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Dave Hansen604ff0d2013-07-01 13:04:49 -07001menu "printk and dmesg options"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002
3config PRINTK_TIME
4 bool "Show timing information on printks"
Randy Dunlapd3b8b6e2006-12-06 20:36:38 -08005 depends on PRINTK
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 help
Kay Sievers649e6ee2012-05-10 04:30:45 +02007 Selecting this option causes time stamps of the printk()
8 messages to be added to the output of the syslog() system
9 call and at the console.
10
11 The timestamp is always recorded internally, and exported
12 to /dev/kmsg. This flag just specifies if the timestamp should
13 be included, not that the timestamp is recorded.
14
15 The behavior is also controlled by the kernel command line
16 parameter printk.time=1. See Documentation/kernel-parameters.txt
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
Alex Elder42a9dc02014-08-06 16:09:01 -070018config MESSAGE_LOGLEVEL_DEFAULT
Mandeep Singh Baines5af5bcb2011-03-22 16:34:23 -070019 int "Default message log level (1-7)"
20 range 1 7
21 default "4"
22 help
23 Default log level for printk statements with no specified priority.
24
25 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
26 that are auditing their logs closely may want to set it to a lower
27 priority.
28
Dave Hansen604ff0d2013-07-01 13:04:49 -070029config BOOT_PRINTK_DELAY
30 bool "Delay each boot printk message by N milliseconds"
31 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
32 help
33 This build option allows you to read kernel boot messages
34 by inserting a short delay after each one. The delay is
35 specified in milliseconds on the kernel command line,
36 using "boot_delay=N".
37
38 It is likely that you would also need to use "lpj=M" to preset
39 the "loops per jiffie" value.
40 See a previous boot log for the "lpj" value to use for your
41 system, and then set "lpj=M" before setting "boot_delay=N".
42 NOTE: Using this option may adversely affect SMP systems.
43 I.e., processors other than the first one may not boot up.
44 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
45 what it believes to be lockup conditions.
46
47config DYNAMIC_DEBUG
48 bool "Enable dynamic printk() support"
49 default n
50 depends on PRINTK
51 depends on DEBUG_FS
52 help
53
54 Compiles debug level messages into the kernel, which would not
55 otherwise be available at runtime. These messages can then be
56 enabled/disabled based on various levels of scope - per source file,
57 function, module, format string, and line number. This mechanism
58 implicitly compiles in all pr_debug() and dev_dbg() calls, which
59 enlarges the kernel text size by about 2%.
60
61 If a source file is compiled with DEBUG flag set, any
62 pr_debug() calls in it are enabled by default, but can be
63 disabled at runtime as below. Note that DEBUG flag is
64 turned on by many CONFIG_*DEBUG* options.
65
66 Usage:
67
68 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
69 which is contained in the 'debugfs' filesystem. Thus, the debugfs
70 filesystem must first be mounted before making use of this feature.
71 We refer the control file as: <debugfs>/dynamic_debug/control. This
72 file contains a list of the debug statements that can be enabled. The
73 format for each line of the file is:
74
75 filename:lineno [module]function flags format
76
77 filename : source file of the debug statement
78 lineno : line number of the debug statement
79 module : module that contains the debug statement
80 function : function that contains the debug statement
81 flags : '=p' means the line is turned 'on' for printing
82 format : the format used for the debug statement
83
84 From a live system:
85
86 nullarbor:~ # cat <debugfs>/dynamic_debug/control
87 # filename:lineno [module]function flags format
88 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
89 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
90 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
91
92 Example usage:
93
94 // enable the message at line 1603 of file svcsock.c
95 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
96 <debugfs>/dynamic_debug/control
97
98 // enable all the messages in file svcsock.c
99 nullarbor:~ # echo -n 'file svcsock.c +p' >
100 <debugfs>/dynamic_debug/control
101
102 // enable all the messages in the NFS server module
103 nullarbor:~ # echo -n 'module nfsd +p' >
104 <debugfs>/dynamic_debug/control
105
106 // enable all 12 messages in the function svc_process()
107 nullarbor:~ # echo -n 'func svc_process +p' >
108 <debugfs>/dynamic_debug/control
109
110 // disable all 12 messages in the function svc_process()
111 nullarbor:~ # echo -n 'func svc_process -p' >
112 <debugfs>/dynamic_debug/control
113
114 See Documentation/dynamic-debug-howto.txt for additional information.
115
116endmenu # "printk and dmesg options"
117
Dave Hansen6dfc0662013-07-01 13:04:46 -0700118menu "Compile-time checks and compiler options"
119
120config DEBUG_INFO
121 bool "Compile the kernel with debug info"
Linus Torvalds12b13832014-02-04 12:20:01 -0800122 depends on DEBUG_KERNEL && !COMPILE_TEST
Dave Hansen6dfc0662013-07-01 13:04:46 -0700123 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
Andi Kleen866ced92014-07-30 20:50:18 +0200146config 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
Andi Kleenbfaf2dd2014-07-30 20:50:19 +0200161config 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
Jan Kiszka3ee7b3f2015-02-17 13:46:36 -0800170config GDB_SCRIPTS
171 bool "Provide GDB scripts for kernel debugging"
172 depends on DEBUG_INFO
173 help
174 This creates the required links to GDB helper scripts in the
175 build directory. If you load vmlinux into gdb, the helper
176 scripts will be automatically imported by gdb as well, and
177 additional functions are available to analyze a Linux kernel
178 instance. See Documentation/gdb-kernel-debugging.txt for further
179 details.
180
Jeff Garzikde488442007-10-25 04:06:13 -0400181config ENABLE_WARN_DEPRECATED
182 bool "Enable __deprecated logic"
183 default y
184 help
185 Enable the __deprecated logic in the kernel build.
186 Disable this to suppress the "warning: 'foo' is deprecated
187 (declared at kernel/power/somefile.c:1234)" messages.
188
Andrew Mortoncebc04b2006-08-14 22:43:18 -0700189config ENABLE_MUST_CHECK
190 bool "Enable __must_check logic"
191 default y
192 help
193 Enable the __must_check logic in the kernel build. Disable this to
194 suppress the "warning: ignoring return value of 'foo', declared with
195 attribute warn_unused_result" messages.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196
Andi Kleen35bb5b12008-02-22 15:15:03 +0100197config FRAME_WARN
198 int "Warn for stack frames larger than (needs gcc 4.4)"
199 range 0 8192
Andrey Ryabinin3f181b42015-10-22 13:32:24 -0700200 default 0 if KASAN
Andi Kleen35bb5b12008-02-22 15:15:03 +0100201 default 1024 if !64BIT
202 default 2048 if 64BIT
203 help
204 Tell gcc to warn at build time for stack frames larger than this.
205 Setting this too low will cause a lot of warnings.
206 Setting it to 0 disables the warning.
207 Requires gcc 4.4
208
Randy Dunlap99657c72009-09-18 12:49:22 -0700209config STRIP_ASM_SYMS
210 bool "Strip assembler-generated symbols during link"
211 default n
212 help
213 Strip internal assembler-generated symbols during a link (symbols
214 that look like '.Lxxx') so they don't pollute the output of
215 get_wchan() and suchlike.
216
Andi Kleen1873e872012-03-28 11:51:18 -0700217config READABLE_ASM
218 bool "Generate readable assembler code"
219 depends on DEBUG_KERNEL
220 help
221 Disable some compiler optimizations that tend to generate human unreadable
222 assembler output. This may make the kernel slightly slower, but it helps
223 to keep kernel developers who have to stare a lot at assembler listings
224 sane.
225
Arjan van de Venf71d20e2006-06-28 04:26:45 -0700226config UNUSED_SYMBOLS
227 bool "Enable unused/obsolete exported symbols"
228 default y if X86
229 help
230 Unused but exported symbols make the kernel needlessly bigger. For
231 that reason most of these unused exports will soon be removed. This
232 option is provided temporarily to provide a transition period in case
233 some external kernel module needs one of these symbols anyway. If you
234 encounter such a case in your module, consider if you are actually
235 using the right API. (rationale: since nobody in the kernel is using
236 this in a module, there is a pretty good chance it's actually the
237 wrong interface to use). If you really need the symbol, please send a
238 mail to the linux kernel mailing list mentioning the symbol and why
239 you really need it, and what the merge plan to the mainline kernel for
240 your module is.
241
Joonsoo Kim48c96a32014-12-12 16:56:01 -0800242config PAGE_OWNER
243 bool "Track page owner"
244 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
245 select DEBUG_FS
246 select STACKTRACE
247 select PAGE_EXTENSION
248 help
249 This keeps track of what call chain is the owner of a page, may
250 help to find bare alloc_page(s) leaks. Even if you include this
251 feature on your build, it is disabled in default. You should pass
252 "page_owner=on" to boot parameter in order to enable it. Eats
253 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
254 for user-space helper.
255
256 If unsure, say N.
257
Don Mullisbf4735a2006-12-10 02:18:37 -0800258config DEBUG_FS
259 bool "Debug Filesystem"
Don Mullisbf4735a2006-12-10 02:18:37 -0800260 help
261 debugfs is a virtual file system that kernel developers use to put
262 debugging files into. Enable this option to be able to read and
263 write to these files.
264
Robert P. J. Dayff543332008-05-20 00:06:00 +0200265 For detailed documentation on the debugfs API, see
266 Documentation/DocBook/filesystems.
267
Don Mullisbf4735a2006-12-10 02:18:37 -0800268 If unsure, say N.
269
270config HEADERS_CHECK
271 bool "Run 'make headers_check' when building vmlinux"
272 depends on !UML
273 help
274 This option will extract the user-visible kernel headers whenever
275 building the kernel, and will run basic sanity checks on them to
276 ensure that exported files do not attempt to include files which
277 were not exported, etc.
278
279 If you're making modifications to header files which are
280 relevant for userspace, say 'Y', and check the headers
281 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
282 your build tree), to make sure they're suitable.
283
Sam Ravnborg91341d42008-01-21 21:31:44 +0100284config DEBUG_SECTION_MISMATCH
285 bool "Enable full Section mismatch analysis"
Sam Ravnborg91341d42008-01-21 21:31:44 +0100286 help
287 The section mismatch analysis checks if there are illegal
288 references from one section to another section.
Michael Wittene809ab02011-04-17 04:08:48 +0000289 During linktime or runtime, some sections are dropped;
290 any use of code/data previously in these sections would
Sam Ravnborg91341d42008-01-21 21:31:44 +0100291 most likely result in an oops.
