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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
Kees Cook0e07f662016-10-27 17:46:41 -0700201 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
Andi Kleen35bb5b12008-02-22 15:15:03 +0100202 default 1024 if !64BIT
203 default 2048 if 64BIT
204 help
205 Tell gcc to warn at build time for stack frames larger than this.
206 Setting this too low will cause a lot of warnings.
207 Setting it to 0 disables the warning.
208 Requires gcc 4.4
209
Randy Dunlap99657c72009-09-18 12:49:22 -0700210config STRIP_ASM_SYMS
211 bool "Strip assembler-generated symbols during link"
212 default n
213 help
214 Strip internal assembler-generated symbols during a link (symbols
215 that look like '.Lxxx') so they don't pollute the output of
216 get_wchan() and suchlike.
217
Andi Kleen1873e872012-03-28 11:51:18 -0700218config READABLE_ASM
219 bool "Generate readable assembler code"
220 depends on DEBUG_KERNEL
221 help
222 Disable some compiler optimizations that tend to generate human unreadable
223 assembler output. This may make the kernel slightly slower, but it helps
224 to keep kernel developers who have to stare a lot at assembler listings
225 sane.
226
Arjan van de Venf71d20e2006-06-28 04:26:45 -0700227config UNUSED_SYMBOLS
228 bool "Enable unused/obsolete exported symbols"
229 default y if X86
230 help
231 Unused but exported symbols make the kernel needlessly bigger. For
232 that reason most of these unused exports will soon be removed. This
233 option is provided temporarily to provide a transition period in case
234 some external kernel module needs one of these symbols anyway. If you
235 encounter such a case in your module, consider if you are actually
236 using the right API. (rationale: since nobody in the kernel is using
237 this in a module, there is a pretty good chance it's actually the
238 wrong interface to use). If you really need the symbol, please send a
239 mail to the linux kernel mailing list mentioning the symbol and why
240 you really need it, and what the merge plan to the mainline kernel for
241 your module is.
242
Joonsoo Kim48c96a32014-12-12 16:56:01 -0800243config PAGE_OWNER
244 bool "Track page owner"
245 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
246 select DEBUG_FS
247 select STACKTRACE
Joonsoo Kimf2ca0b52016-07-26 15:23:55 -0700248 select STACKDEPOT
Joonsoo Kim48c96a32014-12-12 16:56:01 -0800249 select PAGE_EXTENSION
250 help
251 This keeps track of what call chain is the owner of a page, may
252 help to find bare alloc_page(s) leaks. Even if you include this
253 feature on your build, it is disabled in default. You should pass
254 "page_owner=on" to boot parameter in order to enable it. Eats
255 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
256 for user-space helper.
257
258 If unsure, say N.
259
Don Mullisbf4735a2006-12-10 02:18:37 -0800260config DEBUG_FS
261 bool "Debug Filesystem"
Nicolai Stange9fd4dce2016-03-22 14:11:13 +0100262 select SRCU
Don Mullisbf4735a2006-12-10 02:18:37 -0800263 help
264 debugfs is a virtual file system that kernel developers use to put
265 debugging files into. Enable this option to be able to read and
266 write to these files.
267
Robert P. J. Dayff543332008-05-20 00:06:00 +0200268 For detailed documentation on the debugfs API, see
269 Documentation/DocBook/filesystems.
270
Don Mullisbf4735a2006-12-10 02:18:37 -0800271 If unsure, say N.
272
273config HEADERS_CHECK
274 bool "Run 'make headers_check' when building vmlinux"
275 depends on !UML
276 help
277 This option will extract the user-visible kernel headers whenever
278 building the kernel, and will run basic sanity checks on them to
279 ensure that exported files do not attempt to include files which
280 were not exported, etc.
281
282 If you're making modifications to header files which are
283 relevant for userspace, say 'Y', and check the headers
284 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
285 your build tree), to make sure they're suitable.
286
Sam Ravnborg91341d42008-01-21 21:31:44 +0100287config DEBUG_SECTION_MISMATCH
288 bool "Enable full Section mismatch analysis"
Sam Ravnborg91341d42008-01-21 21:31:44 +0100289 help
290 The section mismatch analysis checks if there are illegal
291 references from one section to another section.
Michael Wittene809ab02011-04-17 04:08:48 +0000292 During linktime or runtime, some sections are dropped;
293 any use of code/data previously in these sections would
Sam Ravnborg91341d42008-01-21 21:31:44 +0100294 most likely result in an oops.
Michael Wittene809ab02011-04-17 04:08:48 +0000295 In the code, functions and variables are annotated with
Paul Gortmaker0db06282013-06-19 14:53:51 -0400296 __init,, etc. (see the full list in include/linux/init.h),
Geert Uytterhoevend6fbfa42008-01-30 11:13:23 +0100297 which results in the code/data being placed in specific sections.
Michael Wittene809ab02011-04-17 04:08:48 +0000298 The section mismatch analysis is always performed after a full
299 kernel build, and enabling this option causes the following
300 additional steps to occur:
301 - Add the option -fno-inline-functions-called-once to gcc commands.
302 When inlining a function annotated with __init in a non-init
303 function, we would lose the section information and thus
Sam Ravnborg91341d42008-01-21 21:31:44 +0100304 the analysis would not catch the illegal reference.
Michael Wittene809ab02011-04-17 04:08:48 +0000305 This option tells gcc to inline less (but it does result in
306 a larger kernel).
307 - Run the section mismatch analysis for each module/built-in.o file.
308 When we run the section mismatch analysis on vmlinux.o, we
Uwe Kleine-König67797b922016-09-09 10:04:58 +0200309 lose valuable information about where the mismatch was
Sam Ravnborg91341d42008-01-21 21:31:44 +0100310 introduced.
311 Running the analysis for each module/built-in.o file
Michael Wittene809ab02011-04-17 04:08:48 +0000312 tells where the mismatch happens much closer to the
313 source. The drawback is that the same mismatch is
314 reported at least twice.
315 - Enable verbose reporting from modpost in order to help resolve
316 the section mismatches that are reported.
Sam Ravnborg91341d42008-01-21 21:31:44 +0100317
Nicolas Boichat47490ec2015-10-06 09:44:42 +1030318config SECTION_MISMATCH_WARN_ONLY
319 bool "Make section mismatch errors non-fatal"
320 default y
321 help
322 If you say N here, the build process will fail if there are any
323 section mismatch, instead of just throwing warnings.
324
325 If unsure, say Y.
326
Dave Hansen6dfc0662013-07-01 13:04:46 -0700327#
328# Select this config option from the architecture Kconfig, if it
329# is preferred to always offer frame pointers as a config
330# option on the architecture (regardless of KERNEL_DEBUG):
331#
332config ARCH_WANT_FRAME_POINTERS
333 bool
334 help
335
336config FRAME_POINTER
337 bool "Compile the kernel with frame pointers"
338 depends on DEBUG_KERNEL && \
339 (CRIS || M68K || FRV || UML || \
340 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
341 ARCH_WANT_FRAME_POINTERS
342 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
343 help
344 If you say Y here the resulting kernel image will be slightly
345 larger and slower, but it gives very useful debugging information
346 in case of kernel bugs. (precise oopses/stacktraces/warnings)
347
Josh Poimboeufb9ab5eb2016-02-28 22:22:42 -0600348config STACK_VALIDATION
349 bool "Compile-time stack metadata validation"
350 depends on HAVE_STACK_VALIDATION
351 default n
352 help
353 Add compile-time checks to validate stack metadata, including frame
354 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
355 that runtime stack traces are more reliable.
356
357 For more information, see
358 tools/objtool/Documentation/stack-validation.txt.
359
Dave Hansen6dfc0662013-07-01 13:04:46 -0700360config DEBUG_FORCE_WEAK_PER_CPU
361 bool "Force weak per-cpu definitions"
362 depends on DEBUG_KERNEL
363 help
364 s390 and alpha require percpu variables in modules to be
365 defined weak to work around addressing range issue which
366 puts the following two restrictions on percpu variable
367 definitions.
368
369 1. percpu symbols must be unique whether static or not
370 2. percpu variables can't be defined inside a function
371
372 To ensure that generic code follows the above rules, this
373 option forces all percpu variables to be defined as weak.
374
375endmenu # "Compiler options"
376
377config MAGIC_SYSRQ
378 bool "Magic SysRq key"
379 depends on !UML
380 help
381 If you say Y here, you will have some control over the system even
382 if the system crashes for example during kernel debugging (e.g., you
383 will be able to flush the buffer cache to disk, reboot the system
384 immediately or dump some status information). This is accomplished
385 by pressing various keys while holding SysRq (Alt+PrintScreen). It
386 also works on a serial console (on PC hardware at least), if you
387 send a BREAK and then within 5 seconds a command keypress. The
388 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
389 unless you really know what this hack does.
390
Ben Hutchings8eaede42013-10-07 01:05:46 +0100391config MAGIC_SYSRQ_DEFAULT_ENABLE
392 hex "Enable magic SysRq key functions by default"
393 depends on MAGIC_SYSRQ
394 default 0x1
395 help
396 Specifies which SysRq key functions are enabled by default.
397 This may be set to 1 or 0 to enable or disable them all, or
398 to a bitmask as described in Documentation/sysrq.txt.
399
Adrian Bunkf346f4b2006-01-09 20:54:51 -0800400config DEBUG_KERNEL
401 bool "Kernel debugging"
402 help
403 Say Y here if you are developing drivers or trying to debug and
404 identify kernel problems.
405
Dave Hansen0610c8a2013-07-01 13:04:43 -0700406menu "Memory Debugging"
David Woodhousea304e1b2007-02-12 00:52:00 -0800407
Dave Hansen0610c8a2013-07-01 13:04:43 -0700408source mm/Kconfig.debug
Ingo Molnar82f67cd2007-02-16 01:28:13 -0800409
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700410config DEBUG_OBJECTS
411 bool "Debug object operations"
412 depends on DEBUG_KERNEL
413 help
414 If you say Y here, additional code will be inserted into the
415 kernel to track the life time of various objects and validate
416 the operations on those objects.
