blob: 2307d7c89dac972fae526627ce21ecdd087369de [file] [log] [blame]
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
Joonsoo Kimf2ca0b52016-07-26 15:23:55 -0700247 select STACKDEPOT
Joonsoo Kim48c96a32014-12-12 16:56:01 -0800248 select PAGE_EXTENSION
249 help
250 This keeps track of what call chain is the owner of a page, may
251 help to find bare alloc_page(s) leaks. Even if you include this
252 feature on your build, it is disabled in default. You should pass
253 "page_owner=on" to boot parameter in order to enable it. Eats
254 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
255 for user-space helper.
256
257 If unsure, say N.
258
Don Mullisbf4735a2006-12-10 02:18:37 -0800259config DEBUG_FS
260 bool "Debug Filesystem"
Nicolai Stange9fd4dce2016-03-22 14:11:13 +0100261 select SRCU
Don Mullisbf4735a2006-12-10 02:18:37 -0800262 help
263 debugfs is a virtual file system that kernel developers use to put
264 debugging files into. Enable this option to be able to read and
265 write to these files.
266
Robert P. J. Dayff543332008-05-20 00:06:00 +0200267 For detailed documentation on the debugfs API, see
268 Documentation/DocBook/filesystems.
269
Don Mullisbf4735a2006-12-10 02:18:37 -0800270 If unsure, say N.
271
272config HEADERS_CHECK
273 bool "Run 'make headers_check' when building vmlinux"
274 depends on !UML
275 help
276 This option will extract the user-visible kernel headers whenever
277 building the kernel, and will run basic sanity checks on them to
278 ensure that exported files do not attempt to include files which
279 were not exported, etc.
280
281 If you're making modifications to header files which are
282 relevant for userspace, say 'Y', and check the headers
283 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
284 your build tree), to make sure they're suitable.
285
Sam Ravnborg91341d42008-01-21 21:31:44 +0100286config DEBUG_SECTION_MISMATCH
287 bool "Enable full Section mismatch analysis"
Sam Ravnborg91341d42008-01-21 21:31:44 +0100288 help
289 The section mismatch analysis checks if there are illegal
290 references from one section to another section.
Michael Wittene809ab02011-04-17 04:08:48 +0000291 During linktime or runtime, some sections are dropped;
292 any use of code/data previously in these sections would
Sam Ravnborg91341d42008-01-21 21:31:44 +0100293 most likely result in an oops.
Michael Wittene809ab02011-04-17 04:08:48 +0000294 In the code, functions and variables are annotated with
Paul Gortmaker0db06282013-06-19 14:53:51 -0400295 __init,, etc. (see the full list in include/linux/init.h),
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100296 which results in the code/data being placed in specific sections.
Michael Wittene809ab02011-04-17 04:08:48 +0000297 The section mismatch analysis is always performed after a full
298 kernel build, and enabling this option causes the following
299 additional steps to occur:
300 - Add the option -fno-inline-functions-called-once to gcc commands.
301 When inlining a function annotated with __init in a non-init
302 function, we would lose the section information and thus
Sam Ravnborg91341d42008-01-21 21:31:44 +0100303 the analysis would not catch the illegal reference.
Michael Wittene809ab02011-04-17 04:08:48 +0000304 This option tells gcc to inline less (but it does result in
305 a larger kernel).
306 - Run the section mismatch analysis for each module/built-in.o file.
307 When we run the section mismatch analysis on vmlinux.o, we
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100308 lose valueble information about where the mismatch was
Sam Ravnborg91341d42008-01-21 21:31:44 +0100309 introduced.
310 Running the analysis for each module/built-in.o file
Michael Wittene809ab02011-04-17 04:08:48 +0000311 tells where the mismatch happens much closer to the
312 source. The drawback is that the same mismatch is
313 reported at least twice.
314 - Enable verbose reporting from modpost in order to help resolve
315 the section mismatches that are reported.
Sam Ravnborg91341d42008-01-21 21:31:44 +0100316
Nicolas Boichat47490ec2015-10-06 09:44:42 +1030317config SECTION_MISMATCH_WARN_ONLY
318 bool "Make section mismatch errors non-fatal"
319 default y
320 help
321 If you say N here, the build process will fail if there are any
322 section mismatch, instead of just throwing warnings.
323
324 If unsure, say Y.
325
Dave Hansen6dfc0662013-07-01 13:04:46 -0700326#
327# Select this config option from the architecture Kconfig, if it
328# is preferred to always offer frame pointers as a config
329# option on the architecture (regardless of KERNEL_DEBUG):
330#
331config ARCH_WANT_FRAME_POINTERS
332 bool
333 help
334
335config FRAME_POINTER
336 bool "Compile the kernel with frame pointers"
337 depends on DEBUG_KERNEL && \
338 (CRIS || M68K || FRV || UML || \
339 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
340 ARCH_WANT_FRAME_POINTERS
341 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
342 help
343 If you say Y here the resulting kernel image will be slightly
344 larger and slower, but it gives very useful debugging information
345 in case of kernel bugs. (precise oopses/stacktraces/warnings)
346
Josh Poimboeufb9ab5eb2016-02-28 22:22:42 -0600347config STACK_VALIDATION
348 bool "Compile-time stack metadata validation"
349 depends on HAVE_STACK_VALIDATION
350 default n
351 help
352 Add compile-time checks to validate stack metadata, including frame
353 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
354 that runtime stack traces are more reliable.
355
356 For more information, see
357 tools/objtool/Documentation/stack-validation.txt.
358
Dave Hansen6dfc0662013-07-01 13:04:46 -0700359config DEBUG_FORCE_WEAK_PER_CPU
360 bool "Force weak per-cpu definitions"
361 depends on DEBUG_KERNEL
362 help
363 s390 and alpha require percpu variables in modules to be
364 defined weak to work around addressing range issue which
365 puts the following two restrictions on percpu variable
366 definitions.
367
368 1. percpu symbols must be unique whether static or not
369 2. percpu variables can't be defined inside a function
370
371 To ensure that generic code follows the above rules, this
372 option forces all percpu variables to be defined as weak.
373
374endmenu # "Compiler options"
375
376config MAGIC_SYSRQ
377 bool "Magic SysRq key"
378 depends on !UML
379 help
380 If you say Y here, you will have some control over the system even
381 if the system crashes for example during kernel debugging (e.g., you
382 will be able to flush the buffer cache to disk, reboot the system
383 immediately or dump some status information). This is accomplished
384 by pressing various keys while holding SysRq (Alt+PrintScreen). It
385 also works on a serial console (on PC hardware at least), if you
386 send a BREAK and then within 5 seconds a command keypress. The
387 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
388 unless you really know what this hack does.
389
Ben Hutchings8eaede42013-10-07 01:05:46 +0100390config MAGIC_SYSRQ_DEFAULT_ENABLE
391 hex "Enable magic SysRq key functions by default"
392 depends on MAGIC_SYSRQ
393 default 0x1
394 help
395 Specifies which SysRq key functions are enabled by default.
396 This may be set to 1 or 0 to enable or disable them all, or
397 to a bitmask as described in Documentation/sysrq.txt.
398
Adrian Bunkf346f4b2006-01-09 20:54:51 -0800399config DEBUG_KERNEL
400 bool "Kernel debugging"
401 help
402 Say Y here if you are developing drivers or trying to debug and
403 identify kernel problems.
404
Dave Hansen0610c8a2013-07-01 13:04:43 -0700405menu "Memory Debugging"
David Woodhousea304e1b2007-02-12 00:52:00 -0800406
Dave Hansen0610c8a2013-07-01 13:04:43 -0700407source mm/Kconfig.debug
Ingo Molnar82f67cd2007-02-16 01:28:13 -0800408
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700409config DEBUG_OBJECTS
410 bool "Debug object operations"
411 depends on DEBUG_KERNEL
412 help
413 If you say Y here, additional code will be inserted into the
414 kernel to track the life time of various objects and validate
415 the operations on those objects.
416
417config DEBUG_OBJECTS_SELFTEST
418 bool "Debug objects selftest"
419 depends on DEBUG_OBJECTS
420 help
421 This enables the selftest of the object debug code.
422
423config DEBUG_OBJECTS_FREE
424 bool "Debug objects in freed memory"
425 depends on DEBUG_OBJECTS
426 help
427 This enables checks whether a k/v free operation frees an area
428 which contains an object which has not been deactivated
429 properly. This can make kmalloc/kfree-intensive workloads
430 much slower.
431
Thomas Gleixnerc6f3a972008-04-30 00:55:03 -0700432config DEBUG_OBJECTS_TIMERS
433 bool "Debug timer objects"
434 depends on DEBUG_OBJECTS
435 help
436 If you say Y here, additional code will be inserted into the
437 timer routines to track the life time of timer objects and
438 validate the timer operations.
439
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900440config DEBUG_OBJECTS_WORK
441 bool "Debug work objects"
442 depends on DEBUG_OBJECTS
443 help
444 If you say Y here, additional code will be inserted into the
445 work queue routines to track the life time of work objects and
446 validate the work operations.
447
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400448config DEBUG_OBJECTS_RCU_HEAD
449 bool "Debug RCU callbacks objects"
Mathieu Desnoyersfc2ecf72011-02-23 09:42:14 -0800450 depends on DEBUG_OBJECTS
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400451 help
452 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
453
Tejun Heoe2852ae2010-10-26 14:23:05 -0700454config DEBUG_OBJECTS_PERCPU_COUNTER
455 bool "Debug percpu counter objects"
456 depends on DEBUG_OBJECTS
457 help
458 If you say Y here, additional code will be inserted into the
459 percpu counter routines to track the life time of percpu counter
460 objects and validate the percpu counter operations.
