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604ff0dc | 1 | menu "printk and dmesg options" |
1da177e4 LT |
2 | |
3 | config PRINTK_TIME | |
4 | bool "Show timing information on printks" | |
d3b8b6e5 | 5 | depends on PRINTK |
1da177e4 | 6 | help |
649e6ee3 KS |
7 | Selecting this option causes time stamps of the printk() |
8 | messages to be added to the output of the syslog() system | |
9 | call and at the console. | |
10 | ||
11 | The timestamp is always recorded internally, and exported | |
12 | to /dev/kmsg. This flag just specifies if the timestamp should | |
13 | be included, not that the timestamp is recorded. | |
14 | ||
15 | The behavior is also controlled by the kernel command line | |
8c27ceff | 16 | parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst |
1da177e4 | 17 | |
a8cfdc68 OJ |
18 | config CONSOLE_LOGLEVEL_DEFAULT |
19 | int "Default console loglevel (1-15)" | |
20 | range 1 15 | |
21 | default "7" | |
22 | help | |
23 | Default loglevel to determine what will be printed on the console. | |
24 | ||
25 | Setting a default here is equivalent to passing in loglevel=<x> in | |
26 | the kernel bootargs. loglevel=<x> continues to override whatever | |
27 | value is specified here as well. | |
28 | ||
50f4d9bd | 29 | Note: This does not affect the log level of un-prefixed printk() |
a8cfdc68 OJ |
30 | usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT |
31 | option. | |
32 | ||
42a9dc0b | 33 | config MESSAGE_LOGLEVEL_DEFAULT |
5af5bcb8 MSB |
34 | int "Default message log level (1-7)" |
35 | range 1 7 | |
36 | default "4" | |
37 | help | |
38 | Default log level for printk statements with no specified priority. | |
39 | ||
40 | This was hard-coded to KERN_WARNING since at least 2.6.10 but folks | |
41 | that are auditing their logs closely may want to set it to a lower | |
42 | priority. | |
43 | ||
a8cfdc68 OJ |
44 | Note: This does not affect what message level gets printed on the console |
45 | by default. To change that, use loglevel=<x> in the kernel bootargs, | |
46 | or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. | |
47 | ||
604ff0dc DH |
48 | config BOOT_PRINTK_DELAY |
49 | bool "Delay each boot printk message by N milliseconds" | |
50 | depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY | |
51 | help | |
52 | This build option allows you to read kernel boot messages | |
53 | by inserting a short delay after each one. The delay is | |
54 | specified in milliseconds on the kernel command line, | |
55 | using "boot_delay=N". | |
56 | ||
57 | It is likely that you would also need to use "lpj=M" to preset | |
58 | the "loops per jiffie" value. | |
59 | See a previous boot log for the "lpj" value to use for your | |
60 | system, and then set "lpj=M" before setting "boot_delay=N". | |
61 | NOTE: Using this option may adversely affect SMP systems. | |
62 | I.e., processors other than the first one may not boot up. | |
63 | BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect | |
64 | what it believes to be lockup conditions. | |
65 | ||
66 | config DYNAMIC_DEBUG | |
67 | bool "Enable dynamic printk() support" | |
68 | default n | |
69 | depends on PRINTK | |
70 | depends on DEBUG_FS | |
71 | help | |
72 | ||
73 | Compiles debug level messages into the kernel, which would not | |
74 | otherwise be available at runtime. These messages can then be | |
75 | enabled/disabled based on various levels of scope - per source file, | |
76 | function, module, format string, and line number. This mechanism | |
77 | implicitly compiles in all pr_debug() and dev_dbg() calls, which | |
78 | enlarges the kernel text size by about 2%. | |
79 | ||
80 | If a source file is compiled with DEBUG flag set, any | |
81 | pr_debug() calls in it are enabled by default, but can be | |
82 | disabled at runtime as below. Note that DEBUG flag is | |
83 | turned on by many CONFIG_*DEBUG* options. | |
84 | ||
85 | Usage: | |
86 | ||
87 | Dynamic debugging is controlled via the 'dynamic_debug/control' file, | |
88 | which is contained in the 'debugfs' filesystem. Thus, the debugfs | |
89 | filesystem must first be mounted before making use of this feature. | |