417
418config DEBUG_OBJECTS_SELFTEST
419 bool "Debug objects selftest"
420 depends on DEBUG_OBJECTS
421 help
422 This enables the selftest of the object debug code.
423
424config DEBUG_OBJECTS_FREE
425 bool "Debug objects in freed memory"
426 depends on DEBUG_OBJECTS
427 help
428 This enables checks whether a k/v free operation frees an area
429 which contains an object which has not been deactivated
430 properly. This can make kmalloc/kfree-intensive workloads
431 much slower.
432
Thomas Gleixnerc6f3a972008-04-30 00:55:03 -0700433config DEBUG_OBJECTS_TIMERS
434 bool "Debug timer objects"
435 depends on DEBUG_OBJECTS
436 help
437 If you say Y here, additional code will be inserted into the
438 timer routines to track the life time of timer objects and
439 validate the timer operations.
440
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900441config DEBUG_OBJECTS_WORK
442 bool "Debug work objects"
443 depends on DEBUG_OBJECTS
444 help
445 If you say Y here, additional code will be inserted into the
446 work queue routines to track the life time of work objects and
447 validate the work operations.
448
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400449config DEBUG_OBJECTS_RCU_HEAD
450 bool "Debug RCU callbacks objects"
Mathieu Desnoyersfc2ecf72011-02-23 09:42:14 -0800451 depends on DEBUG_OBJECTS
Mathieu Desnoyers551d55a2010-04-17 08:48:42 -0400452 help
453 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
454
Tejun Heoe2852ae2010-10-26 14:23:05 -0700455config DEBUG_OBJECTS_PERCPU_COUNTER
456 bool "Debug percpu counter objects"
457 depends on DEBUG_OBJECTS
458 help
459 If you say Y here, additional code will be inserted into the
460 percpu counter routines to track the life time of percpu counter
461 objects and validate the percpu counter operations.
462
Ingo Molnar3ae70202008-11-26 10:02:00 +0100463config DEBUG_OBJECTS_ENABLE_DEFAULT
464 int "debug_objects bootup default value (0-1)"
465 range 0 1
466 default "1"
467 depends on DEBUG_OBJECTS
468 help
469 Debug objects boot parameter default value
470
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471config DEBUG_SLAB
Andrew Morton4a2f0ac2006-03-25 03:07:22 -0800472 bool "Debug slab memory allocations"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200473 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 help
475 Say Y here to have the kernel do limited verification on memory
476 allocation as well as poisoning memory on free to catch use of freed
477 memory. This can make kmalloc/kfree-intensive workloads much slower.
478
Al Viro871751e2006-03-25 03:06:39 -0800479config DEBUG_SLAB_LEAK
480 bool "Memory leak debugging"
481 depends on DEBUG_SLAB
482
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700483config SLUB_DEBUG_ON
484 bool "SLUB debugging on by default"
Vegard Nossum7d46d9e2008-04-04 00:51:41 +0200485 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
Christoph Lameterf0630ff2007-07-15 23:38:14 -0700486 default n
487 help
488 Boot with debugging on by default. SLUB boots by default with
489 the runtime debug capabilities switched off. Enabling this is
490 equivalent to specifying the "slub_debug" parameter on boot.
491 There is no support for more fine grained debug control like
492 possible with slub_debug=xxx. SLUB debugging may be switched
493 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
494 "slub_debug=-".
495
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800496config SLUB_STATS
497 default n
498 bool "Enable SLUB performance statistics"
Christoph Lameterab4d5ed2010-10-05 13:57:26 -0500499 depends on SLUB && SYSFS
Christoph Lameter8ff12cf2008-02-07 17:47:41 -0800500 help
501 SLUB statistics are useful to debug SLUBs allocation behavior in
502 order find ways to optimize the allocator. This should never be
503 enabled for production use since keeping statistics slows down
504 the allocator by a few percentage points. The slabinfo command
505 supports the determination of the most active slabs to figure
506 out which slabs are relevant to a particular load.
507 Try running: slabinfo -DA
508
Catalin Marinasb69ec422012-10-08 16:28:11 -0700509config HAVE_DEBUG_KMEMLEAK
510 bool
511
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100512config DEBUG_KMEMLEAK
513 bool "Kernel memory leak detector"
Kees Cook525c1f92013-01-16 18:54:16 -0800514 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
Catalin Marinas79e0d9b2011-04-27 17:06:19 +0100515 select DEBUG_FS
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100516 select STACKTRACE if STACKTRACE_SUPPORT
517 select KALLSYMS
Randy Dunlapb60e26a2009-11-06 15:33:45 -0800518 select CRC32
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100519 help
520 Say Y here if you want to enable the memory leak
521 detector. The memory allocation/freeing is traced in a way
522 similar to the Boehm's conservative garbage collector, the
523 difference being that the orphan objects are not freed but
524 only shown in /sys/kernel/debug/kmemleak. Enabling this
525 feature will introduce an overhead to memory
526 allocations. See Documentation/kmemleak.txt for more
527 details.
528
Catalin Marinasbf96d1e2009-06-23 14:40:27 +0100529 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
530 of finding leaks due to the slab objects poisoning.
531
Catalin Marinas3bba00d2009-06-11 13:24:13 +0100532 In order to access the kmemleak file, debugfs needs to be
533 mounted (usually at /sys/kernel/debug).
534
Catalin Marinasa9d90582009-06-25 10:16:11 +0100535config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
536 int "Maximum kmemleak early log entries"
537 depends on DEBUG_KMEMLEAK
Heiko Carstensdfcc3e62009-10-06 10:33:57 +0200538 range 200 40000
Catalin Marinasa9d90582009-06-25 10:16:11 +0100539 default 400
540 help
541 Kmemleak must track all the memory allocations to avoid
542 reporting false positives. Since memory may be allocated or
543 freed before kmemleak is initialised, an early log buffer is
544 used to store these actions. If kmemleak reports "early log
545 buffer exceeded", please increase this value.
546
Catalin Marinas0822ee42009-06-11 13:24:14 +0100547config DEBUG_KMEMLEAK_TEST
548 tristate "Simple test for the kernel memory leak detector"
Daniel Baluta97182692011-04-04 15:06:44 -0700549 depends on DEBUG_KMEMLEAK && m
Catalin Marinas0822ee42009-06-11 13:24:14 +0100550 help
Daniel Baluta97182692011-04-04 15:06:44 -0700551 This option enables a module that explicitly leaks memory.
Catalin Marinas0822ee42009-06-11 13:24:14 +0100552
553 If unsure, say N.
554
Jason Baronab0155a2010-07-19 11:54:17 +0100555config DEBUG_KMEMLEAK_DEFAULT_OFF
556 bool "Default kmemleak to off"
557 depends on DEBUG_KMEMLEAK
558 help
559 Say Y here to disable kmemleak by default. It can then be enabled
560 on the command line via kmemleak=on.
561
Dave Hansen0610c8a2013-07-01 13:04:43 -0700562config DEBUG_STACK_USAGE
563 bool "Stack utilization instrumentation"
Helge Deller6c31da32016-03-19 17:54:10 +0100564 depends on DEBUG_KERNEL && !IA64
Dave Hansen0610c8a2013-07-01 13:04:43 -0700565 help
566 Enables the display of the minimum amount of free stack which each
567 task has ever had available in the sysrq-T and sysrq-P debug output.
568
569 This option will slow down process creation somewhat.
570
571config DEBUG_VM
572 bool "Debug VM"
573 depends on DEBUG_KERNEL
574 help
575 Enable this to turn on extended checks in the virtual-memory system
576 that may impact performance.
577
578 If unsure, say N.
579
Davidlohr Bueso4f115142014-06-04 16:06:46 -0700580config DEBUG_VM_VMACACHE
581 bool "Debug VMA caching"
582 depends on DEBUG_VM
583 help
584 Enable this to turn on VMA caching debug information. Doing so
585 can cause significant overhead, so only enable it in non-production
586 environments.
587
588 If unsure, say N.
589
Dave Hansen0610c8a2013-07-01 13:04:43 -0700590config DEBUG_VM_RB
591 bool "Debug VM red-black trees"
592 depends on DEBUG_VM
593 help
Davidlohr Buesoa663dad2014-04-18 15:07:22 -0700594 Enable VM red-black tree debugging information and extra validations.
Dave Hansen0610c8a2013-07-01 13:04:43 -0700595
596 If unsure, say N.
597
Kirill A. Shutemov95ad9752016-01-15 16:51:21 -0800598config DEBUG_VM_PGFLAGS
599 bool "Debug page-flags operations"
600 depends on DEBUG_VM
601 help
602 Enables extra validation on page flags operations.
603
604 If unsure, say N.
605
Dave Hansen0610c8a2013-07-01 13:04:43 -0700606config DEBUG_VIRTUAL
607 bool "Debug VM translations"
608 depends on DEBUG_KERNEL && X86
609 help
610 Enable some costly sanity checks in virtual to page code. This can
611 catch mistakes with virt_to_page() and friends.
612
613 If unsure, say N.
614
615config DEBUG_NOMMU_REGIONS
616 bool "Debug the global anon/private NOMMU mapping region tree"
617 depends on DEBUG_KERNEL && !MMU
618 help
619 This option causes the global tree of anonymous and private mapping
620 regions to be regularly checked for invalid topology.
621
622config DEBUG_MEMORY_INIT
623 bool "Debug memory initialisation" if EXPERT
624 default !EXPERT
625 help
626 Enable this for additional checks during memory initialisation.
627 The sanity checks verify aspects of the VM such as the memory model
628 and other information provided by the architecture. Verbose
629 information will be printed at KERN_DEBUG loglevel depending
630 on the mminit_loglevel= command-line option.
631
632 If unsure, say Y
633
634config MEMORY_NOTIFIER_ERROR_INJECT
635 tristate "Memory hotplug notifier error injection module"
636 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
637 help
638 This option provides the ability to inject artificial errors to
639 memory hotplug notifier chain callbacks. It is controlled through
640 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
641
642 If the notifier call chain should be failed with some events
643 notified, write the error code to "actions/<notifier event>/error".
644
645 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
646
647 # cd /sys/kernel/debug/notifier-error-inject/memory
648 # echo -12 > actions/MEM_GOING_OFFLINE/error
649 # echo offline > /sys/devices/system/memory/memoryXXX/state
650 bash: echo: write error: Cannot allocate memory
651
652 To compile this code as a module, choose M here: the module will
653 be called memory-notifier-error-inject.