461
Ingo Molnar3ae70202008-11-26 10:02:00 +0100462config DEBUG_OBJECTS_ENABLE_DEFAULT
463 int "debug_objects bootup default value (0-1)"
464 range 0 1
465 default "1"
466 depends on DEBUG_OBJECTS
467 help
468 Debug objects boot parameter default value
469
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470config DEBUG_SLAB
Andrew Morton4a2f0ac2006-03-25 03:07:22 -0800471 bool "Debug slab memory allocations"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200472 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 help
474 Say Y here to have the kernel do limited verification on memory
475 allocation as well as poisoning memory on free to catch use of freed
476 memory. This can make kmalloc/kfree-intensive workloads much slower.
477
Al Viro871751e2006-03-25 03:06:39 -0800478config DEBUG_SLAB_LEAK
479 bool "Memory leak debugging"
480 depends on DEBUG_SLAB
481
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700482config SLUB_DEBUG_ON
483 bool "SLUB debugging on by default"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200484 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700485 default n
486 help
487 Boot with debugging on by default. SLUB boots by default with
488 the runtime debug capabilities switched off. Enabling this is
489 equivalent to specifying the "slub_debug" parameter on boot.
490 There is no support for more fine grained debug control like
491 possible with slub_debug=xxx. SLUB debugging may be switched
492 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
493 "slub_debug=-".
494
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800495config SLUB_STATS
496 default n
497 bool "Enable SLUB performance statistics"
Christoph Lameterab4d5ed2010-10-05 13:57:26 -0500498 depends on SLUB && SYSFS
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800499 help
500 SLUB statistics are useful to debug SLUBs allocation behavior in
501 order find ways to optimize the allocator. This should never be
502 enabled for production use since keeping statistics slows down
503 the allocator by a few percentage points. The slabinfo command
504 supports the determination of the most active slabs to figure
505 out which slabs are relevant to a particular load.
506 Try running: slabinfo -DA
507
Catalin Marinasb69ec422012-10-08 16:28:11 -0700508config HAVE_DEBUG_KMEMLEAK
509 bool
510
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100511config DEBUG_KMEMLEAK
512 bool "Kernel memory leak detector"
Kees Cook525c1f92013-01-16 18:54:16 -0800513 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
Catalin Marinas79e0d9b2011-04-27 17:06:19 +0100514 select DEBUG_FS
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100515 select STACKTRACE if STACKTRACE_SUPPORT
516 select KALLSYMS
Randy Dunlapb60e26a2009-11-06 15:33:45 -0800517 select CRC32
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100518 help
519 Say Y here if you want to enable the memory leak
520 detector. The memory allocation/freeing is traced in a way
521 similar to the Boehm's conservative garbage collector, the
522 difference being that the orphan objects are not freed but
523 only shown in /sys/kernel/debug/kmemleak. Enabling this
524 feature will introduce an overhead to memory
525 allocations. See Documentation/kmemleak.txt for more
526 details.
527
Catalin Marinasbf96d1e2009-06-23 14:40:27 +0100528 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
529 of finding leaks due to the slab objects poisoning.
530
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100531 In order to access the kmemleak file, debugfs needs to be
532 mounted (usually at /sys/kernel/debug).
533
Catalin Marinasa9d90582009-06-25 10:16:11 +0100534config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
535 int "Maximum kmemleak early log entries"
536 depends on DEBUG_KMEMLEAK
Heiko Carstensdfcc3e62009-10-06 10:33:57 +0200537 range 200 40000
Catalin Marinasa9d90582009-06-25 10:16:11 +0100538 default 400
539 help
540 Kmemleak must track all the memory allocations to avoid
541 reporting false positives. Since memory may be allocated or
542 freed before kmemleak is initialised, an early log buffer is
543 used to store these actions. If kmemleak reports "early log
544 buffer exceeded", please increase this value.
545
Catalin Marinas0822ee42009-06-11 13:24:14 +0100546config DEBUG_KMEMLEAK_TEST
547 tristate "Simple test for the kernel memory leak detector"
Daniel Baluta97182692011-04-04 15:06:44 -0700548 depends on DEBUG_KMEMLEAK && m
Catalin Marinas0822ee42009-06-11 13:24:14 +0100549 help
Daniel Baluta97182692011-04-04 15:06:44 -0700550 This option enables a module that explicitly leaks memory.
Catalin Marinas0822ee42009-06-11 13:24:14 +0100551
552 If unsure, say N.
553
Jason Baronab0155a2010-07-19 11:54:17 +0100554config DEBUG_KMEMLEAK_DEFAULT_OFF
555 bool "Default kmemleak to off"
556 depends on DEBUG_KMEMLEAK
557 help
558 Say Y here to disable kmemleak by default. It can then be enabled
559 on the command line via kmemleak=on.
560
Dave Hansen0610c8a2013-07-01 13:04:43 -0700561config DEBUG_STACK_USAGE
562 bool "Stack utilization instrumentation"
Helge Deller6c31da32016-03-19 17:54:10 +0100563 depends on DEBUG_KERNEL && !IA64
Dave Hansen0610c8a2013-07-01 13:04:43 -0700564 help
565 Enables the display of the minimum amount of free stack which each
566 task has ever had available in the sysrq-T and sysrq-P debug output.
567
568 This option will slow down process creation somewhat.
569
570config DEBUG_VM
571 bool "Debug VM"
572 depends on DEBUG_KERNEL
573 help
574 Enable this to turn on extended checks in the virtual-memory system
575 that may impact performance.
576
577 If unsure, say N.
578
Davidlohr Bueso4f115142014-06-04 16:06:46 -0700579config DEBUG_VM_VMACACHE
580 bool "Debug VMA caching"
581 depends on DEBUG_VM
582 help
583 Enable this to turn on VMA caching debug information. Doing so
584 can cause significant overhead, so only enable it in non-production
585 environments.
586
587 If unsure, say N.
588
Dave Hansen0610c8a2013-07-01 13:04:43 -0700589config DEBUG_VM_RB
590 bool "Debug VM red-black trees"
591 depends on DEBUG_VM
592 help
Davidlohr Buesoa663dad2014-04-18 15:07:22 -0700593 Enable VM red-black tree debugging information and extra validations.
Dave Hansen0610c8a2013-07-01 13:04:43 -0700594
595 If unsure, say N.
596
Kirill A. Shutemov95ad9752016-01-15 16:51:21 -0800597config DEBUG_VM_PGFLAGS
598 bool "Debug page-flags operations"
599 depends on DEBUG_VM
600 help
601 Enables extra validation on page flags operations.
602
603 If unsure, say N.
604
Dave Hansen0610c8a2013-07-01 13:04:43 -0700605config DEBUG_VIRTUAL
606 bool "Debug VM translations"
607 depends on DEBUG_KERNEL && X86
608 help
609 Enable some costly sanity checks in virtual to page code. This can
610 catch mistakes with virt_to_page() and friends.
611
612 If unsure, say N.
613
614config DEBUG_NOMMU_REGIONS
615 bool "Debug the global anon/private NOMMU mapping region tree"
616 depends on DEBUG_KERNEL && !MMU
617 help
618 This option causes the global tree of anonymous and private mapping
619 regions to be regularly checked for invalid topology.
620
621config DEBUG_MEMORY_INIT
622 bool "Debug memory initialisation" if EXPERT
623 default !EXPERT
624 help
625 Enable this for additional checks during memory initialisation.
626 The sanity checks verify aspects of the VM such as the memory model
627 and other information provided by the architecture. Verbose
628 information will be printed at KERN_DEBUG loglevel depending
629 on the mminit_loglevel= command-line option.
630
631 If unsure, say Y
632
633config MEMORY_NOTIFIER_ERROR_INJECT
634 tristate "Memory hotplug notifier error injection module"
635 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
636 help
637 This option provides the ability to inject artificial errors to
638 memory hotplug notifier chain callbacks. It is controlled through
639 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
640
641 If the notifier call chain should be failed with some events
642 notified, write the error code to "actions/<notifier event>/error".
643
644 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
645
646 # cd /sys/kernel/debug/notifier-error-inject/memory
647 # echo -12 > actions/MEM_GOING_OFFLINE/error
648 # echo offline > /sys/devices/system/memory/memoryXXX/state
649 bash: echo: write error: Cannot allocate memory
650
651 To compile this code as a module, choose M here: the module will
652 be called memory-notifier-error-inject.
653
654 If unsure, say N.
655
656config DEBUG_PER_CPU_MAPS
657 bool "Debug access to per_cpu maps"
658 depends on DEBUG_KERNEL
659 depends on SMP
660 help
661 Say Y to verify that the per_cpu map being accessed has
662 been set up. This adds a fair amount of code to kernel memory
663 and decreases performance.
664
665 Say N if unsure.
666
667config DEBUG_HIGHMEM
668 bool "Highmem debugging"
669 depends on DEBUG_KERNEL && HIGHMEM
670 help
Geert Uytterhoevenb1357c92014-04-14 18:55:50 +0200671 This option enables additional error checking for high memory
672 systems. Disable for production systems.
Dave Hansen0610c8a2013-07-01 13:04:43 -0700673
674config HAVE_DEBUG_STACKOVERFLOW
675 bool
676
677config DEBUG_STACKOVERFLOW
678 bool "Check for stack overflows"
679 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
680 ---help---
681 Say Y here if you want to check for overflows of kernel, IRQ
Borislav Petkovedb0ec02015-01-25 19:50:34 +0100682 and exception stacks (if your architecture uses them). This
Dave Hansen0610c8a2013-07-01 13:04:43 -0700683 option will show detailed messages if free stack space drops
684 below a certain limit.
685
686 These kinds of bugs usually occur when call-chains in the
687 kernel get too deep, especially when interrupts are
688 involved.
689
690 Use this in cases where you see apparently random memory
691 corruption, especially if it appears in 'struct thread_info'
692
693 If in doubt, say "N".
694
695source "lib/Kconfig.kmemcheck"
696
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800697source "lib/Kconfig.kasan"
698
Dave Hansen0610c8a2013-07-01 13:04:43 -0700699endmenu # "Memory Debugging"
700
Dmitry Vyukov5c9a8752016-03-22 14:27:30 -0700701config ARCH_HAS_KCOV
702 bool
703 help
704 KCOV does not have any arch-specific code, but currently it is enabled
705 only for x86_64. KCOV requires testing on other archs, and most likely
706 disabling of instrumentation for some early boot code.
