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Dave Hansen604ff0d2013-07-01 13:04:49 -07001menu "printk and dmesg options"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002
3config PRINTK_TIME
4 bool "Show timing information on printks"
Randy Dunlapd3b8b6e2006-12-06 20:36:38 -08005 depends on PRINTK
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 help
Kay Sievers649e6ee2012-05-10 04:30:45 +02007 Selecting this option causes time stamps of the printk()
8 messages to be added to the output of the syslog() system
9 call and at the console.
10
11 The timestamp is always recorded internally, and exported
12 to /dev/kmsg. This flag just specifies if the timestamp should
13 be included, not that the timestamp is recorded.
14
15 The behavior is also controlled by the kernel command line
16 parameter printk.time=1. See Documentation/kernel-parameters.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
Mandeep Singh Baines5af5bcb2011-03-22 16:34:23 -070018config DEFAULT_MESSAGE_LOGLEVEL
19 int "Default message log level (1-7)"
20 range 1 7
21 default "4"
22 help
23 Default log level for printk statements with no specified priority.
24
25 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
26 that are auditing their logs closely may want to set it to a lower
27 priority.
28
Dave Hansen604ff0d2013-07-01 13:04:49 -070029config BOOT_PRINTK_DELAY
30 bool "Delay each boot printk message by N milliseconds"
31 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
32 help
33 This build option allows you to read kernel boot messages
34 by inserting a short delay after each one. The delay is
35 specified in milliseconds on the kernel command line,
36 using "boot_delay=N".
37
38 It is likely that you would also need to use "lpj=M" to preset
39 the "loops per jiffie" value.
40 See a previous boot log for the "lpj" value to use for your
41 system, and then set "lpj=M" before setting "boot_delay=N".
42 NOTE: Using this option may adversely affect SMP systems.
43 I.e., processors other than the first one may not boot up.
44 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
45 what it believes to be lockup conditions.
46
47config DYNAMIC_DEBUG
48 bool "Enable dynamic printk() support"
49 default n
50 depends on PRINTK
51 depends on DEBUG_FS
52 help
53
54 Compiles debug level messages into the kernel, which would not
55 otherwise be available at runtime. These messages can then be
56 enabled/disabled based on various levels of scope - per source file,
57 function, module, format string, and line number. This mechanism
58 implicitly compiles in all pr_debug() and dev_dbg() calls, which
59 enlarges the kernel text size by about 2%.
60
61 If a source file is compiled with DEBUG flag set, any
62 pr_debug() calls in it are enabled by default, but can be
63 disabled at runtime as below. Note that DEBUG flag is
64 turned on by many CONFIG_*DEBUG* options.
65
66 Usage:
67
68 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
69 which is contained in the 'debugfs' filesystem. Thus, the debugfs
70 filesystem must first be mounted before making use of this feature.
71 We refer the control file as: <debugfs>/dynamic_debug/control. This
72 file contains a list of the debug statements that can be enabled. The
73 format for each line of the file is:
74
75 filename:lineno [module]function flags format
76
77 filename : source file of the debug statement
78 lineno : line number of the debug statement
79 module : module that contains the debug statement
80 function : function that contains the debug statement
81 flags : '=p' means the line is turned 'on' for printing
82 format : the format used for the debug statement
83
84 From a live system:
85
86 nullarbor:~ # cat <debugfs>/dynamic_debug/control
87 # filename:lineno [module]function flags format
88 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
89 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
90 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
91
92 Example usage:
93
94 // enable the message at line 1603 of file svcsock.c
95 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
96 <debugfs>/dynamic_debug/control
97
98 // enable all the messages in file svcsock.c
99 nullarbor:~ # echo -n 'file svcsock.c +p' >
100 <debugfs>/dynamic_debug/control
101
102 // enable all the messages in the NFS server module
103 nullarbor:~ # echo -n 'module nfsd +p' >
104 <debugfs>/dynamic_debug/control
105
106 // enable all 12 messages in the function svc_process()
107 nullarbor:~ # echo -n 'func svc_process +p' >
108 <debugfs>/dynamic_debug/control
109
110 // disable all 12 messages in the function svc_process()
111 nullarbor:~ # echo -n 'func svc_process -p' >
112 <debugfs>/dynamic_debug/control
113
114 See Documentation/dynamic-debug-howto.txt for additional information.
115
116endmenu # "printk and dmesg options"
117
Dave Hansen6dfc0662013-07-01 13:04:46 -0700118menu "Compile-time checks and compiler options"
119
120config DEBUG_INFO
121 bool "Compile the kernel with debug info"
122 depends on DEBUG_KERNEL
123 help
124 If you say Y here the resulting kernel image will include
125 debugging info resulting in a larger kernel image.
126 This adds debug symbols to the kernel and modules (gcc -g), and
127 is needed if you intend to use kernel crashdump or binary object
128 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
129 Say Y here only if you plan to debug the kernel.
130
131 If unsure, say N.
132
133config DEBUG_INFO_REDUCED
134 bool "Reduce debugging information"
135 depends on DEBUG_INFO
136 help
137 If you say Y here gcc is instructed to generate less debugging
138 information for structure types. This means that tools that
139 need full debugging information (like kgdb or systemtap) won't
140 be happy. But if you merely need debugging information to
141 resolve line numbers there is no loss. Advantage is that
142 build directory object sizes shrink dramatically over a full
143 DEBUG_INFO build and compile times are reduced too.
144 Only works with newer gcc versions.
145
Jeff Garzikde488442007-10-25 04:06:13 -0400146config ENABLE_WARN_DEPRECATED
147 bool "Enable __deprecated logic"
148 default y
149 help
150 Enable the __deprecated logic in the kernel build.
151 Disable this to suppress the "warning: 'foo' is deprecated
152 (declared at kernel/power/somefile.c:1234)" messages.
153
Andrew Mortoncebc04b2006-08-14 22:43:18 -0700154config ENABLE_MUST_CHECK
155 bool "Enable __must_check logic"
156 default y
157 help
158 Enable the __must_check logic in the kernel build. Disable this to
159 suppress the "warning: ignoring return value of 'foo', declared with
160 attribute warn_unused_result" messages.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
Andi Kleen35bb5b12008-02-22 15:15:03 +0100162config FRAME_WARN
163 int "Warn for stack frames larger than (needs gcc 4.4)"
164 range 0 8192
165 default 1024 if !64BIT
166 default 2048 if 64BIT
167 help
168 Tell gcc to warn at build time for stack frames larger than this.
169 Setting this too low will cause a lot of warnings.
170 Setting it to 0 disables the warning.
171 Requires gcc 4.4
172
Randy Dunlap99657c72009-09-18 12:49:22 -0700173config STRIP_ASM_SYMS
174 bool "Strip assembler-generated symbols during link"
175 default n
176 help
177 Strip internal assembler-generated symbols during a link (symbols
178 that look like '.Lxxx') so they don't pollute the output of
179 get_wchan() and suchlike.
180
Andi Kleen1873e872012-03-28 11:51:18 -0700181config READABLE_ASM
182 bool "Generate readable assembler code"
183 depends on DEBUG_KERNEL
184 help
185 Disable some compiler optimizations that tend to generate human unreadable
186 assembler output. This may make the kernel slightly slower, but it helps
187 to keep kernel developers who have to stare a lot at assembler listings
188 sane.
189
Arjan van de Venf71d20e2006-06-28 04:26:45 -0700190config UNUSED_SYMBOLS
191 bool "Enable unused/obsolete exported symbols"
192 default y if X86
193 help
194 Unused but exported symbols make the kernel needlessly bigger. For
195 that reason most of these unused exports will soon be removed. This
196 option is provided temporarily to provide a transition period in case
197 some external kernel module needs one of these symbols anyway. If you
198 encounter such a case in your module, consider if you are actually
199 using the right API. (rationale: since nobody in the kernel is using
200 this in a module, there is a pretty good chance it's actually the
201 wrong interface to use). If you really need the symbol, please send a
202 mail to the linux kernel mailing list mentioning the symbol and why
203 you really need it, and what the merge plan to the mainline kernel for
204 your module is.