90 | We refer the control file as: <debugfs>/dynamic_debug/control. This | |
91 | file contains a list of the debug statements that can be enabled. The | |
92 | format for each line of the file is: | |
93 | ||
94 | filename:lineno [module]function flags format | |
95 | ||
96 | filename : source file of the debug statement | |
97 | lineno : line number of the debug statement | |
98 | module : module that contains the debug statement | |
99 | function : function that contains the debug statement | |
100 | flags : '=p' means the line is turned 'on' for printing | |
101 | format : the format used for the debug statement | |
102 | ||
103 | From a live system: | |
104 | ||
105 | nullarbor:~ # cat <debugfs>/dynamic_debug/control | |
106 | # filename:lineno [module]function flags format | |
107 | fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" | |
108 | fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" | |
109 | fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" | |
110 | ||
111 | Example usage: | |
112 | ||
113 | // enable the message at line 1603 of file svcsock.c | |
114 | nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > | |
115 | <debugfs>/dynamic_debug/control | |
116 | ||
117 | // enable all the messages in file svcsock.c | |
118 | nullarbor:~ # echo -n 'file svcsock.c +p' > | |
119 | <debugfs>/dynamic_debug/control | |
120 | ||
121 | // enable all the messages in the NFS server module | |
122 | nullarbor:~ # echo -n 'module nfsd +p' > | |
123 | <debugfs>/dynamic_debug/control | |
124 | ||
125 | // enable all 12 messages in the function svc_process() | |
126 | nullarbor:~ # echo -n 'func svc_process +p' > | |
127 | <debugfs>/dynamic_debug/control | |
128 | ||
129 | // disable all 12 messages in the function svc_process() | |
130 | nullarbor:~ # echo -n 'func svc_process -p' > | |
131 | <debugfs>/dynamic_debug/control | |
132 | ||
133 | See Documentation/dynamic-debug-howto.txt for additional information. | |
134 | ||
135 | endmenu # "printk and dmesg options" | |
136 | ||
6dfc0665 DH |
137 | menu "Compile-time checks and compiler options" |
138 | ||
139 | config DEBUG_INFO | |
140 | bool "Compile the kernel with debug info" | |
12b13835 | 141 | depends on DEBUG_KERNEL && !COMPILE_TEST |
6dfc0665 DH |
142 | help |
143 | If you say Y here the resulting kernel image will include | |
144 | debugging info resulting in a larger kernel image. | |
145 | This adds debug symbols to the kernel and modules (gcc -g), and | |
146 | is needed if you intend to use kernel crashdump or binary object | |
147 | tools like crash, kgdb, LKCD, gdb, etc on the kernel. | |
148 | Say Y here only if you plan to debug the kernel. | |
149 | ||
150 | If unsure, say N. | |
151 | ||
152 | config DEBUG_INFO_REDUCED | |
153 | bool "Reduce debugging information" | |
154 | depends on DEBUG_INFO | |
155 | help | |
156 | If you say Y here gcc is instructed to generate less debugging | |
157 | information for structure types. This means that tools that | |
158 | need full debugging information (like kgdb or systemtap) won't | |
159 | be happy. But if you merely need debugging information to | |
160 | resolve line numbers there is no loss. Advantage is that | |
161 | build directory object sizes shrink dramatically over a full | |
162 | DEBUG_INFO build and compile times are reduced too. | |
163 | Only works with newer gcc versions. | |
164 | ||
866ced95 AK |
165 | config DEBUG_INFO_SPLIT |
166 | bool "Produce split debuginfo in .dwo files" | |
167 | depends on DEBUG_INFO | |
168 | help | |
169 | Generate debug info into separate .dwo files. This significantly | |
170 | reduces the build directory size for builds with DEBUG_INFO, | |
171 | because it stores the information only once on disk in .dwo | |
172 | files instead of multiple times in object files and executables. | |
173 | In addition the debug information is also compressed. | |
174 | ||
175 | Requires recent gcc (4.7+) and recent gdb/binutils. | |
176 | Any tool that packages or reads debug information would need | |
177 | to know about the .dwo files and include them. | |
178 | Incompatible with older versions of ccache. | |
