fs/affs/super.c: fix switch indentation
[deliverable/linux.git] / lib / Kconfig.debug
CommitLineData
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
42a9dc0b 18config MESSAGE_LOGLEVEL_DEFAULT
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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 DEBUG_INFO_SPLIT
147 bool "Produce split debuginfo in .dwo files"
148 depends on DEBUG_INFO
149 help
150 Generate debug info into separate .dwo files. This significantly
151 reduces the build directory size for builds with DEBUG_INFO,
152 because it stores the information only once on disk in .dwo
153 files instead of multiple times in object files and executables.
154 In addition the debug information is also compressed.
155
156 Requires recent gcc (4.7+) and recent gdb/binutils.
157 Any tool that packages or reads debug information would need
158 to know about the .dwo files and include them.
159 Incompatible with older versions of ccache.
160
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161config DEBUG_INFO_DWARF4
162 bool "Generate dwarf4 debuginfo"
163 depends on DEBUG_INFO
164 help
165 Generate dwarf4 debug info. This requires recent versions
166 of gcc and gdb. It makes the debug information larger.
167 But it significantly improves the success of resolving
168 variables in gdb on optimized code.
169
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170config ENABLE_WARN_DEPRECATED
171 bool "Enable __deprecated logic"
172 default y
173 help
174 Enable the __deprecated logic in the kernel build.
175 Disable this to suppress the "warning: 'foo' is deprecated
176 (declared at kernel/power/somefile.c:1234)" messages.
177
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178config ENABLE_MUST_CHECK
179 bool "Enable __must_check logic"
180 default y
181 help
182 Enable the __must_check logic in the kernel build. Disable this to
183 suppress the "warning: ignoring return value of 'foo', declared with
184 attribute warn_unused_result" messages.
1da177e4 185
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186config FRAME_WARN
187 int "Warn for stack frames larger than (needs gcc 4.4)"
188 range 0 8192
189 default 1024 if !64BIT
190 default 2048 if 64BIT
191 help
192 Tell gcc to warn at build time for stack frames larger than this.
193 Setting this too low will cause a lot of warnings.
194 Setting it to 0 disables the warning.
195 Requires gcc 4.4
196
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197config STRIP_ASM_SYMS
198 bool "Strip assembler-generated symbols during link"
199 default n
200 help
201 Strip internal assembler-generated symbols during a link (symbols
202 that look like '.Lxxx') so they don't pollute the output of
203 get_wchan() and suchlike.
204
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205config READABLE_ASM
206 bool "Generate readable assembler code"
207 depends on DEBUG_KERNEL
208 help
209 Disable some compiler optimizations that tend to generate human unreadable
210 assembler output. This may make the kernel slightly slower, but it helps
211 to keep kernel developers who have to stare a lot at assembler listings
212 sane.
213
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214config UNUSED_SYMBOLS
215 bool "Enable unused/obsolete exported symbols"
216 default y if X86
217 help
218 Unused but exported symbols make the kernel needlessly bigger. For
219 that reason most of these unused exports will soon be removed. This
220 option is provided temporarily to provide a transition period in case
221 some external kernel module needs one of these symbols anyway. If you
222 encounter such a case in your module, consider if you are actually
223 using the right API. (rationale: since nobody in the kernel is using
224 this in a module, there is a pretty good chance it's actually the
225 wrong interface to use). If you really need the symbol, please send a
226 mail to the linux kernel mailing list mentioning the symbol and why
227 you really need it, and what the merge plan to the mainline kernel for
228 your module is.
229
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230config PAGE_OWNER
231 bool "Track page owner"
232 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
233 select DEBUG_FS
234 select STACKTRACE
235 select PAGE_EXTENSION
236 help
237 This keeps track of what call chain is the owner of a page, may
238 help to find bare alloc_page(s) leaks. Even if you include this
239 feature on your build, it is disabled in default. You should pass
240 "page_owner=on" to boot parameter in order to enable it. Eats
241 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
242 for user-space helper.
243
244 If unsure, say N.
245
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246config DEBUG_FS
247 bool "Debug Filesystem"
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248 help
249 debugfs is a virtual file system that kernel developers use to put
250 debugging files into. Enable this option to be able to read and
251 write to these files.
252
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253 For detailed documentation on the debugfs API, see
254 Documentation/DocBook/filesystems.
255
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256 If unsure, say N.
257
258config HEADERS_CHECK
259 bool "Run 'make headers_check' when building vmlinux"
260 depends on !UML
261 help
262 This option will extract the user-visible kernel headers whenever
263 building the kernel, and will run basic sanity checks on them to
264 ensure that exported files do not attempt to include files which
265 were not exported, etc.
266
267 If you're making modifications to header files which are
268 relevant for userspace, say 'Y', and check the headers
269 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
270 your build tree), to make sure they're suitable.
271
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272config DEBUG_SECTION_MISMATCH
273 bool "Enable full Section mismatch analysis"
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274 help
275 The section mismatch analysis checks if there are illegal
276 references from one section to another section.
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277 During linktime or runtime, some sections are dropped;
278 any use of code/data previously in these sections would
91341d4b 279 most likely result in an oops.
e809ab01 280 In the code, functions and variables are annotated with
0db0628d 281 __init,, etc. (see the full list in include/linux/init.h),
d6fbfa4f 282 which results in the code/data being placed in specific sections.
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283 The section mismatch analysis is always performed after a full
284 kernel build, and enabling this option causes the following
285 additional steps to occur:
286 - Add the option -fno-inline-functions-called-once to gcc commands.
287 When inlining a function annotated with __init in a non-init
288 function, we would lose the section information and thus
91341d4b 289 the analysis would not catch the illegal reference.
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290 This option tells gcc to inline less (but it does result in
291 a larger kernel).
292 - Run the section mismatch analysis for each module/built-in.o file.
293 When we run the section mismatch analysis on vmlinux.o, we
d6fbfa4f 294 lose valueble information about where the mismatch was
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295 introduced.
296 Running the analysis for each module/built-in.o file
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297 tells where the mismatch happens much closer to the
298 source. The drawback is that the same mismatch is
299 reported at least twice.
300 - Enable verbose reporting from modpost in order to help resolve
301 the section mismatches that are reported.
91341d4b 302
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303#
304# Select this config option from the architecture Kconfig, if it
305# is preferred to always offer frame pointers as a config
306# option on the architecture (regardless of KERNEL_DEBUG):
307#
308config ARCH_WANT_FRAME_POINTERS
309 bool
f346f4b3 310 help
f346f4b3 311
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312config FRAME_POINTER
313 bool "Compile the kernel with frame pointers"
314 depends on DEBUG_KERNEL && \
315 (CRIS || M68K || FRV || UML || \
316 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
317 ARCH_WANT_FRAME_POINTERS
318 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
a304e1b8 319 help
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320 If you say Y here the resulting kernel image will be slightly
321 larger and slower, but it gives very useful debugging information
322 in case of kernel bugs. (precise oopses/stacktraces/warnings)
a304e1b8 323
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324config DEBUG_FORCE_WEAK_PER_CPU
325 bool "Force weak per-cpu definitions"
326 depends on DEBUG_KERNEL
8446f1d3 327 help
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328 s390 and alpha require percpu variables in modules to be
329 defined weak to work around addressing range issue which
330 puts the following two restrictions on percpu variable
331 definitions.
8446f1d3 332
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333 1. percpu symbols must be unique whether static or not
334 2. percpu variables can't be defined inside a function
8446f1d3 335
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336 To ensure that generic code follows the above rules, this
337 option forces all percpu variables to be defined as weak.