654
655 If unsure, say N.
656
657config DEBUG_PER_CPU_MAPS
658 bool "Debug access to per_cpu maps"
659 depends on DEBUG_KERNEL
660 depends on SMP
661 help
662 Say Y to verify that the per_cpu map being accessed has
663 been set up. This adds a fair amount of code to kernel memory
664 and decreases performance.
665
666 Say N if unsure.
667
668config DEBUG_HIGHMEM
669 bool "Highmem debugging"
670 depends on DEBUG_KERNEL && HIGHMEM
671 help
Geert Uytterhoevenb1357c92014-04-14 18:55:50 +0200672 This option enables additional error checking for high memory
673 systems. Disable for production systems.
Dave Hansen0610c8a2013-07-01 13:04:43 -0700674
675config HAVE_DEBUG_STACKOVERFLOW
676 bool
677
678config DEBUG_STACKOVERFLOW
679 bool "Check for stack overflows"
680 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
681 ---help---
682 Say Y here if you want to check for overflows of kernel, IRQ
Borislav Petkovedb0ec02015-01-25 19:50:34 +0100683 and exception stacks (if your architecture uses them). This
Dave Hansen0610c8a2013-07-01 13:04:43 -0700684 option will show detailed messages if free stack space drops
685 below a certain limit.
686
687 These kinds of bugs usually occur when call-chains in the
688 kernel get too deep, especially when interrupts are
689 involved.
690
691 Use this in cases where you see apparently random memory
692 corruption, especially if it appears in 'struct thread_info'
693
694 If in doubt, say "N".
695
696source "lib/Kconfig.kmemcheck"
697
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800698source "lib/Kconfig.kasan"
699
Dave Hansen0610c8a2013-07-01 13:04:43 -0700700endmenu # "Memory Debugging"
701
Dmitry Vyukov5c9a8752016-03-22 14:27:30 -0700702config ARCH_HAS_KCOV
703 bool
704 help
705 KCOV does not have any arch-specific code, but currently it is enabled
706 only for x86_64. KCOV requires testing on other archs, and most likely
707 disabling of instrumentation for some early boot code.
708
709config KCOV
710 bool "Code coverage for fuzzing"
711 depends on ARCH_HAS_KCOV
712 select DEBUG_FS
Kees Cooka519167e2016-06-11 09:09:28 -0700713 select GCC_PLUGINS if !COMPILE_TEST
714 select GCC_PLUGIN_SANCOV if !COMPILE_TEST
Dmitry Vyukov5c9a8752016-03-22 14:27:30 -0700715 help
716 KCOV exposes kernel code coverage information in a form suitable
717 for coverage-guided fuzzing (randomized testing).
718
719 If RANDOMIZE_BASE is enabled, PC values will not be stable across
720 different machines and across reboots. If you need stable PC values,
721 disable RANDOMIZE_BASE.
722
723 For more details, see Documentation/kcov.txt.
724
Vegard Nossuma4691de2016-08-02 14:07:30 -0700725config KCOV_INSTRUMENT_ALL
726 bool "Instrument all code by default"
727 depends on KCOV
728 default y if KCOV
729 help
730 If you are doing generic system call fuzzing (like e.g. syzkaller),
731 then you will want to instrument the whole kernel and you should
732 say y here. If you are doing more targeted fuzzing (like e.g.
733 filesystem fuzzing with AFL) then you will want to enable coverage
734 for more specific subsets of files, and should say n here.
735
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736config DEBUG_SHIRQ
737 bool "Debug shared IRQ handlers"
Martin Schwidefsky0244ad02013-08-30 09:39:53 +0200738 depends on DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 help
740 Enable this to generate a spurious interrupt as soon as a shared
741 interrupt handler is registered, and just before one is deregistered.
742 Drivers ought to be able to handle interrupts coming in at those
743 points; some don't and need to be caught.
744
Dave Hansen92aef8fb2013-07-01 13:04:50 -0700745menu "Debug Lockups and Hangs"
746
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747config LOCKUP_DETECTOR
748 bool "Detect Hard and Soft Lockups"
749 depends on DEBUG_KERNEL && !S390
750 help
751 Say Y here to enable the kernel to act as a watchdog to detect
752 hard and soft lockups.
753
754 Softlockups are bugs that cause the kernel to loop in kernel
755 mode for more than 20 seconds, without giving other tasks a
756 chance to run. The current stack trace is displayed upon
757 detection and the system will stay locked up.
758
759 Hardlockups are bugs that cause the CPU to loop in kernel mode
760 for more than 10 seconds, without letting other interrupts have a
761 chance to run. The current stack trace is displayed upon detection
762 and the system will stay locked up.
763
764 The overhead should be minimal. A periodic hrtimer runs to
765 generate interrupts and kick the watchdog task every 4 seconds.
766 An NMI is generated every 10 seconds or so to check for hardlockups.
767
768 The frequency of hrtimer and NMI events and the soft and hard lockup
769 thresholds can be controlled through the sysctl watchdog_thresh.
770
771config HARDLOCKUP_DETECTOR
772 def_bool y
773 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
774 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
775
776config BOOTPARAM_HARDLOCKUP_PANIC
777 bool "Panic (Reboot) On Hard Lockups"
778 depends on HARDLOCKUP_DETECTOR
779 help
780 Say Y here to enable the kernel to panic on "hard lockups",
781 which are bugs that cause the kernel to loop in kernel
782 mode with interrupts disabled for more than 10 seconds (configurable
783 using the watchdog_thresh sysctl).
784
785 Say N if unsure.
786
787config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
788 int
789 depends on HARDLOCKUP_DETECTOR
790 range 0 1
791 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
792 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
793
794config BOOTPARAM_SOFTLOCKUP_PANIC
795 bool "Panic (Reboot) On Soft Lockups"
796 depends on LOCKUP_DETECTOR
797 help
798 Say Y here to enable the kernel to panic on "soft lockups",
799 which are bugs that cause the kernel to loop in kernel
800 mode for more than 20 seconds (configurable using the watchdog_thresh
801 sysctl), without giving other tasks a chance to run.
802
803 The panic can be used in combination with panic_timeout,
804 to cause the system to reboot automatically after a
805 lockup has been detected. This feature is useful for
806 high-availability systems that have uptime guarantees and
807 where a lockup must be resolved ASAP.
808
Ingo Molnar8637c092006-07-03 00:24:38 -0700809 Say N if unsure.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810
811config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
812 int
813 depends on LOCKUP_DETECTOR
814 range 0 1
815 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
816 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700817
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818config DETECT_HUNG_TASK
819 bool "Detect Hung Tasks"
820 depends on DEBUG_KERNEL
821 default LOCKUP_DETECTOR
822 help
823 Say Y here to enable the kernel to detect "hung tasks",
824 which are bugs that cause the task to be stuck in
Vivien Didelot96b03ab2016-09-22 16:55:13 -0400825 uninterruptible "D" state indefinitely.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826
827 When a hung task is detected, the kernel will print the
828 current stack trace (which you should report), but the
829 task will stay in uninterruptible state. If lockdep is
830 enabled then all held locks will also be reported. This
831 feature has negligible overhead.
832
833config DEFAULT_HUNG_TASK_TIMEOUT
834 int "Default timeout for hung task detection (in seconds)"
835 depends on DETECT_HUNG_TASK
836 default 120
837 help
838 This option controls the default timeout (in seconds) used
839 to determine when a task has become non-responsive and should
840 be considered hung.
841
Ingo Molnar408894e2006-01-09 15:59:20 -0800842 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
843 sysctl or by writing a value to
844 /proc/sys/kernel/hung_task_timeout_secs.
845
846 A timeout of 0 disables the check. The default is two minutes.
847 Keeping the default should be fine in most cases.
Tim Chencca57c52006-04-18 22:21:47 -0700848
Ingo Molnar408894e2006-01-09 15:59:20 -0800849config BOOTPARAM_HUNG_TASK_PANIC
850 bool "Panic (Reboot) On Hung Tasks"
851 depends on DETECT_HUNG_TASK
852 help
853 Say Y here to enable the kernel to panic on "hung tasks",
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700854 which are bugs that cause the kernel to leave a task stuck
855 in uninterruptible "D" state.
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700856
857 The panic can be used in combination with panic_timeout,
858 to cause the system to reboot automatically after a
859 hung task has been detected. This feature is useful for
860 high-availability systems that have uptime guarantees and
861 where a hung tasks must be resolved ASAP.
862
863 Say N if unsure.
864
Hugh Dickins048c8bc2006-11-01 05:44:54 +1100865config BOOTPARAM_HUNG_TASK_PANIC_VALUE
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 int
867 depends on DETECT_HUNG_TASK
868 range 0 1
869 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
870 default 1 if BOOTPARAM_HUNG_TASK_PANIC
871
Tejun Heo82607adc2015-12-08 11:28:04 -0500872config WQ_WATCHDOG
873 bool "Detect Workqueue Stalls"
874 depends on DEBUG_KERNEL
875 help
876 Say Y here to enable stall detection on workqueues. If a
877 worker pool doesn't make forward progress on a pending work
878 item for over a given amount of time, 30s by default, a
879 warning message is printed along with dump of workqueue
880 state. This can be configured through kernel parameter
881 "workqueue.watchdog_thresh" and its sysfs counterpart.
882
Dave Hansen92aef8fb2013-07-01 13:04:50 -0700883endmenu # "Debug lockups and hangs"
884
885config PANIC_ON_OOPS
886 bool "Panic on Oops"
887 help
888 Say Y here to enable the kernel to panic when it oopses. This
889 has the same effect as setting oops=panic on the kernel command
890 line.
891
892 This feature is useful to ensure that the kernel does not do
893 anything erroneous after an oops which could result in data
894 corruption or other issues.
895
896 Say N if unsure.
897
898config PANIC_ON_OOPS_VALUE
899 int
900 range 0 1
901 default 0 if !PANIC_ON_OOPS
902 default 1 if PANIC_ON_OOPS
903
Jason Baron5800dc32013-11-25 23:23:04 +0000904config PANIC_TIMEOUT
905 int "panic timeout"
906 default 0
907 help
908 Set the timeout value (in seconds) until a reboot occurs when the
909 the kernel panics. If n = 0, then we wait forever. A timeout
910 value n > 0 will wait n seconds before rebooting, while a timeout
911 value n < 0 will reboot immediately.
