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604ff0dc 1menu "printk and dmesg options"
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2
3config PRINTK_TIME
4 bool "Show timing information on printks"
d3b8b6e5 5 depends on PRINTK
1da177e4 6 help
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7 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
1da177e4 17
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18config 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
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29config 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
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118menu "Compile-time checks and compiler options"
119
120config DEBUG_INFO
121 bool "Compile the kernel with debug info"
12b13835 122 depends on DEBUG_KERNEL && !COMPILE_TEST
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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
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146config 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
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154config 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.
1da177e4 161
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162config 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
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173config 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
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181config 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
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190config 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
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206config DEBUG_FS
207 bool "Debug Filesystem"
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208 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
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213 For detailed documentation on the debugfs API, see
214 Documentation/DocBook/filesystems.
215
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216 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
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232config DEBUG_SECTION_MISMATCH
233 bool "Enable full Section mismatch analysis"
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234 help
235 The section mismatch analysis checks if there are illegal
236 references from one section to another section.
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237 During linktime or runtime, some sections are dropped;
238 any use of code/data previously in these sections would
91341d4b 239 most likely result in an oops.
e809ab01 240 In the code, functions and variables are annotated with
0db0628d 241 __init,, etc. (see the full list in include/linux/init.h),
d6fbfa4f 242 which results in the code/data being placed in specific sections.
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243 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
91341d4b 249 the analysis would not catch the illegal reference.
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250 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
d6fbfa4f 254 lose valueble information about where the mismatch was
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255 introduced.
256 Running the analysis for each module/built-in.o file
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257 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.
91341d4b 262
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263#
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
f346f4b3 270 help
f346f4b3 271
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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
a304e1b8 279 help
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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)
a304e1b8 283
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284config DEBUG_FORCE_WEAK_PER_CPU
285 bool "Force weak per-cpu definitions"
286 depends on DEBUG_KERNEL
8446f1d3 287 help
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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.
8446f1d3 292
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293 1. percpu symbols must be unique whether static or not
294 2. percpu variables can't be defined inside a function
8446f1d3 295
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296 To ensure that generic code follows the above rules, this
297 option forces all percpu variables to be defined as weak.
5f329089 298
6dfc0665 299endmenu # "Compiler options"
8446f1d3 300
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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.
8446f1d3 314
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315config MAGIC_SYSRQ_DEFAULT_ENABLE
316 hex "Enable magic SysRq key functions by default"
317 depends on MAGIC_SYSRQ
318 default 0x1
319 help
320 Specifies which SysRq key functions are enabled by default.
321 This may be set to 1 or 0 to enable or disable them all, or
322 to a bitmask as described in Documentation/sysrq.txt.
323
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324config DEBUG_KERNEL
325 bool "Kernel debugging"
fef2c9bc 326 help
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327 Say Y here if you are developing drivers or trying to debug and
328 identify kernel problems.
fef2c9bc 329
0610c8a8 330menu "Memory Debugging"
fef2c9bc 331
0610c8a8 332source mm/Kconfig.debug
fef2c9bc 333
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334config DEBUG_OBJECTS
335 bool "Debug object operations"
336 depends on DEBUG_KERNEL
9c44bc03 337 help
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338 If you say Y here, additional code will be inserted into the
339 kernel to track the life time of various objects and validate
340 the operations on those objects.
9c44bc03 341
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342config DEBUG_OBJECTS_SELFTEST
343 bool "Debug objects selftest"
344 depends on DEBUG_OBJECTS
345 help
346 This enables the selftest of the object debug code.
9c44bc03 347
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348config DEBUG_OBJECTS_FREE
349 bool "Debug objects in freed memory"
350 depends on DEBUG_OBJECTS
351 help
352 This enables checks whether a k/v free operation frees an area
353 which contains an object which has not been deactivated
354 properly. This can make kmalloc/kfree-intensive workloads
355 much slower.
3ac7fe5a 356
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357config DEBUG_OBJECTS_TIMERS
358 bool "Debug timer objects"
359 depends on DEBUG_OBJECTS
360 help
361 If you say Y here, additional code will be inserted into the
362 timer routines to track the life time of timer objects and
363 validate the timer operations.
364
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365config DEBUG_OBJECTS_WORK
366 bool "Debug work objects"
367 depends on DEBUG_OBJECTS
368 help
369 If you say Y here, additional code will be inserted into the
370 work queue routines to track the life time of work objects and
371 validate the work operations.
372
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373config DEBUG_OBJECTS_RCU_HEAD
374 bool "Debug RCU callbacks objects"
fc2ecf7e 375 depends on DEBUG_OBJECTS
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376 help
377 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
378
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379config DEBUG_OBJECTS_PERCPU_COUNTER
380 bool "Debug percpu counter objects"
381 depends on DEBUG_OBJECTS
382 help
383 If you say Y here, additional code will be inserted into the
384 percpu counter routines to track the life time of percpu counter
385 objects and validate the percpu counter operations.
386
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387config DEBUG_OBJECTS_ENABLE_DEFAULT
388 int "debug_objects bootup default value (0-1)"
389 range 0 1
390 default "1"
391 depends on DEBUG_OBJECTS
392 help
393 Debug objects boot parameter default value
394
1da177e4 395config DEBUG_SLAB
4a2f0acf 396 bool "Debug slab memory allocations"
7d46d9e6 397 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
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398 help
399 Say Y here to have the kernel do limited verification on memory
400 allocation as well as poisoning memory on free to catch use of freed
401 memory. This can make kmalloc/kfree-intensive workloads much slower.
402
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403config DEBUG_SLAB_LEAK
404 bool "Memory leak debugging"
405 depends on DEBUG_SLAB
406
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407config SLUB_DEBUG_ON
408 bool "SLUB debugging on by default"
7d46d9e6 409 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
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410 default n
411 help
412 Boot with debugging on by default. SLUB boots by default with
413 the runtime debug capabilities switched off. Enabling this is
414 equivalent to specifying the "slub_debug" parameter on boot.
415 There is no support for more fine grained debug control like
416 possible with slub_debug=xxx. SLUB debugging may be switched
417 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
418 "slub_debug=-".
419
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420config SLUB_STATS
421 default n
422 bool "Enable SLUB performance statistics"
ab4d5ed5 423 depends on SLUB && SYSFS
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424 help
425 SLUB statistics are useful to debug SLUBs allocation behavior in
426 order find ways to optimize the allocator. This should never be
427 enabled for production use since keeping statistics slows down
428 the allocator by a few percentage points. The slabinfo command
429 supports the determination of the most active slabs to figure
430 out which slabs are relevant to a particular load.