707
708config KCOV
709 bool "Code coverage for fuzzing"
710 depends on ARCH_HAS_KCOV
711 select DEBUG_FS
Kees Cooka519167e2016-06-11 09:09:28 -0700712 select GCC_PLUGINS if !COMPILE_TEST
713 select GCC_PLUGIN_SANCOV if !COMPILE_TEST
Dmitry Vyukov5c9a8752016-03-22 14:27:30 -0700714 help
715 KCOV exposes kernel code coverage information in a form suitable
716 for coverage-guided fuzzing (randomized testing).
717
718 If RANDOMIZE_BASE is enabled, PC values will not be stable across
719 different machines and across reboots. If you need stable PC values,
720 disable RANDOMIZE_BASE.
721
722 For more details, see Documentation/kcov.txt.
723
Vegard Nossuma4691de2016-08-02 14:07:30 -0700724config KCOV_INSTRUMENT_ALL
725 bool "Instrument all code by default"
726 depends on KCOV
727 default y if KCOV
728 help
729 If you are doing generic system call fuzzing (like e.g. syzkaller),
730 then you will want to instrument the whole kernel and you should
731 say y here. If you are doing more targeted fuzzing (like e.g.
732 filesystem fuzzing with AFL) then you will want to enable coverage
733 for more specific subsets of files, and should say n here.
734
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735config DEBUG_SHIRQ
736 bool "Debug shared IRQ handlers"
Martin Schwidefsky0244ad02013-08-30 09:39:53 +0200737 depends on DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 help
739 Enable this to generate a spurious interrupt as soon as a shared
740 interrupt handler is registered, and just before one is deregistered.
741 Drivers ought to be able to handle interrupts coming in at those
742 points; some don't and need to be caught.
743
Dave Hansen92aef8fb2013-07-01 13:04:50 -0700744menu "Debug Lockups and Hangs"
745
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746config LOCKUP_DETECTOR
747 bool "Detect Hard and Soft Lockups"
748 depends on DEBUG_KERNEL && !S390
749 help
750 Say Y here to enable the kernel to act as a watchdog to detect
751 hard and soft lockups.
752
753 Softlockups are bugs that cause the kernel to loop in kernel
754 mode for more than 20 seconds, without giving other tasks a
755 chance to run. The current stack trace is displayed upon
756 detection and the system will stay locked up.
757
758 Hardlockups are bugs that cause the CPU to loop in kernel mode
759 for more than 10 seconds, without letting other interrupts have a
760 chance to run. The current stack trace is displayed upon detection
761 and the system will stay locked up.
762
763 The overhead should be minimal. A periodic hrtimer runs to
764 generate interrupts and kick the watchdog task every 4 seconds.
765 An NMI is generated every 10 seconds or so to check for hardlockups.
766
767 The frequency of hrtimer and NMI events and the soft and hard lockup
768 thresholds can be controlled through the sysctl watchdog_thresh.
769
770config HARDLOCKUP_DETECTOR
771 def_bool y
772 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
773 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
774
775config BOOTPARAM_HARDLOCKUP_PANIC
776 bool "Panic (Reboot) On Hard Lockups"
777 depends on HARDLOCKUP_DETECTOR
778 help
779 Say Y here to enable the kernel to panic on "hard lockups",
780 which are bugs that cause the kernel to loop in kernel
781 mode with interrupts disabled for more than 10 seconds (configurable
782 using the watchdog_thresh sysctl).
783
784 Say N if unsure.
785
786config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
787 int
788 depends on HARDLOCKUP_DETECTOR
789 range 0 1
790 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
791 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
792
793config BOOTPARAM_SOFTLOCKUP_PANIC
794 bool "Panic (Reboot) On Soft Lockups"
795 depends on LOCKUP_DETECTOR
796 help
797 Say Y here to enable the kernel to panic on "soft lockups",
798 which are bugs that cause the kernel to loop in kernel
799 mode for more than 20 seconds (configurable using the watchdog_thresh
800 sysctl), without giving other tasks a chance to run.
801
802 The panic can be used in combination with panic_timeout,
803 to cause the system to reboot automatically after a
804 lockup has been detected. This feature is useful for
805 high-availability systems that have uptime guarantees and
806 where a lockup must be resolved ASAP.
807
Ingo Molnar8637c092006-07-03 00:24:38 -0700808 Say N if unsure.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809
810config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
811 int
812 depends on LOCKUP_DETECTOR
813 range 0 1
814 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
815 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700816
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817config DETECT_HUNG_TASK
818 bool "Detect Hung Tasks"
819 depends on DEBUG_KERNEL
820 default LOCKUP_DETECTOR
821 help
822 Say Y here to enable the kernel to detect "hung tasks",
823 which are bugs that cause the task to be stuck in
824 uninterruptible "D" state indefinitiley.
825
826 When a hung task is detected, the kernel will print the
827 current stack trace (which you should report), but the
828 task will stay in uninterruptible state. If lockdep is
829 enabled then all held locks will also be reported. This
830 feature has negligible overhead.
831
832config DEFAULT_HUNG_TASK_TIMEOUT
833 int "Default timeout for hung task detection (in seconds)"
834 depends on DETECT_HUNG_TASK
835 default 120
836 help
837 This option controls the default timeout (in seconds) used
838 to determine when a task has become non-responsive and should
839 be considered hung.
840
841 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
842 sysctl or by writing a value to
843 /proc/sys/kernel/hung_task_timeout_secs.
844
Ingo Molnar408894e2006-01-09 15:59:20 -0800845 A timeout of 0 disables the check. The default is two minutes.
846 Keeping the default should be fine in most cases.
847
848config BOOTPARAM_HUNG_TASK_PANIC
849 bool "Panic (Reboot) On Hung Tasks"
850 depends on DETECT_HUNG_TASK
Tim Chencca57c52006-04-18 22:21:47 -0700851 help
Ingo Molnar408894e2006-01-09 15:59:20 -0800852 Say Y here to enable the kernel to panic on "hung tasks",
853 which are bugs that cause the kernel to leave a task stuck
854 in uninterruptible "D" state.
855
856 The panic can be used in combination with panic_timeout,
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700857 to cause the system to reboot automatically after a
858 hung task has been detected. This feature is useful for
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700859 high-availability systems that have uptime guarantees and
860 where a hung tasks must be resolved ASAP.
861
862 Say N if unsure.
863
864config BOOTPARAM_HUNG_TASK_PANIC_VALUE
865 int
866 depends on DETECT_HUNG_TASK
867 range 0 1
Hugh Dickins048c8bc2006-11-01 05:44:54 +1100868 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 default 1 if BOOTPARAM_HUNG_TASK_PANIC
870
Tejun Heo82607adc2015-12-08 11:28:04 -0500871config WQ_WATCHDOG
872 bool "Detect Workqueue Stalls"
873 depends on DEBUG_KERNEL
874 help
875 Say Y here to enable stall detection on workqueues. If a
876 worker pool doesn't make forward progress on a pending work
877 item for over a given amount of time, 30s by default, a
878 warning message is printed along with dump of workqueue
879 state. This can be configured through kernel parameter
880 "workqueue.watchdog_thresh" and its sysfs counterpart.
881
Dave Hansen92aef8fb2013-07-01 13:04:50 -0700882endmenu # "Debug lockups and hangs"
883
884config PANIC_ON_OOPS
885 bool "Panic on Oops"
886 help
887 Say Y here to enable the kernel to panic when it oopses. This
888 has the same effect as setting oops=panic on the kernel command
889 line.
890
891 This feature is useful to ensure that the kernel does not do
892 anything erroneous after an oops which could result in data
893 corruption or other issues.
894
895 Say N if unsure.
896
897config PANIC_ON_OOPS_VALUE
898 int
899 range 0 1
900 default 0 if !PANIC_ON_OOPS
901 default 1 if PANIC_ON_OOPS
902
Jason Baron5800dc32013-11-25 23:23:04 +0000903config PANIC_TIMEOUT
904 int "panic timeout"
905 default 0
906 help
907 Set the timeout value (in seconds) until a reboot occurs when the
908 the kernel panics. If n = 0, then we wait forever. A timeout
909 value n > 0 will wait n seconds before rebooting, while a timeout
910 value n < 0 will reboot immediately.
911
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912config SCHED_DEBUG
913 bool "Collect scheduler debugging info"
914 depends on DEBUG_KERNEL && PROC_FS
915 default y
916 help
917 If you say Y here, the /proc/sched_debug file will be provided
918 that can help debug the scheduler. The runtime overhead of this
919 option is minimal.
920
Naveen N. Raof6db8342015-06-25 23:53:37 +0530921config SCHED_INFO
922 bool
923 default n
924
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925config SCHEDSTATS
926 bool "Collect scheduler statistics"
927 depends on DEBUG_KERNEL && PROC_FS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530928 select SCHED_INFO
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 help
930 If you say Y here, additional code will be inserted into the
931 scheduler and related routines to collect statistics about
932 scheduler behavior and provide them in /proc/schedstat. These
933 stats may be useful for both tuning and debugging the scheduler
934 If you aren't debugging the scheduler or trying to tune a specific
935 application, you can say N to avoid the very slight overhead
936 this adds.
937
Aaron Tomlin0d9e2632014-09-12 14:16:19 +0100938config SCHED_STACK_END_CHECK
939 bool "Detect stack corruption on calls to schedule()"
940 depends on DEBUG_KERNEL
941 default n
942 help
943 This option checks for a stack overrun on calls to schedule().
944 If the stack end location is found to be over written always panic as
945 the content of the corrupted region can no longer be trusted.
946 This is to ensure no erroneous behaviour occurs which could result in
947 data corruption or a sporadic crash at a later stage once the region
948 is examined. The runtime overhead introduced is minimal.