912
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913config SCHED_DEBUG
914 bool "Collect scheduler debugging info"
915 depends on DEBUG_KERNEL && PROC_FS
916 default y
917 help
918 If you say Y here, the /proc/sched_debug file will be provided
919 that can help debug the scheduler. The runtime overhead of this
920 option is minimal.
921
Naveen N. Raof6db8342015-06-25 23:53:37 +0530922config SCHED_INFO
923 bool
924 default n
925
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926config SCHEDSTATS
927 bool "Collect scheduler statistics"
928 depends on DEBUG_KERNEL && PROC_FS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530929 select SCHED_INFO
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 help
931 If you say Y here, additional code will be inserted into the
932 scheduler and related routines to collect statistics about
933 scheduler behavior and provide them in /proc/schedstat. These
934 stats may be useful for both tuning and debugging the scheduler
935 If you aren't debugging the scheduler or trying to tune a specific
936 application, you can say N to avoid the very slight overhead
937 this adds.
938
Aaron Tomlin0d9e2632014-09-12 14:16:19 +0100939config SCHED_STACK_END_CHECK
940 bool "Detect stack corruption on calls to schedule()"
941 depends on DEBUG_KERNEL
942 default n
943 help
944 This option checks for a stack overrun on calls to schedule().
945 If the stack end location is found to be over written always panic as
946 the content of the corrupted region can no longer be trusted.
947 This is to ensure no erroneous behaviour occurs which could result in
948 data corruption or a sporadic crash at a later stage once the region
949 is examined. The runtime overhead introduced is minimal.
950
John Stultz3c17ad12015-03-11 21:16:32 -0700951config DEBUG_TIMEKEEPING
952 bool "Enable extra timekeeping sanity checking"
953 help
954 This option will enable additional timekeeping sanity checks
955 which may be helpful when diagnosing issues where timekeeping
956 problems are suspected.
957
958 This may include checks in the timekeeping hotpaths, so this
959 option may have a (very small) performance impact to some
960 workloads.
961
962 If unsure, say N.
963
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964config TIMER_STATS
965 bool "Collect kernel timers statistics"
966 depends on DEBUG_KERNEL && PROC_FS
967 help
968 If you say Y here, additional code will be inserted into the
969 timer routines to collect statistics about kernel timers being
970 reprogrammed. The statistics can be read from /proc/timer_stats.
971 The statistics collection is started by writing 1 to /proc/timer_stats,
972 writing 0 stops it. This feature is useful to collect information
973 about timer usage patterns in kernel and userspace. This feature
974 is lightweight if enabled in the kernel config but not activated
975 (it defaults to deactivated on bootup and will only be activated
976 if some application like powertop activates it explicitly).
977
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978config DEBUG_PREEMPT
979 bool "Debug preemptible kernel"
Kumar Gala01deab92009-10-16 07:21:39 +0000980 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981 default y
982 help
983 If you say Y here then the kernel will use a debug variant of the
984 commonly used smp_processor_id() function and will print warnings
985 if kernel code uses it in a preemption-unsafe way. Also, the kernel
986 will detect preemption count underflows.
987
Dave Hansen9eade162013-07-01 13:04:47 -0700988menu "Lock Debugging (spinlocks, mutexes, etc...)"
989
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700990config DEBUG_RT_MUTEXES
991 bool "RT Mutex debugging, deadlock detection"
992 depends on DEBUG_KERNEL && RT_MUTEXES
993 help
994 This allows rt mutex semantics violations and rt mutex related
995 deadlocks (lockups) to be detected and reported automatically.
996
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997config DEBUG_SPINLOCK
Ingo Molnar4d9f34a2006-07-03 00:24:55 -0700998 bool "Spinlock and rw-lock debugging: basic checks"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 depends on DEBUG_KERNEL
Raghavendra K Te335e3e2012-03-22 15:25:08 +05301000 select UNINLINE_SPIN_UNLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 help
1002 Say Y here and build SMP to catch missing spinlock initialization
1003 and certain other kinds of spinlock errors commonly made. This is
1004 best used in conjunction with the NMI watchdog so that spinlock
1005 deadlocks are also debuggable.
1006
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001007config DEBUG_MUTEXES
1008 bool "Mutex debugging: basic checks"
1009 depends on DEBUG_KERNEL
1010 help
1011 This feature allows mutex semantics violations to be detected and
1012 reported.
1013
Daniel Vetter23010022013-06-20 13:31:17 +02001014config DEBUG_WW_MUTEX_SLOWPATH
1015 bool "Wait/wound mutex debugging: Slowpath testing"
1016 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1017 select DEBUG_LOCK_ALLOC
1018 select DEBUG_SPINLOCK
1019 select DEBUG_MUTEXES
1020 help
1021 This feature enables slowpath testing for w/w mutex users by
1022 injecting additional -EDEADLK wound/backoff cases. Together with
1023 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1024 will test all possible w/w mutex interface abuse with the
1025 exception of simply not acquiring all the required locks.
Rob Clark4d692372014-08-27 11:19:26 -04001026 Note that this feature can introduce significant overhead, so
1027 it really should not be enabled in a production or distro kernel,
1028 even a debug kernel. If you are a driver writer, enable it. If
1029 you are a distro, do not.
Daniel Vetter23010022013-06-20 13:31:17 +02001030
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001031config DEBUG_LOCK_ALLOC
1032 bool "Lock debugging: detect incorrect freeing of live locks"
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001033 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001034 select DEBUG_SPINLOCK
1035 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001036 select LOCKDEP
1037 help
1038 This feature will check whether any held lock (spinlock, rwlock,
1039 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1040 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1041 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1042 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1043 held during task exit.
1044
1045config PROVE_LOCKING
1046 bool "Lock debugging: prove locking correctness"
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001047 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001048 select LOCKDEP
1049 select DEBUG_SPINLOCK
1050 select DEBUG_MUTEXES
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001051 select DEBUG_LOCK_ALLOC
Steven Rostedt46b93b72010-08-31 16:35:20 -04001052 select TRACE_IRQFLAGS
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001053 default n
1054 help
1055 This feature enables the kernel to prove that all locking
1056 that occurs in the kernel runtime is mathematically
1057 correct: that under no circumstance could an arbitrary (and
1058 not yet triggered) combination of observed locking
1059 sequences (on an arbitrary number of CPUs, running an
1060 arbitrary number of tasks and interrupt contexts) cause a
1061 deadlock.
1062
1063 In short, this feature enables the kernel to report locking
1064 related deadlocks before they actually occur.
1065
1066 The proof does not depend on how hard and complex a
1067 deadlock scenario would be to trigger: how many
1068 participant CPUs, tasks and irq-contexts would be needed
1069 for it to trigger. The proof also does not depend on
1070 timing: if a race and a resulting deadlock is possible
1071 theoretically (no matter how unlikely the race scenario
1072 is), it will be proven so and will immediately be
1073 reported by the kernel (once the event is observed that
1074 makes the deadlock theoretically possible).
1075
1076 If a deadlock is impossible (i.e. the locking rules, as
1077 observed by the kernel, are mathematically correct), the
1078 kernel reports nothing.
1079
1080 NOTE: this feature can also be enabled for rwlocks, mutexes
1081 and rwsems - in which case all dependencies between these
1082 different locking variants are observed and mapped too, and
1083 the proof of observed correctness is also maintained for an
1084 arbitrary combination of these separate locking variants.
1085
Davidlohr Bueso214e0ae2014-07-30 13:41:55 -07001086 For more details, see Documentation/locking/lockdep-design.txt.
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001087
Babu Mogere6b5f1b2016-11-02 09:36:32 -07001088config PROVE_LOCKING_SMALL
1089 bool
1090
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001091config LOCKDEP
1092 bool
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001093 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001094 select STACKTRACE
Chen Gangdf2e1ef2014-06-23 13:22:04 -07001095 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001096 select KALLSYMS
1097 select KALLSYMS_ALL
1098
Peter Zijlstraf20786f2007-07-19 01:48:56 -07001099config LOCK_STAT
Danny ter Haarfdfb8702007-09-24 21:24:43 -07001100 bool "Lock usage statistics"
Peter Zijlstraf20786f2007-07-19 01:48:56 -07001101 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1102 select LOCKDEP
1103 select DEBUG_SPINLOCK
1104 select DEBUG_MUTEXES
1105 select DEBUG_LOCK_ALLOC
1106 default n
1107 help
1108 This feature enables tracking lock contention points
1109
Davidlohr Bueso214e0ae2014-07-30 13:41:55 -07001110 For more details, see Documentation/locking/lockstat.txt
Peter Zijlstraa560aa42007-10-07 00:24:33 -07001111
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +01001112 This also enables lock events required by "perf lock",
1113 subcommand of perf.
1114 If you want to use "perf lock", you also need to turn on
1115 CONFIG_EVENT_TRACING.
Hitoshi Mitake84c6f882010-02-04 16:08:15 +09001116
1117 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
Frederic Weisbeckerdd8b1cf2010-02-27 17:10:39 +01001118 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
Hitoshi Mitake84c6f882010-02-04 16:08:15 +09001119
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001120config DEBUG_LOCKDEP
1121 bool "Lock dependency engine debugging"
Adrian Bunk517e7aa2006-07-14 00:24:32 -07001122 depends on DEBUG_KERNEL && LOCKDEP
Ingo Molnar4d9f34a2006-07-03 00:24:55 -07001123 help
1124 If you say Y here, the lock dependency engine will do
1125 additional runtime checks to debug itself, at the price
1126 of more runtime overhead.
1127
Frederic Weisbeckerd902db12011-06-08 19:31:56 +02001128config DEBUG_ATOMIC_SLEEP
1129 bool "Sleep inside atomic section checking"
Frederic Weisbeckere8f7c702011-06-08 01:51:02 +02001130 select PREEMPT_COUNT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 depends on DEBUG_KERNEL
1132 help
1133 If you say Y here, various routines which may sleep will become very
Frederic Weisbeckerd902db12011-06-08 19:31:56 +02001134 noisy if they are called inside atomic sections: when a spinlock is
1135 held, inside an rcu read side critical section, inside preempt disabled
1136 sections, inside an interrupt, etc...