Michael Wittene809ab02011-04-17 04:08:48 +0000292 In the code, functions and variables are annotated with
Paul Gortmaker0db06282013-06-19 14:53:51 -0400293 __init,, etc. (see the full list in include/linux/init.h),
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100294 which results in the code/data being placed in specific sections.
Michael Wittene809ab02011-04-17 04:08:48 +0000295 The section mismatch analysis is always performed after a full
296 kernel build, and enabling this option causes the following
297 additional steps to occur:
298 - Add the option -fno-inline-functions-called-once to gcc commands.
299 When inlining a function annotated with __init in a non-init
300 function, we would lose the section information and thus
Sam Ravnborg91341d42008-01-21 21:31:44 +0100301 the analysis would not catch the illegal reference.
Michael Wittene809ab02011-04-17 04:08:48 +0000302 This option tells gcc to inline less (but it does result in
303 a larger kernel).
304 - Run the section mismatch analysis for each module/built-in.o file.
305 When we run the section mismatch analysis on vmlinux.o, we
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100306 lose valueble information about where the mismatch was
Sam Ravnborg91341d42008-01-21 21:31:44 +0100307 introduced.
308 Running the analysis for each module/built-in.o file
Michael Wittene809ab02011-04-17 04:08:48 +0000309 tells where the mismatch happens much closer to the
310 source. The drawback is that the same mismatch is
311 reported at least twice.
312 - Enable verbose reporting from modpost in order to help resolve
313 the section mismatches that are reported.
Sam Ravnborg91341d42008-01-21 21:31:44 +0100314
Nicolas Boichat47490ec2015-10-06 09:44:42 +1030315config SECTION_MISMATCH_WARN_ONLY
316 bool "Make section mismatch errors non-fatal"
317 default y
318 help
319 If you say N here, the build process will fail if there are any
320 section mismatch, instead of just throwing warnings.
321
322 If unsure, say Y.
323
Dave Hansen6dfc0662013-07-01 13:04:46 -0700324#
325# Select this config option from the architecture Kconfig, if it
326# is preferred to always offer frame pointers as a config
327# option on the architecture (regardless of KERNEL_DEBUG):
328#
329config ARCH_WANT_FRAME_POINTERS
330 bool
331 help
332
333config FRAME_POINTER
334 bool "Compile the kernel with frame pointers"
335 depends on DEBUG_KERNEL && \
336 (CRIS || M68K || FRV || UML || \
337 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
338 ARCH_WANT_FRAME_POINTERS
339 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
340 help
341 If you say Y here the resulting kernel image will be slightly
342 larger and slower, but it gives very useful debugging information
343 in case of kernel bugs. (precise oopses/stacktraces/warnings)
344
345config DEBUG_FORCE_WEAK_PER_CPU
346 bool "Force weak per-cpu definitions"
347 depends on DEBUG_KERNEL
348 help
349 s390 and alpha require percpu variables in modules to be
350 defined weak to work around addressing range issue which
351 puts the following two restrictions on percpu variable
352 definitions.
353
354 1. percpu symbols must be unique whether static or not
355 2. percpu variables can't be defined inside a function
356
357 To ensure that generic code follows the above rules, this
358 option forces all percpu variables to be defined as weak.
359
360endmenu # "Compiler options"
361
362config MAGIC_SYSRQ
363 bool "Magic SysRq key"
364 depends on !UML
365 help
366 If you say Y here, you will have some control over the system even
367 if the system crashes for example during kernel debugging (e.g., you
368 will be able to flush the buffer cache to disk, reboot the system
369 immediately or dump some status information). This is accomplished
370 by pressing various keys while holding SysRq (Alt+PrintScreen). It
371 also works on a serial console (on PC hardware at least), if you
372 send a BREAK and then within 5 seconds a command keypress. The
373 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
374 unless you really know what this hack does.
375
Ben Hutchings8eaede42013-10-07 01:05:46 +0100376config MAGIC_SYSRQ_DEFAULT_ENABLE
377 hex "Enable magic SysRq key functions by default"
378 depends on MAGIC_SYSRQ
379 default 0x1
380 help
381 Specifies which SysRq key functions are enabled by default.
382 This may be set to 1 or 0 to enable or disable them all, or
383 to a bitmask as described in Documentation/sysrq.txt.
384
Adrian Bunkf346f4b2006-01-09 20:54:51 -0800385config DEBUG_KERNEL
386 bool "Kernel debugging"
387 help
388 Say Y here if you are developing drivers or trying to debug and
389 identify kernel problems.
390
Dave Hansen0610c8a2013-07-01 13:04:43 -0700391menu "Memory Debugging"
David Woodhousea304e1b2007-02-12 00:52:00 -0800392
Dave Hansen0610c8a2013-07-01 13:04:43 -0700393source mm/Kconfig.debug
Ingo Molnar82f67cd2007-02-16 01:28:13 -0800394
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700395config DEBUG_OBJECTS
396 bool "Debug object operations"
397 depends on DEBUG_KERNEL
398 help
399 If you say Y here, additional code will be inserted into the
400 kernel to track the life time of various objects and validate
401 the operations on those objects.
402
403config DEBUG_OBJECTS_SELFTEST
404 bool "Debug objects selftest"
405 depends on DEBUG_OBJECTS
406 help
407 This enables the selftest of the object debug code.
408
409config DEBUG_OBJECTS_FREE
410 bool "Debug objects in freed memory"
411 depends on DEBUG_OBJECTS
412 help
413 This enables checks whether a k/v free operation frees an area
414 which contains an object which has not been deactivated
415 properly. This can make kmalloc/kfree-intensive workloads
416 much slower.
417
Thomas Gleixnerc6f3a972008-04-30 00:55:03 -0700418config DEBUG_OBJECTS_TIMERS
419 bool "Debug timer objects"
420 depends on DEBUG_OBJECTS
421 help
422 If you say Y here, additional code will be inserted into the
423 timer routines to track the life time of timer objects and
424 validate the timer operations.
425
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900426config DEBUG_OBJECTS_WORK
427 bool "Debug work objects"
428 depends on DEBUG_OBJECTS
429 help
430 If you say Y here, additional code will be inserted into the
431 work queue routines to track the life time of work objects and
432 validate the work operations.
433
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400434config DEBUG_OBJECTS_RCU_HEAD
435 bool "Debug RCU callbacks objects"
Mathieu Desnoyersfc2ecf72011-02-23 09:42:14 -0800436 depends on DEBUG_OBJECTS
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400437 help
438 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
439
Tejun Heoe2852ae2010-10-26 14:23:05 -0700440config DEBUG_OBJECTS_PERCPU_COUNTER
441 bool "Debug percpu counter objects"
442 depends on DEBUG_OBJECTS
443 help
444 If you say Y here, additional code will be inserted into the
445 percpu counter routines to track the life time of percpu counter
446 objects and validate the percpu counter operations.
447
Ingo Molnar3ae70202008-11-26 10:02:00 +0100448config DEBUG_OBJECTS_ENABLE_DEFAULT
449 int "debug_objects bootup default value (0-1)"
450 range 0 1
451 default "1"
452 depends on DEBUG_OBJECTS
453 help
454 Debug objects boot parameter default value
455
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456config DEBUG_SLAB
Andrew Morton4a2f0ac2006-03-25 03:07:22 -0800457 bool "Debug slab memory allocations"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200458 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 help
460 Say Y here to have the kernel do limited verification on memory
461 allocation as well as poisoning memory on free to catch use of freed
462 memory. This can make kmalloc/kfree-intensive workloads much slower.
463
Al Viro871751e2006-03-25 03:06:39 -0800464config DEBUG_SLAB_LEAK
465 bool "Memory leak debugging"
466 depends on DEBUG_SLAB
467
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700468config SLUB_DEBUG_ON
469 bool "SLUB debugging on by default"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200470 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700471 default n
472 help
473 Boot with debugging on by default. SLUB boots by default with
474 the runtime debug capabilities switched off. Enabling this is
475 equivalent to specifying the "slub_debug" parameter on boot.
476 There is no support for more fine grained debug control like
477 possible with slub_debug=xxx. SLUB debugging may be switched
478 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
479 "slub_debug=-".
480
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800481config SLUB_STATS
482 default n
483 bool "Enable SLUB performance statistics"
Christoph Lameterab4d5ed2010-10-05 13:57:26 -0500484 depends on SLUB && SYSFS
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800485 help
486 SLUB statistics are useful to debug SLUBs allocation behavior in
487 order find ways to optimize the allocator. This should never be
488 enabled for production use since keeping statistics slows down
489 the allocator by a few percentage points. The slabinfo command
490 supports the determination of the most active slabs to figure
491 out which slabs are relevant to a particular load.
492 Try running: slabinfo -DA
493
Catalin Marinasb69ec422012-10-08 16:28:11 -0700494config HAVE_DEBUG_KMEMLEAK
495 bool
496
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100497config DEBUG_KMEMLEAK
498 bool "Kernel memory leak detector"
Kees Cook525c1f92013-01-16 18:54:16 -0800499 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
Catalin Marinas79e0d9b2011-04-27 17:06:19 +0100500 select DEBUG_FS
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100501 select STACKTRACE if STACKTRACE_SUPPORT
502 select KALLSYMS
Randy Dunlapb60e26a2009-11-06 15:33:45 -0800503 select CRC32
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100504 help
505 Say Y here if you want to enable the memory leak
506 detector. The memory allocation/freeing is traced in a way
507 similar to the Boehm's conservative garbage collector, the
508 difference being that the orphan objects are not freed but
509 only shown in /sys/kernel/debug/kmemleak. Enabling this
510 feature will introduce an overhead to memory
511 allocations. See Documentation/kmemleak.txt for more
512 details.
513
Catalin Marinasbf96d1e2009-06-23 14:40:27 +0100514 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
515 of finding leaks due to the slab objects poisoning.
516
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100517 In order to access the kmemleak file, debugfs needs to be
518 mounted (usually at /sys/kernel/debug).
519
Catalin Marinasa9d90582009-06-25 10:16:11 +0100520config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
521 int "Maximum kmemleak early log entries"
522 depends on DEBUG_KMEMLEAK
Heiko Carstensdfcc3e62009-10-06 10:33:57 +0200523 range 200 40000
Catalin Marinasa9d90582009-06-25 10:16:11 +0100524 default 400
525 help
526 Kmemleak must track all the memory allocations to avoid
527 reporting false positives. Since memory may be allocated or
528 freed before kmemleak is initialised, an early log buffer is
529 used to store these actions. If kmemleak reports "early log
530 buffer exceeded", please increase this value.