431 Try running: slabinfo -DA
432
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433config HAVE_DEBUG_KMEMLEAK
434 bool
435
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436config DEBUG_KMEMLEAK
437 bool "Kernel memory leak detector"
525c1f92 438 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
79e0d9bd 439 select DEBUG_FS
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440 select STACKTRACE if STACKTRACE_SUPPORT
441 select KALLSYMS
b60e26a2 442 select CRC32
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443 help
444 Say Y here if you want to enable the memory leak
445 detector. The memory allocation/freeing is traced in a way
446 similar to the Boehm's conservative garbage collector, the
447 difference being that the orphan objects are not freed but
448 only shown in /sys/kernel/debug/kmemleak. Enabling this
449 feature will introduce an overhead to memory
450 allocations. See Documentation/kmemleak.txt for more
451 details.
452
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453 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
454 of finding leaks due to the slab objects poisoning.
455
456 In order to access the kmemleak file, debugfs needs to be
457 mounted (usually at /sys/kernel/debug).
458
459config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
460 int "Maximum kmemleak early log entries"
461 depends on DEBUG_KMEMLEAK
462 range 200 40000
463 default 400
464 help
465 Kmemleak must track all the memory allocations to avoid
466 reporting false positives. Since memory may be allocated or
467 freed before kmemleak is initialised, an early log buffer is
468 used to store these actions. If kmemleak reports "early log
469 buffer exceeded", please increase this value.
470
471config DEBUG_KMEMLEAK_TEST
472 tristate "Simple test for the kernel memory leak detector"
473 depends on DEBUG_KMEMLEAK && m
474 help
475 This option enables a module that explicitly leaks memory.
476
477 If unsure, say N.
478
479config DEBUG_KMEMLEAK_DEFAULT_OFF
480 bool "Default kmemleak to off"
481 depends on DEBUG_KMEMLEAK
482 help
483 Say Y here to disable kmemleak by default. It can then be enabled
484 on the command line via kmemleak=on.
485
486config DEBUG_STACK_USAGE
487 bool "Stack utilization instrumentation"
488 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
489 help
490 Enables the display of the minimum amount of free stack which each
491 task has ever had available in the sysrq-T and sysrq-P debug output.
492
493 This option will slow down process creation somewhat.
494
495config DEBUG_VM
496 bool "Debug VM"
497 depends on DEBUG_KERNEL
498 help
499 Enable this to turn on extended checks in the virtual-memory system
500 that may impact performance.
501
502 If unsure, say N.
503
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504config DEBUG_VM_VMACACHE
505 bool "Debug VMA caching"
506 depends on DEBUG_VM
507 help
508 Enable this to turn on VMA caching debug information. Doing so
509 can cause significant overhead, so only enable it in non-production
510 environments.
511
512 If unsure, say N.
513
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514config DEBUG_VM_RB
515 bool "Debug VM red-black trees"
516 depends on DEBUG_VM
517 help
a663dad6 518 Enable VM red-black tree debugging information and extra validations.
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519
520 If unsure, say N.
521
522config DEBUG_VIRTUAL
523 bool "Debug VM translations"
524 depends on DEBUG_KERNEL && X86
525 help
526 Enable some costly sanity checks in virtual to page code. This can
527 catch mistakes with virt_to_page() and friends.
528
529 If unsure, say N.
530
531config DEBUG_NOMMU_REGIONS
532 bool "Debug the global anon/private NOMMU mapping region tree"
533 depends on DEBUG_KERNEL && !MMU
534 help
535 This option causes the global tree of anonymous and private mapping
536 regions to be regularly checked for invalid topology.
537
538config DEBUG_MEMORY_INIT
539 bool "Debug memory initialisation" if EXPERT
540 default !EXPERT
541 help
542 Enable this for additional checks during memory initialisation.
543 The sanity checks verify aspects of the VM such as the memory model
544 and other information provided by the architecture. Verbose
545 information will be printed at KERN_DEBUG loglevel depending
546 on the mminit_loglevel= command-line option.
547
548 If unsure, say Y
549
550config MEMORY_NOTIFIER_ERROR_INJECT
551 tristate "Memory hotplug notifier error injection module"
552 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
553 help
554 This option provides the ability to inject artificial errors to
555 memory hotplug notifier chain callbacks. It is controlled through
556 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
557
558 If the notifier call chain should be failed with some events
559 notified, write the error code to "actions/<notifier event>/error".
560
561 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
562
563 # cd /sys/kernel/debug/notifier-error-inject/memory
564 # echo -12 > actions/MEM_GOING_OFFLINE/error
565 # echo offline > /sys/devices/system/memory/memoryXXX/state
566 bash: echo: write error: Cannot allocate memory
567
568 To compile this code as a module, choose M here: the module will
569 be called memory-notifier-error-inject.
570
571 If unsure, say N.
572
573config DEBUG_PER_CPU_MAPS
574 bool "Debug access to per_cpu maps"
575 depends on DEBUG_KERNEL
576 depends on SMP
577 help
578 Say Y to verify that the per_cpu map being accessed has
579 been set up. This adds a fair amount of code to kernel memory
580 and decreases performance.
581
582 Say N if unsure.
583
584config DEBUG_HIGHMEM
585 bool "Highmem debugging"
586 depends on DEBUG_KERNEL && HIGHMEM
587 help
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588 This option enables additional error checking for high memory
589 systems. Disable for production systems.
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590
591config HAVE_DEBUG_STACKOVERFLOW
592 bool
593
594config DEBUG_STACKOVERFLOW
595 bool "Check for stack overflows"
596 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
597 ---help---
598 Say Y here if you want to check for overflows of kernel, IRQ
599 and exception stacks (if your archicture uses them). This
600 option will show detailed messages if free stack space drops
601 below a certain limit.
602
603 These kinds of bugs usually occur when call-chains in the
604 kernel get too deep, especially when interrupts are
605 involved.
606
607 Use this in cases where you see apparently random memory
608 corruption, especially if it appears in 'struct thread_info'
609
610 If in doubt, say "N".
611
612source "lib/Kconfig.kmemcheck"
613
614endmenu # "Memory Debugging"
615
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616config DEBUG_SHIRQ
617 bool "Debug shared IRQ handlers"
0244ad00 618 depends on DEBUG_KERNEL
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619 help
620 Enable this to generate a spurious interrupt as soon as a shared
621 interrupt handler is registered, and just before one is deregistered.
622 Drivers ought to be able to handle interrupts coming in at those
623 points; some don't and need to be caught.
624
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625menu "Debug Lockups and Hangs"
626
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627config LOCKUP_DETECTOR
628 bool "Detect Hard and Soft Lockups"
dea20a3f 629 depends on DEBUG_KERNEL && !S390
8446f1d3 630 help
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631 Say Y here to enable the kernel to act as a watchdog to detect
632 hard and soft lockups.