949
John Stultz3c17ad12015-03-11 21:16:32 -0700950config DEBUG_TIMEKEEPING
951 bool "Enable extra timekeeping sanity checking"
952 help
953 This option will enable additional timekeeping sanity checks
954 which may be helpful when diagnosing issues where timekeeping
955 problems are suspected.
956
957 This may include checks in the timekeeping hotpaths, so this
958 option may have a (very small) performance impact to some
959 workloads.
960
961 If unsure, say N.
962
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963config TIMER_STATS
964 bool "Collect kernel timers statistics"
965 depends on DEBUG_KERNEL && PROC_FS
966 help
967 If you say Y here, additional code will be inserted into the
968 timer routines to collect statistics about kernel timers being
969 reprogrammed. The statistics can be read from /proc/timer_stats.
970 The statistics collection is started by writing 1 to /proc/timer_stats,
971 writing 0 stops it. This feature is useful to collect information
972 about timer usage patterns in kernel and userspace. This feature
973 is lightweight if enabled in the kernel config but not activated
974 (it defaults to deactivated on bootup and will only be activated
975 if some application like powertop activates it explicitly).
976
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977config DEBUG_PREEMPT
978 bool "Debug preemptible kernel"
Kumar Gala01deab92009-10-16 07:21:39 +0000979 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 default y
981 help
982 If you say Y here then the kernel will use a debug variant of the
983 commonly used smp_processor_id() function and will print warnings
984 if kernel code uses it in a preemption-unsafe way. Also, the kernel
985 will detect preemption count underflows.
986
Dave Hansen9eade162013-07-01 13:04:47 -0700987menu "Lock Debugging (spinlocks, mutexes, etc...)"
988
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700989config DEBUG_RT_MUTEXES
990 bool "RT Mutex debugging, deadlock detection"
991 depends on DEBUG_KERNEL && RT_MUTEXES
992 help
993 This allows rt mutex semantics violations and rt mutex related
994 deadlocks (lockups) to be detected and reported automatically.
995
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996config DEBUG_SPINLOCK
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700997 bool "Spinlock and rw-lock debugging: basic checks"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 depends on DEBUG_KERNEL
Raghavendra K Te335e3e2012-03-22 15:25:08 +0530999 select UNINLINE_SPIN_UNLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000 help
1001 Say Y here and build SMP to catch missing spinlock initialization
1002 and certain other kinds of spinlock errors commonly made. This is
1003 best used in conjunction with the NMI watchdog so that spinlock
1004 deadlocks are also debuggable.
1005
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001006config DEBUG_MUTEXES
1007 bool "Mutex debugging: basic checks"
1008 depends on DEBUG_KERNEL
1009 help
1010 This feature allows mutex semantics violations to be detected and
1011 reported.
1012
Daniel Vetter23010022013-06-20 13:31:17 +02001013config DEBUG_WW_MUTEX_SLOWPATH
1014 bool "Wait/wound mutex debugging: Slowpath testing"
1015 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1016 select DEBUG_LOCK_ALLOC
1017 select DEBUG_SPINLOCK
1018 select DEBUG_MUTEXES
1019 help
1020 This feature enables slowpath testing for w/w mutex users by
1021 injecting additional -EDEADLK wound/backoff cases. Together with
1022 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1023 will test all possible w/w mutex interface abuse with the
1024 exception of simply not acquiring all the required locks.
Rob Clark4d692372014-08-27 11:19:26 -04001025 Note that this feature can introduce significant overhead, so
1026 it really should not be enabled in a production or distro kernel,
1027 even a debug kernel. If you are a driver writer, enable it. If
1028 you are a distro, do not.
Daniel Vetter23010022013-06-20 13:31:17 +02001029
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001030config DEBUG_LOCK_ALLOC
1031 bool "Lock debugging: detect incorrect freeing of live locks"
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001032 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001033 select DEBUG_SPINLOCK
1034 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001035 select LOCKDEP
1036 help
1037 This feature will check whether any held lock (spinlock, rwlock,
1038 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1039 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1040 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1041 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1042 held during task exit.
1043
1044config PROVE_LOCKING
1045 bool "Lock debugging: prove locking correctness"
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001046 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001047 select LOCKDEP
1048 select DEBUG_SPINLOCK
1049 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001050 select DEBUG_LOCK_ALLOC
Steven Rostedt46b93b72010-08-31 16:35:20 -04001051 select TRACE_IRQFLAGS
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001052 default n
1053 help
1054 This feature enables the kernel to prove that all locking
1055 that occurs in the kernel runtime is mathematically
1056 correct: that under no circumstance could an arbitrary (and
1057 not yet triggered) combination of observed locking
1058 sequences (on an arbitrary number of CPUs, running an
1059 arbitrary number of tasks and interrupt contexts) cause a
1060 deadlock.
1061
1062 In short, this feature enables the kernel to report locking
1063 related deadlocks before they actually occur.
1064
1065 The proof does not depend on how hard and complex a
1066 deadlock scenario would be to trigger: how many
1067 participant CPUs, tasks and irq-contexts would be needed
1068 for it to trigger. The proof also does not depend on
1069 timing: if a race and a resulting deadlock is possible
1070 theoretically (no matter how unlikely the race scenario
1071 is), it will be proven so and will immediately be
1072 reported by the kernel (once the event is observed that
1073 makes the deadlock theoretically possible).
1074
1075 If a deadlock is impossible (i.e. the locking rules, as
1076 observed by the kernel, are mathematically correct), the
1077 kernel reports nothing.
1078
1079 NOTE: this feature can also be enabled for rwlocks, mutexes
1080 and rwsems - in which case all dependencies between these
1081 different locking variants are observed and mapped too, and
1082 the proof of observed correctness is also maintained for an
1083 arbitrary combination of these separate locking variants.
1084
Davidlohr Bueso214e0ae2014-07-30 13:41:55 -07001085 For more details, see Documentation/locking/lockdep-design.txt.
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001086
1087config LOCKDEP
1088 bool
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001089 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001090 select STACKTRACE
Chen Gangdf2e1ef2014-06-23 13:22:04 -07001091 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001092 select KALLSYMS
1093 select KALLSYMS_ALL
1094
Peter Zijlstraf20786f2007-07-19 01:48:56 -07001095config LOCK_STAT
Danny ter Haarfdfb8702007-09-24 21:24:43 -07001096 bool "Lock usage statistics"
Peter Zijlstraf20786f2007-07-19 01:48:56 -07001097 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1098 select LOCKDEP
1099 select DEBUG_SPINLOCK
1100 select DEBUG_MUTEXES
1101 select DEBUG_LOCK_ALLOC
1102 default n
1103 help
1104 This feature enables tracking lock contention points
1105
Davidlohr Bueso214e0ae2014-07-30 13:41:55 -07001106 For more details, see Documentation/locking/lockstat.txt
Peter Zijlstraa560aa42007-10-07 00:24:33 -07001107
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +01001108 This also enables lock events required by "perf lock",
1109 subcommand of perf.
1110 If you want to use "perf lock", you also need to turn on
1111 CONFIG_EVENT_TRACING.
Hitoshi Mitake84c6f882010-02-04 16:08:15 +09001112
1113 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +01001114 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
Hitoshi Mitake84c6f882010-02-04 16:08:15 +09001115
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001116config DEBUG_LOCKDEP
1117 bool "Lock dependency engine debugging"
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001118 depends on DEBUG_KERNEL && LOCKDEP
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001119 help
1120 If you say Y here, the lock dependency engine will do
1121 additional runtime checks to debug itself, at the price
1122 of more runtime overhead.
1123
Frederic Weisbeckerd902db12011-06-08 19:31:56 +02001124config DEBUG_ATOMIC_SLEEP
1125 bool "Sleep inside atomic section checking"
Frederic Weisbeckere8f7c702011-06-08 01:51:02 +02001126 select PREEMPT_COUNT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 depends on DEBUG_KERNEL
1128 help
1129 If you say Y here, various routines which may sleep will become very
Frederic Weisbeckerd902db12011-06-08 19:31:56 +02001130 noisy if they are called inside atomic sections: when a spinlock is
1131 held, inside an rcu read side critical section, inside preempt disabled
1132 sections, inside an interrupt, etc...
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133
Ingo Molnarcae2ed92006-07-03 00:24:48 -07001134config DEBUG_LOCKING_API_SELFTESTS
1135 bool "Locking API boot-time self-tests"
1136 depends on DEBUG_KERNEL
1137 help
1138 Say Y here if you want the kernel to run a short self-test during
1139 bootup. The self-test checks whether common types of locking bugs
1140 are detected by debugging mechanisms or not. (if you disable
1141 lock debugging then those bugs wont be detected of course.)
1142 The following locking APIs are covered: spinlocks, rwlocks,
1143 mutexes and rwsems.
1144
Paul E. McKenney0af3fe12014-02-04 15:51:41 -08001145config LOCK_TORTURE_TEST
1146 tristate "torture tests for locking"
1147 depends on DEBUG_KERNEL
1148 select TORTURE_TEST
1149 default n
1150 help
1151 This option provides a kernel module that runs torture tests
1152 on kernel locking primitives. The kernel module may be built
1153 after the fact on the running kernel to be tested, if desired.
1154
1155 Say Y here if you want kernel locking-primitive torture tests
1156 to be built into the kernel.
1157 Say M if you want these torture tests to build as a module.
1158 Say N if you are unsure.
1159
Dave Hansen9eade162013-07-01 13:04:47 -07001160endmenu # lock debugging
1161
1162config TRACE_IRQFLAGS
1163 bool
1164 help
1165 Enables hooks to interrupt enabling and disabling for
1166 either tracing or lock debugging.