205
Don Mullisbf4735a2006-12-10 02:18:37 -0800206config DEBUG_FS
207 bool "Debug Filesystem"
Don Mullisbf4735a2006-12-10 02:18:37 -0800208 help
209 debugfs is a virtual file system that kernel developers use to put
210 debugging files into. Enable this option to be able to read and
211 write to these files.
212
Robert P. J. Dayff543332008-05-20 00:06:00 +0200213 For detailed documentation on the debugfs API, see
214 Documentation/DocBook/filesystems.
215
Don Mullisbf4735a2006-12-10 02:18:37 -0800216 If unsure, say N.
217
218config HEADERS_CHECK
219 bool "Run 'make headers_check' when building vmlinux"
220 depends on !UML
221 help
222 This option will extract the user-visible kernel headers whenever
223 building the kernel, and will run basic sanity checks on them to
224 ensure that exported files do not attempt to include files which
225 were not exported, etc.
226
227 If you're making modifications to header files which are
228 relevant for userspace, say 'Y', and check the headers
229 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
230 your build tree), to make sure they're suitable.
231
Sam Ravnborg91341d42008-01-21 21:31:44 +0100232config DEBUG_SECTION_MISMATCH
233 bool "Enable full Section mismatch analysis"
Sam Ravnborg91341d42008-01-21 21:31:44 +0100234 help
235 The section mismatch analysis checks if there are illegal
236 references from one section to another section.
Michael Wittene809ab02011-04-17 04:08:48 +0000237 During linktime or runtime, some sections are dropped;
238 any use of code/data previously in these sections would
Sam Ravnborg91341d42008-01-21 21:31:44 +0100239 most likely result in an oops.
Michael Wittene809ab02011-04-17 04:08:48 +0000240 In the code, functions and variables are annotated with
Paul Gortmaker0db06282013-06-19 14:53:51 -0400241 __init,, etc. (see the full list in include/linux/init.h),
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100242 which results in the code/data being placed in specific sections.
Michael Wittene809ab02011-04-17 04:08:48 +0000243 The section mismatch analysis is always performed after a full
244 kernel build, and enabling this option causes the following
245 additional steps to occur:
246 - Add the option -fno-inline-functions-called-once to gcc commands.
247 When inlining a function annotated with __init in a non-init
248 function, we would lose the section information and thus
Sam Ravnborg91341d42008-01-21 21:31:44 +0100249 the analysis would not catch the illegal reference.
Michael Wittene809ab02011-04-17 04:08:48 +0000250 This option tells gcc to inline less (but it does result in
251 a larger kernel).
252 - Run the section mismatch analysis for each module/built-in.o file.
253 When we run the section mismatch analysis on vmlinux.o, we
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100254 lose valueble information about where the mismatch was
Sam Ravnborg91341d42008-01-21 21:31:44 +0100255 introduced.
256 Running the analysis for each module/built-in.o file
Michael Wittene809ab02011-04-17 04:08:48 +0000257 tells where the mismatch happens much closer to the
258 source. The drawback is that the same mismatch is
259 reported at least twice.
260 - Enable verbose reporting from modpost in order to help resolve
261 the section mismatches that are reported.
Sam Ravnborg91341d42008-01-21 21:31:44 +0100262
Dave Hansen6dfc0662013-07-01 13:04:46 -0700263#
264# Select this config option from the architecture Kconfig, if it
265# is preferred to always offer frame pointers as a config
266# option on the architecture (regardless of KERNEL_DEBUG):
267#
268config ARCH_WANT_FRAME_POINTERS
269 bool
270 help
271
272config FRAME_POINTER
273 bool "Compile the kernel with frame pointers"
274 depends on DEBUG_KERNEL && \
275 (CRIS || M68K || FRV || UML || \
276 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
277 ARCH_WANT_FRAME_POINTERS
278 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
279 help
280 If you say Y here the resulting kernel image will be slightly
281 larger and slower, but it gives very useful debugging information
282 in case of kernel bugs. (precise oopses/stacktraces/warnings)
283
284config DEBUG_FORCE_WEAK_PER_CPU
285 bool "Force weak per-cpu definitions"
286 depends on DEBUG_KERNEL
287 help
288 s390 and alpha require percpu variables in modules to be
289 defined weak to work around addressing range issue which
290 puts the following two restrictions on percpu variable
291 definitions.
292
293 1. percpu symbols must be unique whether static or not
294 2. percpu variables can't be defined inside a function
295
296 To ensure that generic code follows the above rules, this
297 option forces all percpu variables to be defined as weak.
298
299endmenu # "Compiler options"
300
301config MAGIC_SYSRQ
302 bool "Magic SysRq key"
303 depends on !UML
304 help
305 If you say Y here, you will have some control over the system even
306 if the system crashes for example during kernel debugging (e.g., you
307 will be able to flush the buffer cache to disk, reboot the system
308 immediately or dump some status information). This is accomplished
309 by pressing various keys while holding SysRq (Alt+PrintScreen). It
310 also works on a serial console (on PC hardware at least), if you
311 send a BREAK and then within 5 seconds a command keypress. The
312 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
313 unless you really know what this hack does.
314
Adrian Bunkf346f4b2006-01-09 20:54:51 -0800315config DEBUG_KERNEL
316 bool "Kernel debugging"
317 help
318 Say Y here if you are developing drivers or trying to debug and
319 identify kernel problems.
320
Dave Hansen0610c8a2013-07-01 13:04:43 -0700321menu "Memory Debugging"
David Woodhousea304e1b2007-02-12 00:52:00 -0800322
Dave Hansen0610c8a2013-07-01 13:04:43 -0700323source mm/Kconfig.debug
Ingo Molnar82f67cd2007-02-16 01:28:13 -0800324
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700325config DEBUG_OBJECTS
326 bool "Debug object operations"
327 depends on DEBUG_KERNEL
328 help
329 If you say Y here, additional code will be inserted into the
330 kernel to track the life time of various objects and validate
331 the operations on those objects.
332
333config DEBUG_OBJECTS_SELFTEST
334 bool "Debug objects selftest"
335 depends on DEBUG_OBJECTS
336 help
337 This enables the selftest of the object debug code.
338
339config DEBUG_OBJECTS_FREE
340 bool "Debug objects in freed memory"
341 depends on DEBUG_OBJECTS
342 help
343 This enables checks whether a k/v free operation frees an area
344 which contains an object which has not been deactivated
345 properly. This can make kmalloc/kfree-intensive workloads
346 much slower.
347
Thomas Gleixnerc6f3a972008-04-30 00:55:03 -0700348config DEBUG_OBJECTS_TIMERS
349 bool "Debug timer objects"
350 depends on DEBUG_OBJECTS
351 help
352 If you say Y here, additional code will be inserted into the
353 timer routines to track the life time of timer objects and
354 validate the timer operations.
355
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900356config DEBUG_OBJECTS_WORK
357 bool "Debug work objects"
358 depends on DEBUG_OBJECTS
359 help
360 If you say Y here, additional code will be inserted into the
361 work queue routines to track the life time of work objects and
362 validate the work operations.
363
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400364config DEBUG_OBJECTS_RCU_HEAD
365 bool "Debug RCU callbacks objects"
Mathieu Desnoyersfc2ecf72011-02-23 09:42:14 -0800366 depends on DEBUG_OBJECTS
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400367 help
368 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
369
Tejun Heoe2852ae2010-10-26 14:23:05 -0700370config DEBUG_OBJECTS_PERCPU_COUNTER
371 bool "Debug percpu counter objects"
372 depends on DEBUG_OBJECTS
373 help
374 If you say Y here, additional code will be inserted into the
375 percpu counter routines to track the life time of percpu counter
376 objects and validate the percpu counter operations.
377
Ingo Molnar3ae70202008-11-26 10:02:00 +0100378config DEBUG_OBJECTS_ENABLE_DEFAULT
379 int "debug_objects bootup default value (0-1)"
380 range 0 1
381 default "1"
382 depends on DEBUG_OBJECTS
383 help
384 Debug objects boot parameter default value
385
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386config DEBUG_SLAB
Andrew Morton4a2f0ac2006-03-25 03:07:22 -0800387 bool "Debug slab memory allocations"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200388 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 help
390 Say Y here to have the kernel do limited verification on memory
391 allocation as well as poisoning memory on free to catch use of freed
392 memory. This can make kmalloc/kfree-intensive workloads much slower.