633
634 Softlockups are bugs that cause the kernel to loop in kernel
5f329089 635 mode for more than 20 seconds, without giving other tasks a
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636 chance to run. The current stack trace is displayed upon
637 detection and the system will stay locked up.
8446f1d3 638
58687acb 639 Hardlockups are bugs that cause the CPU to loop in kernel mode
5f329089 640 for more than 10 seconds, without letting other interrupts have a
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641 chance to run. The current stack trace is displayed upon detection
642 and the system will stay locked up.
8446f1d3 643
58687acb 644 The overhead should be minimal. A periodic hrtimer runs to
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645 generate interrupts and kick the watchdog task every 4 seconds.
646 An NMI is generated every 10 seconds or so to check for hardlockups.
647
648 The frequency of hrtimer and NMI events and the soft and hard lockup
649 thresholds can be controlled through the sysctl watchdog_thresh.
8446f1d3 650
23637d47 651config HARDLOCKUP_DETECTOR
8f1f66ed
JB
652 def_bool y
653 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
654 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
8446f1d3 655
fef2c9bc
DZ
656config BOOTPARAM_HARDLOCKUP_PANIC
657 bool "Panic (Reboot) On Hard Lockups"
8f1f66ed 658 depends on HARDLOCKUP_DETECTOR
fef2c9bc
DZ
659 help
660 Say Y here to enable the kernel to panic on "hard lockups",
661 which are bugs that cause the kernel to loop in kernel
5f329089
FLVC
662 mode with interrupts disabled for more than 10 seconds (configurable
663 using the watchdog_thresh sysctl).
fef2c9bc
DZ
664
665 Say N if unsure.
666
667config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
668 int
8f1f66ed 669 depends on HARDLOCKUP_DETECTOR
fef2c9bc
DZ
670 range 0 1
671 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
672 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
673
9c44bc03
IM
674config BOOTPARAM_SOFTLOCKUP_PANIC
675 bool "Panic (Reboot) On Soft Lockups"
89d7ce2a 676 depends on LOCKUP_DETECTOR
9c44bc03
IM
677 help
678 Say Y here to enable the kernel to panic on "soft lockups",
679 which are bugs that cause the kernel to loop in kernel
5f329089
FLVC
680 mode for more than 20 seconds (configurable using the watchdog_thresh
681 sysctl), without giving other tasks a chance to run.
9c44bc03
IM
682
683 The panic can be used in combination with panic_timeout,
684 to cause the system to reboot automatically after a
685 lockup has been detected. This feature is useful for
686 high-availability systems that have uptime guarantees and
687 where a lockup must be resolved ASAP.
688
689 Say N if unsure.
690
691config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
692 int
e16bb1d7 693 depends on LOCKUP_DETECTOR
9c44bc03
IM
694 range 0 1
695 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
696 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
697
e162b39a
MSB
698config DETECT_HUNG_TASK
699 bool "Detect Hung Tasks"
700 depends on DEBUG_KERNEL
8edbb83e 701 default LOCKUP_DETECTOR
e162b39a 702 help
0610c8a8
DH
703 Say Y here to enable the kernel to detect "hung tasks",
704 which are bugs that cause the task to be stuck in
705 uninterruptible "D" state indefinitiley.
1da177e4 706
0610c8a8
DH
707 When a hung task is detected, the kernel will print the
708 current stack trace (which you should report), but the
709 task will stay in uninterruptible state. If lockdep is
710 enabled then all held locks will also be reported. This
711 feature has negligible overhead.
871751e2 712
0610c8a8
DH
713config DEFAULT_HUNG_TASK_TIMEOUT
714 int "Default timeout for hung task detection (in seconds)"
715 depends on DETECT_HUNG_TASK
716 default 120
f0630fff 717 help
0610c8a8
DH
718 This option controls the default timeout (in seconds) used
719 to determine when a task has become non-responsive and should
720 be considered hung.
f0630fff 721
0610c8a8
DH
722 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
723 sysctl or by writing a value to
724 /proc/sys/kernel/hung_task_timeout_secs.
8ff12cfc 725
0610c8a8
DH
726 A timeout of 0 disables the check. The default is two minutes.
727 Keeping the default should be fine in most cases.
b69ec42b 728
0610c8a8
DH
729config BOOTPARAM_HUNG_TASK_PANIC
730 bool "Panic (Reboot) On Hung Tasks"
731 depends on DETECT_HUNG_TASK
3bba00d7 732 help
0610c8a8
DH
733 Say Y here to enable the kernel to panic on "hung tasks",
734 which are bugs that cause the kernel to leave a task stuck
735 in uninterruptible "D" state.
3bba00d7 736
0610c8a8
DH
737 The panic can be used in combination with panic_timeout,
738 to cause the system to reboot automatically after a
739 hung task has been detected. This feature is useful for
740 high-availability systems that have uptime guarantees and
741 where a hung tasks must be resolved ASAP.
bf96d1e3 742
0610c8a8 743 Say N if unsure.
bf96d1e3 744
0610c8a8
DH
745config BOOTPARAM_HUNG_TASK_PANIC_VALUE
746 int
747 depends on DETECT_HUNG_TASK
748 range 0 1
749 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
750 default 1 if BOOTPARAM_HUNG_TASK_PANIC
3bba00d7 751
92aef8fb
DH
752endmenu # "Debug lockups and hangs"
753
754config PANIC_ON_OOPS
755 bool "Panic on Oops"
a9d9058a 756 help
92aef8fb
DH
757 Say Y here to enable the kernel to panic when it oopses. This
758 has the same effect as setting oops=panic on the kernel command
759 line.
a9d9058a 760
92aef8fb
DH
761 This feature is useful to ensure that the kernel does not do
762 anything erroneous after an oops which could result in data
763 corruption or other issues.
764
765 Say N if unsure.
766
767config PANIC_ON_OOPS_VALUE
768 int
769 range 0 1
770 default 0 if !PANIC_ON_OOPS
771 default 1 if PANIC_ON_OOPS
772
5800dc3c
JB
773config PANIC_TIMEOUT
774 int "panic timeout"
775 default 0
776 help
777 Set the timeout value (in seconds) until a reboot occurs when the
778 the kernel panics. If n = 0, then we wait forever. A timeout
779 value n > 0 will wait n seconds before rebooting, while a timeout
780 value n < 0 will reboot immediately.
781
0610c8a8
DH
782config SCHED_DEBUG
783 bool "Collect scheduler debugging info"
784 depends on DEBUG_KERNEL && PROC_FS
785 default y
0822ee4a 786 help
0610c8a8
DH
787 If you say Y here, the /proc/sched_debug file will be provided
788 that can help debug the scheduler. The runtime overhead of this
789 option is minimal.