5f329089 338
6dfc0665 339endmenu # "Compiler options"
8446f1d3 340
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341config MAGIC_SYSRQ
342 bool "Magic SysRq key"
343 depends on !UML
344 help
345 If you say Y here, you will have some control over the system even
346 if the system crashes for example during kernel debugging (e.g., you
347 will be able to flush the buffer cache to disk, reboot the system
348 immediately or dump some status information). This is accomplished
349 by pressing various keys while holding SysRq (Alt+PrintScreen). It
350 also works on a serial console (on PC hardware at least), if you
351 send a BREAK and then within 5 seconds a command keypress. The
352 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
353 unless you really know what this hack does.
8446f1d3 354
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355config MAGIC_SYSRQ_DEFAULT_ENABLE
356 hex "Enable magic SysRq key functions by default"
357 depends on MAGIC_SYSRQ
358 default 0x1
359 help
360 Specifies which SysRq key functions are enabled by default.
361 This may be set to 1 or 0 to enable or disable them all, or
362 to a bitmask as described in Documentation/sysrq.txt.
363
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364config DEBUG_KERNEL
365 bool "Kernel debugging"
fef2c9bc 366 help
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367 Say Y here if you are developing drivers or trying to debug and
368 identify kernel problems.
fef2c9bc 369
0610c8a8 370menu "Memory Debugging"
fef2c9bc 371
0610c8a8 372source mm/Kconfig.debug
fef2c9bc 373
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374config DEBUG_OBJECTS
375 bool "Debug object operations"
376 depends on DEBUG_KERNEL
9c44bc03 377 help
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378 If you say Y here, additional code will be inserted into the
379 kernel to track the life time of various objects and validate
380 the operations on those objects.
9c44bc03 381
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382config DEBUG_OBJECTS_SELFTEST
383 bool "Debug objects selftest"
384 depends on DEBUG_OBJECTS
385 help
386 This enables the selftest of the object debug code.
9c44bc03 387
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388config DEBUG_OBJECTS_FREE
389 bool "Debug objects in freed memory"
390 depends on DEBUG_OBJECTS
391 help
392 This enables checks whether a k/v free operation frees an area
393 which contains an object which has not been deactivated
394 properly. This can make kmalloc/kfree-intensive workloads
395 much slower.
3ac7fe5a 396
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397config DEBUG_OBJECTS_TIMERS
398 bool "Debug timer objects"
399 depends on DEBUG_OBJECTS
400 help
401 If you say Y here, additional code will be inserted into the
402 timer routines to track the life time of timer objects and
403 validate the timer operations.
404
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405config DEBUG_OBJECTS_WORK
406 bool "Debug work objects"
407 depends on DEBUG_OBJECTS
408 help
409 If you say Y here, additional code will be inserted into the
410 work queue routines to track the life time of work objects and
411 validate the work operations.
412
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413config DEBUG_OBJECTS_RCU_HEAD
414 bool "Debug RCU callbacks objects"
fc2ecf7e 415 depends on DEBUG_OBJECTS
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416 help
417 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
418
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419config DEBUG_OBJECTS_PERCPU_COUNTER
420 bool "Debug percpu counter objects"
421 depends on DEBUG_OBJECTS
422 help
423 If you say Y here, additional code will be inserted into the
424 percpu counter routines to track the life time of percpu counter
425 objects and validate the percpu counter operations.
426
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427config DEBUG_OBJECTS_ENABLE_DEFAULT
428 int "debug_objects bootup default value (0-1)"
429 range 0 1
430 default "1"
431 depends on DEBUG_OBJECTS
432 help
433 Debug objects boot parameter default value
434
1da177e4 435config DEBUG_SLAB
4a2f0acf 436 bool "Debug slab memory allocations"
7d46d9e6 437 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
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438 help
439 Say Y here to have the kernel do limited verification on memory
440 allocation as well as poisoning memory on free to catch use of freed
441 memory. This can make kmalloc/kfree-intensive workloads much slower.
442
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443config DEBUG_SLAB_LEAK
444 bool "Memory leak debugging"
445 depends on DEBUG_SLAB
446
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447config SLUB_DEBUG_ON
448 bool "SLUB debugging on by default"
7d46d9e6 449 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
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450 default n
451 help
452 Boot with debugging on by default. SLUB boots by default with
453 the runtime debug capabilities switched off. Enabling this is
454 equivalent to specifying the "slub_debug" parameter on boot.
455 There is no support for more fine grained debug control like
456 possible with slub_debug=xxx. SLUB debugging may be switched
457 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
458 "slub_debug=-".
459
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460config SLUB_STATS
461 default n
462 bool "Enable SLUB performance statistics"
ab4d5ed5 463 depends on SLUB && SYSFS
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464 help
465 SLUB statistics are useful to debug SLUBs allocation behavior in
466 order find ways to optimize the allocator. This should never be
467 enabled for production use since keeping statistics slows down
468 the allocator by a few percentage points. The slabinfo command
469 supports the determination of the most active slabs to figure
470 out which slabs are relevant to a particular load.
471 Try running: slabinfo -DA
472
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473config HAVE_DEBUG_KMEMLEAK
474 bool
475
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476config DEBUG_KMEMLEAK
477 bool "Kernel memory leak detector"
525c1f92 478 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
79e0d9bd 479 select DEBUG_FS
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480 select STACKTRACE if STACKTRACE_SUPPORT
481 select KALLSYMS
b60e26a2 482 select CRC32
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483 help
484 Say Y here if you want to enable the memory leak
485 detector. The memory allocation/freeing is traced in a way
486 similar to the Boehm's conservative garbage collector, the
487 difference being that the orphan objects are not freed but
488 only shown in /sys/kernel/debug/kmemleak. Enabling this
489 feature will introduce an overhead to memory
490 allocations. See Documentation/kmemleak.txt for more
491 details.
492
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493 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
494 of finding leaks due to the slab objects poisoning.
495
496 In order to access the kmemleak file, debugfs needs to be
497 mounted (usually at /sys/kernel/debug).
498
499config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
500 int "Maximum kmemleak early log entries"
501 depends on DEBUG_KMEMLEAK
502 range 200 40000
503 default 400
504 help
505 Kmemleak must track all the memory allocations to avoid
506 reporting false positives. Since memory may be allocated or
507 freed before kmemleak is initialised, an early log buffer is
508 used to store these actions. If kmemleak reports "early log
509 buffer exceeded", please increase this value.
510
511config DEBUG_KMEMLEAK_TEST
512 tristate "Simple test for the kernel memory leak detector"
513 depends on DEBUG_KMEMLEAK && m
514 help
515 This option enables a module that explicitly leaks memory.
516
517 If unsure, say N.
518
519config DEBUG_KMEMLEAK_DEFAULT_OFF
520 bool "Default kmemleak to off"
521 depends on DEBUG_KMEMLEAK
522 help
523 Say Y here to disable kmemleak by default. It can then be enabled
524 on the command line via kmemleak=on.
525
526config DEBUG_STACK_USAGE
527 bool "Stack utilization instrumentation"
528 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
529 help
530 Enables the display of the minimum amount of free stack which each
531 task has ever had available in the sysrq-T and sysrq-P debug output.
532
533 This option will slow down process creation somewhat.
534
535config DEBUG_VM
536 bool "Debug VM"
537 depends on DEBUG_KERNEL
538 help
539 Enable this to turn on extended checks in the virtual-memory system
540 that may impact performance.
541
542 If unsure, say N.
543
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544config DEBUG_VM_VMACACHE
545 bool "Debug VMA caching"
546 depends on DEBUG_VM
547 help
548 Enable this to turn on VMA caching debug information. Doing so
549 can cause significant overhead, so only enable it in non-production
550 environments.
551
552 If unsure, say N.
553
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554config DEBUG_VM_RB
555 bool "Debug VM red-black trees"
556 depends on DEBUG_VM
557 help
a663dad6 558 Enable VM red-black tree debugging information and extra validations.