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137
Ingo Molnarcae2ed92006-07-03 00:24:48 -07001138config DEBUG_LOCKING_API_SELFTESTS
1139 bool "Locking API boot-time self-tests"
1140 depends on DEBUG_KERNEL
1141 help
1142 Say Y here if you want the kernel to run a short self-test during
1143 bootup. The self-test checks whether common types of locking bugs
1144 are detected by debugging mechanisms or not. (if you disable
1145 lock debugging then those bugs wont be detected of course.)
1146 The following locking APIs are covered: spinlocks, rwlocks,
1147 mutexes and rwsems.
1148
Paul E. McKenney0af3fe12014-02-04 15:51:41 -08001149config LOCK_TORTURE_TEST
1150 tristate "torture tests for locking"
1151 depends on DEBUG_KERNEL
1152 select TORTURE_TEST
1153 default n
1154 help
1155 This option provides a kernel module that runs torture tests
1156 on kernel locking primitives. The kernel module may be built
1157 after the fact on the running kernel to be tested, if desired.
1158
1159 Say Y here if you want kernel locking-primitive torture tests
1160 to be built into the kernel.
1161 Say M if you want these torture tests to build as a module.
1162 Say N if you are unsure.
1163
Dave Hansen9eade162013-07-01 13:04:47 -07001164endmenu # lock debugging
1165
1166config TRACE_IRQFLAGS
1167 bool
1168 help
1169 Enables hooks to interrupt enabling and disabling for
1170 either tracing or lock debugging.
1171
Ingo Molnar8637c092006-07-03 00:24:38 -07001172config STACKTRACE
Dave Jones0c38e1f2014-08-29 15:18:35 -07001173 bool "Stack backtrace support"
Ingo Molnar8637c092006-07-03 00:24:38 -07001174 depends on STACKTRACE_SUPPORT
Dave Jones0c38e1f2014-08-29 15:18:35 -07001175 help
1176 This option causes the kernel to create a /proc/pid/stack for
1177 every process, showing its current stack trace.
1178 It is also used by various kernel debugging features that require
1179 stack trace generation.
Ingo Molnar8637c092006-07-03 00:24:38 -07001180
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181config DEBUG_KOBJECT
1182 bool "kobject debugging"
1183 depends on DEBUG_KERNEL
1184 help
1185 If you say Y here, some extra kobject debugging messages will be sent
1186 to the syslog.
1187
Russell Kingc817a672013-06-27 15:06:14 +01001188config DEBUG_KOBJECT_RELEASE
1189 bool "kobject release debugging"
Linus Torvalds2a999aa2013-10-29 08:33:36 -07001190 depends on DEBUG_OBJECTS_TIMERS
Russell Kingc817a672013-06-27 15:06:14 +01001191 help
1192 kobjects are reference counted objects. This means that their
1193 last reference count put is not predictable, and the kobject can
1194 live on past the point at which a driver decides to drop it's
1195 initial reference to the kobject gained on allocation. An
1196 example of this would be a struct device which has just been
1197 unregistered.
1198
1199 However, some buggy drivers assume that after such an operation,
1200 the memory backing the kobject can be immediately freed. This
1201 goes completely against the principles of a refcounted object.
1202
1203 If you say Y here, the kernel will delay the release of kobjects
1204 on the last reference count to improve the visibility of this
1205 kind of kobject release bug.
1206
Catalin Marinas9b2a60c2012-10-08 16:28:13 -07001207config HAVE_DEBUG_BUGVERBOSE
1208 bool
1209
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210config DEBUG_BUGVERBOSE
David Rientjes6a108a12011-01-20 14:44:16 -08001211 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
Catalin Marinas9b2a60c2012-10-08 16:28:13 -07001212 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
Alexey Dobriyan8420e7e2009-12-14 18:00:25 -08001213 default y
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 help
1215 Say Y here to make BUG() panics output the file name and line number
1216 of the BUG call as well as the EIP and oops trace. This aids
1217 debugging but costs about 70-100K of memory.
1218
Dave Jones199a9af2006-09-29 01:59:00 -07001219config DEBUG_LIST
1220 bool "Debug linked list manipulation"
1221 depends on DEBUG_KERNEL
1222 help
1223 Enable this to turn on extended checks in the linked-list
1224 walking routines.
1225
1226 If unsure, say N.
1227
Dan Streetmanb8cfff62014-06-04 16:11:54 -07001228config DEBUG_PI_LIST
1229 bool "Debug priority linked list manipulation"
1230 depends on DEBUG_KERNEL
1231 help
1232 Enable this to turn on extended checks in the priority-ordered
1233 linked-list (plist) walking routines. This checks the entire
1234 list multiple times during each manipulation.
1235
1236 If unsure, say N.
1237
Jens Axboed6ec0842007-10-22 20:01:06 +02001238config DEBUG_SG
1239 bool "Debug SG table operations"
1240 depends on DEBUG_KERNEL
1241 help
1242 Enable this to turn on checks on scatter-gather tables. This can
1243 help find problems with drivers that do not properly initialize
1244 their sg tables.
1245
1246 If unsure, say N.
1247
Arjan van de Ven1b2439d2008-08-15 15:29:38 -07001248config DEBUG_NOTIFIERS
1249 bool "Debug notifier call chains"
1250 depends on DEBUG_KERNEL
1251 help
1252 Enable this to turn on sanity checking for notifier call chains.
1253 This is most useful for kernel developers to make sure that
1254 modules properly unregister themselves from notifier chains.
1255 This is a relatively cheap check but if you care about maximum
1256 performance, say N.
1257
David Howellse0e81732009-09-02 09:13:40 +01001258config DEBUG_CREDENTIALS
1259 bool "Debug credential management"
1260 depends on DEBUG_KERNEL
1261 help
1262 Enable this to turn on some debug checking for credential
1263 management. The additional code keeps track of the number of
1264 pointers from task_structs to any given cred struct, and checks to
1265 see that this number never exceeds the usage count of the cred
1266 struct.
1267
1268 Furthermore, if SELinux is enabled, this also checks that the
1269 security pointer in the cred struct is never seen to be invalid.
1270
1271 If unsure, say N.
1272
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001273menu "RCU Debugging"
1274
1275config PROVE_RCU
Paul E. McKenney9bae6592015-01-18 18:01:21 -08001276 def_bool PROVE_LOCKING
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001277
1278config PROVE_RCU_REPEATEDLY
1279 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1280 depends on PROVE_RCU
1281 default n
1282 help
1283 By itself, PROVE_RCU will disable checking upon issuing the
1284 first warning (or "splat"). This feature prevents such
1285 disabling, allowing multiple RCU-lockdep warnings to be printed
1286 on a single reboot.
1287
1288 Say Y to allow multiple RCU-lockdep warnings per boot.
1289
1290 Say N if you are unsure.
1291
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001292config SPARSE_RCU_POINTER
1293 bool "RCU debugging: sparse-based checks for pointer usage"
1294 default n
1295 help
1296 This feature enables the __rcu sparse annotation for
1297 RCU-protected pointers. This annotation will cause sparse
1298 to flag any non-RCU used of annotated pointers. This can be
1299 helpful when debugging RCU usage. Please note that this feature
1300 is not intended to enforce code cleanliness; it is instead merely
1301 a debugging aid.
1302
1303 Say Y to make sparse flag questionable use of RCU-protected pointers
1304
1305 Say N if you are unsure.
1306
Paul E. McKenney51b11302014-01-27 11:49:39 -08001307config TORTURE_TEST
1308 tristate
1309 default n
1310
Paul E. McKenney8704baa2015-12-31 18:33:22 -08001311config RCU_PERF_TEST
1312 tristate "performance tests for RCU"
1313 depends on DEBUG_KERNEL
1314 select TORTURE_TEST
1315 select SRCU
1316 select TASKS_RCU
1317 default n
1318 help
1319 This option provides a kernel module that runs performance
1320 tests on the RCU infrastructure. The kernel module may be built
1321 after the fact on the running kernel to be tested, if desired.
1322
1323 Say Y here if you want RCU performance tests to be built into
1324 the kernel.
1325 Say M if you want the RCU performance tests to build as a module.
1326 Say N if you are unsure.
1327
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001328config RCU_TORTURE_TEST
1329 tristate "torture tests for RCU"
1330 depends on DEBUG_KERNEL
Paul E. McKenney51b11302014-01-27 11:49:39 -08001331 select TORTURE_TEST
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001332 select SRCU
Paul E. McKenney82d0f4c2015-04-20 05:42:50 -07001333 select TASKS_RCU
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001334 default n
1335 help
1336 This option provides a kernel module that runs torture tests
1337 on the RCU infrastructure. The kernel module may be built
1338 after the fact on the running kernel to be tested, if desired.
1339
Paul E. McKenney31a72bc2008-06-18 09:26:49 -07001340 Say Y here if you want RCU torture tests to be built into
1341 the kernel.
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001342 Say M if you want the RCU torture tests to build as a module.
1343 Say N if you are unsure.
Ankita Garg8bb31b92006-10-02 02:17:36 -07001344
Paul E. McKenney0f41c0d2015-03-10 18:33:20 -07001345config RCU_TORTURE_TEST_SLOW_PREINIT
1346 bool "Slow down RCU grace-period pre-initialization to expose races"
1347 depends on RCU_TORTURE_TEST
1348 help
1349 This option delays grace-period pre-initialization (the
1350 propagation of CPU-hotplug changes up the rcu_node combining
1351 tree) for a few jiffies between initializing each pair of
1352 consecutive rcu_node structures. This helps to expose races
1353 involving grace-period pre-initialization, in other words, it
1354 makes your kernel less stable. It can also greatly increase
1355 grace-period latency, especially on systems with large numbers
1356 of CPUs. This is useful when torture-testing RCU, but in
1357 almost no other circumstance.
1358
1359 Say Y here if you want your system to crash and hang more often.
1360 Say N if you want a sane system.
1361
1362config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1363 int "How much to slow down RCU grace-period pre-initialization"
1364 range 0 5
1365 default 3
1366 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1367 help
1368 This option specifies the number of jiffies to wait between
1369 each rcu_node structure pre-initialization step.