0822ee4a 790
0610c8a8
DH
791config SCHEDSTATS
792 bool "Collect scheduler statistics"
793 depends on DEBUG_KERNEL && PROC_FS
794 help
795 If you say Y here, additional code will be inserted into the
796 scheduler and related routines to collect statistics about
797 scheduler behavior and provide them in /proc/schedstat. These
798 stats may be useful for both tuning and debugging the scheduler
799 If you aren't debugging the scheduler or trying to tune a specific
800 application, you can say N to avoid the very slight overhead
801 this adds.
0822ee4a 802
0610c8a8
DH
803config TIMER_STATS
804 bool "Collect kernel timers statistics"
805 depends on DEBUG_KERNEL && PROC_FS
ab0155a2 806 help
0610c8a8
DH
807 If you say Y here, additional code will be inserted into the
808 timer routines to collect statistics about kernel timers being
809 reprogrammed. The statistics can be read from /proc/timer_stats.
810 The statistics collection is started by writing 1 to /proc/timer_stats,
811 writing 0 stops it. This feature is useful to collect information
812 about timer usage patterns in kernel and userspace. This feature
813 is lightweight if enabled in the kernel config but not activated
814 (it defaults to deactivated on bootup and will only be activated
815 if some application like powertop activates it explicitly).
ab0155a2 816
1da177e4
LT
817config DEBUG_PREEMPT
818 bool "Debug preemptible kernel"
01deab98 819 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1da177e4
LT
820 default y
821 help
822 If you say Y here then the kernel will use a debug variant of the
823 commonly used smp_processor_id() function and will print warnings
824 if kernel code uses it in a preemption-unsafe way. Also, the kernel
825 will detect preemption count underflows.
826
9eade16b
DH
827menu "Lock Debugging (spinlocks, mutexes, etc...)"
828
e7eebaf6
IM
829config DEBUG_RT_MUTEXES
830 bool "RT Mutex debugging, deadlock detection"
e7eebaf6
IM
831 depends on DEBUG_KERNEL && RT_MUTEXES
832 help
833 This allows rt mutex semantics violations and rt mutex related
834 deadlocks (lockups) to be detected and reported automatically.
835
836config DEBUG_PI_LIST
837 bool
838 default y
839 depends on DEBUG_RT_MUTEXES
840
61a87122
TG
841config RT_MUTEX_TESTER
842 bool "Built-in scriptable tester for rt-mutexes"
a1583d3e 843 depends on DEBUG_KERNEL && RT_MUTEXES
61a87122
TG
844 help
845 This option enables a rt-mutex tester.
846
1da177e4 847config DEBUG_SPINLOCK
4d9f34ad 848 bool "Spinlock and rw-lock debugging: basic checks"
1da177e4 849 depends on DEBUG_KERNEL
e335e3eb 850 select UNINLINE_SPIN_UNLOCK
1da177e4
LT
851 help
852 Say Y here and build SMP to catch missing spinlock initialization
853 and certain other kinds of spinlock errors commonly made. This is
854 best used in conjunction with the NMI watchdog so that spinlock
855 deadlocks are also debuggable.
856
4d9f34ad
IM
857config DEBUG_MUTEXES
858 bool "Mutex debugging: basic checks"
859 depends on DEBUG_KERNEL
860 help
861 This feature allows mutex semantics violations to be detected and
862 reported.
863
23010027
DV
864config DEBUG_WW_MUTEX_SLOWPATH
865 bool "Wait/wound mutex debugging: Slowpath testing"
866 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
867 select DEBUG_LOCK_ALLOC
868 select DEBUG_SPINLOCK
869 select DEBUG_MUTEXES
870 help
871 This feature enables slowpath testing for w/w mutex users by
872 injecting additional -EDEADLK wound/backoff cases. Together with
873 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
874 will test all possible w/w mutex interface abuse with the
875 exception of simply not acquiring all the required locks.
876
4d9f34ad
IM
877config DEBUG_LOCK_ALLOC
878 bool "Lock debugging: detect incorrect freeing of live locks"
517e7aa5 879 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad
IM
880 select DEBUG_SPINLOCK
881 select DEBUG_MUTEXES
4d9f34ad
IM
882 select LOCKDEP
883 help
884 This feature will check whether any held lock (spinlock, rwlock,
885 mutex or rwsem) is incorrectly freed by the kernel, via any of the
886 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
887 vfree(), etc.), whether a live lock is incorrectly reinitialized via
888 spin_lock_init()/mutex_init()/etc., or whether there is any lock
889 held during task exit.
890
891config PROVE_LOCKING
892 bool "Lock debugging: prove locking correctness"
517e7aa5 893 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad
IM
894 select LOCKDEP
895 select DEBUG_SPINLOCK
896 select DEBUG_MUTEXES
4d9f34ad 897 select DEBUG_LOCK_ALLOC
46b93b74 898 select TRACE_IRQFLAGS
4d9f34ad
IM
899 default n
900 help
901 This feature enables the kernel to prove that all locking
902 that occurs in the kernel runtime is mathematically
903 correct: that under no circumstance could an arbitrary (and
904 not yet triggered) combination of observed locking
905 sequences (on an arbitrary number of CPUs, running an
906 arbitrary number of tasks and interrupt contexts) cause a
907 deadlock.
908
909 In short, this feature enables the kernel to report locking
910 related deadlocks before they actually occur.
911
912 The proof does not depend on how hard and complex a
913 deadlock scenario would be to trigger: how many
914 participant CPUs, tasks and irq-contexts would be needed
915 for it to trigger. The proof also does not depend on
916 timing: if a race and a resulting deadlock is possible
917 theoretically (no matter how unlikely the race scenario
918 is), it will be proven so and will immediately be
919 reported by the kernel (once the event is observed that
920 makes the deadlock theoretically possible).
921
922 If a deadlock is impossible (i.e. the locking rules, as
923 observed by the kernel, are mathematically correct), the
924 kernel reports nothing.
925
926 NOTE: this feature can also be enabled for rwlocks, mutexes
927 and rwsems - in which case all dependencies between these
928 different locking variants are observed and mapped too, and
929 the proof of observed correctness is also maintained for an
930 arbitrary combination of these separate locking variants.
931
932 For more details, see Documentation/lockdep-design.txt.
933
934config LOCKDEP
935 bool
517e7aa5 936 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad 937 select STACKTRACE
cc80ae38 938 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC
4d9f34ad
IM
939 select KALLSYMS
940 select KALLSYMS_ALL
941
f20786ff 942config LOCK_STAT
fdfb870f 943 bool "Lock usage statistics"
f20786ff
PZ
944 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
945 select LOCKDEP
946 select DEBUG_SPINLOCK
947 select DEBUG_MUTEXES
948 select DEBUG_LOCK_ALLOC
949 default n
950 help
951 This feature enables tracking lock contention points
952
a560aa48
PZ
953 For more details, see Documentation/lockstat.txt
954
dd8b1cf6
FW
955 This also enables lock events required by "perf lock",
956 subcommand of perf.