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559
560 If unsure, say N.
561
562config DEBUG_VIRTUAL
563 bool "Debug VM translations"
564 depends on DEBUG_KERNEL && X86
565 help
566 Enable some costly sanity checks in virtual to page code. This can
567 catch mistakes with virt_to_page() and friends.
568
569 If unsure, say N.
570
571config DEBUG_NOMMU_REGIONS
572 bool "Debug the global anon/private NOMMU mapping region tree"
573 depends on DEBUG_KERNEL && !MMU
574 help
575 This option causes the global tree of anonymous and private mapping
576 regions to be regularly checked for invalid topology.
577
578config DEBUG_MEMORY_INIT
579 bool "Debug memory initialisation" if EXPERT
580 default !EXPERT
581 help
582 Enable this for additional checks during memory initialisation.
583 The sanity checks verify aspects of the VM such as the memory model
584 and other information provided by the architecture. Verbose
585 information will be printed at KERN_DEBUG loglevel depending
586 on the mminit_loglevel= command-line option.
587
588 If unsure, say Y
589
590config MEMORY_NOTIFIER_ERROR_INJECT
591 tristate "Memory hotplug notifier error injection module"
592 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
593 help
594 This option provides the ability to inject artificial errors to
595 memory hotplug notifier chain callbacks. It is controlled through
596 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
597
598 If the notifier call chain should be failed with some events
599 notified, write the error code to "actions/<notifier event>/error".
600
601 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
602
603 # cd /sys/kernel/debug/notifier-error-inject/memory
604 # echo -12 > actions/MEM_GOING_OFFLINE/error
605 # echo offline > /sys/devices/system/memory/memoryXXX/state
606 bash: echo: write error: Cannot allocate memory
607
608 To compile this code as a module, choose M here: the module will
609 be called memory-notifier-error-inject.
610
611 If unsure, say N.
612
613config DEBUG_PER_CPU_MAPS
614 bool "Debug access to per_cpu maps"
615 depends on DEBUG_KERNEL
616 depends on SMP
617 help
618 Say Y to verify that the per_cpu map being accessed has
619 been set up. This adds a fair amount of code to kernel memory
620 and decreases performance.
621
622 Say N if unsure.
623
624config DEBUG_HIGHMEM
625 bool "Highmem debugging"
626 depends on DEBUG_KERNEL && HIGHMEM
627 help
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628 This option enables additional error checking for high memory
629 systems. Disable for production systems.
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630
631config HAVE_DEBUG_STACKOVERFLOW
632 bool
633
634config DEBUG_STACKOVERFLOW
635 bool "Check for stack overflows"
636 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
637 ---help---
638 Say Y here if you want to check for overflows of kernel, IRQ
edb0ec07 639 and exception stacks (if your architecture uses them). This
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640 option will show detailed messages if free stack space drops
641 below a certain limit.
642
643 These kinds of bugs usually occur when call-chains in the
644 kernel get too deep, especially when interrupts are
645 involved.
646
647 Use this in cases where you see apparently random memory
648 corruption, especially if it appears in 'struct thread_info'
649
650 If in doubt, say "N".
651
652source "lib/Kconfig.kmemcheck"
653
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654source "lib/Kconfig.kasan"
655
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656endmenu # "Memory Debugging"
657
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658config DEBUG_SHIRQ
659 bool "Debug shared IRQ handlers"
0244ad00 660 depends on DEBUG_KERNEL
a304e1b8
DW
661 help
662 Enable this to generate a spurious interrupt as soon as a shared
663 interrupt handler is registered, and just before one is deregistered.
664 Drivers ought to be able to handle interrupts coming in at those
665 points; some don't and need to be caught.
666
92aef8fb
DH
667menu "Debug Lockups and Hangs"
668
58687acb
DZ
669config LOCKUP_DETECTOR
670 bool "Detect Hard and Soft Lockups"
dea20a3f 671 depends on DEBUG_KERNEL && !S390
8446f1d3 672 help
58687acb
DZ
673 Say Y here to enable the kernel to act as a watchdog to detect
674 hard and soft lockups.
675
676 Softlockups are bugs that cause the kernel to loop in kernel
5f329089 677 mode for more than 20 seconds, without giving other tasks a
58687acb
DZ
678 chance to run. The current stack trace is displayed upon
679 detection and the system will stay locked up.
8446f1d3 680
58687acb 681 Hardlockups are bugs that cause the CPU to loop in kernel mode
5f329089 682 for more than 10 seconds, without letting other interrupts have a
58687acb
DZ
683 chance to run. The current stack trace is displayed upon detection
684 and the system will stay locked up.
8446f1d3 685
58687acb 686 The overhead should be minimal. A periodic hrtimer runs to
5f329089
FLVC
687 generate interrupts and kick the watchdog task every 4 seconds.
688 An NMI is generated every 10 seconds or so to check for hardlockups.
689
690 The frequency of hrtimer and NMI events and the soft and hard lockup
691 thresholds can be controlled through the sysctl watchdog_thresh.
8446f1d3 692
23637d47 693config HARDLOCKUP_DETECTOR
8f1f66ed
JB
694 def_bool y
695 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
696 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
8446f1d3 697
fef2c9bc
DZ
698config BOOTPARAM_HARDLOCKUP_PANIC
699 bool "Panic (Reboot) On Hard Lockups"
8f1f66ed 700 depends on HARDLOCKUP_DETECTOR
fef2c9bc
DZ
701 help
702 Say Y here to enable the kernel to panic on "hard lockups",
703 which are bugs that cause the kernel to loop in kernel
5f329089
FLVC
704 mode with interrupts disabled for more than 10 seconds (configurable
705 using the watchdog_thresh sysctl).
fef2c9bc
DZ
706
707 Say N if unsure.
708
709config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
710 int
8f1f66ed 711 depends on HARDLOCKUP_DETECTOR
fef2c9bc
DZ
712 range 0 1
713 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
714 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
715
9c44bc03
IM
716config BOOTPARAM_SOFTLOCKUP_PANIC
717 bool "Panic (Reboot) On Soft Lockups"
89d7ce2a 718 depends on LOCKUP_DETECTOR
9c44bc03
IM
719 help
720 Say Y here to enable the kernel to panic on "soft lockups",
721 which are bugs that cause the kernel to loop in kernel
5f329089
FLVC
722 mode for more than 20 seconds (configurable using the watchdog_thresh
723 sysctl), without giving other tasks a chance to run.
9c44bc03
IM
724
725 The panic can be used in combination with panic_timeout,
726 to cause the system to reboot automatically after a
727 lockup has been detected. This feature is useful for
728 high-availability systems that have uptime guarantees and
729 where a lockup must be resolved ASAP.
730
731 Say N if unsure.
732
733config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
734 int
e16bb1d7 735 depends on LOCKUP_DETECTOR
9c44bc03
IM
736 range 0 1
737 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
738 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
739
e162b39a
MSB
740config DETECT_HUNG_TASK
741 bool "Detect Hung Tasks"
742 depends on DEBUG_KERNEL
8edbb83e 743 default LOCKUP_DETECTOR
e162b39a 744 help
0610c8a8
DH
745 Say Y here to enable the kernel to detect "hung tasks",
746 which are bugs that cause the task to be stuck in
747 uninterruptible "D" state indefinitiley.
1da177e4 748
0610c8a8
DH
749 When a hung task is detected, the kernel will print the
750 current stack trace (which you should report), but the
751 task will stay in uninterruptible state. If lockdep is
752 enabled then all held locks will also be reported. This
753 feature has negligible overhead.
871751e2 754
0610c8a8
DH
755config DEFAULT_HUNG_TASK_TIMEOUT
756 int "Default timeout for hung task detection (in seconds)"
757 depends on DETECT_HUNG_TASK
758 default 120
f0630fff 759 help
0610c8a8
DH
760 This option controls the default timeout (in seconds) used
761 to determine when a task has become non-responsive and should
762 be considered hung.
f0630fff 763
0610c8a8
DH
764 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
765 sysctl or by writing a value to
766 /proc/sys/kernel/hung_task_timeout_secs.