1167
Ingo Molnar8637c092006-07-03 00:24:38 -07001168config STACKTRACE
Dave Jones0c38e1f2014-08-29 15:18:35 -07001169 bool "Stack backtrace support"
Ingo Molnar8637c092006-07-03 00:24:38 -07001170 depends on STACKTRACE_SUPPORT
Dave Jones0c38e1f2014-08-29 15:18:35 -07001171 help
1172 This option causes the kernel to create a /proc/pid/stack for
1173 every process, showing its current stack trace.
1174 It is also used by various kernel debugging features that require
1175 stack trace generation.
Ingo Molnar8637c092006-07-03 00:24:38 -07001176
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177config DEBUG_KOBJECT
1178 bool "kobject debugging"
1179 depends on DEBUG_KERNEL
1180 help
1181 If you say Y here, some extra kobject debugging messages will be sent
1182 to the syslog.
1183
Russell Kingc817a672013-06-27 15:06:14 +01001184config DEBUG_KOBJECT_RELEASE
1185 bool "kobject release debugging"
Linus Torvalds2a999aa2013-10-29 08:33:36 -07001186 depends on DEBUG_OBJECTS_TIMERS
Russell Kingc817a672013-06-27 15:06:14 +01001187 help
1188 kobjects are reference counted objects. This means that their
1189 last reference count put is not predictable, and the kobject can
1190 live on past the point at which a driver decides to drop it's
1191 initial reference to the kobject gained on allocation. An
1192 example of this would be a struct device which has just been
1193 unregistered.
1194
1195 However, some buggy drivers assume that after such an operation,
1196 the memory backing the kobject can be immediately freed. This
1197 goes completely against the principles of a refcounted object.
1198
1199 If you say Y here, the kernel will delay the release of kobjects
1200 on the last reference count to improve the visibility of this
1201 kind of kobject release bug.
1202
Catalin Marinas9b2a60c2012-10-08 16:28:13 -07001203config HAVE_DEBUG_BUGVERBOSE
1204 bool
1205
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206config DEBUG_BUGVERBOSE
David Rientjes6a108a12011-01-20 14:44:16 -08001207 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
Catalin Marinas9b2a60c2012-10-08 16:28:13 -07001208 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
Alexey Dobriyan8420e7e2009-12-14 18:00:25 -08001209 default y
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 help
1211 Say Y here to make BUG() panics output the file name and line number
1212 of the BUG call as well as the EIP and oops trace. This aids
1213 debugging but costs about 70-100K of memory.
1214
Dave Jones199a9af2006-09-29 01:59:00 -07001215config DEBUG_LIST
1216 bool "Debug linked list manipulation"
1217 depends on DEBUG_KERNEL
1218 help
1219 Enable this to turn on extended checks in the linked-list
1220 walking routines.
1221
1222 If unsure, say N.
1223
Dan Streetmanb8cfff62014-06-04 16:11:54 -07001224config DEBUG_PI_LIST
1225 bool "Debug priority linked list manipulation"
1226 depends on DEBUG_KERNEL
1227 help
1228 Enable this to turn on extended checks in the priority-ordered
1229 linked-list (plist) walking routines. This checks the entire
1230 list multiple times during each manipulation.
1231
1232 If unsure, say N.
1233
Jens Axboed6ec0842007-10-22 20:01:06 +02001234config DEBUG_SG
1235 bool "Debug SG table operations"
1236 depends on DEBUG_KERNEL
1237 help
1238 Enable this to turn on checks on scatter-gather tables. This can
1239 help find problems with drivers that do not properly initialize
1240 their sg tables.
1241
1242 If unsure, say N.
1243
Arjan van de Ven1b2439d2008-08-15 15:29:38 -07001244config DEBUG_NOTIFIERS
1245 bool "Debug notifier call chains"
1246 depends on DEBUG_KERNEL
1247 help
1248 Enable this to turn on sanity checking for notifier call chains.
1249 This is most useful for kernel developers to make sure that
1250 modules properly unregister themselves from notifier chains.
1251 This is a relatively cheap check but if you care about maximum
1252 performance, say N.
1253
David Howellse0e81732009-09-02 09:13:40 +01001254config DEBUG_CREDENTIALS
1255 bool "Debug credential management"
1256 depends on DEBUG_KERNEL
1257 help
1258 Enable this to turn on some debug checking for credential
1259 management. The additional code keeps track of the number of
1260 pointers from task_structs to any given cred struct, and checks to
1261 see that this number never exceeds the usage count of the cred
1262 struct.
1263
1264 Furthermore, if SELinux is enabled, this also checks that the
1265 security pointer in the cred struct is never seen to be invalid.
1266
1267 If unsure, say N.
1268
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001269menu "RCU Debugging"
1270
1271config PROVE_RCU
Paul E. McKenney9bae6592015-01-18 18:01:21 -08001272 def_bool PROVE_LOCKING
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001273
1274config PROVE_RCU_REPEATEDLY
1275 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1276 depends on PROVE_RCU
1277 default n
1278 help
1279 By itself, PROVE_RCU will disable checking upon issuing the
1280 first warning (or "splat"). This feature prevents such
1281 disabling, allowing multiple RCU-lockdep warnings to be printed
1282 on a single reboot.
1283
1284 Say Y to allow multiple RCU-lockdep warnings per boot.
1285
1286 Say N if you are unsure.
1287
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001288config SPARSE_RCU_POINTER
1289 bool "RCU debugging: sparse-based checks for pointer usage"
1290 default n
1291 help
1292 This feature enables the __rcu sparse annotation for
1293 RCU-protected pointers. This annotation will cause sparse
1294 to flag any non-RCU used of annotated pointers. This can be
1295 helpful when debugging RCU usage. Please note that this feature
1296 is not intended to enforce code cleanliness; it is instead merely
1297 a debugging aid.
1298
1299 Say Y to make sparse flag questionable use of RCU-protected pointers
1300
1301 Say N if you are unsure.
1302
Paul E. McKenney51b11302014-01-27 11:49:39 -08001303config TORTURE_TEST
1304 tristate
1305 default n
1306
Paul E. McKenney8704baa2015-12-31 18:33:22 -08001307config RCU_PERF_TEST
1308 tristate "performance tests for RCU"
1309 depends on DEBUG_KERNEL
1310 select TORTURE_TEST
1311 select SRCU
1312 select TASKS_RCU
1313 default n
1314 help
1315 This option provides a kernel module that runs performance
1316 tests on the RCU infrastructure. The kernel module may be built
1317 after the fact on the running kernel to be tested, if desired.
1318
1319 Say Y here if you want RCU performance tests to be built into
1320 the kernel.
1321 Say M if you want the RCU performance tests to build as a module.
1322 Say N if you are unsure.
1323
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001324config RCU_TORTURE_TEST
1325 tristate "torture tests for RCU"
1326 depends on DEBUG_KERNEL
Paul E. McKenney51b11302014-01-27 11:49:39 -08001327 select TORTURE_TEST
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001328 select SRCU
Paul E. McKenney82d0f4c2015-04-20 05:42:50 -07001329 select TASKS_RCU
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001330 default n
1331 help
1332 This option provides a kernel module that runs torture tests
1333 on the RCU infrastructure. The kernel module may be built
1334 after the fact on the running kernel to be tested, if desired.
1335
Paul E. McKenney31a72bc2008-06-18 09:26:49 -07001336 Say Y here if you want RCU torture tests to be built into
1337 the kernel.
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001338 Say M if you want the RCU torture tests to build as a module.
1339 Say N if you are unsure.
Ankita Garg8bb31b92006-10-02 02:17:36 -07001340
Paul E. McKenney0f41c0d2015-03-10 18:33:20 -07001341config RCU_TORTURE_TEST_SLOW_PREINIT
1342 bool "Slow down RCU grace-period pre-initialization to expose races"
1343 depends on RCU_TORTURE_TEST
1344 help
1345 This option delays grace-period pre-initialization (the
1346 propagation of CPU-hotplug changes up the rcu_node combining
1347 tree) for a few jiffies between initializing each pair of
1348 consecutive rcu_node structures. This helps to expose races
1349 involving grace-period pre-initialization, in other words, it
1350 makes your kernel less stable. It can also greatly increase
1351 grace-period latency, especially on systems with large numbers
1352 of CPUs. This is useful when torture-testing RCU, but in
1353 almost no other circumstance.
1354
1355 Say Y here if you want your system to crash and hang more often.
1356 Say N if you want a sane system.
1357
1358config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1359 int "How much to slow down RCU grace-period pre-initialization"
1360 range 0 5
1361 default 3
1362 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1363 help
1364 This option specifies the number of jiffies to wait between
1365 each rcu_node structure pre-initialization step.
1366
Paul E. McKenney37745d22015-01-22 18:24:08 -08001367config RCU_TORTURE_TEST_SLOW_INIT
1368 bool "Slow down RCU grace-period initialization to expose races"
1369 depends on RCU_TORTURE_TEST
1370 help
Paul E. McKenney0f41c0d2015-03-10 18:33:20 -07001371 This option delays grace-period initialization for a few
1372 jiffies between initializing each pair of consecutive
Paul E. McKenney37745d22015-01-22 18:24:08 -08001373 rcu_node structures. This helps to expose races involving
1374 grace-period initialization, in other words, it makes your
1375 kernel less stable. It can also greatly increase grace-period
1376 latency, especially on systems with large numbers of CPUs.
1377 This is useful when torture-testing RCU, but in almost no
1378 other circumstance.
1379
1380 Say Y here if you want your system to crash and hang more often.
1381 Say N if you want a sane system.
1382
1383config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1384 int "How much to slow down RCU grace-period initialization"
1385 range 0 5
Paul E. McKenney186bea52015-01-29 16:37:19 -08001386 default 3
Paul E. McKenney8d7dc922015-04-14 19:33:59 -07001387 depends on RCU_TORTURE_TEST_SLOW_INIT
Paul E. McKenney37745d22015-01-22 18:24:08 -08001388 help
1389 This option specifies the number of jiffies to wait between
1390 each rcu_node structure initialization.