393
Al Viro871751e2006-03-25 03:06:39 -0800394config DEBUG_SLAB_LEAK
395 bool "Memory leak debugging"
396 depends on DEBUG_SLAB
397
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700398config SLUB_DEBUG_ON
399 bool "SLUB debugging on by default"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200400 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700401 default n
402 help
403 Boot with debugging on by default. SLUB boots by default with
404 the runtime debug capabilities switched off. Enabling this is
405 equivalent to specifying the "slub_debug" parameter on boot.
406 There is no support for more fine grained debug control like
407 possible with slub_debug=xxx. SLUB debugging may be switched
408 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
409 "slub_debug=-".
410
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800411config SLUB_STATS
412 default n
413 bool "Enable SLUB performance statistics"
Christoph Lameterab4d5ed2010-10-05 13:57:26 -0500414 depends on SLUB && SYSFS
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800415 help
416 SLUB statistics are useful to debug SLUBs allocation behavior in
417 order find ways to optimize the allocator. This should never be
418 enabled for production use since keeping statistics slows down
419 the allocator by a few percentage points. The slabinfo command
420 supports the determination of the most active slabs to figure
421 out which slabs are relevant to a particular load.
422 Try running: slabinfo -DA
423
Catalin Marinasb69ec422012-10-08 16:28:11 -0700424config HAVE_DEBUG_KMEMLEAK
425 bool
426
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100427config DEBUG_KMEMLEAK
428 bool "Kernel memory leak detector"
Kees Cook525c1f92013-01-16 18:54:16 -0800429 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
Catalin Marinas79e0d9b2011-04-27 17:06:19 +0100430 select DEBUG_FS
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100431 select STACKTRACE if STACKTRACE_SUPPORT
432 select KALLSYMS
Randy Dunlapb60e26a2009-11-06 15:33:45 -0800433 select CRC32
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100434 help
435 Say Y here if you want to enable the memory leak
436 detector. The memory allocation/freeing is traced in a way
437 similar to the Boehm's conservative garbage collector, the
438 difference being that the orphan objects are not freed but
439 only shown in /sys/kernel/debug/kmemleak. Enabling this
440 feature will introduce an overhead to memory
441 allocations. See Documentation/kmemleak.txt for more
442 details.
443
Catalin Marinasbf96d1e2009-06-23 14:40:27 +0100444 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
445 of finding leaks due to the slab objects poisoning.
446
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100447 In order to access the kmemleak file, debugfs needs to be
448 mounted (usually at /sys/kernel/debug).
449
Catalin Marinasa9d90582009-06-25 10:16:11 +0100450config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
451 int "Maximum kmemleak early log entries"
452 depends on DEBUG_KMEMLEAK
Heiko Carstensdfcc3e62009-10-06 10:33:57 +0200453 range 200 40000
Catalin Marinasa9d90582009-06-25 10:16:11 +0100454 default 400
455 help
456 Kmemleak must track all the memory allocations to avoid
457 reporting false positives. Since memory may be allocated or
458 freed before kmemleak is initialised, an early log buffer is
459 used to store these actions. If kmemleak reports "early log
460 buffer exceeded", please increase this value.
461
Catalin Marinas0822ee42009-06-11 13:24:14 +0100462config DEBUG_KMEMLEAK_TEST
463 tristate "Simple test for the kernel memory leak detector"
Daniel Baluta97182692011-04-04 15:06:44 -0700464 depends on DEBUG_KMEMLEAK && m
Catalin Marinas0822ee42009-06-11 13:24:14 +0100465 help
Daniel Baluta97182692011-04-04 15:06:44 -0700466 This option enables a module that explicitly leaks memory.
Catalin Marinas0822ee42009-06-11 13:24:14 +0100467
468 If unsure, say N.
469
Jason Baronab0155a2010-07-19 11:54:17 +0100470config DEBUG_KMEMLEAK_DEFAULT_OFF
471 bool "Default kmemleak to off"
472 depends on DEBUG_KMEMLEAK
473 help
474 Say Y here to disable kmemleak by default. It can then be enabled
475 on the command line via kmemleak=on.
476
Dave Hansen0610c8a2013-07-01 13:04:43 -0700477config DEBUG_STACK_USAGE
478 bool "Stack utilization instrumentation"
479 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
480 help
481 Enables the display of the minimum amount of free stack which each
482 task has ever had available in the sysrq-T and sysrq-P debug output.
483
484 This option will slow down process creation somewhat.
485
486config DEBUG_VM
487 bool "Debug VM"
488 depends on DEBUG_KERNEL
489 help
490 Enable this to turn on extended checks in the virtual-memory system
491 that may impact performance.
492
493 If unsure, say N.
494
495config DEBUG_VM_RB
496 bool "Debug VM red-black trees"
497 depends on DEBUG_VM
498 help
499 Enable this to turn on more extended checks in the virtual-memory
500 system that may impact performance.
501
502 If unsure, say N.
503
504config DEBUG_VIRTUAL
505 bool "Debug VM translations"
506 depends on DEBUG_KERNEL && X86
507 help
508 Enable some costly sanity checks in virtual to page code. This can
509 catch mistakes with virt_to_page() and friends.
510
511 If unsure, say N.
512
513config DEBUG_NOMMU_REGIONS
514 bool "Debug the global anon/private NOMMU mapping region tree"
515 depends on DEBUG_KERNEL && !MMU
516 help
517 This option causes the global tree of anonymous and private mapping
518 regions to be regularly checked for invalid topology.
519
520config DEBUG_MEMORY_INIT
521 bool "Debug memory initialisation" if EXPERT
522 default !EXPERT
523 help
524 Enable this for additional checks during memory initialisation.
525 The sanity checks verify aspects of the VM such as the memory model
526 and other information provided by the architecture. Verbose
527 information will be printed at KERN_DEBUG loglevel depending
528 on the mminit_loglevel= command-line option.
529
530 If unsure, say Y
531
532config MEMORY_NOTIFIER_ERROR_INJECT
533 tristate "Memory hotplug notifier error injection module"
534 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
535 help
536 This option provides the ability to inject artificial errors to
537 memory hotplug notifier chain callbacks. It is controlled through
538 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
539
540 If the notifier call chain should be failed with some events
541 notified, write the error code to "actions/<notifier event>/error".
542
543 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
544
545 # cd /sys/kernel/debug/notifier-error-inject/memory
546 # echo -12 > actions/MEM_GOING_OFFLINE/error
547 # echo offline > /sys/devices/system/memory/memoryXXX/state
548 bash: echo: write error: Cannot allocate memory
549
550 To compile this code as a module, choose M here: the module will
551 be called memory-notifier-error-inject.
552
553 If unsure, say N.
554
555config DEBUG_PER_CPU_MAPS
556 bool "Debug access to per_cpu maps"
557 depends on DEBUG_KERNEL
558 depends on SMP
559 help
560 Say Y to verify that the per_cpu map being accessed has
561 been set up. This adds a fair amount of code to kernel memory
562 and decreases performance.
563
564 Say N if unsure.
565
566config DEBUG_HIGHMEM
567 bool "Highmem debugging"
568 depends on DEBUG_KERNEL && HIGHMEM
569 help
570 This options enables addition error checking for high memory systems.
571 Disable for production systems.
572
573config HAVE_DEBUG_STACKOVERFLOW
574 bool
575
576config DEBUG_STACKOVERFLOW
577 bool "Check for stack overflows"
578 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
579 ---help---
580 Say Y here if you want to check for overflows of kernel, IRQ
581 and exception stacks (if your archicture uses them). This
582 option will show detailed messages if free stack space drops
583 below a certain limit.
584
585 These kinds of bugs usually occur when call-chains in the
586 kernel get too deep, especially when interrupts are
587 involved.
588
589 Use this in cases where you see apparently random memory
590 corruption, especially if it appears in 'struct thread_info'
591
592 If in doubt, say "N".
593
594source "lib/Kconfig.kmemcheck"
595
596endmenu # "Memory Debugging"
597
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598config DEBUG_SHIRQ
599 bool "Debug shared IRQ handlers"
Martin Schwidefsky0244ad02013-08-30 09:39:53 +0200600 depends on DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 help
602 Enable this to generate a spurious interrupt as soon as a shared
603 interrupt handler is registered, and just before one is deregistered.