8ff12cfc 767
0610c8a8
DH
768 A timeout of 0 disables the check. The default is two minutes.
769 Keeping the default should be fine in most cases.
b69ec42b 770
0610c8a8
DH
771config BOOTPARAM_HUNG_TASK_PANIC
772 bool "Panic (Reboot) On Hung Tasks"
773 depends on DETECT_HUNG_TASK
3bba00d7 774 help
0610c8a8
DH
775 Say Y here to enable the kernel to panic on "hung tasks",
776 which are bugs that cause the kernel to leave a task stuck
777 in uninterruptible "D" state.
3bba00d7 778
0610c8a8
DH
779 The panic can be used in combination with panic_timeout,
780 to cause the system to reboot automatically after a
781 hung task has been detected. This feature is useful for
782 high-availability systems that have uptime guarantees and
783 where a hung tasks must be resolved ASAP.
bf96d1e3 784
0610c8a8 785 Say N if unsure.
bf96d1e3 786
0610c8a8
DH
787config BOOTPARAM_HUNG_TASK_PANIC_VALUE
788 int
789 depends on DETECT_HUNG_TASK
790 range 0 1
791 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
792 default 1 if BOOTPARAM_HUNG_TASK_PANIC
3bba00d7 793
92aef8fb
DH
794endmenu # "Debug lockups and hangs"
795
796config PANIC_ON_OOPS
797 bool "Panic on Oops"
a9d9058a 798 help
92aef8fb
DH
799 Say Y here to enable the kernel to panic when it oopses. This
800 has the same effect as setting oops=panic on the kernel command
801 line.
a9d9058a 802
92aef8fb
DH
803 This feature is useful to ensure that the kernel does not do
804 anything erroneous after an oops which could result in data
805 corruption or other issues.
806
807 Say N if unsure.
808
809config PANIC_ON_OOPS_VALUE
810 int
811 range 0 1
812 default 0 if !PANIC_ON_OOPS
813 default 1 if PANIC_ON_OOPS
814
5800dc3c
JB
815config PANIC_TIMEOUT
816 int "panic timeout"
817 default 0
818 help
819 Set the timeout value (in seconds) until a reboot occurs when the
820 the kernel panics. If n = 0, then we wait forever. A timeout
821 value n > 0 will wait n seconds before rebooting, while a timeout
822 value n < 0 will reboot immediately.
823
0610c8a8
DH
824config SCHED_DEBUG
825 bool "Collect scheduler debugging info"
826 depends on DEBUG_KERNEL && PROC_FS
827 default y
0822ee4a 828 help
0610c8a8
DH
829 If you say Y here, the /proc/sched_debug file will be provided
830 that can help debug the scheduler. The runtime overhead of this
831 option is minimal.
0822ee4a 832
0610c8a8
DH
833config SCHEDSTATS
834 bool "Collect scheduler statistics"
835 depends on DEBUG_KERNEL && PROC_FS
836 help
837 If you say Y here, additional code will be inserted into the
838 scheduler and related routines to collect statistics about
839 scheduler behavior and provide them in /proc/schedstat. These
840 stats may be useful for both tuning and debugging the scheduler
841 If you aren't debugging the scheduler or trying to tune a specific
842 application, you can say N to avoid the very slight overhead
843 this adds.
0822ee4a 844
0d9e2632
AT
845config SCHED_STACK_END_CHECK
846 bool "Detect stack corruption on calls to schedule()"
847 depends on DEBUG_KERNEL
848 default n
849 help
850 This option checks for a stack overrun on calls to schedule().
851 If the stack end location is found to be over written always panic as
852 the content of the corrupted region can no longer be trusted.
853 This is to ensure no erroneous behaviour occurs which could result in
854 data corruption or a sporadic crash at a later stage once the region
855 is examined. The runtime overhead introduced is minimal.
856
0610c8a8
DH
857config TIMER_STATS
858 bool "Collect kernel timers statistics"
859 depends on DEBUG_KERNEL && PROC_FS
ab0155a2 860 help
0610c8a8
DH
861 If you say Y here, additional code will be inserted into the
862 timer routines to collect statistics about kernel timers being
863 reprogrammed. The statistics can be read from /proc/timer_stats.
864 The statistics collection is started by writing 1 to /proc/timer_stats,
865 writing 0 stops it. This feature is useful to collect information
866 about timer usage patterns in kernel and userspace. This feature
867 is lightweight if enabled in the kernel config but not activated
868 (it defaults to deactivated on bootup and will only be activated
869 if some application like powertop activates it explicitly).
ab0155a2 870
1da177e4
LT
871config DEBUG_PREEMPT
872 bool "Debug preemptible kernel"
01deab98 873 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1da177e4
LT
874 default y
875 help
876 If you say Y here then the kernel will use a debug variant of the
877 commonly used smp_processor_id() function and will print warnings
878 if kernel code uses it in a preemption-unsafe way. Also, the kernel
879 will detect preemption count underflows.
880
9eade16b
DH
881menu "Lock Debugging (spinlocks, mutexes, etc...)"
882
e7eebaf6
IM
883config DEBUG_RT_MUTEXES
884 bool "RT Mutex debugging, deadlock detection"
e7eebaf6
IM
885 depends on DEBUG_KERNEL && RT_MUTEXES
886 help
887 This allows rt mutex semantics violations and rt mutex related
888 deadlocks (lockups) to be detected and reported automatically.
889
61a87122
TG
890config RT_MUTEX_TESTER
891 bool "Built-in scriptable tester for rt-mutexes"
6cc620bc 892 depends on DEBUG_KERNEL && RT_MUTEXES && BROKEN
61a87122
TG
893 help
894 This option enables a rt-mutex tester.
895
1da177e4 896config DEBUG_SPINLOCK
4d9f34ad 897 bool "Spinlock and rw-lock debugging: basic checks"
1da177e4 898 depends on DEBUG_KERNEL
e335e3eb 899 select UNINLINE_SPIN_UNLOCK
1da177e4
LT
900 help
901 Say Y here and build SMP to catch missing spinlock initialization
902 and certain other kinds of spinlock errors commonly made. This is
903 best used in conjunction with the NMI watchdog so that spinlock
904 deadlocks are also debuggable.
905
4d9f34ad
IM
906config DEBUG_MUTEXES
907 bool "Mutex debugging: basic checks"
908 depends on DEBUG_KERNEL
909 help
910 This feature allows mutex semantics violations to be detected and
911 reported.
912
23010027
DV
913config DEBUG_WW_MUTEX_SLOWPATH
914 bool "Wait/wound mutex debugging: Slowpath testing"
915 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
916 select DEBUG_LOCK_ALLOC
917 select DEBUG_SPINLOCK
918 select DEBUG_MUTEXES
919 help
920 This feature enables slowpath testing for w/w mutex users by
921 injecting additional -EDEADLK wound/backoff cases. Together with
922 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
923 will test all possible w/w mutex interface abuse with the
924 exception of simply not acquiring all the required locks.
4d692373
RC
925 Note that this feature can introduce significant overhead, so
926 it really should not be enabled in a production or distro kernel,
927 even a debug kernel. If you are a driver writer, enable it. If
928 you are a distro, do not.
23010027 929
4d9f34ad
IM
930config DEBUG_LOCK_ALLOC
931 bool "Lock debugging: detect incorrect freeing of live locks"
517e7aa5 932 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad
IM
933 select DEBUG_SPINLOCK
934 select DEBUG_MUTEXES
4d9f34ad
IM
935 select LOCKDEP
936 help
937 This feature will check whether any held lock (spinlock, rwlock,
938 mutex or rwsem) is incorrectly freed by the kernel, via any of the
939 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
940 vfree(), etc.), whether a live lock is incorrectly reinitialized via
941 spin_lock_init()/mutex_init()/etc., or whether there is any lock
942 held during task exit.