531
Catalin Marinas0822ee42009-06-11 13:24:14 +0100532config DEBUG_KMEMLEAK_TEST
533 tristate "Simple test for the kernel memory leak detector"
Daniel Baluta97182692011-04-04 15:06:44 -0700534 depends on DEBUG_KMEMLEAK && m
Catalin Marinas0822ee42009-06-11 13:24:14 +0100535 help
Daniel Baluta97182692011-04-04 15:06:44 -0700536 This option enables a module that explicitly leaks memory.
Catalin Marinas0822ee42009-06-11 13:24:14 +0100537
538 If unsure, say N.
539
Jason Baronab0155a2010-07-19 11:54:17 +0100540config DEBUG_KMEMLEAK_DEFAULT_OFF
541 bool "Default kmemleak to off"
542 depends on DEBUG_KMEMLEAK
543 help
544 Say Y here to disable kmemleak by default. It can then be enabled
545 on the command line via kmemleak=on.
546
Dave Hansen0610c8a2013-07-01 13:04:43 -0700547config DEBUG_STACK_USAGE
548 bool "Stack utilization instrumentation"
549 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
550 help
551 Enables the display of the minimum amount of free stack which each
552 task has ever had available in the sysrq-T and sysrq-P debug output.
553
554 This option will slow down process creation somewhat.
555
556config DEBUG_VM
557 bool "Debug VM"
558 depends on DEBUG_KERNEL
559 help
560 Enable this to turn on extended checks in the virtual-memory system
561 that may impact performance.
562
563 If unsure, say N.
564
Davidlohr Bueso4f115142014-06-04 16:06:46 -0700565config DEBUG_VM_VMACACHE
566 bool "Debug VMA caching"
567 depends on DEBUG_VM
568 help
569 Enable this to turn on VMA caching debug information. Doing so
570 can cause significant overhead, so only enable it in non-production
571 environments.
572
573 If unsure, say N.
574
Dave Hansen0610c8a2013-07-01 13:04:43 -0700575config DEBUG_VM_RB
576 bool "Debug VM red-black trees"
577 depends on DEBUG_VM
578 help
Davidlohr Buesoa663dad2014-04-18 15:07:22 -0700579 Enable VM red-black tree debugging information and extra validations.
Dave Hansen0610c8a2013-07-01 13:04:43 -0700580
581 If unsure, say N.
582
Kirill A. Shutemov95ad9752016-01-15 16:51:21 -0800583config DEBUG_VM_PGFLAGS
584 bool "Debug page-flags operations"
585 depends on DEBUG_VM
586 help
587 Enables extra validation on page flags operations.
588
589 If unsure, say N.
590
Dave Hansen0610c8a2013-07-01 13:04:43 -0700591config DEBUG_VIRTUAL
592 bool "Debug VM translations"
593 depends on DEBUG_KERNEL && X86
594 help
595 Enable some costly sanity checks in virtual to page code. This can
596 catch mistakes with virt_to_page() and friends.
597
598 If unsure, say N.
599
600config DEBUG_NOMMU_REGIONS
601 bool "Debug the global anon/private NOMMU mapping region tree"
602 depends on DEBUG_KERNEL && !MMU
603 help
604 This option causes the global tree of anonymous and private mapping
605 regions to be regularly checked for invalid topology.
606
607config DEBUG_MEMORY_INIT
608 bool "Debug memory initialisation" if EXPERT
609 default !EXPERT
610 help
611 Enable this for additional checks during memory initialisation.
612 The sanity checks verify aspects of the VM such as the memory model
613 and other information provided by the architecture. Verbose
614 information will be printed at KERN_DEBUG loglevel depending
615 on the mminit_loglevel= command-line option.
616
617 If unsure, say Y
618
619config MEMORY_NOTIFIER_ERROR_INJECT
620 tristate "Memory hotplug notifier error injection module"
621 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
622 help
623 This option provides the ability to inject artificial errors to
624 memory hotplug notifier chain callbacks. It is controlled through
625 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
626
627 If the notifier call chain should be failed with some events
628 notified, write the error code to "actions/<notifier event>/error".
629
630 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
631
632 # cd /sys/kernel/debug/notifier-error-inject/memory
633 # echo -12 > actions/MEM_GOING_OFFLINE/error
634 # echo offline > /sys/devices/system/memory/memoryXXX/state
635 bash: echo: write error: Cannot allocate memory
636
637 To compile this code as a module, choose M here: the module will
638 be called memory-notifier-error-inject.
639
640 If unsure, say N.
641
642config DEBUG_PER_CPU_MAPS
643 bool "Debug access to per_cpu maps"
644 depends on DEBUG_KERNEL
645 depends on SMP
646 help
647 Say Y to verify that the per_cpu map being accessed has
648 been set up. This adds a fair amount of code to kernel memory
649 and decreases performance.
650
651 Say N if unsure.
652
653config DEBUG_HIGHMEM
654 bool "Highmem debugging"
655 depends on DEBUG_KERNEL && HIGHMEM
656 help
Geert Uytterhoevenb1357c92014-04-14 18:55:50 +0200657 This option enables additional error checking for high memory
658 systems. Disable for production systems.
Dave Hansen0610c8a2013-07-01 13:04:43 -0700659
660config HAVE_DEBUG_STACKOVERFLOW
661 bool
662
663config DEBUG_STACKOVERFLOW
664 bool "Check for stack overflows"
665 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
666 ---help---
667 Say Y here if you want to check for overflows of kernel, IRQ
Borislav Petkovedb0ec02015-01-25 19:50:34 +0100668 and exception stacks (if your architecture uses them). This
Dave Hansen0610c8a2013-07-01 13:04:43 -0700669 option will show detailed messages if free stack space drops
670 below a certain limit.
671
672 These kinds of bugs usually occur when call-chains in the
673 kernel get too deep, especially when interrupts are
674 involved.
675
676 Use this in cases where you see apparently random memory
677 corruption, especially if it appears in 'struct thread_info'
678
679 If in doubt, say "N".
680
681source "lib/Kconfig.kmemcheck"
682
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800683source "lib/Kconfig.kasan"
684
Dave Hansen0610c8a2013-07-01 13:04:43 -0700685endmenu # "Memory Debugging"
686
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687config DEBUG_SHIRQ
688 bool "Debug shared IRQ handlers"
Martin Schwidefsky0244ad02013-08-30 09:39:53 +0200689 depends on DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 help
691 Enable this to generate a spurious interrupt as soon as a shared
692 interrupt handler is registered, and just before one is deregistered.
693 Drivers ought to be able to handle interrupts coming in at those
694 points; some don't and need to be caught.
695
Dave Hansen92aef8fb2013-07-01 13:04:50 -0700696menu "Debug Lockups and Hangs"
697
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698config LOCKUP_DETECTOR
699 bool "Detect Hard and Soft Lockups"
700 depends on DEBUG_KERNEL && !S390
701 help
702 Say Y here to enable the kernel to act as a watchdog to detect
703 hard and soft lockups.
704
705 Softlockups are bugs that cause the kernel to loop in kernel
706 mode for more than 20 seconds, without giving other tasks a
707 chance to run. The current stack trace is displayed upon
708 detection and the system will stay locked up.
709
710 Hardlockups are bugs that cause the CPU to loop in kernel mode
711 for more than 10 seconds, without letting other interrupts have a
712 chance to run. The current stack trace is displayed upon detection
713 and the system will stay locked up.
714
715 The overhead should be minimal. A periodic hrtimer runs to
716 generate interrupts and kick the watchdog task every 4 seconds.
717 An NMI is generated every 10 seconds or so to check for hardlockups.
718
719 The frequency of hrtimer and NMI events and the soft and hard lockup
720 thresholds can be controlled through the sysctl watchdog_thresh.
721
722config HARDLOCKUP_DETECTOR
723 def_bool y
724 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
725 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
726
727config BOOTPARAM_HARDLOCKUP_PANIC
728 bool "Panic (Reboot) On Hard Lockups"
729 depends on HARDLOCKUP_DETECTOR
730 help
731 Say Y here to enable the kernel to panic on "hard lockups",
732 which are bugs that cause the kernel to loop in kernel
733 mode with interrupts disabled for more than 10 seconds (configurable
734 using the watchdog_thresh sysctl).
735
736 Say N if unsure.
737
738config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
739 int
740 depends on HARDLOCKUP_DETECTOR
741 range 0 1
742 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
743 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
744
745config BOOTPARAM_SOFTLOCKUP_PANIC
746 bool "Panic (Reboot) On Soft Lockups"
747 depends on LOCKUP_DETECTOR
748 help
749 Say Y here to enable the kernel to panic on "soft lockups",
750 which are bugs that cause the kernel to loop in kernel
751 mode for more than 20 seconds (configurable using the watchdog_thresh
752 sysctl), without giving other tasks a chance to run.
753
754 The panic can be used in combination with panic_timeout,
755 to cause the system to reboot automatically after a
756 lockup has been detected. This feature is useful for
757 high-availability systems that have uptime guarantees and
758 where a lockup must be resolved ASAP.
759
Ingo Molnar8637c092006-07-03 00:24:38 -0700760 Say N if unsure.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761
762config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
763 int
764 depends on LOCKUP_DETECTOR
765 range 0 1
766 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
767 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700768
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769config DETECT_HUNG_TASK
770 bool "Detect Hung Tasks"
771 depends on DEBUG_KERNEL
772 default LOCKUP_DETECTOR
773 help
774 Say Y here to enable the kernel to detect "hung tasks",
775 which are bugs that cause the task to be stuck in
776 uninterruptible "D" state indefinitiley.
777
778 When a hung task is detected, the kernel will print the
779 current stack trace (which you should report), but the
780 task will stay in uninterruptible state. If lockdep is
781 enabled then all held locks will also be reported. This
782 feature has negligible overhead.
783
784config DEFAULT_HUNG_TASK_TIMEOUT
785 int "Default timeout for hung task detection (in seconds)"
786 depends on DETECT_HUNG_TASK
787 default 120
788 help
789 This option controls the default timeout (in seconds) used
790 to determine when a task has become non-responsive and should
791 be considered hung.
792
793 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
794 sysctl or by writing a value to
795 /proc/sys/kernel/hung_task_timeout_secs.
796
Ingo Molnar408894e2006-01-09 15:59:20 -0800797 A timeout of 0 disables the check. The default is two minutes.