604 Drivers ought to be able to handle interrupts coming in at those
605 points; some don't and need to be caught.
606
Dave Hansen92aef8fb2013-07-01 13:04:50 -0700607menu "Debug Lockups and Hangs"
608
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609config LOCKUP_DETECTOR
610 bool "Detect Hard and Soft Lockups"
611 depends on DEBUG_KERNEL && !S390
612 help
613 Say Y here to enable the kernel to act as a watchdog to detect
614 hard and soft lockups.
615
616 Softlockups are bugs that cause the kernel to loop in kernel
617 mode for more than 20 seconds, without giving other tasks a
618 chance to run. The current stack trace is displayed upon
619 detection and the system will stay locked up.
620
621 Hardlockups are bugs that cause the CPU to loop in kernel mode
622 for more than 10 seconds, without letting other interrupts have a
623 chance to run. The current stack trace is displayed upon detection
624 and the system will stay locked up.
625
626 The overhead should be minimal. A periodic hrtimer runs to
627 generate interrupts and kick the watchdog task every 4 seconds.
628 An NMI is generated every 10 seconds or so to check for hardlockups.
629
630 The frequency of hrtimer and NMI events and the soft and hard lockup
631 thresholds can be controlled through the sysctl watchdog_thresh.
632
633config HARDLOCKUP_DETECTOR
634 def_bool y
635 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
636 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
637
638config BOOTPARAM_HARDLOCKUP_PANIC
639 bool "Panic (Reboot) On Hard Lockups"
640 depends on HARDLOCKUP_DETECTOR
641 help
642 Say Y here to enable the kernel to panic on "hard lockups",
643 which are bugs that cause the kernel to loop in kernel
644 mode with interrupts disabled for more than 10 seconds (configurable
645 using the watchdog_thresh sysctl).
646
647 Say N if unsure.
648
649config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
650 int
651 depends on HARDLOCKUP_DETECTOR
652 range 0 1
653 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
654 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
655
656config BOOTPARAM_SOFTLOCKUP_PANIC
657 bool "Panic (Reboot) On Soft Lockups"
658 depends on LOCKUP_DETECTOR
659 help
660 Say Y here to enable the kernel to panic on "soft lockups",
661 which are bugs that cause the kernel to loop in kernel
662 mode for more than 20 seconds (configurable using the watchdog_thresh
663 sysctl), without giving other tasks a chance to run.
664
665 The panic can be used in combination with panic_timeout,
666 to cause the system to reboot automatically after a
667 lockup has been detected. This feature is useful for
668 high-availability systems that have uptime guarantees and
669 where a lockup must be resolved ASAP.
670
Ingo Molnar8637c092006-07-03 00:24:38 -0700671 Say N if unsure.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672
673config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
674 int
675 depends on LOCKUP_DETECTOR
676 range 0 1
677 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
678 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700679
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680config DETECT_HUNG_TASK
681 bool "Detect Hung Tasks"
682 depends on DEBUG_KERNEL
683 default LOCKUP_DETECTOR
684 help
685 Say Y here to enable the kernel to detect "hung tasks",
686 which are bugs that cause the task to be stuck in
687 uninterruptible "D" state indefinitiley.
688
689 When a hung task is detected, the kernel will print the
690 current stack trace (which you should report), but the
691 task will stay in uninterruptible state. If lockdep is
692 enabled then all held locks will also be reported. This
693 feature has negligible overhead.
694
695config DEFAULT_HUNG_TASK_TIMEOUT
696 int "Default timeout for hung task detection (in seconds)"
697 depends on DETECT_HUNG_TASK
698 default 120
699 help
700 This option controls the default timeout (in seconds) used
701 to determine when a task has become non-responsive and should
702 be considered hung.
703
704 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
705 sysctl or by writing a value to
706 /proc/sys/kernel/hung_task_timeout_secs.
707
Ingo Molnar408894e2006-01-09 15:59:20 -0800708 A timeout of 0 disables the check. The default is two minutes.
709 Keeping the default should be fine in most cases.
710
711config BOOTPARAM_HUNG_TASK_PANIC
712 bool "Panic (Reboot) On Hung Tasks"
713 depends on DETECT_HUNG_TASK
Tim Chencca57c52006-04-18 22:21:47 -0700714 help
Ingo Molnar408894e2006-01-09 15:59:20 -0800715 Say Y here to enable the kernel to panic on "hung tasks",
716 which are bugs that cause the kernel to leave a task stuck
717 in uninterruptible "D" state.
718
719 The panic can be used in combination with panic_timeout,
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700720 to cause the system to reboot automatically after a
721 hung task has been detected. This feature is useful for
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700722 high-availability systems that have uptime guarantees and
723 where a hung tasks must be resolved ASAP.
724
725 Say N if unsure.
726
727config BOOTPARAM_HUNG_TASK_PANIC_VALUE
728 int
729 depends on DETECT_HUNG_TASK
730 range 0 1
Hugh Dickins048c8bc2006-11-01 05:44:54 +1100731 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732 default 1 if BOOTPARAM_HUNG_TASK_PANIC
733
Dave Hansen92aef8fb2013-07-01 13:04:50 -0700734endmenu # "Debug lockups and hangs"
735
736config PANIC_ON_OOPS
737 bool "Panic on Oops"
738 help
739 Say Y here to enable the kernel to panic when it oopses. This
740 has the same effect as setting oops=panic on the kernel command
741 line.
742
743 This feature is useful to ensure that the kernel does not do
744 anything erroneous after an oops which could result in data
745 corruption or other issues.
746
747 Say N if unsure.
748
749config PANIC_ON_OOPS_VALUE
750 int
751 range 0 1
752 default 0 if !PANIC_ON_OOPS
753 default 1 if PANIC_ON_OOPS
754
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755config SCHED_DEBUG
756 bool "Collect scheduler debugging info"
757 depends on DEBUG_KERNEL && PROC_FS
758 default y
759 help
760 If you say Y here, the /proc/sched_debug file will be provided
761 that can help debug the scheduler. The runtime overhead of this
762 option is minimal.
763
764config SCHEDSTATS
765 bool "Collect scheduler statistics"
766 depends on DEBUG_KERNEL && PROC_FS
767 help
768 If you say Y here, additional code will be inserted into the
769 scheduler and related routines to collect statistics about
770 scheduler behavior and provide them in /proc/schedstat. These
771 stats may be useful for both tuning and debugging the scheduler
772 If you aren't debugging the scheduler or trying to tune a specific
773 application, you can say N to avoid the very slight overhead
774 this adds.
775
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700776config TIMER_STATS
777 bool "Collect kernel timers statistics"
778 depends on DEBUG_KERNEL && PROC_FS
779 help
780 If you say Y here, additional code will be inserted into the
781 timer routines to collect statistics about kernel timers being
782 reprogrammed. The statistics can be read from /proc/timer_stats.
783 The statistics collection is started by writing 1 to /proc/timer_stats,
784 writing 0 stops it. This feature is useful to collect information
785 about timer usage patterns in kernel and userspace. This feature
786 is lightweight if enabled in the kernel config but not activated
787 (it defaults to deactivated on bootup and will only be activated
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700788 if some application like powertop activates it explicitly).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790config DEBUG_PREEMPT
791 bool "Debug preemptible kernel"
Kumar Gala01deab92009-10-16 07:21:39 +0000792 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 default y
794 help
795 If you say Y here then the kernel will use a debug variant of the
796 commonly used smp_processor_id() function and will print warnings
797 if kernel code uses it in a preemption-unsafe way. Also, the kernel
798 will detect preemption count underflows.
799
Dave Hansen9eade162013-07-01 13:04:47 -0700800menu "Lock Debugging (spinlocks, mutexes, etc...)"
801
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802config DEBUG_RT_MUTEXES
803 bool "RT Mutex debugging, deadlock detection"
804 depends on DEBUG_KERNEL && RT_MUTEXES
805 help
806 This allows rt mutex semantics violations and rt mutex related
807 deadlocks (lockups) to be detected and reported automatically.