957 If you want to use "perf lock", you also need to turn on
958 CONFIG_EVENT_TRACING.
84c6f88f
HM
959
960 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
dd8b1cf6 961 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
84c6f88f 962
4d9f34ad
IM
963config DEBUG_LOCKDEP
964 bool "Lock dependency engine debugging"
517e7aa5 965 depends on DEBUG_KERNEL && LOCKDEP
4d9f34ad
IM
966 help
967 If you say Y here, the lock dependency engine will do
968 additional runtime checks to debug itself, at the price
969 of more runtime overhead.
970
d902db1e
FW
971config DEBUG_ATOMIC_SLEEP
972 bool "Sleep inside atomic section checking"
e8f7c70f 973 select PREEMPT_COUNT
1da177e4
LT
974 depends on DEBUG_KERNEL
975 help
976 If you say Y here, various routines which may sleep will become very
d902db1e
FW
977 noisy if they are called inside atomic sections: when a spinlock is
978 held, inside an rcu read side critical section, inside preempt disabled
979 sections, inside an interrupt, etc...
1da177e4 980
cae2ed9a
IM
981config DEBUG_LOCKING_API_SELFTESTS
982 bool "Locking API boot-time self-tests"
983 depends on DEBUG_KERNEL
984 help
985 Say Y here if you want the kernel to run a short self-test during
986 bootup. The self-test checks whether common types of locking bugs
987 are detected by debugging mechanisms or not. (if you disable
988 lock debugging then those bugs wont be detected of course.)
989 The following locking APIs are covered: spinlocks, rwlocks,
990 mutexes and rwsems.
991
0af3fe1e
PM
992config LOCK_TORTURE_TEST
993 tristate "torture tests for locking"
994 depends on DEBUG_KERNEL
995 select TORTURE_TEST
996 default n
997 help
998 This option provides a kernel module that runs torture tests
999 on kernel locking primitives. The kernel module may be built
1000 after the fact on the running kernel to be tested, if desired.
1001
1002 Say Y here if you want kernel locking-primitive torture tests
1003 to be built into the kernel.
1004 Say M if you want these torture tests to build as a module.
1005 Say N if you are unsure.
1006
9eade16b 1007endmenu # lock debugging
8637c099 1008
9eade16b
DH
1009config TRACE_IRQFLAGS
1010 bool
5ca43f6c 1011 help
9eade16b
DH
1012 Enables hooks to interrupt enabling and disabling for
1013 either tracing or lock debugging.
5ca43f6c 1014
8637c099
IM
1015config STACKTRACE
1016 bool
1017 depends on STACKTRACE_SUPPORT
5ca43f6c 1018
1da177e4
LT
1019config DEBUG_KOBJECT
1020 bool "kobject debugging"
1021 depends on DEBUG_KERNEL
1022 help
1023 If you say Y here, some extra kobject debugging messages will be sent
1024 to the syslog.
1025
c817a67e
RK
1026config DEBUG_KOBJECT_RELEASE
1027 bool "kobject release debugging"
2a999aa0 1028 depends on DEBUG_OBJECTS_TIMERS
c817a67e
RK
1029 help
1030 kobjects are reference counted objects. This means that their
1031 last reference count put is not predictable, and the kobject can
1032 live on past the point at which a driver decides to drop it's
1033 initial reference to the kobject gained on allocation. An
1034 example of this would be a struct device which has just been
1035 unregistered.
1036
1037 However, some buggy drivers assume that after such an operation,
1038 the memory backing the kobject can be immediately freed. This
1039 goes completely against the principles of a refcounted object.
1040
1041 If you say Y here, the kernel will delay the release of kobjects
1042 on the last reference count to improve the visibility of this
1043 kind of kobject release bug.
1044
9b2a60c4
CM
1045config HAVE_DEBUG_BUGVERBOSE
1046 bool
1047
1da177e4 1048config DEBUG_BUGVERBOSE
6a108a14 1049 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
9b2a60c4 1050 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
8420e7ef 1051 default y
1da177e4
LT
1052 help
1053 Say Y here to make BUG() panics output the file name and line number
1054 of the BUG call as well as the EIP and oops trace. This aids
1055 debugging but costs about 70-100K of memory.
1056
199a9afc
DJ
1057config DEBUG_LIST
1058 bool "Debug linked list manipulation"
1059 depends on DEBUG_KERNEL
1060 help
1061 Enable this to turn on extended checks in the linked-list
1062 walking routines.
1063
1064 If unsure, say N.
1065
d6ec0842
JA
1066config DEBUG_SG
1067 bool "Debug SG table operations"
1068 depends on DEBUG_KERNEL
1069 help
1070 Enable this to turn on checks on scatter-gather tables. This can
1071 help find problems with drivers that do not properly initialize
1072 their sg tables.
1073
1074 If unsure, say N.
1075
1b2439db
AV
1076config DEBUG_NOTIFIERS
1077 bool "Debug notifier call chains"
1078 depends on DEBUG_KERNEL
1079 help
1080 Enable this to turn on sanity checking for notifier call chains.
1081 This is most useful for kernel developers to make sure that
1082 modules properly unregister themselves from notifier chains.
1083 This is a relatively cheap check but if you care about maximum
1084 performance, say N.
1085
e0e81739
DH
1086config DEBUG_CREDENTIALS
1087 bool "Debug credential management"
1088 depends on DEBUG_KERNEL
1089 help
1090 Enable this to turn on some debug checking for credential
1091 management. The additional code keeps track of the number of
1092 pointers from task_structs to any given cred struct, and checks to
1093 see that this number never exceeds the usage count of the cred
1094 struct.
1095
1096 Furthermore, if SELinux is enabled, this also checks that the
1097 security pointer in the cred struct is never seen to be invalid.
1098
1099 If unsure, say N.
1100
2f03e3ca
DH
1101menu "RCU Debugging"
1102
1103config PROVE_RCU
1104 bool "RCU debugging: prove RCU correctness"
1105 depends on PROVE_LOCKING
1106 default n
1107 help
1108 This feature enables lockdep extensions that check for correct
1109 use of RCU APIs. This is currently under development. Say Y
1110 if you want to debug RCU usage or help work on the PROVE_RCU
1111 feature.