798 Keeping the default should be fine in most cases.
799
800config BOOTPARAM_HUNG_TASK_PANIC
801 bool "Panic (Reboot) On Hung Tasks"
802 depends on DETECT_HUNG_TASK
Tim Chencca57c52006-04-18 22:21:47 -0700803 help
Ingo Molnar408894e2006-01-09 15:59:20 -0800804 Say Y here to enable the kernel to panic on "hung tasks",
805 which are bugs that cause the kernel to leave a task stuck
806 in uninterruptible "D" state.
807
808 The panic can be used in combination with panic_timeout,
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700809 to cause the system to reboot automatically after a
810 hung task has been detected. This feature is useful for
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700811 high-availability systems that have uptime guarantees and
812 where a hung tasks must be resolved ASAP.
813
814 Say N if unsure.
815
816config BOOTPARAM_HUNG_TASK_PANIC_VALUE
817 int
818 depends on DETECT_HUNG_TASK
819 range 0 1
Hugh Dickins048c8bc2006-11-01 05:44:54 +1100820 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 default 1 if BOOTPARAM_HUNG_TASK_PANIC
822
Tejun Heo82607adc2015-12-08 11:28:04 -0500823config WQ_WATCHDOG
824 bool "Detect Workqueue Stalls"
825 depends on DEBUG_KERNEL
826 help
827 Say Y here to enable stall detection on workqueues. If a
828 worker pool doesn't make forward progress on a pending work
829 item for over a given amount of time, 30s by default, a
830 warning message is printed along with dump of workqueue
831 state. This can be configured through kernel parameter
832 "workqueue.watchdog_thresh" and its sysfs counterpart.
833
Dave Hansen92aef8fb2013-07-01 13:04:50 -0700834endmenu # "Debug lockups and hangs"
835
836config PANIC_ON_OOPS
837 bool "Panic on Oops"
838 help
839 Say Y here to enable the kernel to panic when it oopses. This
840 has the same effect as setting oops=panic on the kernel command
841 line.
842
843 This feature is useful to ensure that the kernel does not do
844 anything erroneous after an oops which could result in data
845 corruption or other issues.
846
847 Say N if unsure.
848
849config PANIC_ON_OOPS_VALUE
850 int
851 range 0 1
852 default 0 if !PANIC_ON_OOPS
853 default 1 if PANIC_ON_OOPS
854
Jason Baron5800dc32013-11-25 23:23:04 +0000855config PANIC_TIMEOUT
856 int "panic timeout"
857 default 0
858 help
859 Set the timeout value (in seconds) until a reboot occurs when the
860 the kernel panics. If n = 0, then we wait forever. A timeout
861 value n > 0 will wait n seconds before rebooting, while a timeout
862 value n < 0 will reboot immediately.
863
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864config SCHED_DEBUG
865 bool "Collect scheduler debugging info"
866 depends on DEBUG_KERNEL && PROC_FS
867 default y
868 help
869 If you say Y here, the /proc/sched_debug file will be provided
870 that can help debug the scheduler. The runtime overhead of this
871 option is minimal.
872
Naveen N. Raof6db8342015-06-25 23:53:37 +0530873config SCHED_INFO
874 bool
875 default n
876
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877config SCHEDSTATS
878 bool "Collect scheduler statistics"
879 depends on DEBUG_KERNEL && PROC_FS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530880 select SCHED_INFO
Linus Torvalds1da177e2005-04-16 15:20:36 -0700881 help
882 If you say Y here, additional code will be inserted into the
883 scheduler and related routines to collect statistics about
884 scheduler behavior and provide them in /proc/schedstat. These
885 stats may be useful for both tuning and debugging the scheduler
886 If you aren't debugging the scheduler or trying to tune a specific
887 application, you can say N to avoid the very slight overhead
888 this adds.
889
Aaron Tomlin0d9e2632014-09-12 14:16:19 +0100890config SCHED_STACK_END_CHECK
891 bool "Detect stack corruption on calls to schedule()"
892 depends on DEBUG_KERNEL
893 default n
894 help
895 This option checks for a stack overrun on calls to schedule().
896 If the stack end location is found to be over written always panic as
897 the content of the corrupted region can no longer be trusted.
898 This is to ensure no erroneous behaviour occurs which could result in
899 data corruption or a sporadic crash at a later stage once the region
900 is examined. The runtime overhead introduced is minimal.
901
John Stultz3c17ad12015-03-11 21:16:32 -0700902config DEBUG_TIMEKEEPING
903 bool "Enable extra timekeeping sanity checking"
904 help
905 This option will enable additional timekeeping sanity checks
906 which may be helpful when diagnosing issues where timekeeping
907 problems are suspected.
908
909 This may include checks in the timekeeping hotpaths, so this
910 option may have a (very small) performance impact to some
911 workloads.
912
913 If unsure, say N.
914
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915config TIMER_STATS
916 bool "Collect kernel timers statistics"
917 depends on DEBUG_KERNEL && PROC_FS
918 help
919 If you say Y here, additional code will be inserted into the
920 timer routines to collect statistics about kernel timers being
921 reprogrammed. The statistics can be read from /proc/timer_stats.
922 The statistics collection is started by writing 1 to /proc/timer_stats,
923 writing 0 stops it. This feature is useful to collect information
924 about timer usage patterns in kernel and userspace. This feature
925 is lightweight if enabled in the kernel config but not activated
926 (it defaults to deactivated on bootup and will only be activated
927 if some application like powertop activates it explicitly).
928
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929config DEBUG_PREEMPT
930 bool "Debug preemptible kernel"
Kumar Gala01deab92009-10-16 07:21:39 +0000931 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 default y
933 help
934 If you say Y here then the kernel will use a debug variant of the
935 commonly used smp_processor_id() function and will print warnings
936 if kernel code uses it in a preemption-unsafe way. Also, the kernel
937 will detect preemption count underflows.
938
Dave Hansen9eade162013-07-01 13:04:47 -0700939menu "Lock Debugging (spinlocks, mutexes, etc...)"
940
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700941config DEBUG_RT_MUTEXES
942 bool "RT Mutex debugging, deadlock detection"
943 depends on DEBUG_KERNEL && RT_MUTEXES
944 help
945 This allows rt mutex semantics violations and rt mutex related
946 deadlocks (lockups) to be detected and reported automatically.
947
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948config DEBUG_SPINLOCK
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700949 bool "Spinlock and rw-lock debugging: basic checks"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950 depends on DEBUG_KERNEL
Raghavendra K Te335e3e2012-03-22 15:25:08 +0530951 select UNINLINE_SPIN_UNLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 help
953 Say Y here and build SMP to catch missing spinlock initialization
954 and certain other kinds of spinlock errors commonly made. This is
955 best used in conjunction with the NMI watchdog so that spinlock
956 deadlocks are also debuggable.
957
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700958config DEBUG_MUTEXES
959 bool "Mutex debugging: basic checks"
960 depends on DEBUG_KERNEL
961 help
962 This feature allows mutex semantics violations to be detected and
963 reported.
964
Daniel Vetter23010022013-06-20 13:31:17 +0200965config DEBUG_WW_MUTEX_SLOWPATH
966 bool "Wait/wound mutex debugging: Slowpath testing"
967 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
968 select DEBUG_LOCK_ALLOC
969 select DEBUG_SPINLOCK
970 select DEBUG_MUTEXES
971 help
972 This feature enables slowpath testing for w/w mutex users by
973 injecting additional -EDEADLK wound/backoff cases. Together with
974 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
975 will test all possible w/w mutex interface abuse with the
976 exception of simply not acquiring all the required locks.
Rob Clark4d692372014-08-27 11:19:26 -0400977 Note that this feature can introduce significant overhead, so
978 it really should not be enabled in a production or distro kernel,
979 even a debug kernel. If you are a driver writer, enable it. If
980 you are a distro, do not.
Daniel Vetter23010022013-06-20 13:31:17 +0200981
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700982config DEBUG_LOCK_ALLOC
983 bool "Lock debugging: detect incorrect freeing of live locks"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700984 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700985 select DEBUG_SPINLOCK
986 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700987 select LOCKDEP
988 help
989 This feature will check whether any held lock (spinlock, rwlock,
990 mutex or rwsem) is incorrectly freed by the kernel, via any of the
991 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
992 vfree(), etc.), whether a live lock is incorrectly reinitialized via
993 spin_lock_init()/mutex_init()/etc., or whether there is any lock
994 held during task exit.
995
996config PROVE_LOCKING
997 bool "Lock debugging: prove locking correctness"
Adrian Bunk517e7aa2006-07-14 00:24:32 -0700998 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700999 select LOCKDEP
1000 select DEBUG_SPINLOCK
1001 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001002 select DEBUG_LOCK_ALLOC
Steven Rostedt46b93b72010-08-31 16:35:20 -04001003 select TRACE_IRQFLAGS
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001004 default n
1005 help
1006 This feature enables the kernel to prove that all locking
1007 that occurs in the kernel runtime is mathematically
1008 correct: that under no circumstance could an arbitrary (and
1009 not yet triggered) combination of observed locking
1010 sequences (on an arbitrary number of CPUs, running an
1011 arbitrary number of tasks and interrupt contexts) cause a
1012 deadlock.
1013
1014 In short, this feature enables the kernel to report locking
1015 related deadlocks before they actually occur.
1016
1017 The proof does not depend on how hard and complex a
1018 deadlock scenario would be to trigger: how many
1019 participant CPUs, tasks and irq-contexts would be needed
1020 for it to trigger. The proof also does not depend on
1021 timing: if a race and a resulting deadlock is possible
1022 theoretically (no matter how unlikely the race scenario
1023 is), it will be proven so and will immediately be
1024 reported by the kernel (once the event is observed that
1025 makes the deadlock theoretically possible).
1026
1027 If a deadlock is impossible (i.e. the locking rules, as
1028 observed by the kernel, are mathematically correct), the
1029 kernel reports nothing.
1030
1031 NOTE: this feature can also be enabled for rwlocks, mutexes
1032 and rwsems - in which case all dependencies between these
1033 different locking variants are observed and mapped too, and
1034 the proof of observed correctness is also maintained for an
1035 arbitrary combination of these separate locking variants.
1036
Davidlohr Bueso214e0ae2014-07-30 13:41:55 -07001037 For more details, see Documentation/locking/lockdep-design.txt.