1370
Paul E. McKenney37745d22015-01-22 18:24:08 -08001371config RCU_TORTURE_TEST_SLOW_INIT
1372 bool "Slow down RCU grace-period initialization to expose races"
1373 depends on RCU_TORTURE_TEST
1374 help
Paul E. McKenney0f41c0d2015-03-10 18:33:20 -07001375 This option delays grace-period initialization for a few
1376 jiffies between initializing each pair of consecutive
Paul E. McKenney37745d22015-01-22 18:24:08 -08001377 rcu_node structures. This helps to expose races involving
1378 grace-period initialization, in other words, it makes your
1379 kernel less stable. It can also greatly increase grace-period
1380 latency, especially on systems with large numbers of CPUs.
1381 This is useful when torture-testing RCU, but in almost no
1382 other circumstance.
1383
1384 Say Y here if you want your system to crash and hang more often.
1385 Say N if you want a sane system.
1386
1387config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1388 int "How much to slow down RCU grace-period initialization"
1389 range 0 5
Paul E. McKenney186bea52015-01-29 16:37:19 -08001390 default 3
Paul E. McKenney8d7dc922015-04-14 19:33:59 -07001391 depends on RCU_TORTURE_TEST_SLOW_INIT
Paul E. McKenney37745d22015-01-22 18:24:08 -08001392 help
1393 This option specifies the number of jiffies to wait between
1394 each rcu_node structure initialization.
1395
Paul E. McKenney0f41c0d2015-03-10 18:33:20 -07001396config RCU_TORTURE_TEST_SLOW_CLEANUP
1397 bool "Slow down RCU grace-period cleanup to expose races"
1398 depends on RCU_TORTURE_TEST
1399 help
1400 This option delays grace-period cleanup for a few jiffies
1401 between cleaning up each pair of consecutive rcu_node
1402 structures. This helps to expose races involving grace-period
1403 cleanup, in other words, it makes your kernel less stable.
1404 It can also greatly increase grace-period latency, especially
1405 on systems with large numbers of CPUs. This is useful when
1406 torture-testing RCU, but in almost no other circumstance.
1407
1408 Say Y here if you want your system to crash and hang more often.
1409 Say N if you want a sane system.
1410
1411config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1412 int "How much to slow down RCU grace-period cleanup"
1413 range 0 5
1414 default 3
1415 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1416 help
1417 This option specifies the number of jiffies to wait between
1418 each rcu_node structure cleanup operation.
1419
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001420config RCU_CPU_STALL_TIMEOUT
1421 int "RCU CPU stall timeout in seconds"
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -07001422 depends on RCU_STALL_COMMON
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001423 range 3 300
Paul E. McKenneyc8960542012-10-25 17:59:23 -07001424 default 21
Paul E. McKenneyb1637602010-06-02 16:21:38 -07001425 help
1426 If a given RCU grace period extends more than the specified
1427 number of seconds, a CPU stall warning is printed. If the
1428 RCU grace period persists, additional CPU stall warnings are
1429 printed at more widely spaced intervals.
1430
Paul E. McKenney5c8806a2012-01-06 15:10:44 -08001431config RCU_TRACE
1432 bool "Enable tracing for RCU"
1433 depends on DEBUG_KERNEL
Paul E. McKenney52494532012-11-14 16:26:40 -08001434 select TRACE_CLOCK
Paul E. McKenney5c8806a2012-01-06 15:10:44 -08001435 help
1436 This option provides tracing in RCU which presents stats
1437 in debugfs for debugging RCU implementation.
1438
1439 Say Y here if you want to enable RCU tracing
1440 Say N if you are unsure.
1441
Paul E. McKenney1ce46ee2015-05-05 23:04:22 -07001442config RCU_EQS_DEBUG
Paul E. McKenneyeb6d5b02015-06-30 09:56:31 -07001443 bool "Provide debugging asserts for adding NO_HZ support to an arch"
Paul E. McKenney1ce46ee2015-05-05 23:04:22 -07001444 depends on DEBUG_KERNEL
1445 help
1446 This option provides consistency checks in RCU's handling of
1447 NO_HZ. These checks have proven quite helpful in detecting
1448 bugs in arch-specific NO_HZ code.
1449
1450 Say N here if you need ultimate kernel/user switch latencies
1451 Say Y if you are unsure
1452
Dave Hansen2f03e3c2013-01-07 08:19:23 -08001453endmenu # "RCU Debugging"
1454
Tejun Heof303fcc2016-02-09 17:59:38 -05001455config DEBUG_WQ_FORCE_RR_CPU
1456 bool "Force round-robin CPU selection for unbound work items"
1457 depends on DEBUG_KERNEL
1458 default n
1459 help
1460 Workqueue used to implicitly guarantee that work items queued
1461 without explicit CPU specified are put on the local CPU. This
1462 guarantee is no longer true and while local CPU is still
1463 preferred work items may be put on foreign CPUs. Kernel
1464 parameter "workqueue.debug_force_rr_cpu" is added to force
1465 round-robin CPU selection to flush out usages which depend on the
1466 now broken guarantee. This config option enables the debug
1467 feature by default. When enabled, memory and cache locality will
1468 be impacted.
1469
Tejun Heo870d6652008-08-25 19:47:25 +09001470config DEBUG_BLOCK_EXT_DEVT
1471 bool "Force extended block device numbers and spread them"
1472 depends on DEBUG_KERNEL
1473 depends on BLOCK
Jens Axboe759f8ca2008-08-29 09:06:29 +02001474 default n
Tejun Heo870d6652008-08-25 19:47:25 +09001475 help
Tejun Heo0e11e342008-10-13 10:46:01 +02001476 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1477 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1478 YOU ARE DOING. Distros, please enable this and fix whatever
1479 is broken.
1480
Tejun Heo870d6652008-08-25 19:47:25 +09001481 Conventionally, block device numbers are allocated from
1482 predetermined contiguous area. However, extended block area
1483 may introduce non-contiguous block device numbers. This
1484 option forces most block device numbers to be allocated from
1485 the extended space and spreads them to discover kernel or
1486 userland code paths which assume predetermined contiguous
1487 device number allocation.
1488
Tejun Heo55dc7db2008-09-01 13:44:35 +02001489 Note that turning on this debug option shuffles all the
1490 device numbers for all IDE and SCSI devices including libata
1491 ones, so root partition specified using device number
1492 directly (via rdev or root=MAJ:MIN) won't work anymore.
1493 Textual device names (root=/dev/sdXn) will continue to work.
1494
Tejun Heo870d6652008-08-25 19:47:25 +09001495 Say N if you are unsure.
1496
Thomas Gleixner757c9892016-02-26 18:43:32 +00001497config CPU_HOTPLUG_STATE_CONTROL
1498 bool "Enable CPU hotplug state control"
1499 depends on DEBUG_KERNEL
1500 depends on HOTPLUG_CPU
1501 default n
1502 help
1503 Allows to write steps between "offline" and "online" to the CPUs
1504 sysfs target file so states can be stepped granular. This is a debug
1505 option for now as the hotplug machinery cannot be stopped and
1506 restarted at arbitrary points yet.
1507
1508 Say N if your are unsure.
1509
Akinobu Mita8d438282012-07-30 14:43:02 -07001510config NOTIFIER_ERROR_INJECTION
1511 tristate "Notifier error injection"
1512 depends on DEBUG_KERNEL
1513 select DEBUG_FS
1514 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001515 This option provides the ability to inject artificial errors to
Akinobu Mita8d438282012-07-30 14:43:02 -07001516 specified notifier chain callbacks. It is useful to test the error
1517 handling of notifier call chain failures.
1518
1519 Say N if unsure.
1520
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001521config CPU_NOTIFIER_ERROR_INJECT
1522 tristate "CPU notifier error injection module"
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001523 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001524 help
1525 This option provides a kernel module that can be used to test
Masanari Iidae41e85c2012-11-30 16:44:39 +09001526 the error handling of the cpu notifiers by injecting artificial
Akinobu Mitaf5a9f522012-07-30 14:43:03 -07001527 errors to CPU notifier chain callbacks. It is controlled through
1528 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1529
1530 If the notifier call chain should be failed with some events
1531 notified, write the error code to "actions/<notifier event>/error".
1532
1533 Example: Inject CPU offline error (-1 == -EPERM)
1534
1535 # cd /sys/kernel/debug/notifier-error-inject/cpu
1536 # echo -1 > actions/CPU_DOWN_PREPARE/error
1537 # echo 0 > /sys/devices/system/cpu/cpu1/online
1538 bash: echo: write error: Operation not permitted
Akinobu Mitac9d221f2010-05-26 14:43:36 -07001539
1540 To compile this code as a module, choose M here: the module will
1541 be called cpu-notifier-error-inject.
1542
1543 If unsure, say N.
1544
Akinobu Mita048b9c32012-07-30 14:43:07 -07001545config PM_NOTIFIER_ERROR_INJECT
1546 tristate "PM notifier error injection module"
1547 depends on PM && NOTIFIER_ERROR_INJECTION
1548 default m if PM_DEBUG
1549 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001550 This option provides the ability to inject artificial errors to
Akinobu Mita048b9c32012-07-30 14:43:07 -07001551 PM notifier chain callbacks. It is controlled through debugfs
1552 interface /sys/kernel/debug/notifier-error-inject/pm
1553
1554 If the notifier call chain should be failed with some events
1555 notified, write the error code to "actions/<notifier event>/error".
1556
1557 Example: Inject PM suspend error (-12 = -ENOMEM)
1558
1559 # cd /sys/kernel/debug/notifier-error-inject/pm/
1560 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1561 # echo mem > /sys/power/state
1562 bash: echo: write error: Cannot allocate memory
1563
1564 To compile this code as a module, choose M here: the module will
1565 be called pm-notifier-error-inject.
1566
1567 If unsure, say N.
1568
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001569config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1570 tristate "OF reconfig notifier error injection module"
1571 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001572 help
Masanari Iidae41e85c2012-11-30 16:44:39 +09001573 This option provides the ability to inject artificial errors to
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001574 OF reconfig notifier chain callbacks. It is controlled
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001575 through debugfs interface under
Benjamin Herrenschmidtd526e852012-12-14 10:32:52 +11001576 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001577
1578 If the notifier call chain should be failed with some events
1579 notified, write the error code to "actions/<notifier event>/error".
1580
1581 To compile this code as a module, choose M here: the module will
Akinobu Mitae12a95f2013-04-30 15:28:49 -07001582 be called of-reconfig-notifier-error-inject.