1112
1113 Say N if you are unsure.
1114
1115config PROVE_RCU_REPEATEDLY
1116 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1117 depends on PROVE_RCU
1118 default n
1119 help
1120 By itself, PROVE_RCU will disable checking upon issuing the
1121 first warning (or "splat"). This feature prevents such
1122 disabling, allowing multiple RCU-lockdep warnings to be printed
1123 on a single reboot.
1124
1125 Say Y to allow multiple RCU-lockdep warnings per boot.
1126
1127 Say N if you are unsure.
1128
1129config PROVE_RCU_DELAY
1130 bool "RCU debugging: preemptible RCU race provocation"
1131 depends on DEBUG_KERNEL && PREEMPT_RCU
1132 default n
1133 help
1134 There is a class of races that involve an unlikely preemption
1135 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
1136 been set to INT_MIN. This feature inserts a delay at that
1137 point to increase the probability of these races.
1138
1139 Say Y to increase probability of preemption of __rcu_read_unlock().
1140
1141 Say N if you are unsure.
1142
1143config SPARSE_RCU_POINTER
1144 bool "RCU debugging: sparse-based checks for pointer usage"
1145 default n
1146 help
1147 This feature enables the __rcu sparse annotation for
1148 RCU-protected pointers. This annotation will cause sparse
1149 to flag any non-RCU used of annotated pointers. This can be
1150 helpful when debugging RCU usage. Please note that this feature
1151 is not intended to enforce code cleanliness; it is instead merely
1152 a debugging aid.
1153
1154 Say Y to make sparse flag questionable use of RCU-protected pointers
1155
1156 Say N if you are unsure.
1157
51b1130e
PM
1158config TORTURE_TEST
1159 tristate
1160 default n
1161
a241ec65
PM
1162config RCU_TORTURE_TEST
1163 tristate "torture tests for RCU"
1164 depends on DEBUG_KERNEL
51b1130e 1165 select TORTURE_TEST
a241ec65
PM
1166 default n
1167 help
1168 This option provides a kernel module that runs torture tests
1169 on the RCU infrastructure. The kernel module may be built
1170 after the fact on the running kernel to be tested, if desired.
1171
31a72bce
PM
1172 Say Y here if you want RCU torture tests to be built into
1173 the kernel.
a241ec65
PM
1174 Say M if you want the RCU torture tests to build as a module.
1175 Say N if you are unsure.
8bb31b9d 1176
31a72bce
PM
1177config RCU_TORTURE_TEST_RUNNABLE
1178 bool "torture tests for RCU runnable by default"
1179 depends on RCU_TORTURE_TEST = y
1180 default n
1181 help
1182 This option provides a way to build the RCU torture tests
1183 directly into the kernel without them starting up at boot
1184 time. You can use /proc/sys/kernel/rcutorture_runnable
1185 to manually override this setting. This /proc file is
1186 available only when the RCU torture tests have been built
1187 into the kernel.
1188
1189 Say Y here if you want the RCU torture tests to start during
1190 boot (you probably don't).
1191 Say N here if you want the RCU torture tests to start only
1192 after being manually enabled via /proc.
1193
b163760e
PM
1194config RCU_CPU_STALL_TIMEOUT
1195 int "RCU CPU stall timeout in seconds"
6bfc09e2 1196 depends on RCU_STALL_COMMON
b163760e 1197 range 3 300
c896054f 1198 default 21
b163760e
PM
1199 help
1200 If a given RCU grace period extends more than the specified
1201 number of seconds, a CPU stall warning is printed. If the
1202 RCU grace period persists, additional CPU stall warnings are
1203 printed at more widely spaced intervals.
1204
1ed509a2
PM
1205config RCU_CPU_STALL_VERBOSE
1206 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
a00e0d71 1207 depends on TREE_PREEMPT_RCU
55ec936f 1208 default y
1ed509a2
PM
1209 help
1210 This option causes RCU to printk detailed per-task information
1211 for any tasks that are stalling the current RCU grace period.
67182ae1
PM
1212
1213 Say N if you are unsure.
1214
1ed509a2
PM
1215 Say Y if you want to enable such checks.
1216
a858af28
PM
1217config RCU_CPU_STALL_INFO
1218 bool "Print additional diagnostics on RCU CPU stall"
1219 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1220 default n
1221 help
1222 For each stalled CPU that is aware of the current RCU grace
1223 period, print out additional per-CPU diagnostic information
1224 regarding scheduling-clock ticks, idle state, and,
1225 for RCU_FAST_NO_HZ kernels, idle-entry state.
1226
1227 Say N if you are unsure.
1228
1229 Say Y if you want to enable such diagnostics.
1230
5c8806a0
PM
1231config RCU_TRACE
1232 bool "Enable tracing for RCU"
6dab2778 1233 depends on DEBUG_KERNEL
52494535 1234 select TRACE_CLOCK
6dab2778 1235 help
5c8806a0
PM
1236 This option provides tracing in RCU which presents stats
1237 in debugfs for debugging RCU implementation.
ad118c54 1238
5c8806a0 1239 Say Y here if you want to enable RCU tracing
6dab2778
AV
1240 Say N if you are unsure.
1241
2f03e3ca
DH
1242endmenu # "RCU Debugging"
1243
870d6656
TH
1244config DEBUG_BLOCK_EXT_DEVT
1245 bool "Force extended block device numbers and spread them"
1246 depends on DEBUG_KERNEL
1247 depends on BLOCK
759f8ca3 1248 default n
870d6656 1249 help
0e11e342
TH
1250 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1251 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1252 YOU ARE DOING. Distros, please enable this and fix whatever
1253 is broken.
1254
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1255 Conventionally, block device numbers are allocated from
1256 predetermined contiguous area. However, extended block area
1257 may introduce non-contiguous block device numbers. This
1258 option forces most block device numbers to be allocated from
1259 the extended space and spreads them to discover kernel or
1260 userland code paths which assume predetermined contiguous
1261 device number allocation.
1262
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1263 Note that turning on this debug option shuffles all the
1264 device numbers for all IDE and SCSI devices including libata
1265 ones, so root partition specified using device number
1266 directly (via rdev or root=MAJ:MIN) won't work anymore.
1267 Textual device names (root=/dev/sdXn) will continue to work.
1268
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1269 Say N if you are unsure.
1270
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1271config NOTIFIER_ERROR_INJECTION
1272 tristate "Notifier error injection"
1273 depends on DEBUG_KERNEL
1274 select DEBUG_FS
1275 help
e41e85cc 1276 This option provides the ability to inject artificial errors to
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1277 specified notifier chain callbacks. It is useful to test the error
1278 handling of notifier call chain failures.