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001038
1039config LOCKDEP
1040 bool
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001041 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001042 select STACKTRACE
Chen Gangdf2e1ef2014-06-23 13:22:04 -07001043 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001044 select KALLSYMS
1045 select KALLSYMS_ALL
1046
Peter Zijlstraf20786f2007-07-19 01:48:56 -07001047config LOCK_STAT
Danny ter Haarfdfb8702007-09-24 21:24:43 -07001048 bool "Lock usage statistics"
Peter Zijlstraf20786f2007-07-19 01:48:56 -07001049 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1050 select LOCKDEP
1051 select DEBUG_SPINLOCK
1052 select DEBUG_MUTEXES
1053 select DEBUG_LOCK_ALLOC
1054 default n
1055 help
1056 This feature enables tracking lock contention points
1057
Davidlohr Bueso214e0ae2014-07-30 13:41:55 -07001058 For more details, see Documentation/locking/lockstat.txt
Peter Zijlstraa560aa42007-10-07 00:24:33 -07001059
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +01001060 This also enables lock events required by "perf lock",
1061 subcommand of perf.
1062 If you want to use "perf lock", you also need to turn on
1063 CONFIG_EVENT_TRACING.
Hitoshi Mitake84c6f882010-02-04 16:08:15 +09001064
1065 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +01001066 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
Hitoshi Mitake84c6f882010-02-04 16:08:15 +09001067
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001068config DEBUG_LOCKDEP
1069 bool "Lock dependency engine debugging"
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001070 depends on DEBUG_KERNEL && LOCKDEP
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001071 help
1072 If you say Y here, the lock dependency engine will do
1073 additional runtime checks to debug itself, at the price
1074 of more runtime overhead.
1075
Frederic Weisbeckerd902db12011-06-08 19:31:56 +02001076config DEBUG_ATOMIC_SLEEP
1077 bool "Sleep inside atomic section checking"
Frederic Weisbeckere8f7c702011-06-08 01:51:02 +02001078 select PREEMPT_COUNT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079 depends on DEBUG_KERNEL
1080 help
1081 If you say Y here, various routines which may sleep will become very
Frederic Weisbeckerd902db12011-06-08 19:31:56 +02001082 noisy if they are called inside atomic sections: when a spinlock is
1083 held, inside an rcu read side critical section, inside preempt disabled
1084 sections, inside an interrupt, etc...
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085
Ingo Molnarcae2ed92006-07-03 00:24:48 -07001086config DEBUG_LOCKING_API_SELFTESTS
1087 bool "Locking API boot-time self-tests"
1088 depends on DEBUG_KERNEL
1089 help
1090 Say Y here if you want the kernel to run a short self-test during
1091 bootup. The self-test checks whether common types of locking bugs
1092 are detected by debugging mechanisms or not. (if you disable
1093 lock debugging then those bugs wont be detected of course.)
1094 The following locking APIs are covered: spinlocks, rwlocks,
1095 mutexes and rwsems.
1096
Paul E. McKenney0af3fe12014-02-04 15:51:41 -08001097config LOCK_TORTURE_TEST
1098 tristate "torture tests for locking"
1099 depends on DEBUG_KERNEL
1100 select TORTURE_TEST
1101 default n
1102 help
1103 This option provides a kernel module that runs torture tests
1104 on kernel locking primitives. The kernel module may be built
1105 after the fact on the running kernel to be tested, if desired.
1106
1107 Say Y here if you want kernel locking-primitive torture tests
1108 to be built into the kernel.
1109 Say M if you want these torture tests to build as a module.
1110 Say N if you are unsure.
1111
Dave Hansen9eade162013-07-01 13:04:47 -07001112endmenu # lock debugging
1113
1114config TRACE_IRQFLAGS
1115 bool
1116 help
1117 Enables hooks to interrupt enabling and disabling for
1118 either tracing or lock debugging.
1119
Ingo Molnar8637c092006-07-03 00:24:38 -07001120config STACKTRACE
Dave Jones0c38e1f2014-08-29 15:18:35 -07001121 bool "Stack backtrace support"
Ingo Molnar8637c092006-07-03 00:24:38 -07001122 depends on STACKTRACE_SUPPORT
Dave Jones0c38e1f2014-08-29 15:18:35 -07001123 help
1124 This option causes the kernel to create a /proc/pid/stack for
1125 every process, showing its current stack trace.
1126 It is also used by various kernel debugging features that require
1127 stack trace generation.
Ingo Molnar8637c092006-07-03 00:24:38 -07001128
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129config DEBUG_KOBJECT
1130 bool "kobject debugging"
1131 depends on DEBUG_KERNEL
1132 help
1133 If you say Y here, some extra kobject debugging messages will be sent
1134 to the syslog.
1135
Russell Kingc817a672013-06-27 15:06:14 +01001136config DEBUG_KOBJECT_RELEASE
1137 bool "kobject release debugging"
Linus Torvalds2a999aa2013-10-29 08:33:36 -07001138 depends on DEBUG_OBJECTS_TIMERS
Russell Kingc817a672013-06-27 15:06:14 +01001139 help
1140 kobjects are reference counted objects. This means that their
1141 last reference count put is not predictable, and the kobject can
1142 live on past the point at which a driver decides to drop it's
1143 initial reference to the kobject gained on allocation. An
1144 example of this would be a struct device which has just been
1145 unregistered.
1146
1147 However, some buggy drivers assume that after such an operation,
1148 the memory backing the kobject can be immediately freed. This
1149 goes completely against the principles of a refcounted object.
1150
1151 If you say Y here, the kernel will delay the release of kobjects
1152 on the last reference count to improve the visibility of this
1153 kind of kobject release bug.
1154
Catalin Marinas9b2a60c2012-10-08 16:28:13 -07001155config HAVE_DEBUG_BUGVERBOSE
1156 bool
1157
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158config DEBUG_BUGVERBOSE
David Rientjes6a108a12011-01-20 14:44:16 -08001159 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
Catalin Marinas9b2a60c2012-10-08 16:28:13 -07001160 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
Alexey Dobriyan8420e7e2009-12-14 18:00:25 -08001161 default y
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 help
1163 Say Y here to make BUG() panics output the file name and line number
1164 of the BUG call as well as the EIP and oops trace. This aids
1165 debugging but costs about 70-100K of memory.
1166
Dave Jones199a9af2006-09-29 01:59:00 -07001167config DEBUG_LIST
1168 bool "Debug linked list manipulation"
1169 depends on DEBUG_KERNEL
1170 help
1171 Enable this to turn on extended checks in the linked-list
1172 walking routines.
1173
1174 If unsure, say N.
1175
Dan Streetmanb8cfff62014-06-04 16:11:54 -07001176config DEBUG_PI_LIST
1177 bool "Debug priority linked list manipulation"
1178 depends on DEBUG_KERNEL
1179 help
1180 Enable this to turn on extended checks in the priority-ordered
1181 linked-list (plist) walking routines. This checks the entire
1182 list multiple times during each manipulation.
1183
1184 If unsure, say N.
1185
Jens Axboed6ec0842007-10-22 20:01:06 +02001186config DEBUG_SG
1187 bool "Debug SG table operations"
1188 depends on DEBUG_KERNEL
1189 help
1190 Enable this to turn on checks on scatter-gather tables. This can
1191 help find problems with drivers that do not properly initialize
1192 their sg tables.
1193
1194 If unsure, say N.
1195
Arjan van de Ven1b2439d2008-08-15 15:29:38 -07001196config DEBUG_NOTIFIERS
1197 bool "Debug notifier call chains"
1198 depends on DEBUG_KERNEL
1199 help
1200 Enable this to turn on sanity checking for notifier call chains.
1201 This is most useful for kernel developers to make sure that
1202 modules properly unregister themselves from notifier chains.
1203 This is a relatively cheap check but if you care about maximum
1204 performance, say N.
1205
David Howellse0e81732009-09-02 09:13:40 +01001206config DEBUG_CREDENTIALS
1207 bool "Debug credential management"
1208 depends on DEBUG_KERNEL
1209 help
1210 Enable this to turn on some debug checking for credential
1211 management. The additional code keeps track of the number of
1212 pointers from task_structs to any given cred struct, and checks to
1213 see that this number never exceeds the usage count of the cred
1214 struct.
1215
1216 Furthermore, if SELinux is enabled, this also checks that the
1217 security pointer in the cred struct is never seen to be invalid.
1218
1219 If unsure, say N.
1220
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001221menu "RCU Debugging"
1222
1223config PROVE_RCU
Paul E. McKenney9bae6592015-01-18 18:01:21 -08001224 def_bool PROVE_LOCKING
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001225
1226config PROVE_RCU_REPEATEDLY
1227 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1228 depends on PROVE_RCU
1229 default n
1230 help
1231 By itself, PROVE_RCU will disable checking upon issuing the
1232 first warning (or "splat"). This feature prevents such
1233 disabling, allowing multiple RCU-lockdep warnings to be printed
1234 on a single reboot.
1235
1236 Say Y to allow multiple RCU-lockdep warnings per boot.
1237
1238 Say N if you are unsure.
1239
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001240config SPARSE_RCU_POINTER
1241 bool "RCU debugging: sparse-based checks for pointer usage"
1242 default n
1243 help
1244 This feature enables the __rcu sparse annotation for
1245 RCU-protected pointers. This annotation will cause sparse
1246 to flag any non-RCU used of annotated pointers. This can be
1247 helpful when debugging RCU usage. Please note that this feature
1248 is not intended to enforce code cleanliness; it is instead merely
1249 a debugging aid.
1250
1251 Say Y to make sparse flag questionable use of RCU-protected pointers
1252
1253 Say N if you are unsure.
1254
Paul E. McKenney51b11302014-01-27 11:49:39 -08001255config TORTURE_TEST
1256 tristate
1257 default n
1258
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001259config RCU_TORTURE_TEST
1260 tristate "torture tests for RCU"
1261 depends on DEBUG_KERNEL
Paul E. McKenney51b11302014-01-27 11:49:39 -08001262 select TORTURE_TEST
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001263 select SRCU
Paul E. McKenney82d0f4c2015-04-20 05:42:50 -07001264 select TASKS_RCU
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001265 default n
1266 help
1267 This option provides a kernel module that runs torture tests
1268 on the RCU infrastructure. The kernel module may be built
1269 after the fact on the running kernel to be tested, if desired.
1270
Paul E. McKenney31a72bc2008-06-18 09:26:49 -07001271 Say Y here if you want RCU torture tests to be built into
1272 the kernel.
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001273 Say M if you want the RCU torture tests to build as a module.