808
809config DEBUG_PI_LIST
810 bool
811 default y
812 depends on DEBUG_RT_MUTEXES
813
814config RT_MUTEX_TESTER
815 bool "Built-in scriptable tester for rt-mutexes"
816 depends on DEBUG_KERNEL && RT_MUTEXES
817 help
818 This option enables a rt-mutex tester.
819
820config DEBUG_SPINLOCK
821 bool "Spinlock and rw-lock debugging: basic checks"
822 depends on DEBUG_KERNEL
Raghavendra K Te335e3e2012-03-22 15:25:08 +0530823 select UNINLINE_SPIN_UNLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 help
825 Say Y here and build SMP to catch missing spinlock initialization
826 and certain other kinds of spinlock errors commonly made. This is
827 best used in conjunction with the NMI watchdog so that spinlock
828 deadlocks are also debuggable.
829
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700830config DEBUG_MUTEXES
831 bool "Mutex debugging: basic checks"
832 depends on DEBUG_KERNEL
833 help
834 This feature allows mutex semantics violations to be detected and
835 reported.
836
Daniel Vetter23010022013-06-20 13:31:17 +0200837config DEBUG_WW_MUTEX_SLOWPATH
838 bool "Wait/wound mutex debugging: Slowpath testing"
839 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
840 select DEBUG_LOCK_ALLOC
841 select DEBUG_SPINLOCK
842 select DEBUG_MUTEXES
843 help
844 This feature enables slowpath testing for w/w mutex users by
845 injecting additional -EDEADLK wound/backoff cases. Together with
846 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
847 will test all possible w/w mutex interface abuse with the
848 exception of simply not acquiring all the required locks.
849
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700850config DEBUG_LOCK_ALLOC
851 bool "Lock debugging: detect incorrect freeing of live locks"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700852 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700853 select DEBUG_SPINLOCK
854 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700855 select LOCKDEP
856 help
857 This feature will check whether any held lock (spinlock, rwlock,
858 mutex or rwsem) is incorrectly freed by the kernel, via any of the
859 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
860 vfree(), etc.), whether a live lock is incorrectly reinitialized via
861 spin_lock_init()/mutex_init()/etc., or whether there is any lock
862 held during task exit.
863
864config PROVE_LOCKING
865 bool "Lock debugging: prove locking correctness"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700866 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700867 select LOCKDEP
868 select DEBUG_SPINLOCK
869 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700870 select DEBUG_LOCK_ALLOC
Steven Rostedt46b93b72010-08-31 16:35:20 -0400871 select TRACE_IRQFLAGS
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700872 default n
873 help
874 This feature enables the kernel to prove that all locking
875 that occurs in the kernel runtime is mathematically
876 correct: that under no circumstance could an arbitrary (and
877 not yet triggered) combination of observed locking
878 sequences (on an arbitrary number of CPUs, running an
879 arbitrary number of tasks and interrupt contexts) cause a
880 deadlock.
881
882 In short, this feature enables the kernel to report locking
883 related deadlocks before they actually occur.
884
885 The proof does not depend on how hard and complex a
886 deadlock scenario would be to trigger: how many
887 participant CPUs, tasks and irq-contexts would be needed
888 for it to trigger. The proof also does not depend on
889 timing: if a race and a resulting deadlock is possible
890 theoretically (no matter how unlikely the race scenario
891 is), it will be proven so and will immediately be
892 reported by the kernel (once the event is observed that
893 makes the deadlock theoretically possible).
894
895 If a deadlock is impossible (i.e. the locking rules, as
896 observed by the kernel, are mathematically correct), the
897 kernel reports nothing.
898
899 NOTE: this feature can also be enabled for rwlocks, mutexes
900 and rwsems - in which case all dependencies between these
901 different locking variants are observed and mapped too, and
902 the proof of observed correctness is also maintained for an
903 arbitrary combination of these separate locking variants.
904
905 For more details, see Documentation/lockdep-design.txt.
906
907config LOCKDEP
908 bool
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700909 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700910 select STACKTRACE
Vineet Guptacc80ae32013-08-27 13:52:51 +0530911 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700912 select KALLSYMS
913 select KALLSYMS_ALL
914
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700915config LOCK_STAT
Danny ter Haarfdfb8702007-09-24 21:24:43 -0700916 bool "Lock usage statistics"
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700917 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
918 select LOCKDEP
919 select DEBUG_SPINLOCK
920 select DEBUG_MUTEXES
921 select DEBUG_LOCK_ALLOC
922 default n
923 help
924 This feature enables tracking lock contention points
925
Peter Zijlstraa560aa42007-10-07 00:24:33 -0700926 For more details, see Documentation/lockstat.txt
927
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +0100928 This also enables lock events required by "perf lock",
929 subcommand of perf.
930 If you want to use "perf lock", you also need to turn on
931 CONFIG_EVENT_TRACING.
Hitoshi Mitake84c6f882010-02-04 16:08:15 +0900932
933 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +0100934 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
Hitoshi Mitake84c6f882010-02-04 16:08:15 +0900935
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700936config DEBUG_LOCKDEP
937 bool "Lock dependency engine debugging"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700938 depends on DEBUG_KERNEL && LOCKDEP
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700939 help
940 If you say Y here, the lock dependency engine will do
941 additional runtime checks to debug itself, at the price
942 of more runtime overhead.
943
Frederic Weisbeckerd902db12011-06-08 19:31:56 +0200944config DEBUG_ATOMIC_SLEEP
945 bool "Sleep inside atomic section checking"
Frederic Weisbeckere8f7c702011-06-08 01:51:02 +0200946 select PREEMPT_COUNT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947 depends on DEBUG_KERNEL
948 help
949 If you say Y here, various routines which may sleep will become very
Frederic Weisbeckerd902db12011-06-08 19:31:56 +0200950 noisy if they are called inside atomic sections: when a spinlock is
951 held, inside an rcu read side critical section, inside preempt disabled
952 sections, inside an interrupt, etc...
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700954config DEBUG_LOCKING_API_SELFTESTS
955 bool "Locking API boot-time self-tests"
956 depends on DEBUG_KERNEL
957 help
958 Say Y here if you want the kernel to run a short self-test during
959 bootup. The self-test checks whether common types of locking bugs
960 are detected by debugging mechanisms or not. (if you disable
961 lock debugging then those bugs wont be detected of course.)
962 The following locking APIs are covered: spinlocks, rwlocks,
963 mutexes and rwsems.
964
Dave Hansen9eade162013-07-01 13:04:47 -0700965endmenu # lock debugging
966
967config TRACE_IRQFLAGS
968 bool
969 help
970 Enables hooks to interrupt enabling and disabling for
971 either tracing or lock debugging.
972
Ingo Molnar8637c092006-07-03 00:24:38 -0700973config STACKTRACE
974 bool
975 depends on STACKTRACE_SUPPORT
976
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977config DEBUG_KOBJECT
978 bool "kobject debugging"
979 depends on DEBUG_KERNEL
980 help
981 If you say Y here, some extra kobject debugging messages will be sent
982 to the syslog.
983
Russell Kingc817a672013-06-27 15:06:14 +0100984config DEBUG_KOBJECT_RELEASE
985 bool "kobject release debugging"
986 depends on DEBUG_KERNEL
987 help
988 kobjects are reference counted objects. This means that their
989 last reference count put is not predictable, and the kobject can
990 live on past the point at which a driver decides to drop it's
991 initial reference to the kobject gained on allocation. An
992 example of this would be a struct device which has just been
993 unregistered.
994
995 However, some buggy drivers assume that after such an operation,
996 the memory backing the kobject can be immediately freed. This
997 goes completely against the principles of a refcounted object.
998
999 If you say Y here, the kernel will delay the release of kobjects
1000 on the last reference count to improve the visibility of this
1001 kind of kobject release bug.
1002
Catalin Marinas9b2a60c2012-10-08 16:28:13 -07001003config HAVE_DEBUG_BUGVERBOSE
1004 bool
1005
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006config DEBUG_BUGVERBOSE
David Rientjes6a108a12011-01-20 14:44:16 -08001007 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
Catalin Marinas9b2a60c2012-10-08 16:28:13 -07001008 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
Alexey Dobriyan8420e7e2009-12-14 18:00:25 -08001009 default y
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010 help
1011 Say Y here to make BUG() panics output the file name and line number
1012 of the BUG call as well as the EIP and oops trace. This aids
1013 debugging but costs about 70-100K of memory.