943
944config PROVE_LOCKING
945 bool "Lock debugging: prove locking correctness"
517e7aa5 946 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad
IM
947 select LOCKDEP
948 select DEBUG_SPINLOCK
949 select DEBUG_MUTEXES
4d9f34ad 950 select DEBUG_LOCK_ALLOC
46b93b74 951 select TRACE_IRQFLAGS
4d9f34ad
IM
952 default n
953 help
954 This feature enables the kernel to prove that all locking
955 that occurs in the kernel runtime is mathematically
956 correct: that under no circumstance could an arbitrary (and
957 not yet triggered) combination of observed locking
958 sequences (on an arbitrary number of CPUs, running an
959 arbitrary number of tasks and interrupt contexts) cause a
960 deadlock.
961
962 In short, this feature enables the kernel to report locking
963 related deadlocks before they actually occur.
964
965 The proof does not depend on how hard and complex a
966 deadlock scenario would be to trigger: how many
967 participant CPUs, tasks and irq-contexts would be needed
968 for it to trigger. The proof also does not depend on
969 timing: if a race and a resulting deadlock is possible
970 theoretically (no matter how unlikely the race scenario
971 is), it will be proven so and will immediately be
972 reported by the kernel (once the event is observed that
973 makes the deadlock theoretically possible).
974
975 If a deadlock is impossible (i.e. the locking rules, as
976 observed by the kernel, are mathematically correct), the
977 kernel reports nothing.
978
979 NOTE: this feature can also be enabled for rwlocks, mutexes
980 and rwsems - in which case all dependencies between these
981 different locking variants are observed and mapped too, and
982 the proof of observed correctness is also maintained for an
983 arbitrary combination of these separate locking variants.
984
214e0aed 985 For more details, see Documentation/locking/lockdep-design.txt.
4d9f34ad
IM
986
987config LOCKDEP
988 bool
517e7aa5 989 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad 990 select STACKTRACE
df2e1ef6 991 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
4d9f34ad
IM
992 select KALLSYMS
993 select KALLSYMS_ALL
994
f20786ff 995config LOCK_STAT
fdfb870f 996 bool "Lock usage statistics"
f20786ff
PZ
997 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
998 select LOCKDEP
999 select DEBUG_SPINLOCK
1000 select DEBUG_MUTEXES
1001 select DEBUG_LOCK_ALLOC
1002 default n
1003 help
1004 This feature enables tracking lock contention points
1005
214e0aed 1006 For more details, see Documentation/locking/lockstat.txt
a560aa48 1007
dd8b1cf6
FW
1008 This also enables lock events required by "perf lock",
1009 subcommand of perf.
1010 If you want to use "perf lock", you also need to turn on
1011 CONFIG_EVENT_TRACING.
84c6f88f
HM
1012
1013 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
dd8b1cf6 1014 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
84c6f88f 1015
4d9f34ad
IM
1016config DEBUG_LOCKDEP
1017 bool "Lock dependency engine debugging"
517e7aa5 1018 depends on DEBUG_KERNEL && LOCKDEP
4d9f34ad
IM
1019 help
1020 If you say Y here, the lock dependency engine will do
1021 additional runtime checks to debug itself, at the price
1022 of more runtime overhead.
1023
d902db1e
FW
1024config DEBUG_ATOMIC_SLEEP
1025 bool "Sleep inside atomic section checking"
e8f7c70f 1026 select PREEMPT_COUNT
1da177e4
LT
1027 depends on DEBUG_KERNEL
1028 help
1029 If you say Y here, various routines which may sleep will become very
d902db1e
FW
1030 noisy if they are called inside atomic sections: when a spinlock is
1031 held, inside an rcu read side critical section, inside preempt disabled
1032 sections, inside an interrupt, etc...
1da177e4 1033
cae2ed9a
IM
1034config DEBUG_LOCKING_API_SELFTESTS
1035 bool "Locking API boot-time self-tests"
1036 depends on DEBUG_KERNEL
1037 help
1038 Say Y here if you want the kernel to run a short self-test during
1039 bootup. The self-test checks whether common types of locking bugs
1040 are detected by debugging mechanisms or not. (if you disable
1041 lock debugging then those bugs wont be detected of course.)
1042 The following locking APIs are covered: spinlocks, rwlocks,
1043 mutexes and rwsems.
1044
0af3fe1e
PM
1045config LOCK_TORTURE_TEST
1046 tristate "torture tests for locking"
1047 depends on DEBUG_KERNEL
1048 select TORTURE_TEST
1049 default n
1050 help
1051 This option provides a kernel module that runs torture tests
1052 on kernel locking primitives. The kernel module may be built
1053 after the fact on the running kernel to be tested, if desired.
1054
1055 Say Y here if you want kernel locking-primitive torture tests
1056 to be built into the kernel.
1057 Say M if you want these torture tests to build as a module.
1058 Say N if you are unsure.
1059
9eade16b 1060endmenu # lock debugging
8637c099 1061
9eade16b
DH
1062config TRACE_IRQFLAGS
1063 bool
5ca43f6c 1064 help
9eade16b
DH
1065 Enables hooks to interrupt enabling and disabling for
1066 either tracing or lock debugging.
5ca43f6c 1067
8637c099 1068config STACKTRACE
0c38e1fe 1069 bool "Stack backtrace support"
8637c099 1070 depends on STACKTRACE_SUPPORT
0c38e1fe
DJ
1071 help
1072 This option causes the kernel to create a /proc/pid/stack for
1073 every process, showing its current stack trace.
1074 It is also used by various kernel debugging features that require
1075 stack trace generation.
5ca43f6c 1076
1da177e4
LT
1077config DEBUG_KOBJECT
1078 bool "kobject debugging"
1079 depends on DEBUG_KERNEL
1080 help
1081 If you say Y here, some extra kobject debugging messages will be sent
1082 to the syslog.
1083
c817a67e
RK
1084config DEBUG_KOBJECT_RELEASE
1085 bool "kobject release debugging"
2a999aa0 1086 depends on DEBUG_OBJECTS_TIMERS
c817a67e
RK
1087 help
1088 kobjects are reference counted objects. This means that their
1089 last reference count put is not predictable, and the kobject can
1090 live on past the point at which a driver decides to drop it's
1091 initial reference to the kobject gained on allocation. An
1092 example of this would be a struct device which has just been
1093 unregistered.
1094
1095 However, some buggy drivers assume that after such an operation,
1096 the memory backing the kobject can be immediately freed. This
1097 goes completely against the principles of a refcounted object.
1098
1099 If you say Y here, the kernel will delay the release of kobjects
1100 on the last reference count to improve the visibility of this
1101 kind of kobject release bug.
1102
9b2a60c4
CM
1103config HAVE_DEBUG_BUGVERBOSE
1104 bool
1105
1da177e4 1106config DEBUG_BUGVERBOSE
6a108a14 1107 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
9b2a60c4 1108 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
8420e7ef 1109 default y
1da177e4
LT
1110 help
1111 Say Y here to make BUG() panics output the file name and line number
1112 of the BUG call as well as the EIP and oops trace. This aids
1113 debugging but costs about 70-100K of memory.
1114
199a9afc
DJ
1115config DEBUG_LIST
1116 bool "Debug linked list manipulation"
1117 depends on DEBUG_KERNEL
1118 help
1119 Enable this to turn on extended checks in the linked-list
1120 walking routines.