1391
Paul E. McKenney0f41c0d2015-03-10 18:33:20 -07001392config RCU_TORTURE_TEST_SLOW_CLEANUP
1393 bool "Slow down RCU grace-period cleanup to expose races"
1394 depends on RCU_TORTURE_TEST
1395 help
1396 This option delays grace-period cleanup for a few jiffies
1397 between cleaning up each pair of consecutive rcu_node
1398 structures. This helps to expose races involving grace-period
1399 cleanup, in other words, it makes your kernel less stable.
1400 It can also greatly increase grace-period latency, especially
1401 on systems with large numbers of CPUs. This is useful when
1402 torture-testing RCU, but in almost no other circumstance.
1403
1404 Say Y here if you want your system to crash and hang more often.
1405 Say N if you want a sane system.
1406
1407config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1408 int "How much to slow down RCU grace-period cleanup"
1409 range 0 5
1410 default 3
1411 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1412 help
1413 This option specifies the number of jiffies to wait between
1414 each rcu_node structure cleanup operation.
1415
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001416config RCU_CPU_STALL_TIMEOUT
1417 int "RCU CPU stall timeout in seconds"
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -07001418 depends on RCU_STALL_COMMON
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001419 range 3 300
Paul E. McKenneyc8960542012-10-25 17:59:23 -07001420 default 21
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001421 help
1422 If a given RCU grace period extends more than the specified
1423 number of seconds, a CPU stall warning is printed. If the
1424 RCU grace period persists, additional CPU stall warnings are
1425 printed at more widely spaced intervals.
1426
Paul E. McKenney5c8806a2012-01-06 15:10:44 -08001427config RCU_TRACE
1428 bool "Enable tracing for RCU"
1429 depends on DEBUG_KERNEL
Paul E. McKenney52494532012-11-14 16:26:40 -08001430 select TRACE_CLOCK
Paul E. McKenney5c8806a2012-01-06 15:10:44 -08001431 help
1432 This option provides tracing in RCU which presents stats
1433 in debugfs for debugging RCU implementation.
1434
1435 Say Y here if you want to enable RCU tracing
1436 Say N if you are unsure.
1437
Paul E. McKenney1ce46ee2015-05-05 23:04:22 -07001438config RCU_EQS_DEBUG
Paul E. McKenneyeb6d5b02015-06-30 09:56:31 -07001439 bool "Provide debugging asserts for adding NO_HZ support to an arch"
Paul E. McKenney1ce46ee2015-05-05 23:04:22 -07001440 depends on DEBUG_KERNEL
1441 help
1442 This option provides consistency checks in RCU's handling of
1443 NO_HZ. These checks have proven quite helpful in detecting
1444 bugs in arch-specific NO_HZ code.
1445
1446 Say N here if you need ultimate kernel/user switch latencies
1447 Say Y if you are unsure
1448
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001449endmenu # "RCU Debugging"
1450
Tejun Heof303fcc2016-02-09 17:59:38 -05001451config DEBUG_WQ_FORCE_RR_CPU
1452 bool "Force round-robin CPU selection for unbound work items"
1453 depends on DEBUG_KERNEL
1454 default n
1455 help
1456 Workqueue used to implicitly guarantee that work items queued
1457 without explicit CPU specified are put on the local CPU. This
1458 guarantee is no longer true and while local CPU is still
1459 preferred work items may be put on foreign CPUs. Kernel
1460 parameter "workqueue.debug_force_rr_cpu" is added to force
1461 round-robin CPU selection to flush out usages which depend on the
1462 now broken guarantee. This config option enables the debug
1463 feature by default. When enabled, memory and cache locality will
1464 be impacted.
1465
Tejun Heo870d6652008-08-25 19:47:25 +09001466config DEBUG_BLOCK_EXT_DEVT
1467 bool "Force extended block device numbers and spread them"
1468 depends on DEBUG_KERNEL
1469 depends on BLOCK
Jens Axboe759f8ca2008-08-29 09:06:29 +02001470 default n
Tejun Heo870d6652008-08-25 19:47:25 +09001471 help
Tejun Heo0e11e342008-10-13 10:46:01 +02001472 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1473 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1474 YOU ARE DOING. Distros, please enable this and fix whatever
1475 is broken.
1476
Tejun Heo870d6652008-08-25 19:47:25 +09001477 Conventionally, block device numbers are allocated from
1478 predetermined contiguous area. However, extended block area
1479 may introduce non-contiguous block device numbers. This
1480 option forces most block device numbers to be allocated from
1481 the extended space and spreads them to discover kernel or
1482 userland code paths which assume predetermined contiguous
1483 device number allocation.
1484
Tejun Heo55dc7db2008-09-01 13:44:35 +02001485 Note that turning on this debug option shuffles all the
1486 device numbers for all IDE and SCSI devices including libata
1487 ones, so root partition specified using device number
1488 directly (via rdev or root=MAJ:MIN) won't work anymore.
1489 Textual device names (root=/dev/sdXn) will continue to work.
1490
Tejun Heo870d6652008-08-25 19:47:25 +09001491 Say N if you are unsure.
1492
Thomas Gleixner757c9892016-02-26 18:43:32 +00001493config CPU_HOTPLUG_STATE_CONTROL
1494 bool "Enable CPU hotplug state control"
1495 depends on DEBUG_KERNEL
1496 depends on HOTPLUG_CPU
1497 default n
1498 help
1499 Allows to write steps between "offline" and "online" to the CPUs
1500 sysfs target file so states can be stepped granular. This is a debug
1501 option for now as the hotplug machinery cannot be stopped and
1502 restarted at arbitrary points yet.
1503
1504 Say N if your are unsure.
1505
Akinobu Mita8d438282012-07-30 14:43:02 -07001506config NOTIFIER_ERROR_INJECTION
1507 tristate "Notifier error injection"
1508 depends on DEBUG_KERNEL
1509 select DEBUG_FS
1510 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001511 This option provides the ability to inject artificial errors to
Akinobu Mita8d438282012-07-30 14:43:02 -07001512 specified notifier chain callbacks. It is useful to test the error
1513 handling of notifier call chain failures.
1514
1515 Say N if unsure.
1516
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001517config CPU_NOTIFIER_ERROR_INJECT
1518 tristate "CPU notifier error injection module"
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001519 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001520 help
1521 This option provides a kernel module that can be used to test
Masanari Iidae41e85c2012-11-30 16:44:39 +09001522 the error handling of the cpu notifiers by injecting artificial
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001523 errors to CPU notifier chain callbacks. It is controlled through
1524 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1525
1526 If the notifier call chain should be failed with some events
1527 notified, write the error code to "actions/<notifier event>/error".
1528
1529 Example: Inject CPU offline error (-1 == -EPERM)
1530
1531 # cd /sys/kernel/debug/notifier-error-inject/cpu
1532 # echo -1 > actions/CPU_DOWN_PREPARE/error
1533 # echo 0 > /sys/devices/system/cpu/cpu1/online
1534 bash: echo: write error: Operation not permitted
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001535
1536 To compile this code as a module, choose M here: the module will
1537 be called cpu-notifier-error-inject.
1538
1539 If unsure, say N.
1540
Akinobu Mita048b9c32012-07-30 14:43:07 -07001541config PM_NOTIFIER_ERROR_INJECT
1542 tristate "PM notifier error injection module"
1543 depends on PM && NOTIFIER_ERROR_INJECTION
1544 default m if PM_DEBUG
1545 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001546 This option provides the ability to inject artificial errors to
Akinobu Mita048b9c32012-07-30 14:43:07 -07001547 PM notifier chain callbacks. It is controlled through debugfs
1548 interface /sys/kernel/debug/notifier-error-inject/pm
1549
1550 If the notifier call chain should be failed with some events
1551 notified, write the error code to "actions/<notifier event>/error".
1552
1553 Example: Inject PM suspend error (-12 = -ENOMEM)
1554
1555 # cd /sys/kernel/debug/notifier-error-inject/pm/
1556 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1557 # echo mem > /sys/power/state
1558 bash: echo: write error: Cannot allocate memory
1559
1560 To compile this code as a module, choose M here: the module will
1561 be called pm-notifier-error-inject.
1562
1563 If unsure, say N.
1564
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001565config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1566 tristate "OF reconfig notifier error injection module"
1567 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001568 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001569 This option provides the ability to inject artificial errors to
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001570 OF reconfig notifier chain callbacks. It is controlled
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001571 through debugfs interface under
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001572 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001573
1574 If the notifier call chain should be failed with some events
1575 notified, write the error code to "actions/<notifier event>/error".
1576
1577 To compile this code as a module, choose M here: the module will
Akinobu Mitae12a95f2013-04-30 15:28:49 -07001578 be called of-reconfig-notifier-error-inject.
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001579
1580 If unsure, say N.
1581
Nikolay Aleksandrov02fff962015-11-28 13:45:28 +01001582config NETDEV_NOTIFIER_ERROR_INJECT
1583 tristate "Netdev notifier error injection module"
1584 depends on NET && NOTIFIER_ERROR_INJECTION
1585 help
1586 This option provides the ability to inject artificial errors to
1587 netdevice notifier chain callbacks. It is controlled through debugfs
1588 interface /sys/kernel/debug/notifier-error-inject/netdev
1589
1590 If the notifier call chain should be failed with some events
1591 notified, write the error code to "actions/<notifier event>/error".
1592
1593 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1594
1595 # cd /sys/kernel/debug/notifier-error-inject/netdev
1596 # echo -22 > actions/NETDEV_CHANGEMTU/error
1597 # ip link set eth0 mtu 1024
1598 RTNETLINK answers: Invalid argument
1599
1600 To compile this code as a module, choose M here: the module will
1601 be called netdev-notifier-error-inject.