1274 Say N if you are unsure.
Ankita Garg8bb31b92006-10-02 02:17:36 -07001275
Paul E. McKenney31a72bc2008-06-18 09:26:49 -07001276config RCU_TORTURE_TEST_RUNNABLE
1277 bool "torture tests for RCU runnable by default"
1278 depends on RCU_TORTURE_TEST = y
1279 default n
1280 help
1281 This option provides a way to build the RCU torture tests
1282 directly into the kernel without them starting up at boot
1283 time. You can use /proc/sys/kernel/rcutorture_runnable
1284 to manually override this setting. This /proc file is
1285 available only when the RCU torture tests have been built
1286 into the kernel.
1287
1288 Say Y here if you want the RCU torture tests to start during
1289 boot (you probably don't).
1290 Say N here if you want the RCU torture tests to start only
1291 after being manually enabled via /proc.
1292
Paul E. McKenney0f41c0d2015-03-10 18:33:20 -07001293config RCU_TORTURE_TEST_SLOW_PREINIT
1294 bool "Slow down RCU grace-period pre-initialization to expose races"
1295 depends on RCU_TORTURE_TEST
1296 help
1297 This option delays grace-period pre-initialization (the
1298 propagation of CPU-hotplug changes up the rcu_node combining
1299 tree) for a few jiffies between initializing each pair of
1300 consecutive rcu_node structures. This helps to expose races
1301 involving grace-period pre-initialization, in other words, it
1302 makes your kernel less stable. It can also greatly increase
1303 grace-period latency, especially on systems with large numbers
1304 of CPUs. This is useful when torture-testing RCU, but in
1305 almost no other circumstance.
1306
1307 Say Y here if you want your system to crash and hang more often.
1308 Say N if you want a sane system.
1309
1310config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1311 int "How much to slow down RCU grace-period pre-initialization"
1312 range 0 5
1313 default 3
1314 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1315 help
1316 This option specifies the number of jiffies to wait between
1317 each rcu_node structure pre-initialization step.
1318
Paul E. McKenney37745d22015-01-22 18:24:08 -08001319config RCU_TORTURE_TEST_SLOW_INIT
1320 bool "Slow down RCU grace-period initialization to expose races"
1321 depends on RCU_TORTURE_TEST
1322 help
Paul E. McKenney0f41c0d2015-03-10 18:33:20 -07001323 This option delays grace-period initialization for a few
1324 jiffies between initializing each pair of consecutive
Paul E. McKenney37745d22015-01-22 18:24:08 -08001325 rcu_node structures. This helps to expose races involving
1326 grace-period initialization, in other words, it makes your
1327 kernel less stable. It can also greatly increase grace-period
1328 latency, especially on systems with large numbers of CPUs.
1329 This is useful when torture-testing RCU, but in almost no
1330 other circumstance.
1331
1332 Say Y here if you want your system to crash and hang more often.
1333 Say N if you want a sane system.
1334
1335config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1336 int "How much to slow down RCU grace-period initialization"
1337 range 0 5
Paul E. McKenney186bea52015-01-29 16:37:19 -08001338 default 3
Paul E. McKenney8d7dc922015-04-14 19:33:59 -07001339 depends on RCU_TORTURE_TEST_SLOW_INIT
Paul E. McKenney37745d22015-01-22 18:24:08 -08001340 help
1341 This option specifies the number of jiffies to wait between
1342 each rcu_node structure initialization.
1343
Paul E. McKenney0f41c0d2015-03-10 18:33:20 -07001344config RCU_TORTURE_TEST_SLOW_CLEANUP
1345 bool "Slow down RCU grace-period cleanup to expose races"
1346 depends on RCU_TORTURE_TEST
1347 help
1348 This option delays grace-period cleanup for a few jiffies
1349 between cleaning up each pair of consecutive rcu_node
1350 structures. This helps to expose races involving grace-period
1351 cleanup, in other words, it makes your kernel less stable.
1352 It can also greatly increase grace-period latency, especially
1353 on systems with large numbers of CPUs. This is useful when
1354 torture-testing RCU, but in almost no other circumstance.
1355
1356 Say Y here if you want your system to crash and hang more often.
1357 Say N if you want a sane system.
1358
1359config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1360 int "How much to slow down RCU grace-period cleanup"
1361 range 0 5
1362 default 3
1363 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1364 help
1365 This option specifies the number of jiffies to wait between
1366 each rcu_node structure cleanup operation.
1367
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001368config RCU_CPU_STALL_TIMEOUT
1369 int "RCU CPU stall timeout in seconds"
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -07001370 depends on RCU_STALL_COMMON
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001371 range 3 300
Paul E. McKenneyc8960542012-10-25 17:59:23 -07001372 default 21
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001373 help
1374 If a given RCU grace period extends more than the specified
1375 number of seconds, a CPU stall warning is printed. If the
1376 RCU grace period persists, additional CPU stall warnings are
1377 printed at more widely spaced intervals.
1378
Paul E. McKenney5c8806a2012-01-06 15:10:44 -08001379config RCU_TRACE
1380 bool "Enable tracing for RCU"
1381 depends on DEBUG_KERNEL
Paul E. McKenney52494532012-11-14 16:26:40 -08001382 select TRACE_CLOCK
Paul E. McKenney5c8806a2012-01-06 15:10:44 -08001383 help
1384 This option provides tracing in RCU which presents stats
1385 in debugfs for debugging RCU implementation.
1386
1387 Say Y here if you want to enable RCU tracing
1388 Say N if you are unsure.
1389
Paul E. McKenney1ce46ee2015-05-05 23:04:22 -07001390config RCU_EQS_DEBUG
Paul E. McKenneyeb6d5b02015-06-30 09:56:31 -07001391 bool "Provide debugging asserts for adding NO_HZ support to an arch"
Paul E. McKenney1ce46ee2015-05-05 23:04:22 -07001392 depends on DEBUG_KERNEL
1393 help
1394 This option provides consistency checks in RCU's handling of
1395 NO_HZ. These checks have proven quite helpful in detecting
1396 bugs in arch-specific NO_HZ code.
1397
1398 Say N here if you need ultimate kernel/user switch latencies
1399 Say Y if you are unsure
1400
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001401endmenu # "RCU Debugging"
1402
Tejun Heof303fcc2016-02-09 17:59:38 -05001403config DEBUG_WQ_FORCE_RR_CPU
1404 bool "Force round-robin CPU selection for unbound work items"
1405 depends on DEBUG_KERNEL
1406 default n
1407 help
1408 Workqueue used to implicitly guarantee that work items queued
1409 without explicit CPU specified are put on the local CPU. This
1410 guarantee is no longer true and while local CPU is still
1411 preferred work items may be put on foreign CPUs. Kernel
1412 parameter "workqueue.debug_force_rr_cpu" is added to force
1413 round-robin CPU selection to flush out usages which depend on the
1414 now broken guarantee. This config option enables the debug
1415 feature by default. When enabled, memory and cache locality will
1416 be impacted.
1417
Tejun Heo870d6652008-08-25 19:47:25 +09001418config DEBUG_BLOCK_EXT_DEVT
1419 bool "Force extended block device numbers and spread them"
1420 depends on DEBUG_KERNEL
1421 depends on BLOCK
Jens Axboe759f8ca2008-08-29 09:06:29 +02001422 default n
Tejun Heo870d6652008-08-25 19:47:25 +09001423 help
Tejun Heo0e11e342008-10-13 10:46:01 +02001424 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1425 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1426 YOU ARE DOING. Distros, please enable this and fix whatever
1427 is broken.
1428
Tejun Heo870d6652008-08-25 19:47:25 +09001429 Conventionally, block device numbers are allocated from
1430 predetermined contiguous area. However, extended block area
1431 may introduce non-contiguous block device numbers. This
1432 option forces most block device numbers to be allocated from
1433 the extended space and spreads them to discover kernel or
1434 userland code paths which assume predetermined contiguous
1435 device number allocation.
1436
Tejun Heo55dc7db2008-09-01 13:44:35 +02001437 Note that turning on this debug option shuffles all the
1438 device numbers for all IDE and SCSI devices including libata
1439 ones, so root partition specified using device number
1440 directly (via rdev or root=MAJ:MIN) won't work anymore.
1441 Textual device names (root=/dev/sdXn) will continue to work.
1442
Tejun Heo870d6652008-08-25 19:47:25 +09001443 Say N if you are unsure.
1444
Akinobu Mita8d438282012-07-30 14:43:02 -07001445config NOTIFIER_ERROR_INJECTION
1446 tristate "Notifier error injection"
1447 depends on DEBUG_KERNEL
1448 select DEBUG_FS
1449 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001450 This option provides the ability to inject artificial errors to
Akinobu Mita8d438282012-07-30 14:43:02 -07001451 specified notifier chain callbacks. It is useful to test the error
1452 handling of notifier call chain failures.
1453
1454 Say N if unsure.
1455
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001456config CPU_NOTIFIER_ERROR_INJECT
1457 tristate "CPU notifier error injection module"
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001458 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001459 help
1460 This option provides a kernel module that can be used to test
Masanari Iidae41e85c2012-11-30 16:44:39 +09001461 the error handling of the cpu notifiers by injecting artificial
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001462 errors to CPU notifier chain callbacks. It is controlled through
1463 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1464
1465 If the notifier call chain should be failed with some events
1466 notified, write the error code to "actions/<notifier event>/error".
1467
1468 Example: Inject CPU offline error (-1 == -EPERM)
1469
1470 # cd /sys/kernel/debug/notifier-error-inject/cpu
1471 # echo -1 > actions/CPU_DOWN_PREPARE/error
1472 # echo 0 > /sys/devices/system/cpu/cpu1/online
1473 bash: echo: write error: Operation not permitted
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001474
1475 To compile this code as a module, choose M here: the module will
1476 be called cpu-notifier-error-inject.
1477
1478 If unsure, say N.
1479
Akinobu Mita048b9c32012-07-30 14:43:07 -07001480config PM_NOTIFIER_ERROR_INJECT
1481 tristate "PM notifier error injection module"
1482 depends on PM && NOTIFIER_ERROR_INJECTION
1483 default m if PM_DEBUG
1484 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001485 This option provides the ability to inject artificial errors to
Akinobu Mita048b9c32012-07-30 14:43:07 -07001486 PM notifier chain callbacks. It is controlled through debugfs
1487 interface /sys/kernel/debug/notifier-error-inject/pm
1488
1489 If the notifier call chain should be failed with some events
1490 notified, write the error code to "actions/<notifier event>/error".
1491
1492 Example: Inject PM suspend error (-12 = -ENOMEM)
1493
1494 # cd /sys/kernel/debug/notifier-error-inject/pm/
1495 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1496 # echo mem > /sys/power/state
1497 bash: echo: write error: Cannot allocate memory
1498
1499 To compile this code as a module, choose M here: the module will
1500 be called pm-notifier-error-inject.