1121
1122 If unsure, say N.
1123
b8cfff68
DS
1124config DEBUG_PI_LIST
1125 bool "Debug priority linked list manipulation"
1126 depends on DEBUG_KERNEL
1127 help
1128 Enable this to turn on extended checks in the priority-ordered
1129 linked-list (plist) walking routines. This checks the entire
1130 list multiple times during each manipulation.
1131
1132 If unsure, say N.
1133
d6ec0842
JA
1134config DEBUG_SG
1135 bool "Debug SG table operations"
1136 depends on DEBUG_KERNEL
1137 help
1138 Enable this to turn on checks on scatter-gather tables. This can
1139 help find problems with drivers that do not properly initialize
1140 their sg tables.
1141
1142 If unsure, say N.
1143
1b2439db
AV
1144config DEBUG_NOTIFIERS
1145 bool "Debug notifier call chains"
1146 depends on DEBUG_KERNEL
1147 help
1148 Enable this to turn on sanity checking for notifier call chains.
1149 This is most useful for kernel developers to make sure that
1150 modules properly unregister themselves from notifier chains.
1151 This is a relatively cheap check but if you care about maximum
1152 performance, say N.
1153
e0e81739
DH
1154config DEBUG_CREDENTIALS
1155 bool "Debug credential management"
1156 depends on DEBUG_KERNEL
1157 help
1158 Enable this to turn on some debug checking for credential
1159 management. The additional code keeps track of the number of
1160 pointers from task_structs to any given cred struct, and checks to
1161 see that this number never exceeds the usage count of the cred
1162 struct.
1163
1164 Furthermore, if SELinux is enabled, this also checks that the
1165 security pointer in the cred struct is never seen to be invalid.
1166
1167 If unsure, say N.
1168
2f03e3ca
DH
1169menu "RCU Debugging"
1170
1171config PROVE_RCU
1172 bool "RCU debugging: prove RCU correctness"
1173 depends on PROVE_LOCKING
1174 default n
1175 help
1176 This feature enables lockdep extensions that check for correct
1177 use of RCU APIs. This is currently under development. Say Y
1178 if you want to debug RCU usage or help work on the PROVE_RCU
1179 feature.
1180
1181 Say N if you are unsure.
1182
1183config PROVE_RCU_REPEATEDLY
1184 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1185 depends on PROVE_RCU
1186 default n
1187 help
1188 By itself, PROVE_RCU will disable checking upon issuing the
1189 first warning (or "splat"). This feature prevents such
1190 disabling, allowing multiple RCU-lockdep warnings to be printed
1191 on a single reboot.
1192
1193 Say Y to allow multiple RCU-lockdep warnings per boot.
1194
1195 Say N if you are unsure.
1196
2f03e3ca
DH
1197config SPARSE_RCU_POINTER
1198 bool "RCU debugging: sparse-based checks for pointer usage"
1199 default n
1200 help
1201 This feature enables the __rcu sparse annotation for
1202 RCU-protected pointers. This annotation will cause sparse
1203 to flag any non-RCU used of annotated pointers. This can be
1204 helpful when debugging RCU usage. Please note that this feature
1205 is not intended to enforce code cleanliness; it is instead merely
1206 a debugging aid.
1207
1208 Say Y to make sparse flag questionable use of RCU-protected pointers
1209
1210 Say N if you are unsure.
1211
51b1130e
PM
1212config TORTURE_TEST
1213 tristate
1214 default n
1215
a241ec65
PM
1216config RCU_TORTURE_TEST
1217 tristate "torture tests for RCU"
1218 depends on DEBUG_KERNEL
51b1130e 1219 select TORTURE_TEST
83fe27ea 1220 select SRCU
a241ec65
PM
1221 default n
1222 help
1223 This option provides a kernel module that runs torture tests
1224 on the RCU infrastructure. The kernel module may be built
1225 after the fact on the running kernel to be tested, if desired.
1226
31a72bce
PM
1227 Say Y here if you want RCU torture tests to be built into
1228 the kernel.
a241ec65
PM
1229 Say M if you want the RCU torture tests to build as a module.
1230 Say N if you are unsure.
8bb31b9d 1231
31a72bce
PM
1232config RCU_TORTURE_TEST_RUNNABLE
1233 bool "torture tests for RCU runnable by default"
1234 depends on RCU_TORTURE_TEST = y
1235 default n
1236 help
1237 This option provides a way to build the RCU torture tests
1238 directly into the kernel without them starting up at boot
1239 time. You can use /proc/sys/kernel/rcutorture_runnable
1240 to manually override this setting. This /proc file is
1241 available only when the RCU torture tests have been built
1242 into the kernel.
1243
1244 Say Y here if you want the RCU torture tests to start during
1245 boot (you probably don't).
1246 Say N here if you want the RCU torture tests to start only
1247 after being manually enabled via /proc.
1248
b163760e
PM
1249config RCU_CPU_STALL_TIMEOUT
1250 int "RCU CPU stall timeout in seconds"
6bfc09e2 1251 depends on RCU_STALL_COMMON
b163760e 1252 range 3 300
c896054f 1253 default 21
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1254 help
1255 If a given RCU grace period extends more than the specified
1256 number of seconds, a CPU stall warning is printed. If the
1257 RCU grace period persists, additional CPU stall warnings are
1258 printed at more widely spaced intervals.
1259
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1260config RCU_CPU_STALL_INFO
1261 bool "Print additional diagnostics on RCU CPU stall"
28f6569a 1262 depends on (TREE_RCU || PREEMPT_RCU) && DEBUG_KERNEL
68158fe2 1263 default y
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1264 help
1265 For each stalled CPU that is aware of the current RCU grace
1266 period, print out additional per-CPU diagnostic information
1267 regarding scheduling-clock ticks, idle state, and,
1268 for RCU_FAST_NO_HZ kernels, idle-entry state.
1269
1270 Say N if you are unsure.
1271
1272 Say Y if you want to enable such diagnostics.
1273
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1274config RCU_TRACE
1275 bool "Enable tracing for RCU"
6dab2778 1276 depends on DEBUG_KERNEL
52494535 1277 select TRACE_CLOCK
6dab2778 1278 help
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PM
1279 This option provides tracing in RCU which presents stats
1280 in debugfs for debugging RCU implementation.
ad118c54 1281
5c8806a0 1282 Say Y here if you want to enable RCU tracing
6dab2778
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1283 Say N if you are unsure.
1284
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1285endmenu # "RCU Debugging"
1286
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1287config DEBUG_BLOCK_EXT_DEVT
1288 bool "Force extended block device numbers and spread them"
1289 depends on DEBUG_KERNEL
1290 depends on BLOCK
759f8ca3 1291 default n
870d6656 1292 help
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1293 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1294 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1295 YOU ARE DOING. Distros, please enable this and fix whatever
1296 is broken.
1297
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1298 Conventionally, block device numbers are allocated from
1299 predetermined contiguous area. However, extended block area
1300 may introduce non-contiguous block device numbers. This
1301 option forces most block device numbers to be allocated from
1302 the extended space and spreads them to discover kernel or
1303 userland code paths which assume predetermined contiguous
1304 device number allocation.
1305
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1306 Note that turning on this debug option shuffles all the
1307 device numbers for all IDE and SCSI devices including libata
1308 ones, so root partition specified using device number
1309 directly (via rdev or root=MAJ:MIN) won't work anymore.
1310 Textual device names (root=/dev/sdXn) will continue to work.
1311
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1312 Say N if you are unsure.
1313
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1314config NOTIFIER_ERROR_INJECTION
1315 tristate "Notifier error injection"
1316 depends on DEBUG_KERNEL
1317 select DEBUG_FS
1318 help
e41e85cc 1319 This option provides the ability to inject artificial errors to
8d438288
AM
1320 specified notifier chain callbacks. It is useful to test the error
1321 handling of notifier call chain failures.