1279
1280 Say N if unsure.
1281
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1282config CPU_NOTIFIER_ERROR_INJECT
1283 tristate "CPU notifier error injection module"
f5a9f52e 1284 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
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1285 help
1286 This option provides a kernel module that can be used to test
e41e85cc 1287 the error handling of the cpu notifiers by injecting artificial
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1288 errors to CPU notifier chain callbacks. It is controlled through
1289 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1290
1291 If the notifier call chain should be failed with some events
1292 notified, write the error code to "actions/<notifier event>/error".
1293
1294 Example: Inject CPU offline error (-1 == -EPERM)
1295
1296 # cd /sys/kernel/debug/notifier-error-inject/cpu
1297 # echo -1 > actions/CPU_DOWN_PREPARE/error
1298 # echo 0 > /sys/devices/system/cpu/cpu1/online
1299 bash: echo: write error: Operation not permitted
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1300
1301 To compile this code as a module, choose M here: the module will
1302 be called cpu-notifier-error-inject.
1303
1304 If unsure, say N.
1305
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1306config PM_NOTIFIER_ERROR_INJECT
1307 tristate "PM notifier error injection module"
1308 depends on PM && NOTIFIER_ERROR_INJECTION
1309 default m if PM_DEBUG
1310 help
e41e85cc 1311 This option provides the ability to inject artificial errors to
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1312 PM notifier chain callbacks. It is controlled through debugfs
1313 interface /sys/kernel/debug/notifier-error-inject/pm
1314
1315 If the notifier call chain should be failed with some events
1316 notified, write the error code to "actions/<notifier event>/error".
1317
1318 Example: Inject PM suspend error (-12 = -ENOMEM)
1319
1320 # cd /sys/kernel/debug/notifier-error-inject/pm/
1321 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1322 # echo mem > /sys/power/state
1323 bash: echo: write error: Cannot allocate memory
1324
1325 To compile this code as a module, choose M here: the module will
1326 be called pm-notifier-error-inject.
1327
1328 If unsure, say N.
1329
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1330config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1331 tristate "OF reconfig notifier error injection module"
1332 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
08dfb4dd 1333 help
e41e85cc 1334 This option provides the ability to inject artificial errors to
d526e85f 1335 OF reconfig notifier chain callbacks. It is controlled
08dfb4dd 1336 through debugfs interface under
d526e85f 1337 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
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1338
1339 If the notifier call chain should be failed with some events
1340 notified, write the error code to "actions/<notifier event>/error".
1341
1342 To compile this code as a module, choose M here: the module will
e12a95f4 1343 be called of-reconfig-notifier-error-inject.
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1344
1345 If unsure, say N.
1346
6ff1cb35 1347config FAULT_INJECTION
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1348 bool "Fault-injection framework"
1349 depends on DEBUG_KERNEL
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1350 help
1351 Provide fault-injection framework.
1352 For more details, see Documentation/fault-injection/.
6ff1cb35 1353
8a8b6502 1354config FAILSLAB
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1355 bool "Fault-injection capability for kmalloc"
1356 depends on FAULT_INJECTION
773ff60e 1357 depends on SLAB || SLUB
8a8b6502 1358 help
1ab8509a 1359 Provide fault-injection capability for kmalloc.
8a8b6502 1360
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1361config FAIL_PAGE_ALLOC
1362 bool "Fault-injection capabilitiy for alloc_pages()"
1ab8509a 1363 depends on FAULT_INJECTION
933e312e 1364 help
1ab8509a 1365 Provide fault-injection capability for alloc_pages().
933e312e 1366
c17bb495 1367config FAIL_MAKE_REQUEST
86327d19 1368 bool "Fault-injection capability for disk IO"
581d4e28 1369 depends on FAULT_INJECTION && BLOCK
c17bb495 1370 help
1ab8509a 1371 Provide fault-injection capability for disk IO.
c17bb495 1372
581d4e28 1373config FAIL_IO_TIMEOUT
f4d01439 1374 bool "Fault-injection capability for faking disk interrupts"
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1375 depends on FAULT_INJECTION && BLOCK
1376 help
1377 Provide fault-injection capability on end IO handling. This
1378 will make the block layer "forget" an interrupt as configured,
1379 thus exercising the error handling.
1380
1381 Only works with drivers that use the generic timeout handling,
1382 for others it wont do anything.
1383
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1384config FAIL_MMC_REQUEST
1385 bool "Fault-injection capability for MMC IO"
1386 select DEBUG_FS
1387 depends on FAULT_INJECTION && MMC
1388 help
1389 Provide fault-injection capability for MMC IO.
1390 This will make the mmc core return data errors. This is
1391 useful to test the error handling in the mmc block device
1392 and to test how the mmc host driver handles retries from
1393 the block device.
1394
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1395config FAULT_INJECTION_DEBUG_FS
1396 bool "Debugfs entries for fault-injection capabilities"
1ab8509a 1397 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
6ff1cb35 1398 help
1ab8509a 1399 Enable configuration of fault-injection capabilities via debugfs.
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1400
1401config FAULT_INJECTION_STACKTRACE_FILTER
1402 bool "stacktrace filter for fault-injection capabilities"
1403 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
6d690dca 1404 depends on !X86_64
1df49008 1405 select STACKTRACE
cc80ae38 1406 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
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1407 help
1408 Provide stacktrace filter for fault-injection capabilities
267c4025 1409
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1410config LATENCYTOP
1411 bool "Latency measuring infrastructure"
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1412 depends on HAVE_LATENCYTOP_SUPPORT
1413 depends on DEBUG_KERNEL
1414 depends on STACKTRACE_SUPPORT
1415 depends on PROC_FS
cc80ae38 1416 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
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1417 select KALLSYMS
1418 select KALLSYMS_ALL
1419 select STACKTRACE
1420 select SCHEDSTATS
1421 select SCHED_DEBUG
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1422 help
1423 Enable this option if you want to use the LatencyTOP tool
1424 to find out which userspace is blocking on what kernel operations.
1425
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1426config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1427 bool
1428
1429config DEBUG_STRICT_USER_COPY_CHECKS
1430 bool "Strict user copy size checks"
1431 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1432 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1433 help
1434 Enabling this option turns a certain set of sanity checks for user
1435 copy operations into compile time failures.
1436
1437 The copy_from_user() etc checks are there to help test if there
1438 are sufficient security checks on the length argument of
1439 the copy operation, by having gcc prove that the argument is
1440 within bounds.
1441
1442 If unsure, say N.
1443
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1444source kernel/trace/Kconfig
1445
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1446menu "Runtime Testing"
1447
1448config LKDTM
1449 tristate "Linux Kernel Dump Test Tool Module"
1450 depends on DEBUG_FS
1451 depends on BLOCK
1452 default n
1453 help
1454 This module enables testing of the different dumping mechanisms by
1455 inducing system failures at predefined crash points.