1501
1502 If unsure, say N.
1503
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001504config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1505 tristate "OF reconfig notifier error injection module"
1506 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001507 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001508 This option provides the ability to inject artificial errors to
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001509 OF reconfig notifier chain callbacks. It is controlled
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001510 through debugfs interface under
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001511 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001512
1513 If the notifier call chain should be failed with some events
1514 notified, write the error code to "actions/<notifier event>/error".
1515
1516 To compile this code as a module, choose M here: the module will
Akinobu Mitae12a95f2013-04-30 15:28:49 -07001517 be called of-reconfig-notifier-error-inject.
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001518
1519 If unsure, say N.
1520
Nikolay Aleksandrov02fff962015-11-28 13:45:28 +01001521config NETDEV_NOTIFIER_ERROR_INJECT
1522 tristate "Netdev notifier error injection module"
1523 depends on NET && NOTIFIER_ERROR_INJECTION
1524 help
1525 This option provides the ability to inject artificial errors to
1526 netdevice notifier chain callbacks. It is controlled through debugfs
1527 interface /sys/kernel/debug/notifier-error-inject/netdev
1528
1529 If the notifier call chain should be failed with some events
1530 notified, write the error code to "actions/<notifier event>/error".
1531
1532 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1533
1534 # cd /sys/kernel/debug/notifier-error-inject/netdev
1535 # echo -22 > actions/NETDEV_CHANGEMTU/error
1536 # ip link set eth0 mtu 1024
1537 RTNETLINK answers: Invalid argument
1538
1539 To compile this code as a module, choose M here: the module will
1540 be called netdev-notifier-error-inject.
1541
1542 If unsure, say N.
1543
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001544config FAULT_INJECTION
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001545 bool "Fault-injection framework"
1546 depends on DEBUG_KERNEL
Akinobu Mita329409a2006-12-08 02:39:48 -08001547 help
1548 Provide fault-injection framework.
1549 For more details, see Documentation/fault-injection/.
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001550
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001551config FAILSLAB
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001552 bool "Fault-injection capability for kmalloc"
1553 depends on FAULT_INJECTION
Akinobu Mita773ff602008-12-23 19:37:01 +09001554 depends on SLAB || SLUB
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001555 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001556 Provide fault-injection capability for kmalloc.
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001557
Akinobu Mita933e3122006-12-08 02:39:45 -08001558config FAIL_PAGE_ALLOC
1559 bool "Fault-injection capabilitiy for alloc_pages()"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001560 depends on FAULT_INJECTION
Akinobu Mita933e3122006-12-08 02:39:45 -08001561 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001562 Provide fault-injection capability for alloc_pages().
Akinobu Mita933e3122006-12-08 02:39:45 -08001563
Akinobu Mitac17bb492006-12-08 02:39:46 -08001564config FAIL_MAKE_REQUEST
Dave Jones86327d12006-12-12 20:16:36 +01001565 bool "Fault-injection capability for disk IO"
Jens Axboe581d4e22008-09-14 05:56:33 -07001566 depends on FAULT_INJECTION && BLOCK
Akinobu Mitac17bb492006-12-08 02:39:46 -08001567 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001568 Provide fault-injection capability for disk IO.
Akinobu Mitac17bb492006-12-08 02:39:46 -08001569
Jens Axboe581d4e22008-09-14 05:56:33 -07001570config FAIL_IO_TIMEOUT
Takuya Yoshikawaf4d014392010-07-21 16:05:53 +09001571 bool "Fault-injection capability for faking disk interrupts"
Jens Axboe581d4e22008-09-14 05:56:33 -07001572 depends on FAULT_INJECTION && BLOCK
1573 help
1574 Provide fault-injection capability on end IO handling. This
1575 will make the block layer "forget" an interrupt as configured,
1576 thus exercising the error handling.
1577
1578 Only works with drivers that use the generic timeout handling,
1579 for others it wont do anything.
1580
Per Forlin1b676f72011-08-19 14:52:37 +02001581config FAIL_MMC_REQUEST
1582 bool "Fault-injection capability for MMC IO"
Adrien Schildknecht28ff4fd2015-11-10 20:12:19 +01001583 depends on FAULT_INJECTION_DEBUG_FS && MMC
Per Forlin1b676f72011-08-19 14:52:37 +02001584 help
1585 Provide fault-injection capability for MMC IO.
1586 This will make the mmc core return data errors. This is
1587 useful to test the error handling in the mmc block device
1588 and to test how the mmc host driver handles retries from
1589 the block device.
1590
Davidlohr Buesoab51fba2015-06-29 23:26:02 -07001591config FAIL_FUTEX
1592 bool "Fault-injection capability for futexes"
1593 select DEBUG_FS
1594 depends on FAULT_INJECTION && FUTEX
1595 help
1596 Provide fault-injection capability for futexes.
1597
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001598config FAULT_INJECTION_DEBUG_FS
1599 bool "Debugfs entries for fault-injection capabilities"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001600 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001601 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001602 Enable configuration of fault-injection capabilities via debugfs.
Akinobu Mita1df49002007-02-20 13:57:56 -08001603
1604config FAULT_INJECTION_STACKTRACE_FILTER
1605 bool "stacktrace filter for fault-injection capabilities"
1606 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
Akinobu Mita6d690dc2007-05-12 10:36:53 -07001607 depends on !X86_64
Akinobu Mita1df49002007-02-20 13:57:56 -08001608 select STACKTRACE
Chen Gangdf2e1ef2014-06-23 13:22:04 -07001609 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
Akinobu Mita1df49002007-02-20 13:57:56 -08001610 help
1611 Provide stacktrace filter for fault-injection capabilities
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001612
Arjan van de Ven97455122008-01-25 21:08:34 +01001613config LATENCYTOP
1614 bool "Latency measuring infrastructure"
Randy Dunlap625fdca2010-08-12 12:31:21 -07001615 depends on DEBUG_KERNEL
1616 depends on STACKTRACE_SUPPORT
1617 depends on PROC_FS
Vineet Guptacc80ae32013-08-27 13:52:51 +05301618 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
Arjan van de Ven97455122008-01-25 21:08:34 +01001619 select KALLSYMS
1620 select KALLSYMS_ALL
1621 select STACKTRACE
1622 select SCHEDSTATS
1623 select SCHED_DEBUG
Arjan van de Ven97455122008-01-25 21:08:34 +01001624 help
1625 Enable this option if you want to use the LatencyTOP tool
1626 to find out which userspace is blocking on what kernel operations.
1627
Stephen Boyd446f24d2013-04-30 15:28:42 -07001628config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1629 bool
1630
1631config DEBUG_STRICT_USER_COPY_CHECKS
1632 bool "Strict user copy size checks"
1633 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1634 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1635 help
1636 Enabling this option turns a certain set of sanity checks for user
1637 copy operations into compile time failures.
1638
1639 The copy_from_user() etc checks are there to help test if there
1640 are sufficient security checks on the length argument of
1641 the copy operation, by having gcc prove that the argument is
1642 within bounds.
1643
1644 If unsure, say N.
1645
Arnaldo Carvalho de Melo16444a82008-05-12 21:20:42 +02001646source kernel/trace/Kconfig
1647
Dave Hansen881c5142013-07-01 13:04:44 -07001648menu "Runtime Testing"
1649
1650config LKDTM
1651 tristate "Linux Kernel Dump Test Tool Module"
1652 depends on DEBUG_FS
1653 depends on BLOCK
1654 default n
1655 help
1656 This module enables testing of the different dumping mechanisms by
1657 inducing system failures at predefined crash points.
1658 If you don't need it: say N
1659 Choose M here to compile this code as a module. The module will be
1660 called lkdtm.
1661
1662 Documentation on how to use the module can be found in
1663 Documentation/fault-injection/provoke-crashes.txt
1664
1665config TEST_LIST_SORT
1666 bool "Linked list sorting test"
1667 depends on DEBUG_KERNEL
1668 help
1669 Enable this to turn on 'list_sort()' function test. This test is
1670 executed only once during system boot, so affects only boot time.
1671
1672 If unsure, say N.
1673
1674config KPROBES_SANITY_TEST
1675 bool "Kprobes sanity tests"
1676 depends on DEBUG_KERNEL
1677 depends on KPROBES
1678 default n
1679 help
1680 This option provides for testing basic kprobes functionality on
1681 boot. A sample kprobe, jprobe and kretprobe are inserted and
1682 verified for functionality.
1683
1684 Say N if you are unsure.
1685
1686config BACKTRACE_SELF_TEST
1687 tristate "Self test for the backtrace code"
1688 depends on DEBUG_KERNEL
1689 default n
1690 help
1691 This option provides a kernel module that can be used to test
1692 the kernel stack backtrace code. This option is not useful
1693 for distributions or general kernels, but only for kernel
1694 developers working on architecture code.
1695
1696 Note that if you want to also test saved backtraces, you will
1697 have to enable STACKTRACE as well.
1698
1699 Say N if you are unsure.
1700
Michel Lespinasse910a7422012-10-08 16:30:39 -07001701config RBTREE_TEST
1702 tristate "Red-Black tree test"
Cody P Schafer7c993e12013-09-11 14:25:19 -07001703 depends on DEBUG_KERNEL
Michel Lespinasse910a7422012-10-08 16:30:39 -07001704 help
1705 A benchmark measuring the performance of the rbtree library.
1706 Also includes rbtree invariant checks.
1707
Michel Lespinassefff3fd82012-10-08 16:31:23 -07001708config INTERVAL_TREE_TEST
1709 tristate "Interval tree test"
1710 depends on m && DEBUG_KERNEL
Chris Wilsona88cc102014-03-17 12:21:54 +00001711 select INTERVAL_TREE
Michel Lespinassefff3fd82012-10-08 16:31:23 -07001712 help
1713 A benchmark measuring the performance of the interval tree library
1714
Greg Thelen623fd802013-11-12 15:08:34 -08001715config PERCPU_TEST
1716 tristate "Per cpu operations test"
1717 depends on m && DEBUG_KERNEL
1718 help
1719 Enable this option to build test module which validates per-cpu
1720 operations.