1014
Dave Hansenad775f52008-02-15 14:38:01 -08001015config DEBUG_WRITECOUNT
1016 bool "Debug filesystem writers count"
1017 depends on DEBUG_KERNEL
1018 help
1019 Enable this to catch wrong use of the writers count in struct
1020 vfsmount. This will increase the size of each file struct by
1021 32 bits.
1022
1023 If unsure, say N.
1024
Dave Jones199a9af2006-09-29 01:59:00 -07001025config DEBUG_LIST
1026 bool "Debug linked list manipulation"
1027 depends on DEBUG_KERNEL
1028 help
1029 Enable this to turn on extended checks in the linked-list
1030 walking routines.
1031
1032 If unsure, say N.
1033
Jens Axboed6ec0842007-10-22 20:01:06 +02001034config DEBUG_SG
1035 bool "Debug SG table operations"
1036 depends on DEBUG_KERNEL
1037 help
1038 Enable this to turn on checks on scatter-gather tables. This can
1039 help find problems with drivers that do not properly initialize
1040 their sg tables.
1041
1042 If unsure, say N.
1043
Arjan van de Ven1b2439d2008-08-15 15:29:38 -07001044config DEBUG_NOTIFIERS
1045 bool "Debug notifier call chains"
1046 depends on DEBUG_KERNEL
1047 help
1048 Enable this to turn on sanity checking for notifier call chains.
1049 This is most useful for kernel developers to make sure that
1050 modules properly unregister themselves from notifier chains.
1051 This is a relatively cheap check but if you care about maximum
1052 performance, say N.
1053
David Howellse0e81732009-09-02 09:13:40 +01001054config DEBUG_CREDENTIALS
1055 bool "Debug credential management"
1056 depends on DEBUG_KERNEL
1057 help
1058 Enable this to turn on some debug checking for credential
1059 management. The additional code keeps track of the number of
1060 pointers from task_structs to any given cred struct, and checks to
1061 see that this number never exceeds the usage count of the cred
1062 struct.
1063
1064 Furthermore, if SELinux is enabled, this also checks that the
1065 security pointer in the cred struct is never seen to be invalid.
1066
1067 If unsure, say N.
1068
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001069menu "RCU Debugging"
1070
1071config PROVE_RCU
1072 bool "RCU debugging: prove RCU correctness"
1073 depends on PROVE_LOCKING
1074 default n
1075 help
1076 This feature enables lockdep extensions that check for correct
1077 use of RCU APIs. This is currently under development. Say Y
1078 if you want to debug RCU usage or help work on the PROVE_RCU
1079 feature.
1080
1081 Say N if you are unsure.
1082
1083config PROVE_RCU_REPEATEDLY
1084 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1085 depends on PROVE_RCU
1086 default n
1087 help
1088 By itself, PROVE_RCU will disable checking upon issuing the
1089 first warning (or "splat"). This feature prevents such
1090 disabling, allowing multiple RCU-lockdep warnings to be printed
1091 on a single reboot.
1092
1093 Say Y to allow multiple RCU-lockdep warnings per boot.
1094
1095 Say N if you are unsure.
1096
1097config PROVE_RCU_DELAY
1098 bool "RCU debugging: preemptible RCU race provocation"
1099 depends on DEBUG_KERNEL && PREEMPT_RCU
1100 default n
1101 help
1102 There is a class of races that involve an unlikely preemption
1103 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
1104 been set to INT_MIN. This feature inserts a delay at that
1105 point to increase the probability of these races.
1106
1107 Say Y to increase probability of preemption of __rcu_read_unlock().
1108
1109 Say N if you are unsure.
1110
1111config SPARSE_RCU_POINTER
1112 bool "RCU debugging: sparse-based checks for pointer usage"
1113 default n
1114 help
1115 This feature enables the __rcu sparse annotation for
1116 RCU-protected pointers. This annotation will cause sparse
1117 to flag any non-RCU used of annotated pointers. This can be
1118 helpful when debugging RCU usage. Please note that this feature
1119 is not intended to enforce code cleanliness; it is instead merely
1120 a debugging aid.
1121
1122 Say Y to make sparse flag questionable use of RCU-protected pointers
1123
1124 Say N if you are unsure.
1125
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001126config RCU_TORTURE_TEST
1127 tristate "torture tests for RCU"
1128 depends on DEBUG_KERNEL
1129 default n
1130 help
1131 This option provides a kernel module that runs torture tests
1132 on the RCU infrastructure. The kernel module may be built
1133 after the fact on the running kernel to be tested, if desired.
1134
Paul E. McKenney31a72bc2008-06-18 09:26:49 -07001135 Say Y here if you want RCU torture tests to be built into
1136 the kernel.
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001137 Say M if you want the RCU torture tests to build as a module.
1138 Say N if you are unsure.
Ankita Garg8bb31b92006-10-02 02:17:36 -07001139
Paul E. McKenney31a72bc2008-06-18 09:26:49 -07001140config RCU_TORTURE_TEST_RUNNABLE
1141 bool "torture tests for RCU runnable by default"
1142 depends on RCU_TORTURE_TEST = y
1143 default n
1144 help
1145 This option provides a way to build the RCU torture tests
1146 directly into the kernel without them starting up at boot
1147 time. You can use /proc/sys/kernel/rcutorture_runnable
1148 to manually override this setting. This /proc file is
1149 available only when the RCU torture tests have been built
1150 into the kernel.
1151
1152 Say Y here if you want the RCU torture tests to start during
1153 boot (you probably don't).
1154 Say N here if you want the RCU torture tests to start only
1155 after being manually enabled via /proc.
1156
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001157config RCU_CPU_STALL_TIMEOUT
1158 int "RCU CPU stall timeout in seconds"
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -07001159 depends on RCU_STALL_COMMON
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001160 range 3 300
Paul E. McKenneyc8960542012-10-25 17:59:23 -07001161 default 21
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001162 help
1163 If a given RCU grace period extends more than the specified
1164 number of seconds, a CPU stall warning is printed. If the
1165 RCU grace period persists, additional CPU stall warnings are
1166 printed at more widely spaced intervals.
1167
Paul E. McKenney1ed509a2010-02-22 17:05:05 -08001168config RCU_CPU_STALL_VERBOSE
1169 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
Paul E. McKenneya00e0d712011-02-08 17:14:39 -08001170 depends on TREE_PREEMPT_RCU
Paul E. McKenney55ec9362010-04-13 12:22:33 -07001171 default y
Paul E. McKenney1ed509a2010-02-22 17:05:05 -08001172 help
1173 This option causes RCU to printk detailed per-task information
1174 for any tasks that are stalling the current RCU grace period.
Paul E. McKenney64db4cf2008-12-18 21:55:32 +01001175
1176 Say N if you are unsure.
1177
Paul E. McKenney1ed509a2010-02-22 17:05:05 -08001178 Say Y if you want to enable such checks.
1179
Paul E. McKenneya858af22012-01-16 13:29:10 -08001180config RCU_CPU_STALL_INFO
1181 bool "Print additional diagnostics on RCU CPU stall"
1182 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1183 default n
1184 help
1185 For each stalled CPU that is aware of the current RCU grace
1186 period, print out additional per-CPU diagnostic information
1187 regarding scheduling-clock ticks, idle state, and,
1188 for RCU_FAST_NO_HZ kernels, idle-entry state.
1189
1190 Say N if you are unsure.
1191
1192 Say Y if you want to enable such diagnostics.
1193
Paul E. McKenney5c8806a2012-01-06 15:10:44 -08001194config RCU_TRACE
1195 bool "Enable tracing for RCU"
1196 depends on DEBUG_KERNEL
Paul E. McKenney52494532012-11-14 16:26:40 -08001197 select TRACE_CLOCK
Paul E. McKenney5c8806a2012-01-06 15:10:44 -08001198 help
1199 This option provides tracing in RCU which presents stats
1200 in debugfs for debugging RCU implementation.