1602
1603 If unsure, say N.
1604
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001605config FAULT_INJECTION
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001606 bool "Fault-injection framework"
1607 depends on DEBUG_KERNEL
Akinobu Mita329409a2006-12-08 02:39:48 -08001608 help
1609 Provide fault-injection framework.
1610 For more details, see Documentation/fault-injection/.
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001611
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001612config FAILSLAB
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001613 bool "Fault-injection capability for kmalloc"
1614 depends on FAULT_INJECTION
Akinobu Mita773ff602008-12-23 19:37:01 +09001615 depends on SLAB || SLUB
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001616 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001617 Provide fault-injection capability for kmalloc.
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001618
Akinobu Mita933e3122006-12-08 02:39:45 -08001619config FAIL_PAGE_ALLOC
1620 bool "Fault-injection capabilitiy for alloc_pages()"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001621 depends on FAULT_INJECTION
Akinobu Mita933e3122006-12-08 02:39:45 -08001622 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001623 Provide fault-injection capability for alloc_pages().
Akinobu Mita933e3122006-12-08 02:39:45 -08001624
Akinobu Mitac17bb492006-12-08 02:39:46 -08001625config FAIL_MAKE_REQUEST
Dave Jones86327d12006-12-12 20:16:36 +01001626 bool "Fault-injection capability for disk IO"
Jens Axboe581d4e22008-09-14 05:56:33 -07001627 depends on FAULT_INJECTION && BLOCK
Akinobu Mitac17bb492006-12-08 02:39:46 -08001628 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001629 Provide fault-injection capability for disk IO.
Akinobu Mitac17bb492006-12-08 02:39:46 -08001630
Jens Axboe581d4e22008-09-14 05:56:33 -07001631config FAIL_IO_TIMEOUT
Takuya Yoshikawaf4d014392010-07-21 16:05:53 +09001632 bool "Fault-injection capability for faking disk interrupts"
Jens Axboe581d4e22008-09-14 05:56:33 -07001633 depends on FAULT_INJECTION && BLOCK
1634 help
1635 Provide fault-injection capability on end IO handling. This
1636 will make the block layer "forget" an interrupt as configured,
1637 thus exercising the error handling.
1638
1639 Only works with drivers that use the generic timeout handling,
1640 for others it wont do anything.
1641
Per Forlin1b676f72011-08-19 14:52:37 +02001642config FAIL_MMC_REQUEST
1643 bool "Fault-injection capability for MMC IO"
Adrien Schildknecht28ff4fd2015-11-10 20:12:19 +01001644 depends on FAULT_INJECTION_DEBUG_FS && MMC
Per Forlin1b676f72011-08-19 14:52:37 +02001645 help
1646 Provide fault-injection capability for MMC IO.
1647 This will make the mmc core return data errors. This is
1648 useful to test the error handling in the mmc block device
1649 and to test how the mmc host driver handles retries from
1650 the block device.
1651
Davidlohr Buesoab51fba2015-06-29 23:26:02 -07001652config FAIL_FUTEX
1653 bool "Fault-injection capability for futexes"
1654 select DEBUG_FS
1655 depends on FAULT_INJECTION && FUTEX
1656 help
1657 Provide fault-injection capability for futexes.
1658
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001659config FAULT_INJECTION_DEBUG_FS
1660 bool "Debugfs entries for fault-injection capabilities"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001661 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001662 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001663 Enable configuration of fault-injection capabilities via debugfs.
Akinobu Mita1df49002007-02-20 13:57:56 -08001664
1665config FAULT_INJECTION_STACKTRACE_FILTER
1666 bool "stacktrace filter for fault-injection capabilities"
1667 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
Akinobu Mita6d690dc2007-05-12 10:36:53 -07001668 depends on !X86_64
Akinobu Mita1df49002007-02-20 13:57:56 -08001669 select STACKTRACE
Chen Gangdf2e1ef2014-06-23 13:22:04 -07001670 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
Akinobu Mita1df49002007-02-20 13:57:56 -08001671 help
1672 Provide stacktrace filter for fault-injection capabilities
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001673
Arjan van de Ven97455122008-01-25 21:08:34 +01001674config LATENCYTOP
1675 bool "Latency measuring infrastructure"
Randy Dunlap625fdca2010-08-12 12:31:21 -07001676 depends on DEBUG_KERNEL
1677 depends on STACKTRACE_SUPPORT
1678 depends on PROC_FS
Vineet Guptacc80ae32013-08-27 13:52:51 +05301679 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
Arjan van de Ven97455122008-01-25 21:08:34 +01001680 select KALLSYMS
1681 select KALLSYMS_ALL
1682 select STACKTRACE
1683 select SCHEDSTATS
1684 select SCHED_DEBUG
Arjan van de Ven97455122008-01-25 21:08:34 +01001685 help
1686 Enable this option if you want to use the LatencyTOP tool
1687 to find out which userspace is blocking on what kernel operations.
1688
Stephen Boyd446f24d2013-04-30 15:28:42 -07001689config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1690 bool
1691
1692config DEBUG_STRICT_USER_COPY_CHECKS
1693 bool "Strict user copy size checks"
1694 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1695 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1696 help
1697 Enabling this option turns a certain set of sanity checks for user
1698 copy operations into compile time failures.
1699
1700 The copy_from_user() etc checks are there to help test if there
1701 are sufficient security checks on the length argument of
1702 the copy operation, by having gcc prove that the argument is
1703 within bounds.
1704
1705 If unsure, say N.
1706
Arnaldo Carvalho de Melo16444a82008-05-12 21:20:42 +02001707source kernel/trace/Kconfig
1708
Dave Hansen881c5142013-07-01 13:04:44 -07001709menu "Runtime Testing"
1710
1711config LKDTM
1712 tristate "Linux Kernel Dump Test Tool Module"
1713 depends on DEBUG_FS
1714 depends on BLOCK
1715 default n
1716 help
1717 This module enables testing of the different dumping mechanisms by
1718 inducing system failures at predefined crash points.
1719 If you don't need it: say N
1720 Choose M here to compile this code as a module. The module will be
1721 called lkdtm.
1722
1723 Documentation on how to use the module can be found in
1724 Documentation/fault-injection/provoke-crashes.txt
1725
1726config TEST_LIST_SORT
1727 bool "Linked list sorting test"
1728 depends on DEBUG_KERNEL
1729 help
1730 Enable this to turn on 'list_sort()' function test. This test is
1731 executed only once during system boot, so affects only boot time.
1732
1733 If unsure, say N.
1734
1735config KPROBES_SANITY_TEST
1736 bool "Kprobes sanity tests"
1737 depends on DEBUG_KERNEL
1738 depends on KPROBES
1739 default n
1740 help
1741 This option provides for testing basic kprobes functionality on
1742 boot. A sample kprobe, jprobe and kretprobe are inserted and
1743 verified for functionality.
1744
1745 Say N if you are unsure.
1746
1747config BACKTRACE_SELF_TEST
1748 tristate "Self test for the backtrace code"
1749 depends on DEBUG_KERNEL
1750 default n
1751 help
1752 This option provides a kernel module that can be used to test
1753 the kernel stack backtrace code. This option is not useful
1754 for distributions or general kernels, but only for kernel
1755 developers working on architecture code.
1756
1757 Note that if you want to also test saved backtraces, you will
1758 have to enable STACKTRACE as well.
1759
1760 Say N if you are unsure.
1761
Michel Lespinasse910a7422012-10-08 16:30:39 -07001762config RBTREE_TEST
1763 tristate "Red-Black tree test"
Cody P Schafer7c993e12013-09-11 14:25:19 -07001764 depends on DEBUG_KERNEL
Michel Lespinasse910a7422012-10-08 16:30:39 -07001765 help
1766 A benchmark measuring the performance of the rbtree library.
1767 Also includes rbtree invariant checks.
1768
Michel Lespinassefff3fd82012-10-08 16:31:23 -07001769config INTERVAL_TREE_TEST
1770 tristate "Interval tree test"
1771 depends on m && DEBUG_KERNEL
Chris Wilsona88cc102014-03-17 12:21:54 +00001772 select INTERVAL_TREE
Michel Lespinassefff3fd82012-10-08 16:31:23 -07001773 help
1774 A benchmark measuring the performance of the interval tree library
1775
Greg Thelen623fd802013-11-12 15:08:34 -08001776config PERCPU_TEST
1777 tristate "Per cpu operations test"
1778 depends on m && DEBUG_KERNEL
1779 help
1780 Enable this option to build test module which validates per-cpu
1781 operations.
1782
1783 If unsure, say N.
1784
Dave Hansen881c5142013-07-01 13:04:44 -07001785config ATOMIC64_SELFTEST
1786 bool "Perform an atomic64_t self-test at boot"
1787 help
1788 Enable this option to test the atomic64_t functions at boot.
1789
1790 If unsure, say N.
1791
1792config ASYNC_RAID6_TEST
1793 tristate "Self test for hardware accelerated raid6 recovery"
1794 depends on ASYNC_RAID6_RECOV
1795 select ASYNC_MEMCPY
1796 ---help---
1797 This is a one-shot self test that permutes through the
1798 recovery of all the possible two disk failure scenarios for a
1799 N-disk array. Recovery is performed with the asynchronous
1800 raid6 recovery routines, and will optionally use an offload
1801 engine if one is available.
