DMA. | |
1298 | ||
1299 | Usage: | |
1300 | ||
1301 | If ohci1394_dma=early is used as boot parameter, it will initialize | |
1302 | all OHCI1394 controllers which are found in the PCI config space. | |
1303 | ||
1304 | As all changes to the FireWire bus such as enabling and disabling | |
1305 | devices cause a bus reset and thereby disable remote DMA for all | |
1306 | devices, be sure to have the cable plugged and FireWire enabled on | |
1307 | the debugging host before booting the debug target for debugging. | |
1308 | ||
1309 | This code (~1k) is freed after boot. By then, the firewire stack | |
1310 | in charge of the OHCI-1394 controllers should be used instead. | |
1311 | ||
1312 | See Documentation/debugging-via-ohci1394.txt for more information. | |
9745512c | 1313 | |
080de8c2 SR |
1314 | config FIREWIRE_OHCI_REMOTE_DMA |
1315 | bool "Remote debugging over FireWire with firewire-ohci" | |
1316 | depends on FIREWIRE_OHCI | |
1317 | help | |
1318 | This option lets you use the FireWire bus for remote debugging | |
1319 | with help of the firewire-ohci driver. It enables unfiltered | |
1320 | remote DMA in firewire-ohci. | |
1321 | See Documentation/debugging-via-ohci1394.txt for more information. | |
1322 | ||
1323 | If unsure, say N. | |
1324 | ||
152de30b | 1325 | config BUILD_DOCSRC |
3794f3e8 RD |
1326 | bool "Build targets in Documentation/ tree" |
1327 | depends on HEADERS_CHECK | |
1328 | help | |
1329 | This option attempts to build objects from the source files in the | |
1330 | kernel Documentation/ tree. | |
1331 | ||
1332 | Say N if you are unsure. | |
1333 | ||
e9d376f0 | 1334 | config DYNAMIC_DEBUG |
86151fdf | 1335 | bool "Enable dynamic printk() support" |
346e15be JB |
1336 | default n |
1337 | depends on PRINTK | |
86151fdf | 1338 | depends on DEBUG_FS |
346e15be JB |
1339 | help |
1340 | ||
1341 | Compiles debug level messages into the kernel, which would not | |
1342 | otherwise be available at runtime. These messages can then be | |
86151fdf JB |
1343 | enabled/disabled based on various levels of scope - per source file, |
1344 | function, module, format string, and line number. This mechanism | |
29e36c9f JC |
1345 | implicitly compiles in all pr_debug() and dev_dbg() calls, which |
1346 | enlarges the kernel text size by about 2%. | |
1347 | ||
1348 | If a source file is compiled with DEBUG flag set, any | |
1349 | pr_debug() calls in it are enabled by default, but can be | |
1350 | disabled at runtime as below. Note that DEBUG flag is | |
1351 | turned on by many CONFIG_*DEBUG* options. | |
346e15be JB |
1352 | |
1353 | Usage: | |
1354 | ||
2b2f68b5 | 1355 | Dynamic debugging is controlled via the 'dynamic_debug/control' file, |
86151fdf JB |
1356 | which is contained in the 'debugfs' filesystem. Thus, the debugfs |
1357 | filesystem must first be mounted before making use of this feature. | |
2b2f68b5 | 1358 | We refer the control file as: <debugfs>/dynamic_debug/control. This |
86151fdf JB |
1359 | file contains a list of the debug statements that can be enabled. The |
1360 | format for each line of the file is: | |
346e15be | 1361 | |
86151fdf | 1362 | filename:lineno [module]function flags format |
346e15be | 1363 | |
86151fdf JB |
1364 | filename : source file of the debug statement |
1365 | lineno : line number of the debug statement | |
1366 | module : module that contains the debug statement | |
1367 | function : function that contains the debug statement | |