1201
1202 Say Y here if you want to enable RCU tracing
1203 Say N if you are unsure.
1204
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001205endmenu # "RCU Debugging"
1206
Tejun Heo870d6652008-08-25 19:47:25 +09001207config DEBUG_BLOCK_EXT_DEVT
1208 bool "Force extended block device numbers and spread them"
1209 depends on DEBUG_KERNEL
1210 depends on BLOCK
Jens Axboe759f8ca2008-08-29 09:06:29 +02001211 default n
Tejun Heo870d6652008-08-25 19:47:25 +09001212 help
Tejun Heo0e11e342008-10-13 10:46:01 +02001213 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1214 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1215 YOU ARE DOING. Distros, please enable this and fix whatever
1216 is broken.
1217
Tejun Heo870d6652008-08-25 19:47:25 +09001218 Conventionally, block device numbers are allocated from
1219 predetermined contiguous area. However, extended block area
1220 may introduce non-contiguous block device numbers. This
1221 option forces most block device numbers to be allocated from
1222 the extended space and spreads them to discover kernel or
1223 userland code paths which assume predetermined contiguous
1224 device number allocation.
1225
Tejun Heo55dc7db2008-09-01 13:44:35 +02001226 Note that turning on this debug option shuffles all the
1227 device numbers for all IDE and SCSI devices including libata
1228 ones, so root partition specified using device number
1229 directly (via rdev or root=MAJ:MIN) won't work anymore.
1230 Textual device names (root=/dev/sdXn) will continue to work.
1231
Tejun Heo870d6652008-08-25 19:47:25 +09001232 Say N if you are unsure.
1233
Akinobu Mita8d438282012-07-30 14:43:02 -07001234config NOTIFIER_ERROR_INJECTION
1235 tristate "Notifier error injection"
1236 depends on DEBUG_KERNEL
1237 select DEBUG_FS
1238 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001239 This option provides the ability to inject artificial errors to
Akinobu Mita8d438282012-07-30 14:43:02 -07001240 specified notifier chain callbacks. It is useful to test the error
1241 handling of notifier call chain failures.
1242
1243 Say N if unsure.
1244
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001245config CPU_NOTIFIER_ERROR_INJECT
1246 tristate "CPU notifier error injection module"
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001247 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001248 help
1249 This option provides a kernel module that can be used to test
Masanari Iidae41e85c2012-11-30 16:44:39 +09001250 the error handling of the cpu notifiers by injecting artificial
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001251 errors to CPU notifier chain callbacks. It is controlled through
1252 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1253
1254 If the notifier call chain should be failed with some events
1255 notified, write the error code to "actions/<notifier event>/error".
1256
1257 Example: Inject CPU offline error (-1 == -EPERM)
1258
1259 # cd /sys/kernel/debug/notifier-error-inject/cpu
1260 # echo -1 > actions/CPU_DOWN_PREPARE/error
1261 # echo 0 > /sys/devices/system/cpu/cpu1/online
1262 bash: echo: write error: Operation not permitted
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001263
1264 To compile this code as a module, choose M here: the module will
1265 be called cpu-notifier-error-inject.
1266
1267 If unsure, say N.
1268
Akinobu Mita048b9c32012-07-30 14:43:07 -07001269config PM_NOTIFIER_ERROR_INJECT
1270 tristate "PM notifier error injection module"
1271 depends on PM && NOTIFIER_ERROR_INJECTION
1272 default m if PM_DEBUG
1273 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001274 This option provides the ability to inject artificial errors to
Akinobu Mita048b9c32012-07-30 14:43:07 -07001275 PM notifier chain callbacks. It is controlled through debugfs
1276 interface /sys/kernel/debug/notifier-error-inject/pm
1277
1278 If the notifier call chain should be failed with some events
1279 notified, write the error code to "actions/<notifier event>/error".
1280
1281 Example: Inject PM suspend error (-12 = -ENOMEM)
1282
1283 # cd /sys/kernel/debug/notifier-error-inject/pm/
1284 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1285 # echo mem > /sys/power/state
1286 bash: echo: write error: Cannot allocate memory
1287
1288 To compile this code as a module, choose M here: the module will
1289 be called pm-notifier-error-inject.
1290
1291 If unsure, say N.
1292
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001293config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1294 tristate "OF reconfig notifier error injection module"
1295 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001296 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001297 This option provides the ability to inject artificial errors to
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001298 OF reconfig notifier chain callbacks. It is controlled
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001299 through debugfs interface under
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001300 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001301
1302 If the notifier call chain should be failed with some events
1303 notified, write the error code to "actions/<notifier event>/error".
1304
1305 To compile this code as a module, choose M here: the module will
Akinobu Mitae12a95f2013-04-30 15:28:49 -07001306 be called of-reconfig-notifier-error-inject.
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001307
1308 If unsure, say N.
1309
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001310config FAULT_INJECTION
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001311 bool "Fault-injection framework"
1312 depends on DEBUG_KERNEL
Akinobu Mita329409a2006-12-08 02:39:48 -08001313 help
1314 Provide fault-injection framework.
1315 For more details, see Documentation/fault-injection/.
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001316
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001317config FAILSLAB
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001318 bool "Fault-injection capability for kmalloc"
1319 depends on FAULT_INJECTION
Akinobu Mita773ff602008-12-23 19:37:01 +09001320 depends on SLAB || SLUB
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001321 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001322 Provide fault-injection capability for kmalloc.
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001323
Akinobu Mita933e3122006-12-08 02:39:45 -08001324config FAIL_PAGE_ALLOC
1325 bool "Fault-injection capabilitiy for alloc_pages()"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001326 depends on FAULT_INJECTION
Akinobu Mita933e3122006-12-08 02:39:45 -08001327 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001328 Provide fault-injection capability for alloc_pages().
Akinobu Mita933e3122006-12-08 02:39:45 -08001329
Akinobu Mitac17bb492006-12-08 02:39:46 -08001330config FAIL_MAKE_REQUEST
Dave Jones86327d12006-12-12 20:16:36 +01001331 bool "Fault-injection capability for disk IO"
Jens Axboe581d4e22008-09-14 05:56:33 -07001332 depends on FAULT_INJECTION && BLOCK
Akinobu Mitac17bb492006-12-08 02:39:46 -08001333 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001334 Provide fault-injection capability for disk IO.
Akinobu Mitac17bb492006-12-08 02:39:46 -08001335
Jens Axboe581d4e22008-09-14 05:56:33 -07001336config FAIL_IO_TIMEOUT
Takuya Yoshikawaf4d014392010-07-21 16:05:53 +09001337 bool "Fault-injection capability for faking disk interrupts"
Jens Axboe581d4e22008-09-14 05:56:33 -07001338 depends on FAULT_INJECTION && BLOCK
1339 help
1340 Provide fault-injection capability on end IO handling. This
1341 will make the block layer "forget" an interrupt as configured,
1342 thus exercising the error handling.
1343
1344 Only works with drivers that use the generic timeout handling,
1345 for others it wont do anything.
1346
Per Forlin1b676f72011-08-19 14:52:37 +02001347config FAIL_MMC_REQUEST
1348 bool "Fault-injection capability for MMC IO"
1349 select DEBUG_FS
1350 depends on FAULT_INJECTION && MMC
1351 help
1352 Provide fault-injection capability for MMC IO.
1353 This will make the mmc core return data errors. This is
1354 useful to test the error handling in the mmc block device
1355 and to test how the mmc host driver handles retries from
1356 the block device.
1357
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001358config FAULT_INJECTION_DEBUG_FS
1359 bool "Debugfs entries for fault-injection capabilities"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001360 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001361 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001362 Enable configuration of fault-injection capabilities via debugfs.
Akinobu Mita1df49002007-02-20 13:57:56 -08001363
1364config FAULT_INJECTION_STACKTRACE_FILTER
1365 bool "stacktrace filter for fault-injection capabilities"
1366 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
Akinobu Mita6d690dc2007-05-12 10:36:53 -07001367 depends on !X86_64
Akinobu Mita1df49002007-02-20 13:57:56 -08001368 select STACKTRACE
Vineet Guptacc80ae32013-08-27 13:52:51 +05301369 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
Akinobu Mita1df49002007-02-20 13:57:56 -08001370 help
1371 Provide stacktrace filter for fault-injection capabilities
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001372
Arjan van de Ven97455122008-01-25 21:08:34 +01001373config LATENCYTOP
1374 bool "Latency measuring infrastructure"
Randy Dunlap625fdca2010-08-12 12:31:21 -07001375 depends on HAVE_LATENCYTOP_SUPPORT
1376 depends on DEBUG_KERNEL
1377 depends on STACKTRACE_SUPPORT
1378 depends on PROC_FS
Vineet Guptacc80ae32013-08-27 13:52:51 +05301379 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
Arjan van de Ven97455122008-01-25 21:08:34 +01001380 select KALLSYMS
1381 select KALLSYMS_ALL
1382 select STACKTRACE
1383 select SCHEDSTATS
1384 select SCHED_DEBUG
Arjan van de Ven97455122008-01-25 21:08:34 +01001385 help
1386 Enable this option if you want to use the LatencyTOP tool
1387 to find out which userspace is blocking on what kernel operations.