Akinobu Mita08dfb4d2012-07-30 14:43:13 -07001583
1584 If unsure, say N.
1585
Nikolay Aleksandrov02fff962015-11-28 13:45:28 +01001586config NETDEV_NOTIFIER_ERROR_INJECT
1587 tristate "Netdev notifier error injection module"
1588 depends on NET && NOTIFIER_ERROR_INJECTION
1589 help
1590 This option provides the ability to inject artificial errors to
1591 netdevice notifier chain callbacks. It is controlled through debugfs
1592 interface /sys/kernel/debug/notifier-error-inject/netdev
1593
1594 If the notifier call chain should be failed with some events
1595 notified, write the error code to "actions/<notifier event>/error".
1596
1597 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1598
1599 # cd /sys/kernel/debug/notifier-error-inject/netdev
1600 # echo -22 > actions/NETDEV_CHANGEMTU/error
1601 # ip link set eth0 mtu 1024
1602 RTNETLINK answers: Invalid argument
1603
1604 To compile this code as a module, choose M here: the module will
1605 be called netdev-notifier-error-inject.
1606
1607 If unsure, say N.
1608
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001609config FAULT_INJECTION
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001610 bool "Fault-injection framework"
1611 depends on DEBUG_KERNEL
Akinobu Mita329409a2006-12-08 02:39:48 -08001612 help
1613 Provide fault-injection framework.
1614 For more details, see Documentation/fault-injection/.
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001615
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001616config FAILSLAB
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001617 bool "Fault-injection capability for kmalloc"
1618 depends on FAULT_INJECTION
Akinobu Mita773ff602008-12-23 19:37:01 +09001619 depends on SLAB || SLUB
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001620 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001621 Provide fault-injection capability for kmalloc.
Akinobu Mita8a8b6502006-12-08 02:39:44 -08001622
Akinobu Mita933e3122006-12-08 02:39:45 -08001623config FAIL_PAGE_ALLOC
1624 bool "Fault-injection capabilitiy for alloc_pages()"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001625 depends on FAULT_INJECTION
Akinobu Mita933e3122006-12-08 02:39:45 -08001626 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001627 Provide fault-injection capability for alloc_pages().
Akinobu Mita933e3122006-12-08 02:39:45 -08001628
Akinobu Mitac17bb492006-12-08 02:39:46 -08001629config FAIL_MAKE_REQUEST
Dave Jones86327d12006-12-12 20:16:36 +01001630 bool "Fault-injection capability for disk IO"
Jens Axboe581d4e22008-09-14 05:56:33 -07001631 depends on FAULT_INJECTION && BLOCK
Akinobu Mitac17bb492006-12-08 02:39:46 -08001632 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001633 Provide fault-injection capability for disk IO.
Akinobu Mitac17bb492006-12-08 02:39:46 -08001634
Jens Axboe581d4e22008-09-14 05:56:33 -07001635config FAIL_IO_TIMEOUT
Takuya Yoshikawaf4d014392010-07-21 16:05:53 +09001636 bool "Fault-injection capability for faking disk interrupts"
Jens Axboe581d4e22008-09-14 05:56:33 -07001637 depends on FAULT_INJECTION && BLOCK
1638 help
1639 Provide fault-injection capability on end IO handling. This
1640 will make the block layer "forget" an interrupt as configured,
1641 thus exercising the error handling.
1642
1643 Only works with drivers that use the generic timeout handling,
1644 for others it wont do anything.
1645
Per Forlin1b676f72011-08-19 14:52:37 +02001646config FAIL_MMC_REQUEST
1647 bool "Fault-injection capability for MMC IO"
Adrien Schildknecht28ff4fd2015-11-10 20:12:19 +01001648 depends on FAULT_INJECTION_DEBUG_FS && MMC
Per Forlin1b676f72011-08-19 14:52:37 +02001649 help
1650 Provide fault-injection capability for MMC IO.
1651 This will make the mmc core return data errors. This is
1652 useful to test the error handling in the mmc block device
1653 and to test how the mmc host driver handles retries from
1654 the block device.
1655
Davidlohr Buesoab51fba2015-06-29 23:26:02 -07001656config FAIL_FUTEX
1657 bool "Fault-injection capability for futexes"
1658 select DEBUG_FS
1659 depends on FAULT_INJECTION && FUTEX
1660 help
1661 Provide fault-injection capability for futexes.
1662
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001663config FAULT_INJECTION_DEBUG_FS
1664 bool "Debugfs entries for fault-injection capabilities"
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001665 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
Akinobu Mita6ff1cb32006-12-08 02:39:43 -08001666 help
Andrew Morton1ab8509a2006-12-08 02:39:49 -08001667 Enable configuration of fault-injection capabilities via debugfs.
Akinobu Mita1df49002007-02-20 13:57:56 -08001668
1669config FAULT_INJECTION_STACKTRACE_FILTER
1670 bool "stacktrace filter for fault-injection capabilities"
1671 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
Akinobu Mita6d690dc2007-05-12 10:36:53 -07001672 depends on !X86_64
Akinobu Mita1df49002007-02-20 13:57:56 -08001673 select STACKTRACE
Chen Gangdf2e1ef2014-06-23 13:22:04 -07001674 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
Akinobu Mita1df49002007-02-20 13:57:56 -08001675 help
1676 Provide stacktrace filter for fault-injection capabilities
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001677
Arjan van de Ven97455122008-01-25 21:08:34 +01001678config LATENCYTOP
1679 bool "Latency measuring infrastructure"
Randy Dunlap625fdca2010-08-12 12:31:21 -07001680 depends on DEBUG_KERNEL
1681 depends on STACKTRACE_SUPPORT
1682 depends on PROC_FS
Vineet Guptacc80ae32013-08-27 13:52:51 +05301683 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
Arjan van de Ven97455122008-01-25 21:08:34 +01001684 select KALLSYMS
1685 select KALLSYMS_ALL
1686 select STACKTRACE
1687 select SCHEDSTATS
1688 select SCHED_DEBUG
Arjan van de Ven97455122008-01-25 21:08:34 +01001689 help
1690 Enable this option if you want to use the LatencyTOP tool
1691 to find out which userspace is blocking on what kernel operations.
1692
Arnaldo Carvalho de Melo16444a82008-05-12 21:20:42 +02001693source kernel/trace/Kconfig
1694
Dave Hansen881c5142013-07-01 13:04:44 -07001695menu "Runtime Testing"
1696
1697config LKDTM
1698 tristate "Linux Kernel Dump Test Tool Module"
1699 depends on DEBUG_FS
1700 depends on BLOCK
1701 default n
1702 help
1703 This module enables testing of the different dumping mechanisms by
1704 inducing system failures at predefined crash points.
1705 If you don't need it: say N
1706 Choose M here to compile this code as a module. The module will be
1707 called lkdtm.
1708
1709 Documentation on how to use the module can be found in
1710 Documentation/fault-injection/provoke-crashes.txt
1711
1712config TEST_LIST_SORT
1713 bool "Linked list sorting test"
1714 depends on DEBUG_KERNEL
1715 help
1716 Enable this to turn on 'list_sort()' function test. This test is
1717 executed only once during system boot, so affects only boot time.
1718
1719 If unsure, say N.
1720
1721config KPROBES_SANITY_TEST
1722 bool "Kprobes sanity tests"
1723 depends on DEBUG_KERNEL
1724 depends on KPROBES
1725 default n
1726 help
1727 This option provides for testing basic kprobes functionality on
1728 boot. A sample kprobe, jprobe and kretprobe are inserted and
1729 verified for functionality.
1730
1731 Say N if you are unsure.
1732
1733config BACKTRACE_SELF_TEST
1734 tristate "Self test for the backtrace code"
1735 depends on DEBUG_KERNEL
1736 default n
1737 help
1738 This option provides a kernel module that can be used to test
1739 the kernel stack backtrace code. This option is not useful
1740 for distributions or general kernels, but only for kernel
1741 developers working on architecture code.
1742
1743 Note that if you want to also test saved backtraces, you will
1744 have to enable STACKTRACE as well.
1745
1746 Say N if you are unsure.
1747
Michel Lespinasse910a7422012-10-08 16:30:39 -07001748config RBTREE_TEST
1749 tristate "Red-Black tree test"
Cody P Schafer7c993e12013-09-11 14:25:19 -07001750 depends on DEBUG_KERNEL
Michel Lespinasse910a7422012-10-08 16:30:39 -07001751 help
1752 A benchmark measuring the performance of the rbtree library.
1753 Also includes rbtree invariant checks.
1754
Michel Lespinassefff3fd82012-10-08 16:31:23 -07001755config INTERVAL_TREE_TEST
1756 tristate "Interval tree test"
1757 depends on m && DEBUG_KERNEL
Chris Wilsona88cc102014-03-17 12:21:54 +00001758 select INTERVAL_TREE
Michel Lespinassefff3fd82012-10-08 16:31:23 -07001759 help
1760 A benchmark measuring the performance of the interval tree library
1761
Greg Thelen623fd802013-11-12 15:08:34 -08001762config PERCPU_TEST
1763 tristate "Per cpu operations test"
1764 depends on m && DEBUG_KERNEL
1765 help
1766 Enable this option to build test module which validates per-cpu
1767 operations.
1768
1769 If unsure, say N.
1770
Dave Hansen881c5142013-07-01 13:04:44 -07001771config ATOMIC64_SELFTEST
1772 bool "Perform an atomic64_t self-test at boot"
1773 help
1774 Enable this option to test the atomic64_t functions at boot.
1775
1776 If unsure, say N.
1777
1778config ASYNC_RAID6_TEST
1779 tristate "Self test for hardware accelerated raid6 recovery"
1780 depends on ASYNC_RAID6_RECOV
1781 select ASYNC_MEMCPY
1782 ---help---
1783 This is a one-shot self test that permutes through the
1784 recovery of all the possible two disk failure scenarios for a
1785 N-disk array. Recovery is performed with the asynchronous
1786 raid6 recovery routines, and will optionally use an offload
1787 engine if one is available.