1721
1722 If unsure, say N.
1723
Dave Hansen881c5142013-07-01 13:04:44 -07001724config ATOMIC64_SELFTEST
1725 bool "Perform an atomic64_t self-test at boot"
1726 help
1727 Enable this option to test the atomic64_t functions at boot.
1728
1729 If unsure, say N.
1730
1731config ASYNC_RAID6_TEST
1732 tristate "Self test for hardware accelerated raid6 recovery"
1733 depends on ASYNC_RAID6_RECOV
1734 select ASYNC_MEMCPY
1735 ---help---
1736 This is a one-shot self test that permutes through the
1737 recovery of all the possible two disk failure scenarios for a
1738 N-disk array. Recovery is performed with the asynchronous
1739 raid6 recovery routines, and will optionally use an offload
1740 engine if one is available.
1741
1742 If unsure, say N.
1743
Andy Shevchenko64d1d772015-02-12 15:02:21 -08001744config TEST_HEXDUMP
1745 tristate "Test functions located in the hexdump module at runtime"
1746
Dave Hansen881c5142013-07-01 13:04:44 -07001747config TEST_STRING_HELPERS
1748 tristate "Test functions located in the string_helpers module at runtime"
1749
1750config TEST_KSTRTOX
1751 tristate "Test kstrto*() family of functions at runtime"
1752
Rasmus Villemoes707cc722015-11-06 16:30:29 -08001753config TEST_PRINTF
1754 tristate "Test printf() family of functions at runtime"
1755
Thomas Graf7e1e7762014-08-02 11:47:44 +02001756config TEST_RHASHTABLE
Geert Uytterhoeven9d6dbe12015-01-29 15:40:25 +01001757 tristate "Perform selftest on resizable hash table"
Thomas Graf7e1e7762014-08-02 11:47:44 +02001758 default n
1759 help
1760 Enable this option to test the rhashtable functions at boot.
1761
1762 If unsure, say N.
1763
Dave Hansen881c5142013-07-01 13:04:44 -07001764endmenu # runtime tests
1765
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001766config PROVIDE_OHCI1394_DMA_INIT
Stefan Richter080de8c2008-02-28 20:54:43 +01001767 bool "Remote debugging over FireWire early on boot"
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001768 depends on PCI && X86
1769 help
1770 If you want to debug problems which hang or crash the kernel early
1771 on boot and the crashing machine has a FireWire port, you can use
1772 this feature to remotely access the memory of the crashed machine
1773 over FireWire. This employs remote DMA as part of the OHCI1394
1774 specification which is now the standard for FireWire controllers.
1775
1776 With remote DMA, you can monitor the printk buffer remotely using
1777 firescope and access all memory below 4GB using fireproxy from gdb.
1778 Even controlling a kernel debugger is possible using remote DMA.
1779
1780 Usage:
1781
1782 If ohci1394_dma=early is used as boot parameter, it will initialize
1783 all OHCI1394 controllers which are found in the PCI config space.
1784
1785 As all changes to the FireWire bus such as enabling and disabling
1786 devices cause a bus reset and thereby disable remote DMA for all
1787 devices, be sure to have the cable plugged and FireWire enabled on
1788 the debugging host before booting the debug target for debugging.
1789
1790 This code (~1k) is freed after boot. By then, the firewire stack
1791 in charge of the OHCI-1394 controllers should be used instead.
1792
1793 See Documentation/debugging-via-ohci1394.txt for more information.
Arjan van de Ven97455122008-01-25 21:08:34 +01001794
Randy Dunlap152de302009-02-20 15:38:47 -08001795config BUILD_DOCSRC
Randy Dunlap3794f3e2008-08-12 15:09:06 -07001796 bool "Build targets in Documentation/ tree"
1797 depends on HEADERS_CHECK
1798 help
1799 This option attempts to build objects from the source files in the
1800 kernel Documentation/ tree.
1801
1802 Say N if you are unsure.
1803
Joerg Roedel5ee00bd2009-01-09 12:14:24 +01001804config DMA_API_DEBUG
1805 bool "Enable debugging of DMA-API usage"
1806 depends on HAVE_DMA_API_DEBUG
1807 help
1808 Enable this option to debug the use of the DMA API by device drivers.
1809 With this option you will be able to detect common bugs in device
1810 drivers like double-freeing of DMA mappings or freeing mappings that
1811 were never allocated.
Dan Williams0abdd7a2014-01-21 15:48:12 -08001812
1813 This also attempts to catch cases where a page owned by DMA is
1814 accessed by the cpu in a way that could cause data corruption. For
1815 example, this enables cow_user_page() to check that the source page is
1816 not undergoing DMA.
1817
1818 This option causes a performance degradation. Use only if you want to
1819 debug device drivers and dma interactions.
1820
1821 If unsure, say N.
Jason Baron346e15b2008-08-12 16:46:19 -04001822
Valentin Rothberg8a6f0b42014-10-13 15:51:38 -07001823config TEST_LKM
Kees Cook93e9ef82014-01-23 15:54:37 -08001824 tristate "Test module loading with 'hello world' module"
1825 default n
1826 depends on m
1827 help
1828 This builds the "test_module" module that emits "Hello, world"
1829 on printk when loaded. It is designed to be used for basic
1830 evaluation of the module loading subsystem (for example when
1831 validating module verification). It lacks any extra dependencies,
1832 and will not normally be loaded by the system unless explicitly
1833 requested by name.
1834
1835 If unsure, say N.
1836
Kees Cook3e2a4c12014-01-23 15:54:38 -08001837config TEST_USER_COPY
1838 tristate "Test user/kernel boundary protections"
1839 default n
1840 depends on m
1841 help
1842 This builds the "test_user_copy" module that runs sanity checks
1843 on the copy_to/from_user infrastructure, making sure basic
1844 user/kernel boundary testing is working. If it fails to load,
1845 a regression has been detected in the user/kernel memory boundary
1846 protections.
1847
1848 If unsure, say N.
1849
Alexei Starovoitov64a89462014-05-08 14:10:52 -07001850config TEST_BPF
1851 tristate "Test BPF filter functionality"
1852 default n
Randy Dunlap98920ba2014-05-13 09:58:44 -07001853 depends on m && NET
Alexei Starovoitov64a89462014-05-08 14:10:52 -07001854 help
1855 This builds the "test_bpf" module that runs various test vectors
1856 against the BPF interpreter or BPF JIT compiler depending on the
1857 current setting. This is in particular useful for BPF JIT compiler
1858 development, but also to run regression tests against changes in
Alexei Starovoitov3c731eb2014-09-26 00:17:07 -07001859 the interpreter code. It also enables test stubs for eBPF maps and
1860 verifier used by user space verifier testsuite.
Alexei Starovoitov64a89462014-05-08 14:10:52 -07001861
1862 If unsure, say N.
1863
Kees Cook0a8adf52014-07-14 14:38:12 -07001864config TEST_FIRMWARE
1865 tristate "Test firmware loading via userspace interface"
1866 default n
1867 depends on FW_LOADER
1868 help
1869 This builds the "test_firmware" module that creates a userspace
1870 interface for testing firmware loading. This can be used to
1871 control the triggering of firmware loading without needing an
1872 actual firmware-using device. The contents can be rechecked by
1873 userspace.
1874
1875 If unsure, say N.
1876
David Rileye704f932014-06-16 14:58:32 -07001877config TEST_UDELAY
1878 tristate "udelay test driver"
1879 default n
1880 help
1881 This builds the "udelay_test" module that helps to make sure
1882 that udelay() is working properly.
1883
1884 If unsure, say N.
1885
Vladimir Murzin4a207992015-04-14 15:48:27 -07001886config MEMTEST
1887 bool "Memtest"
1888 depends on HAVE_MEMBLOCK
1889 ---help---
1890 This option adds a kernel parameter 'memtest', which allows memtest
1891 to be set.
1892 memtest=0, mean disabled; -- default
1893 memtest=1, mean do 1 test pattern;
1894 ...
Vladimir Murzin8d8cfb42015-04-14 15:48:40 -07001895 memtest=17, mean do 17 test patterns.
Vladimir Murzin4a207992015-04-14 15:48:27 -07001896 If you are unsure how to answer this question, answer N.
1897
Ingo Molnar2bf9e0a2015-08-03 11:42:57 +02001898config TEST_STATIC_KEYS
1899 tristate "Test static keys"
Jason Baron579e1ac2015-07-30 03:59:44 +00001900 default n
1901 depends on m
1902 help
Ingo Molnar2bf9e0a2015-08-03 11:42:57 +02001903 Test the static key interfaces.
Jason Baron579e1ac2015-07-30 03:59:44 +00001904
1905 If unsure, say N.
1906
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001907source "samples/Kconfig"
Jason Wesseldc7d5522008-04-17 20:05:37 +02001908
1909source "lib/Kconfig.kgdb"
Pekka Enberg0a4af3b2009-02-26 21:38:56 +02001910
Andrey Ryabininc6d30852016-01-20 15:00:55 -08001911source "lib/Kconfig.ubsan"
1912
Dan Williams21266be2015-11-19 18:19:29 -08001913config ARCH_HAS_DEVMEM_IS_ALLOWED
1914 bool
1915
1916config STRICT_DEVMEM
1917 bool "Filter access to /dev/mem"
1918 depends on MMU
1919 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1920 default y if TILE || PPC
1921 ---help---
1922 If this option is disabled, you allow userspace (root) access to all
1923 of memory, including kernel and userspace memory. Accidental
1924 access to this is obviously disastrous, but specific access can
1925 be used by people debugging the kernel. Note that with PAT support
1926 enabled, even in this case there are restrictions on /dev/mem
1927 use due to the cache aliasing requirements.
1928
Dan Williams90a545e2015-11-23 15:49:03 -08001929 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1930 file only allows userspace access to PCI space and the BIOS code and
1931 data regions. This is sufficient for dosemu and X and all common
1932 users of /dev/mem.
1933
1934 If in doubt, say Y.
1935
1936config IO_STRICT_DEVMEM
1937 bool "Filter I/O access to /dev/mem"
1938 depends on STRICT_DEVMEM
Dan Williams90a545e2015-11-23 15:49:03 -08001939 ---help---
1940 If this option is disabled, you allow userspace (root) access to all
1941 io-memory regardless of whether a driver is actively using that
1942 range. Accidental access to this is obviously disastrous, but
1943 specific access can be used by people debugging kernel drivers.
1944
Dan Williams21266be2015-11-19 18:19:29 -08001945 If this option is switched on, the /dev/mem file only allows
Dan Williams90a545e2015-11-23 15:49:03 -08001946 userspace access to *idle* io-memory ranges (see /proc/iomem) This
1947 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1948 if the driver using a given range cannot be disabled.
Dan Williams21266be2015-11-19 18:19:29 -08001949
1950 If in doubt, say Y.