1388
Stephen Boyd446f24d2013-04-30 15:28:42 -07001389config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1390 bool
1391
1392config DEBUG_STRICT_USER_COPY_CHECKS
1393 bool "Strict user copy size checks"
1394 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1395 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1396 help
1397 Enabling this option turns a certain set of sanity checks for user
1398 copy operations into compile time failures.
1399
1400 The copy_from_user() etc checks are there to help test if there
1401 are sufficient security checks on the length argument of
1402 the copy operation, by having gcc prove that the argument is
1403 within bounds.
1404
1405 If unsure, say N.
1406
Arnaldo Carvalho de Melo16444a82008-05-12 21:20:42 +02001407source kernel/trace/Kconfig
1408
Dave Hansen881c5142013-07-01 13:04:44 -07001409menu "Runtime Testing"
1410
1411config LKDTM
1412 tristate "Linux Kernel Dump Test Tool Module"
1413 depends on DEBUG_FS
1414 depends on BLOCK
1415 default n
1416 help
1417 This module enables testing of the different dumping mechanisms by
1418 inducing system failures at predefined crash points.
1419 If you don't need it: say N
1420 Choose M here to compile this code as a module. The module will be
1421 called lkdtm.
1422
1423 Documentation on how to use the module can be found in
1424 Documentation/fault-injection/provoke-crashes.txt
1425
1426config TEST_LIST_SORT
1427 bool "Linked list sorting test"
1428 depends on DEBUG_KERNEL
1429 help
1430 Enable this to turn on 'list_sort()' function test. This test is
1431 executed only once during system boot, so affects only boot time.
1432
1433 If unsure, say N.
1434
1435config KPROBES_SANITY_TEST
1436 bool "Kprobes sanity tests"
1437 depends on DEBUG_KERNEL
1438 depends on KPROBES
1439 default n
1440 help
1441 This option provides for testing basic kprobes functionality on
1442 boot. A sample kprobe, jprobe and kretprobe are inserted and
1443 verified for functionality.
1444
1445 Say N if you are unsure.
1446
1447config BACKTRACE_SELF_TEST
1448 tristate "Self test for the backtrace code"
1449 depends on DEBUG_KERNEL
1450 default n
1451 help
1452 This option provides a kernel module that can be used to test
1453 the kernel stack backtrace code. This option is not useful
1454 for distributions or general kernels, but only for kernel
1455 developers working on architecture code.
1456
1457 Note that if you want to also test saved backtraces, you will
1458 have to enable STACKTRACE as well.
1459
1460 Say N if you are unsure.
1461
Michel Lespinasse910a7422012-10-08 16:30:39 -07001462config RBTREE_TEST
1463 tristate "Red-Black tree test"
Cody P Schafer7c993e12013-09-11 14:25:19 -07001464 depends on DEBUG_KERNEL
Michel Lespinasse910a7422012-10-08 16:30:39 -07001465 help
1466 A benchmark measuring the performance of the rbtree library.
1467 Also includes rbtree invariant checks.
1468
Michel Lespinassefff3fd82012-10-08 16:31:23 -07001469config INTERVAL_TREE_TEST
1470 tristate "Interval tree test"
1471 depends on m && DEBUG_KERNEL
1472 help
1473 A benchmark measuring the performance of the interval tree library
1474
Dave Hansen881c5142013-07-01 13:04:44 -07001475config ATOMIC64_SELFTEST
1476 bool "Perform an atomic64_t self-test at boot"
1477 help
1478 Enable this option to test the atomic64_t functions at boot.
1479
1480 If unsure, say N.
1481
1482config ASYNC_RAID6_TEST
1483 tristate "Self test for hardware accelerated raid6 recovery"
1484 depends on ASYNC_RAID6_RECOV
1485 select ASYNC_MEMCPY
1486 ---help---
1487 This is a one-shot self test that permutes through the
1488 recovery of all the possible two disk failure scenarios for a
1489 N-disk array. Recovery is performed with the asynchronous
1490 raid6 recovery routines, and will optionally use an offload
1491 engine if one is available.
1492
1493 If unsure, say N.
1494
1495config TEST_STRING_HELPERS
1496 tristate "Test functions located in the string_helpers module at runtime"
1497
1498config TEST_KSTRTOX
1499 tristate "Test kstrto*() family of functions at runtime"
1500
1501endmenu # runtime tests
1502
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001503config PROVIDE_OHCI1394_DMA_INIT
Stefan Richter080de8c2008-02-28 20:54:43 +01001504 bool "Remote debugging over FireWire early on boot"
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001505 depends on PCI && X86
1506 help
1507 If you want to debug problems which hang or crash the kernel early
1508 on boot and the crashing machine has a FireWire port, you can use
1509 this feature to remotely access the memory of the crashed machine
1510 over FireWire. This employs remote DMA as part of the OHCI1394
1511 specification which is now the standard for FireWire controllers.
1512
1513 With remote DMA, you can monitor the printk buffer remotely using
1514 firescope and access all memory below 4GB using fireproxy from gdb.
1515 Even controlling a kernel debugger is possible using remote DMA.
1516
1517 Usage:
1518
1519 If ohci1394_dma=early is used as boot parameter, it will initialize
1520 all OHCI1394 controllers which are found in the PCI config space.
1521
1522 As all changes to the FireWire bus such as enabling and disabling
1523 devices cause a bus reset and thereby disable remote DMA for all
1524 devices, be sure to have the cable plugged and FireWire enabled on
1525 the debugging host before booting the debug target for debugging.
1526
1527 This code (~1k) is freed after boot. By then, the firewire stack
1528 in charge of the OHCI-1394 controllers should be used instead.
1529
1530 See Documentation/debugging-via-ohci1394.txt for more information.
Arjan van de Ven97455122008-01-25 21:08:34 +01001531
Stefan Richter080de8c2008-02-28 20:54:43 +01001532config FIREWIRE_OHCI_REMOTE_DMA
1533 bool "Remote debugging over FireWire with firewire-ohci"
1534 depends on FIREWIRE_OHCI
1535 help
1536 This option lets you use the FireWire bus for remote debugging
1537 with help of the firewire-ohci driver. It enables unfiltered
1538 remote DMA in firewire-ohci.
1539 See Documentation/debugging-via-ohci1394.txt for more information.
1540
1541 If unsure, say N.
1542
Randy Dunlap152de302009-02-20 15:38:47 -08001543config BUILD_DOCSRC
Randy Dunlap3794f3e2008-08-12 15:09:06 -07001544 bool "Build targets in Documentation/ tree"
1545 depends on HEADERS_CHECK
1546 help
1547 This option attempts to build objects from the source files in the
1548 kernel Documentation/ tree.
1549
1550 Say N if you are unsure.
1551
Joerg Roedel5ee00bd2009-01-09 12:14:24 +01001552config DMA_API_DEBUG
1553 bool "Enable debugging of DMA-API usage"
1554 depends on HAVE_DMA_API_DEBUG
1555 help
1556 Enable this option to debug the use of the DMA API by device drivers.
1557 With this option you will be able to detect common bugs in device
1558 drivers like double-freeing of DMA mappings or freeing mappings that
1559 were never allocated.
1560 This option causes a performance degredation. Use only if you want
1561 to debug device drivers. If unsure, say N.
Jason Baron346e15b2008-08-12 16:46:19 -04001562
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001563source "samples/Kconfig"
Jason Wesseldc7d5522008-04-17 20:05:37 +02001564
1565source "lib/Kconfig.kgdb"
Pekka Enberg0a4af3b2009-02-26 21:38:56 +02001566