1456 If you don't need it: say N
1457 Choose M here to compile this code as a module. The module will be
1458 called lkdtm.
1459
1460 Documentation on how to use the module can be found in
1461 Documentation/fault-injection/provoke-crashes.txt
1462
1463config TEST_LIST_SORT
1464 bool "Linked list sorting test"
1465 depends on DEBUG_KERNEL
1466 help
1467 Enable this to turn on 'list_sort()' function test. This test is
1468 executed only once during system boot, so affects only boot time.
1469
1470 If unsure, say N.
1471
1472config KPROBES_SANITY_TEST
1473 bool "Kprobes sanity tests"
1474 depends on DEBUG_KERNEL
1475 depends on KPROBES
1476 default n
1477 help
1478 This option provides for testing basic kprobes functionality on
1479 boot. A sample kprobe, jprobe and kretprobe are inserted and
1480 verified for functionality.
1481
1482 Say N if you are unsure.
1483
1484config BACKTRACE_SELF_TEST
1485 tristate "Self test for the backtrace code"
1486 depends on DEBUG_KERNEL
1487 default n
1488 help
1489 This option provides a kernel module that can be used to test
1490 the kernel stack backtrace code. This option is not useful
1491 for distributions or general kernels, but only for kernel
1492 developers working on architecture code.
1493
1494 Note that if you want to also test saved backtraces, you will
1495 have to enable STACKTRACE as well.
1496
1497 Say N if you are unsure.
1498
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1499config RBTREE_TEST
1500 tristate "Red-Black tree test"
7c993e11 1501 depends on DEBUG_KERNEL
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1502 help
1503 A benchmark measuring the performance of the rbtree library.
1504 Also includes rbtree invariant checks.
1505
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1506config INTERVAL_TREE_TEST
1507 tristate "Interval tree test"
1508 depends on m && DEBUG_KERNEL
1509 help
1510 A benchmark measuring the performance of the interval tree library
1511
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1512config PERCPU_TEST
1513 tristate "Per cpu operations test"
1514 depends on m && DEBUG_KERNEL
1515 help
1516 Enable this option to build test module which validates per-cpu
1517 operations.
1518
1519 If unsure, say N.
1520
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1521config ATOMIC64_SELFTEST
1522 bool "Perform an atomic64_t self-test at boot"
1523 help
1524 Enable this option to test the atomic64_t functions at boot.
1525
1526 If unsure, say N.
1527
1528config ASYNC_RAID6_TEST
1529 tristate "Self test for hardware accelerated raid6 recovery"
1530 depends on ASYNC_RAID6_RECOV
1531 select ASYNC_MEMCPY
1532 ---help---
1533 This is a one-shot self test that permutes through the
1534 recovery of all the possible two disk failure scenarios for a
1535 N-disk array. Recovery is performed with the asynchronous
1536 raid6 recovery routines, and will optionally use an offload
1537 engine if one is available.
1538
1539 If unsure, say N.
1540
1541config TEST_STRING_HELPERS
1542 tristate "Test functions located in the string_helpers module at runtime"
1543
1544config TEST_KSTRTOX
1545 tristate "Test kstrto*() family of functions at runtime"
1546
1547endmenu # runtime tests
1548
f212ec4b 1549config PROVIDE_OHCI1394_DMA_INIT
080de8c2 1550 bool "Remote debugging over FireWire early on boot"
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BK
1551 depends on PCI && X86
1552 help
1553 If you want to debug problems which hang or crash the kernel early
1554 on boot and the crashing machine has a FireWire port, you can use
1555 this feature to remotely access the memory of the crashed machine
1556 over FireWire. This employs remote DMA as part of the OHCI1394
1557 specification which is now the standard for FireWire controllers.
1558
1559 With remote DMA, you can monitor the printk buffer remotely using
1560 firescope and access all memory below 4GB using fireproxy from gdb.
1561 Even controlling a kernel debugger is possible using remote DMA.
1562
1563 Usage:
1564
1565 If ohci1394_dma=early is used as boot parameter, it will initialize
1566 all OHCI1394 controllers which are found in the PCI config space.
1567
1568 As all changes to the FireWire bus such as enabling and disabling
1569 devices cause a bus reset and thereby disable remote DMA for all
1570 devices, be sure to have the cable plugged and FireWire enabled on
1571 the debugging host before booting the debug target for debugging.
1572
1573 This code (~1k) is freed after boot. By then, the firewire stack
1574 in charge of the OHCI-1394 controllers should be used instead.
1575
1576 See Documentation/debugging-via-ohci1394.txt for more information.
9745512c 1577
152de30b 1578config BUILD_DOCSRC
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1579 bool "Build targets in Documentation/ tree"
1580 depends on HEADERS_CHECK
1581 help
1582 This option attempts to build objects from the source files in the
1583 kernel Documentation/ tree.
1584
1585 Say N if you are unsure.
1586
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JR
1587config DMA_API_DEBUG
1588 bool "Enable debugging of DMA-API usage"
1589 depends on HAVE_DMA_API_DEBUG
1590 help
1591 Enable this option to debug the use of the DMA API by device drivers.
1592 With this option you will be able to detect common bugs in device
1593 drivers like double-freeing of DMA mappings or freeing mappings that
1594 were never allocated.
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1595
1596 This also attempts to catch cases where a page owned by DMA is
1597 accessed by the cpu in a way that could cause data corruption. For
1598 example, this enables cow_user_page() to check that the source page is
1599 not undergoing DMA.
1600
1601 This option causes a performance degradation. Use only if you want to
1602 debug device drivers and dma interactions.
1603
1604 If unsure, say N.
346e15be 1605
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1606config TEST_MODULE
1607 tristate "Test module loading with 'hello world' module"
1608 default n
1609 depends on m
1610 help
1611 This builds the "test_module" module that emits "Hello, world"
1612 on printk when loaded. It is designed to be used for basic
1613 evaluation of the module loading subsystem (for example when
1614 validating module verification). It lacks any extra dependencies,
1615 and will not normally be loaded by the system unless explicitly
1616 requested by name.
1617
1618 If unsure, say N.
1619
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KC
1620config TEST_USER_COPY
1621 tristate "Test user/kernel boundary protections"
1622 default n
1623 depends on m
1624 help
1625 This builds the "test_user_copy" module that runs sanity checks
1626 on the copy_to/from_user infrastructure, making sure basic
1627 user/kernel boundary testing is working. If it fails to load,
1628 a regression has been detected in the user/kernel memory boundary
1629 protections.
1630
1631 If unsure, say N.
1632
267c4025 1633source "samples/Kconfig"
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JW
1634
1635source "lib/Kconfig.kgdb"
0a4af3b0 1636