29e36c9f | 1368 | flags : '=p' means the line is turned 'on' for printing |
86151fdf | 1369 | format : the format used for the debug statement |
346e15be JB |
1370 | |
1371 | From a live system: | |
1372 | ||
2b2f68b5 | 1373 | nullarbor:~ # cat <debugfs>/dynamic_debug/control |
86151fdf | 1374 | # filename:lineno [module]function flags format |
29e36c9f JC |
1375 | fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" |
1376 | fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" | |
1377 | fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" | |
346e15be | 1378 | |
86151fdf | 1379 | Example usage: |
346e15be | 1380 | |
86151fdf JB |
1381 | // enable the message at line 1603 of file svcsock.c |
1382 | nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > | |
2b2f68b5 | 1383 | <debugfs>/dynamic_debug/control |
346e15be | 1384 | |
86151fdf JB |
1385 | // enable all the messages in file svcsock.c |
1386 | nullarbor:~ # echo -n 'file svcsock.c +p' > | |
2b2f68b5 | 1387 | <debugfs>/dynamic_debug/control |
346e15be | 1388 | |
86151fdf JB |
1389 | // enable all the messages in the NFS server module |
1390 | nullarbor:~ # echo -n 'module nfsd +p' > | |
2b2f68b5 | 1391 | <debugfs>/dynamic_debug/control |
346e15be | 1392 | |
86151fdf JB |
1393 | // enable all 12 messages in the function svc_process() |
1394 | nullarbor:~ # echo -n 'func svc_process +p' > | |
2b2f68b5 | 1395 | <debugfs>/dynamic_debug/control |
346e15be | 1396 | |
86151fdf JB |
1397 | // disable all 12 messages in the function svc_process() |
1398 | nullarbor:~ # echo -n 'func svc_process -p' > | |
2b2f68b5 | 1399 | <debugfs>/dynamic_debug/control |
346e15be | 1400 | |
86151fdf | 1401 | See Documentation/dynamic-debug-howto.txt for additional information. |
346e15be | 1402 | |
5ee00bd4 JR |
1403 | config DMA_API_DEBUG |
1404 | bool "Enable debugging of DMA-API usage" | |
1405 | depends on HAVE_DMA_API_DEBUG | |
1406 | help | |
1407 | Enable this option to debug the use of the DMA API by device drivers. | |
1408 | With this option you will be able to detect common bugs in device | |
1409 | drivers like double-freeing of DMA mappings or freeing mappings that | |
1410 | were never allocated. | |
1411 | This option causes a performance degredation. Use only if you want | |
1412 | to debug device drivers. If unsure, say N. | |
346e15be | 1413 | |
86a89380 LB |
1414 | config ATOMIC64_SELFTEST |
1415 | bool "Perform an atomic64_t self-test at boot" | |
1416 | help | |
1417 | Enable this option to test the atomic64_t functions at boot. | |
1418 | ||
1419 | If unsure, say N. | |
1420 | ||
400fb7f6 DW |
1421 | config ASYNC_RAID6_TEST |
1422 | tristate "Self test for hardware accelerated raid6 recovery" | |
1423 | depends on ASYNC_RAID6_RECOV | |
1424 | select ASYNC_MEMCPY | |
1425 | ---help--- | |
1426 | This is a one-shot self test that permutes through the | |
1427 | recovery of all the possible two disk failure scenarios for a | |
1428 | N-disk array. Recovery is performed with the asynchronous | |
1429 | raid6 recovery routines, and will optionally use an offload | |
1430 | engine if one is available. | |
1431 | ||
1432 | If unsure, say N. | |
1433 | ||
267c4025 | 1434 | source "samples/Kconfig" |
dc7d5527 JW |
1435 | |
1436 | source "lib/Kconfig.kgdb" | |
0a4af3b0 PE |
1437 | |
1438 | source "lib/Kconfig.kmemcheck" | |
33ee3b2e AD |
1439 | |
1440 | config TEST_KSTRTOX | |
1441 | tristate "Test kstrto*() family of functions at runtime" |