1322
1323 Say N if unsure.
1324
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1325config CPU_NOTIFIER_ERROR_INJECT
1326 tristate "CPU notifier error injection module"
f5a9f52e 1327 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
c9d221f8
AM
1328 help
1329 This option provides a kernel module that can be used to test
e41e85cc 1330 the error handling of the cpu notifiers by injecting artificial
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1331 errors to CPU notifier chain callbacks. It is controlled through
1332 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1333
1334 If the notifier call chain should be failed with some events
1335 notified, write the error code to "actions/<notifier event>/error".
1336
1337 Example: Inject CPU offline error (-1 == -EPERM)
1338
1339 # cd /sys/kernel/debug/notifier-error-inject/cpu
1340 # echo -1 > actions/CPU_DOWN_PREPARE/error
1341 # echo 0 > /sys/devices/system/cpu/cpu1/online
1342 bash: echo: write error: Operation not permitted
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1343
1344 To compile this code as a module, choose M here: the module will
1345 be called cpu-notifier-error-inject.
1346
1347 If unsure, say N.
1348
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1349config PM_NOTIFIER_ERROR_INJECT
1350 tristate "PM notifier error injection module"
1351 depends on PM && NOTIFIER_ERROR_INJECTION
1352 default m if PM_DEBUG
1353 help
e41e85cc 1354 This option provides the ability to inject artificial errors to
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AM
1355 PM notifier chain callbacks. It is controlled through debugfs
1356 interface /sys/kernel/debug/notifier-error-inject/pm
1357
1358 If the notifier call chain should be failed with some events
1359 notified, write the error code to "actions/<notifier event>/error".
1360
1361 Example: Inject PM suspend error (-12 = -ENOMEM)
1362
1363 # cd /sys/kernel/debug/notifier-error-inject/pm/
1364 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1365 # echo mem > /sys/power/state
1366 bash: echo: write error: Cannot allocate memory
1367
1368 To compile this code as a module, choose M here: the module will
1369 be called pm-notifier-error-inject.
1370
1371 If unsure, say N.
1372
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1373config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1374 tristate "OF reconfig notifier error injection module"
1375 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
08dfb4dd 1376 help
e41e85cc 1377 This option provides the ability to inject artificial errors to
d526e85f 1378 OF reconfig notifier chain callbacks. It is controlled
08dfb4dd 1379 through debugfs interface under
d526e85f 1380 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
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1381
1382 If the notifier call chain should be failed with some events
1383 notified, write the error code to "actions/<notifier event>/error".
1384
1385 To compile this code as a module, choose M here: the module will
e12a95f4 1386 be called of-reconfig-notifier-error-inject.
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1387
1388 If unsure, say N.
1389
6ff1cb35 1390config FAULT_INJECTION
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1391 bool "Fault-injection framework"
1392 depends on DEBUG_KERNEL
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1393 help
1394 Provide fault-injection framework.
1395 For more details, see Documentation/fault-injection/.
6ff1cb35 1396
8a8b6502 1397config FAILSLAB
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1398 bool "Fault-injection capability for kmalloc"
1399 depends on FAULT_INJECTION
773ff60e 1400 depends on SLAB || SLUB
8a8b6502 1401 help
1ab8509a 1402 Provide fault-injection capability for kmalloc.
8a8b6502 1403
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1404config FAIL_PAGE_ALLOC
1405 bool "Fault-injection capabilitiy for alloc_pages()"
1ab8509a 1406 depends on FAULT_INJECTION
933e312e 1407 help
1ab8509a 1408 Provide fault-injection capability for alloc_pages().
933e312e 1409
c17bb495 1410config FAIL_MAKE_REQUEST
86327d19 1411 bool "Fault-injection capability for disk IO"
581d4e28 1412 depends on FAULT_INJECTION && BLOCK
c17bb495 1413 help
1ab8509a 1414 Provide fault-injection capability for disk IO.
c17bb495 1415
581d4e28 1416config FAIL_IO_TIMEOUT
f4d01439 1417 bool "Fault-injection capability for faking disk interrupts"
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JA
1418 depends on FAULT_INJECTION && BLOCK
1419 help
1420 Provide fault-injection capability on end IO handling. This
1421 will make the block layer "forget" an interrupt as configured,
1422 thus exercising the error handling.
1423
1424 Only works with drivers that use the generic timeout handling,
1425 for others it wont do anything.
1426
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PF
1427config FAIL_MMC_REQUEST
1428 bool "Fault-injection capability for MMC IO"
1429 select DEBUG_FS
1430 depends on FAULT_INJECTION && MMC
1431 help
1432 Provide fault-injection capability for MMC IO.
1433 This will make the mmc core return data errors. This is
1434 useful to test the error handling in the mmc block device
1435 and to test how the mmc host driver handles retries from
1436 the block device.
1437
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1438config FAULT_INJECTION_DEBUG_FS
1439 bool "Debugfs entries for fault-injection capabilities"
1ab8509a 1440 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
6ff1cb35 1441 help
1ab8509a 1442 Enable configuration of fault-injection capabilities via debugfs.
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1443
1444config FAULT_INJECTION_STACKTRACE_FILTER
1445 bool "stacktrace filter for fault-injection capabilities"
1446 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
6d690dca 1447 depends on !X86_64
1df49008 1448 select STACKTRACE
df2e1ef6 1449 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
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1450 help
1451 Provide stacktrace filter for fault-injection capabilities
267c4025 1452
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AV
1453config LATENCYTOP
1454 bool "Latency measuring infrastructure"
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1455 depends on HAVE_LATENCYTOP_SUPPORT
1456 depends on DEBUG_KERNEL
1457 depends on STACKTRACE_SUPPORT
1458 depends on PROC_FS
cc80ae38 1459 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
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AV
1460 select KALLSYMS
1461 select KALLSYMS_ALL
1462 select STACKTRACE
1463 select SCHEDSTATS
1464 select SCHED_DEBUG
9745512c
AV
1465 help
1466 Enable this option if you want to use the LatencyTOP tool
1467 to find out which userspace is blocking on what kernel operations.
1468
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1469config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1470 bool
1471
1472config DEBUG_STRICT_USER_COPY_CHECKS
1473 bool "Strict user copy size checks"
1474 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1475 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1476 help
1477 Enabling this option turns a certain set of sanity checks for user
1478 copy operations into compile time failures.
1479
1480 The copy_from_user() etc checks are there to help test if there
1481 are sufficient security checks on the length argument of
1482 the copy operation, by having gcc prove that the argument is
1483 within bounds.
1484
1485 If unsure, say N.
1486
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ACM
1487source kernel/trace/Kconfig
1488
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DH
1489menu "Runtime Testing"
1490
1491config LKDTM
1492 tristate "Linux Kernel Dump Test Tool Module"
1493 depends on DEBUG_FS
1494 depends on BLOCK
1495 default n
1496 help
1497 This module enables testing of the different dumping mechanisms by
1498 inducing system failures at predefined crash points.
1499 If you don't need it: say N
1500 Choose M here to compile this code as a module. The module will be
1501 called lkdtm.
1502
1503 Documentation on how to use the module can be found in
1504 Documentation/fault-injection/provoke-crashes.txt
1505
1506config TEST_LIST_SORT
1507 bool "Linked list sorting test"
1508 depends on DEBUG_KERNEL
1509 help
1510 Enable this to turn on 'list_sort()' function test. This test is
1511 executed only once during system boot, so affects only boot time.
1512
1513 If unsure, say N.
1514
1515config KPROBES_SANITY_TEST
1516 bool "Kprobes sanity tests"
1517 depends on DEBUG_KERNEL
1518 depends on KPROBES
1519 default n
1520 help
1521 This option provides for testing basic kprobes functionality on
1522 boot. A sample kprobe, jprobe and kretprobe are inserted and
1523 verified for functionality.