1788
1789 If unsure, say N.
1790
Andy Shevchenko64d1d772015-02-12 15:02:21 -08001791config TEST_HEXDUMP
1792 tristate "Test functions located in the hexdump module at runtime"
1793
Dave Hansen881c5142013-07-01 13:04:44 -07001794config TEST_STRING_HELPERS
1795 tristate "Test functions located in the string_helpers module at runtime"
1796
1797config TEST_KSTRTOX
1798 tristate "Test kstrto*() family of functions at runtime"
1799
Rasmus Villemoes707cc722015-11-06 16:30:29 -08001800config TEST_PRINTF
1801 tristate "Test printf() family of functions at runtime"
1802
David Decotigny5fd003f2016-02-19 09:24:00 -05001803config TEST_BITMAP
1804 tristate "Test bitmap_*() family of functions at runtime"
1805 default n
1806 help
1807 Enable this option to test the bitmap functions at boot.
1808
1809 If unsure, say N.
1810
Andy Shevchenkocfaff0e2016-05-30 17:40:41 +03001811config TEST_UUID
1812 tristate "Test functions located in the uuid module at runtime"
1813
Thomas Graf7e1e7762014-08-02 11:47:44 +02001814config TEST_RHASHTABLE
Geert Uytterhoeven9d6dbe12015-01-29 15:40:25 +01001815 tristate "Perform selftest on resizable hash table"
Thomas Graf7e1e7762014-08-02 11:47:44 +02001816 default n
1817 help
1818 Enable this option to test the rhashtable functions at boot.
1819
1820 If unsure, say N.
1821
George Spelvin468a9422016-05-26 22:11:51 -04001822config TEST_HASH
1823 tristate "Perform selftest on hash functions"
1824 default n
1825 help
1826 Enable this option to test the kernel's integer (<linux/hash,h>)
1827 and string (<linux/stringhash.h>) hash functions on boot
1828 (or module load).
1829
1830 This is intended to help people writing architecture-specific
1831 optimized versions. If unsure, say N.
1832
Dave Hansen881c5142013-07-01 13:04:44 -07001833endmenu # runtime tests
1834
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001835config PROVIDE_OHCI1394_DMA_INIT
Stefan Richter080de8c2008-02-28 20:54:43 +01001836 bool "Remote debugging over FireWire early on boot"
Bernhard Kaindlf212ec42008-01-30 13:34:11 +01001837 depends on PCI && X86
1838 help
1839 If you want to debug problems which hang or crash the kernel early
1840 on boot and the crashing machine has a FireWire port, you can use
1841 this feature to remotely access the memory of the crashed machine
1842 over FireWire. This employs remote DMA as part of the OHCI1394
1843 specification which is now the standard for FireWire controllers.
1844
1845 With remote DMA, you can monitor the printk buffer remotely using
1846 firescope and access all memory below 4GB using fireproxy from gdb.
1847 Even controlling a kernel debugger is possible using remote DMA.
1848
1849 Usage:
1850
1851 If ohci1394_dma=early is used as boot parameter, it will initialize
1852 all OHCI1394 controllers which are found in the PCI config space.
1853
1854 As all changes to the FireWire bus such as enabling and disabling
1855 devices cause a bus reset and thereby disable remote DMA for all
1856 devices, be sure to have the cable plugged and FireWire enabled on
1857 the debugging host before booting the debug target for debugging.
1858
1859 This code (~1k) is freed after boot. By then, the firewire stack
1860 in charge of the OHCI-1394 controllers should be used instead.
1861
1862 See Documentation/debugging-via-ohci1394.txt for more information.
Arjan van de Ven97455122008-01-25 21:08:34 +01001863
Joerg Roedel5ee00bd2009-01-09 12:14:24 +01001864config DMA_API_DEBUG
1865 bool "Enable debugging of DMA-API usage"
1866 depends on HAVE_DMA_API_DEBUG
1867 help
1868 Enable this option to debug the use of the DMA API by device drivers.
1869 With this option you will be able to detect common bugs in device
1870 drivers like double-freeing of DMA mappings or freeing mappings that
1871 were never allocated.
Dan Williams0abdd7a2014-01-21 15:48:12 -08001872
1873 This also attempts to catch cases where a page owned by DMA is
1874 accessed by the cpu in a way that could cause data corruption. For
1875 example, this enables cow_user_page() to check that the source page is
1876 not undergoing DMA.
1877
1878 This option causes a performance degradation. Use only if you want to
1879 debug device drivers and dma interactions.
1880
1881 If unsure, say N.
Jason Baron346e15b2008-08-12 16:46:19 -04001882
Valentin Rothberg8a6f0b42014-10-13 15:51:38 -07001883config TEST_LKM
Kees Cook93e9ef82014-01-23 15:54:37 -08001884 tristate "Test module loading with 'hello world' module"
1885 default n
1886 depends on m
1887 help
1888 This builds the "test_module" module that emits "Hello, world"
1889 on printk when loaded. It is designed to be used for basic
1890 evaluation of the module loading subsystem (for example when
1891 validating module verification). It lacks any extra dependencies,
1892 and will not normally be loaded by the system unless explicitly
1893 requested by name.
1894
1895 If unsure, say N.
1896
Kees Cook3e2a4c12014-01-23 15:54:38 -08001897config TEST_USER_COPY
1898 tristate "Test user/kernel boundary protections"
1899 default n
1900 depends on m
1901 help
1902 This builds the "test_user_copy" module that runs sanity checks
1903 on the copy_to/from_user infrastructure, making sure basic
1904 user/kernel boundary testing is working. If it fails to load,
1905 a regression has been detected in the user/kernel memory boundary
1906 protections.
1907
1908 If unsure, say N.
1909
Alexei Starovoitov64a89462014-05-08 14:10:52 -07001910config TEST_BPF
1911 tristate "Test BPF filter functionality"
1912 default n
Randy Dunlap98920ba2014-05-13 09:58:44 -07001913 depends on m && NET
Alexei Starovoitov64a89462014-05-08 14:10:52 -07001914 help
1915 This builds the "test_bpf" module that runs various test vectors
1916 against the BPF interpreter or BPF JIT compiler depending on the
1917 current setting. This is in particular useful for BPF JIT compiler
1918 development, but also to run regression tests against changes in
Alexei Starovoitov3c731eb2014-09-26 00:17:07 -07001919 the interpreter code. It also enables test stubs for eBPF maps and
1920 verifier used by user space verifier testsuite.
Alexei Starovoitov64a89462014-05-08 14:10:52 -07001921
1922 If unsure, say N.
1923
Kees Cook0a8adf52014-07-14 14:38:12 -07001924config TEST_FIRMWARE
1925 tristate "Test firmware loading via userspace interface"
1926 default n
1927 depends on FW_LOADER
1928 help
1929 This builds the "test_firmware" module that creates a userspace
1930 interface for testing firmware loading. This can be used to
1931 control the triggering of firmware loading without needing an
1932 actual firmware-using device. The contents can be rechecked by
1933 userspace.
1934
1935 If unsure, say N.
1936
David Rileye704f932014-06-16 14:58:32 -07001937config TEST_UDELAY
1938 tristate "udelay test driver"
1939 default n
1940 help
1941 This builds the "udelay_test" module that helps to make sure
1942 that udelay() is working properly.
1943
1944 If unsure, say N.
1945
Vladimir Murzin4a207992015-04-14 15:48:27 -07001946config MEMTEST
1947 bool "Memtest"
1948 depends on HAVE_MEMBLOCK
1949 ---help---
1950 This option adds a kernel parameter 'memtest', which allows memtest
1951 to be set.
1952 memtest=0, mean disabled; -- default
1953 memtest=1, mean do 1 test pattern;
1954 ...
Vladimir Murzin8d8cfb42015-04-14 15:48:40 -07001955 memtest=17, mean do 17 test patterns.
Vladimir Murzin4a207992015-04-14 15:48:27 -07001956 If you are unsure how to answer this question, answer N.
1957
Ingo Molnar2bf9e0a2015-08-03 11:42:57 +02001958config TEST_STATIC_KEYS
1959 tristate "Test static keys"
Jason Baron579e1ac2015-07-30 03:59:44 +00001960 default n
1961 depends on m
1962 help
Ingo Molnar2bf9e0a2015-08-03 11:42:57 +02001963 Test the static key interfaces.
Jason Baron579e1ac2015-07-30 03:59:44 +00001964
1965 If unsure, say N.
1966
Mathieu Desnoyers267c4022007-10-18 23:41:07 -07001967source "samples/Kconfig"
Jason Wesseldc7d5522008-04-17 20:05:37 +02001968
1969source "lib/Kconfig.kgdb"
Pekka Enberg0a4af3b2009-02-26 21:38:56 +02001970
Andrey Ryabininc6d30852016-01-20 15:00:55 -08001971source "lib/Kconfig.ubsan"
1972
Dan Williams21266be2015-11-19 18:19:29 -08001973config ARCH_HAS_DEVMEM_IS_ALLOWED
1974 bool
1975
1976config STRICT_DEVMEM
1977 bool "Filter access to /dev/mem"
1978 depends on MMU
1979 depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1980 default y if TILE || PPC
1981 ---help---
1982 If this option is disabled, you allow userspace (root) access to all
1983 of memory, including kernel and userspace memory. Accidental
1984 access to this is obviously disastrous, but specific access can
1985 be used by people debugging the kernel. Note that with PAT support
1986 enabled, even in this case there are restrictions on /dev/mem
1987 use due to the cache aliasing requirements.
1988
Dan Williams90a545e2015-11-23 15:49:03 -08001989 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1990 file only allows userspace access to PCI space and the BIOS code and
1991 data regions. This is sufficient for dosemu and X and all common
1992 users of /dev/mem.
1993
1994 If in doubt, say Y.
1995
1996config IO_STRICT_DEVMEM
1997 bool "Filter I/O access to /dev/mem"
1998 depends on STRICT_DEVMEM
Dan Williams90a545e2015-11-23 15:49:03 -08001999 ---help---
2000 If this option is disabled, you allow userspace (root) access to all
2001 io-memory regardless of whether a driver is actively using that
2002 range. Accidental access to this is obviously disastrous, but
2003 specific access can be used by people debugging kernel drivers.
2004
Dan Williams21266be2015-11-19 18:19:29 -08002005 If this option is switched on, the /dev/mem file only allows
Dan Williams90a545e2015-11-23 15:49:03 -08002006 userspace access to *idle* io-memory ranges (see /proc/iomem) This
2007 may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2008 if the driver using a given range cannot be disabled.
Dan Williams21266be2015-11-19 18:19:29 -08002009
2010 If in doubt, say Y.