1802
1803 If unsure, say N.
1804
Andy Shevchenko64d1d772015-02-12 15:02:21 -08001805config TEST_HEXDUMP
1806 tristate "Test functions located in the hexdump module at runtime"
1807
Dave Hansen881c5142013-07-01 13:04:44 -07001808config TEST_STRING_HELPERS
1809 tristate "Test functions located in the string_helpers module at runtime"
1810
1811config TEST_KSTRTOX
1812 tristate "Test kstrto*() family of functions at runtime"
1813
Rasmus Villemoes707cc722015-11-06 16:30:29 -08001814config TEST_PRINTF
1815 tristate "Test printf() family of functions at runtime"
1816
David Decotigny5fd003f2016-02-19 09:24:00 -05001817config TEST_BITMAP
1818 tristate "Test bitmap_*() family of functions at runtime"
1819 default n
1820 help
1821 Enable this option to test the bitmap functions at boot.
1822
1823 If unsure, say N.
1824
Andy Shevchenkocfaff0e2016-05-30 17:40:41 +03001825config TEST_UUID
1826 tristate "Test functions located in the uuid module at runtime"
1827
Thomas Graf7e1e7762014-08-02 11:47:44 +02001828config TEST_RHASHTABLE
Geert Uytterhoeven9d6dbe12015-01-29 15:40:25 +01001829 tristate "Perform selftest on resizable hash table"
Thomas Graf7e1e7762014-08-02 11:47:44 +02001830 default n
1831 help
1832 Enable this option to test the rhashtable functions at boot.
1833
1834 If unsure, say N.
1835
George Spelvin468a9422016-05-26 22:11:51 -04001836config TEST_HASH
1837 tristate "Perform selftest on hash functions"
1838 default n
1839 help
1840 Enable this option to test the kernel's integer (<linux/hash,h>)
1841 and string (<linux/stringhash.h>) hash functions on boot
1842 (or module load).
1843
1844 This is intended to help people writing architecture-specific
1845 optimized versions. If unsure, say N.
1846
Dave Hansen881c5142013-07-01 13:04:44 -07001847endmenu # runtime tests
1848
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001849config PROVIDE_OHCI1394_DMA_INIT
Stefan Richter080de8c2008-02-28 20:54:43 +01001850 bool "Remote debugging over FireWire early on boot"
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001851 depends on PCI && X86
1852 help
1853 If you want to debug problems which hang or crash the kernel early
1854 on boot and the crashing machine has a FireWire port, you can use
1855 this feature to remotely access the memory of the crashed machine
1856 over FireWire. This employs remote DMA as part of the OHCI1394
1857 specification which is now the standard for FireWire controllers.
1858
1859 With remote DMA, you can monitor the printk buffer remotely using
1860 firescope and access all memory below 4GB using fireproxy from gdb.
1861 Even controlling a kernel debugger is possible using remote DMA.
1862
1863 Usage:
1864
1865 If ohci1394_dma=early is used as boot parameter, it will initialize
1866 all OHCI1394 controllers which are found in the PCI config space.
1867
1868 As all changes to the FireWire bus such as enabling and disabling
1869 devices cause a bus reset and thereby disable remote DMA for all
1870 devices, be sure to have the cable plugged and FireWire enabled on
1871 the debugging host before booting the debug target for debugging.
1872
1873 This code (~1k) is freed after boot. By then, the firewire stack
1874 in charge of the OHCI-1394 controllers should be used instead.
1875
1876 See Documentation/debugging-via-ohci1394.txt for more information.
Arjan van de Ven97455122008-01-25 21:08:34 +01001877
Randy Dunlap152de302009-02-20 15:38:47 -08001878config BUILD_DOCSRC
Randy Dunlap3794f3e2008-08-12 15:09:06 -07001879 bool "Build targets in Documentation/ tree"
1880 depends on HEADERS_CHECK
1881 help
1882 This option attempts to build objects from the source files in the
1883 kernel Documentation/ tree.
1884
1885 Say N if you are unsure.
1886
Joerg Roedel5ee00bd2009-01-09 12:14:24 +01001887config DMA_API_DEBUG
1888 bool "Enable debugging of DMA-API usage"
1889 depends on HAVE_DMA_API_DEBUG
1890 help
1891 Enable this option to debug the use of the DMA API by device drivers.
1892 With this option you will be able to detect common bugs in device
1893 drivers like double-freeing of DMA mappings or freeing mappings that
1894 were never allocated.
Dan Williams0abdd7a2014-01-21 15:48:12 -08001895
1896 This also attempts to catch cases where a page owned by DMA is
1897 accessed by the cpu in a way that could cause data corruption. For
1898 example, this enables cow_user_page() to check that the source page is
1899 not undergoing DMA.
1900
1901 This option causes a performance degradation. Use only if you want to
1902 debug device drivers and dma interactions.
1903
1904 If unsure, say N.
Jason Baron346e15b2008-08-12 16:46:19 -04001905
Valentin Rothberg8a6f0b42014-10-13 15:51:38 -07001906config TEST_LKM
Kees Cook93e9ef82014-01-23 15:54:37 -08001907 tristate "Test module loading with 'hello world' module"
1908 default n
1909 depends on m
1910 help
1911 This builds the "test_module" module that emits "Hello, world"
1912 on printk when loaded. It is designed to be used for basic
1913 evaluation of the module loading subsystem (for example when
1914 validating module verification). It lacks any extra dependencies,
1915 and will not normally be loaded by the system unless explicitly
1916 requested by name.
1917
1918 If unsure, say N.
1919
Kees Cook3e2a4c12014-01-23 15:54:38 -08001920config TEST_USER_COPY
1921 tristate "Test user/kernel boundary protections"
1922 default n
1923 depends on m
1924 help
1925 This builds the "test_user_copy" module that runs sanity checks
1926 on the copy_to/from_user infrastructure, making sure basic
1927 user/kernel boundary testing is working. If it fails to load,
1928 a regression has been detected in the user/kernel memory boundary
1929 protections.
1930
1931 If unsure, say N.
1932
Alexei Starovoitov64a89462014-05-08 14:10:52 -07001933config TEST_BPF
1934 tristate "Test BPF filter functionality"
1935 default n
Randy Dunlap98920ba2014-05-13 09:58:44 -07001936 depends on m && NET
Alexei Starovoitov64a89462014-05-08 14:10:52 -07001937 help
1938 This builds the "test_bpf" module that runs various test vectors
1939 against the BPF interpreter or BPF JIT compiler depending on the
1940 current setting. This is in particular useful for BPF JIT compiler
1941 development, but also to run regression tests against changes in
Alexei Starovoitov3c731eb2014-09-26 00:17:07 -07001942 the interpreter code. It also enables test stubs for eBPF maps and
1943 verifier used by user space verifier testsuite.
Alexei Starovoitov64a89462014-05-08 14:10:52 -07001944
1945 If unsure, say N.
1946
Kees Cook0a8adf52014-07-14 14:38:12 -07001947config TEST_FIRMWARE
1948 tristate "Test firmware loading via userspace interface"
1949 default n
1950 depends on FW_LOADER
1951 help
1952 This builds the "test_firmware" module that creates a userspace
1953 interface for testing firmware loading. This can be used to
1954 control the triggering of firmware loading without needing an
1955 actual firmware-using device. The contents can be rechecked by
1956 userspace.
1957
1958 If unsure, say N.
1959
David Rileye704f932014-06-16 14:58:32 -07001960config TEST_UDELAY
1961 tristate "udelay test driver"
1962 default n
1963 help
1964 This builds the "udelay_test" module that helps to make sure
1965 that udelay() is working properly.
1966
1967 If unsure, say N.
1968
Vladimir Murzin4a207992015-04-14 15:48:27 -07001969config MEMTEST
1970 bool "Memtest"
1971 depends on HAVE_MEMBLOCK
1972 ---help---
1973 This option adds a kernel parameter 'memtest', which allows memtest
1974 to be set.
1975 memtest=0, mean disabled; -- default
1976 memtest=1, mean do 1 test pattern;
1977 ...
Vladimir Murzin8d8cfb42015-04-14 15:48:40 -07001978 memtest=17, mean do 17 test patterns.
Vladimir Murzin4a207992015-04-14 15:48:27 -07001979 If you are unsure how to answer this question, answer N.
1980
Ingo Molnar2bf9e0a2015-08-03 11:42:57 +02001981config TEST_STATIC_KEYS
1982 tristate "Test static keys"
Jason Baron579e1ac2015-07-30 03:59:44 +00001983 default n
1984 depends on m
1985 help
Ingo Molnar2bf9e0a2015-08-03 11:42:57 +02001986 Test the static key interfaces.
Jason Baron579e1ac2015-07-30 03:59:44 +00001987
1988 If unsure, say N.
1989
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001990source "samples/Kconfig"
Jason Wesseldc7d5522008-04-17 20:05:37 +02001991
1992source "lib/Kconfig.kgdb"
Pekka Enberg0a4af3b2009-02-26 21:38:56 +02001993
Andrey Ryabininc6d30852016-01-20 15:00:55 -08001994source "lib/Kconfig.ubsan"
1995
Dan Williams21266be2015-11-19 18:19:29 -08001996config ARCH_HAS_DEVMEM_IS_ALLOWED
1997 bool
1998
1999config STRICT_DEVMEM
2000 bool "Filter access to /dev/mem"
2001 depends on MMU
2002 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2003 default y if TILE || PPC
2004 ---help---
2005 If this option is disabled, you allow userspace (root) access to all
2006 of memory, including kernel and userspace memory. Accidental
2007 access to this is obviously disastrous, but specific access can
2008 be used by people debugging the kernel. Note that with PAT support
2009 enabled, even in this case there are restrictions on /dev/mem
2010 use due to the cache aliasing requirements.
2011
Dan Williams90a545e2015-11-23 15:49:03 -08002012 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2013 file only allows userspace access to PCI space and the BIOS code and
2014 data regions. This is sufficient for dosemu and X and all common
2015 users of /dev/mem.
2016
2017 If in doubt, say Y.
2018
2019config IO_STRICT_DEVMEM
2020 bool "Filter I/O access to /dev/mem"
2021 depends on STRICT_DEVMEM
Dan Williams90a545e2015-11-23 15:49:03 -08002022 ---help---
2023 If this option is disabled, you allow userspace (root) access to all
2024 io-memory regardless of whether a driver is actively using that
2025 range. Accidental access to this is obviously disastrous, but
2026 specific access can be used by people debugging kernel drivers.
2027
Dan Williams21266be2015-11-19 18:19:29 -08002028 If this option is switched on, the /dev/mem file only allows
Dan Williams90a545e2015-11-23 15:49:03 -08002029 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2030 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2031 if the driver using a given range cannot be disabled.
Dan Williams21266be2015-11-19 18:19:29 -08002032
2033 If in doubt, say Y.