1524
1525 Say N if you are unsure.
1526
1527config BACKTRACE_SELF_TEST
1528 tristate "Self test for the backtrace code"
1529 depends on DEBUG_KERNEL
1530 default n
1531 help
1532 This option provides a kernel module that can be used to test
1533 the kernel stack backtrace code. This option is not useful
1534 for distributions or general kernels, but only for kernel
1535 developers working on architecture code.
1536
1537 Note that if you want to also test saved backtraces, you will
1538 have to enable STACKTRACE as well.
1539
1540 Say N if you are unsure.
1541
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ML
1542config RBTREE_TEST
1543 tristate "Red-Black tree test"
7c993e11 1544 depends on DEBUG_KERNEL
910a742d
ML
1545 help
1546 A benchmark measuring the performance of the rbtree library.
1547 Also includes rbtree invariant checks.
1548
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ML
1549config INTERVAL_TREE_TEST
1550 tristate "Interval tree test"
1551 depends on m && DEBUG_KERNEL
a88cc108 1552 select INTERVAL_TREE
fff3fd8a
ML
1553 help
1554 A benchmark measuring the performance of the interval tree library
1555
623fd807
GT
1556config PERCPU_TEST
1557 tristate "Per cpu operations test"
1558 depends on m && DEBUG_KERNEL
1559 help
1560 Enable this option to build test module which validates per-cpu
1561 operations.
1562
1563 If unsure, say N.
1564
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DH
1565config ATOMIC64_SELFTEST
1566 bool "Perform an atomic64_t self-test at boot"
1567 help
1568 Enable this option to test the atomic64_t functions at boot.
1569
1570 If unsure, say N.
1571
1572config ASYNC_RAID6_TEST
1573 tristate "Self test for hardware accelerated raid6 recovery"
1574 depends on ASYNC_RAID6_RECOV
1575 select ASYNC_MEMCPY
1576 ---help---
1577 This is a one-shot self test that permutes through the
1578 recovery of all the possible two disk failure scenarios for a
1579 N-disk array. Recovery is performed with the asynchronous
1580 raid6 recovery routines, and will optionally use an offload
1581 engine if one is available.
1582
1583 If unsure, say N.
1584
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AS
1585config TEST_HEXDUMP
1586 tristate "Test functions located in the hexdump module at runtime"
1587
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1588config TEST_STRING_HELPERS
1589 tristate "Test functions located in the string_helpers module at runtime"
1590
1591config TEST_KSTRTOX
1592 tristate "Test kstrto*() family of functions at runtime"
1593
7e1e7763 1594config TEST_RHASHTABLE
9d6dbe1b 1595 tristate "Perform selftest on resizable hash table"
7e1e7763
TG
1596 default n
1597 help
1598 Enable this option to test the rhashtable functions at boot.
1599
1600 If unsure, say N.
1601
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DH
1602endmenu # runtime tests
1603
f212ec4b 1604config PROVIDE_OHCI1394_DMA_INIT
080de8c2 1605 bool "Remote debugging over FireWire early on boot"
f212ec4b
BK
1606 depends on PCI && X86
1607 help
1608 If you want to debug problems which hang or crash the kernel early
1609 on boot and the crashing machine has a FireWire port, you can use
1610 this feature to remotely access the memory of the crashed machine
1611 over FireWire. This employs remote DMA as part of the OHCI1394
1612 specification which is now the standard for FireWire controllers.
1613
1614 With remote DMA, you can monitor the printk buffer remotely using
1615 firescope and access all memory below 4GB using fireproxy from gdb.
1616 Even controlling a kernel debugger is possible using remote DMA.
1617
1618 Usage:
1619
1620 If ohci1394_dma=early is used as boot parameter, it will initialize
1621 all OHCI1394 controllers which are found in the PCI config space.
1622
1623 As all changes to the FireWire bus such as enabling and disabling
1624 devices cause a bus reset and thereby disable remote DMA for all
1625 devices, be sure to have the cable plugged and FireWire enabled on
1626 the debugging host before booting the debug target for debugging.
1627
1628 This code (~1k) is freed after boot. By then, the firewire stack
1629 in charge of the OHCI-1394 controllers should be used instead.
1630
1631 See Documentation/debugging-via-ohci1394.txt for more information.
9745512c 1632
152de30b 1633config BUILD_DOCSRC
3794f3e8
RD
1634 bool "Build targets in Documentation/ tree"
1635 depends on HEADERS_CHECK
1636 help
1637 This option attempts to build objects from the source files in the
1638 kernel Documentation/ tree.
1639
1640 Say N if you are unsure.
1641
5ee00bd4
JR
1642config DMA_API_DEBUG
1643 bool "Enable debugging of DMA-API usage"
1644 depends on HAVE_DMA_API_DEBUG
1645 help
1646 Enable this option to debug the use of the DMA API by device drivers.
1647 With this option you will be able to detect common bugs in device
1648 drivers like double-freeing of DMA mappings or freeing mappings that
1649 were never allocated.
0abdd7a8
DW
1650
1651 This also attempts to catch cases where a page owned by DMA is
1652 accessed by the cpu in a way that could cause data corruption. For
1653 example, this enables cow_user_page() to check that the source page is
1654 not undergoing DMA.
1655
1656 This option causes a performance degradation. Use only if you want to
1657 debug device drivers and dma interactions.
1658
1659 If unsure, say N.
346e15be 1660
8a6f0b47 1661config TEST_LKM
93e9ef83
KC
1662 tristate "Test module loading with 'hello world' module"
1663 default n
1664 depends on m
1665 help
1666 This builds the "test_module" module that emits "Hello, world"
1667 on printk when loaded. It is designed to be used for basic
1668 evaluation of the module loading subsystem (for example when
1669 validating module verification). It lacks any extra dependencies,
1670 and will not normally be loaded by the system unless explicitly
1671 requested by name.
1672
1673 If unsure, say N.
1674
3e2a4c18
KC
1675config TEST_USER_COPY
1676 tristate "Test user/kernel boundary protections"
1677 default n
1678 depends on m
1679 help
1680 This builds the "test_user_copy" module that runs sanity checks
1681 on the copy_to/from_user infrastructure, making sure basic
1682 user/kernel boundary testing is working. If it fails to load,
1683 a regression has been detected in the user/kernel memory boundary
1684 protections.
1685
1686 If unsure, say N.
1687
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AS
1688config TEST_BPF
1689 tristate "Test BPF filter functionality"
1690 default n
98920ba6 1691 depends on m && NET
64a8946b
AS
1692 help
1693 This builds the "test_bpf" module that runs various test vectors
1694 against the BPF interpreter or BPF JIT compiler depending on the
1695 current setting. This is in particular useful for BPF JIT compiler
1696 development, but also to run regression tests against changes in
3c731eba
AS
1697 the interpreter code. It also enables test stubs for eBPF maps and
1698 verifier used by user space verifier testsuite.
64a8946b
AS
1699
1700 If unsure, say N.
1701
0a8adf58
KC
1702config TEST_FIRMWARE
1703 tristate "Test firmware loading via userspace interface"
1704 default n
1705 depends on FW_LOADER
1706 help
1707 This builds the "test_firmware" module that creates a userspace
1708 interface for testing firmware loading. This can be used to
1709 control the triggering of firmware loading without needing an
1710 actual firmware-using device. The contents can be rechecked by
1711 userspace.
1712
1713 If unsure, say N.
1714
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DR
1715config TEST_UDELAY
1716 tristate "udelay test driver"
1717 default n
1718 help
1719 This builds the "udelay_test" module that helps to make sure
1720 that udelay() is working properly.
1721
1722 If unsure, say N.
1723
267c4025 1724source "samples/Kconfig"
dc7d5527
JW
1725
1726source "lib/Kconfig.kgdb"
0a4af3b0 1727
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