179 | ||
bfaf2dd3 AK |
180 | config DEBUG_INFO_DWARF4 |
181 | bool "Generate dwarf4 debuginfo" | |
182 | depends on DEBUG_INFO | |
183 | help | |
184 | Generate dwarf4 debug info. This requires recent versions | |
185 | of gcc and gdb. It makes the debug information larger. | |
186 | But it significantly improves the success of resolving | |
187 | variables in gdb on optimized code. | |
188 | ||
3ee7b3fa JK |
189 | config GDB_SCRIPTS |
190 | bool "Provide GDB scripts for kernel debugging" | |
191 | depends on DEBUG_INFO | |
192 | help | |
193 | This creates the required links to GDB helper scripts in the | |
194 | build directory. If you load vmlinux into gdb, the helper | |
195 | scripts will be automatically imported by gdb as well, and | |
196 | additional functions are available to analyze a Linux kernel | |
700199b0 AP |
197 | instance. See Documentation/dev-tools/gdb-kernel-debugging.rst |
198 | for further details. | |
3ee7b3fa | 199 | |
de488443 JG |
200 | config ENABLE_WARN_DEPRECATED |
201 | bool "Enable __deprecated logic" | |
202 | default y | |
203 | help | |
204 | Enable the __deprecated logic in the kernel build. | |
205 | Disable this to suppress the "warning: 'foo' is deprecated | |
206 | (declared at kernel/power/somefile.c:1234)" messages. | |
207 | ||
cebc04ba AM |
208 | config ENABLE_MUST_CHECK |
209 | bool "Enable __must_check logic" | |
210 | default y | |
211 | help | |
212 | Enable the __must_check logic in the kernel build. Disable this to | |
213 | suppress the "warning: ignoring return value of 'foo', declared with | |
214 | attribute warn_unused_result" messages. | |
1da177e4 | 215 | |
35bb5b1e AK |
216 | config FRAME_WARN |
217 | int "Warn for stack frames larger than (needs gcc 4.4)" | |
218 | range 0 8192 | |
3f181b4d | 219 | default 0 if KASAN |
0e07f663 | 220 | default 2048 if GCC_PLUGIN_LATENT_ENTROPY |
35bb5b1e AK |
221 | default 1024 if !64BIT |
222 | default 2048 if 64BIT | |
223 | help | |
224 | Tell gcc to warn at build time for stack frames larger than this. | |
225 | Setting this too low will cause a lot of warnings. | |
226 | Setting it to 0 disables the warning. | |
227 | Requires gcc 4.4 | |
228 | ||
99657c78 RD |
229 | config STRIP_ASM_SYMS |
230 | bool "Strip assembler-generated symbols during link" | |
231 | default n | |
232 | help | |
233 | Strip internal assembler-generated symbols during a link (symbols | |
234 | that look like '.Lxxx') so they don't pollute the output of | |
235 | get_wchan() and suchlike. | |
236 | ||
1873e870 AK |
237 | config READABLE_ASM |
238 | bool "Generate readable assembler code" | |
239 | depends on DEBUG_KERNEL | |
240 | help | |
241 | Disable some compiler optimizations that tend to generate human unreadable | |
242 | assembler output. This may make the kernel slightly slower, but it helps | |
243 | to keep kernel developers who have to stare a lot at assembler listings | |
244 | sane. | |
245 | ||
f71d20e9 AV |
246 | config UNUSED_SYMBOLS |
247 | bool "Enable unused/obsolete exported symbols" | |
248 | default y if X86 | |
249 | help | |
250 | Unused but exported symbols make the kernel needlessly bigger. For | |
251 | that reason most of these unused exports will soon be removed. This | |
252 | option is provided temporarily to provide a transition period in case | |
253 | some external kernel module needs one of these symbols anyway. If you | |
254 | encounter such a case in your module, consider if you are actually | |
255 | using the right API. (rationale: since nobody in the kernel is using | |
256 | this in a module, there is a pretty good chance it's actually the | |
257 | wrong interface to use). If you really need the symbol, please send a | |
258 | mail to the linux kernel mailing list mentioning the symbol and why | |
259 | you really need it, and what the merge plan to the mainline kernel for | |
260 | your module is. | |
261 | ||
48c96a36 JK |
262 | config PAGE_OWNER |
263 | bool "Track page owner" | |
264 | depends on DEBUG_KERNEL && STACKTRACE_SUPPORT | |
265 | select DEBUG_FS | |
266 | select STACKTRACE | |
f2ca0b55 | 267 | select STACKDEPOT |
48c96a36 JK |
268 | select PAGE_EXTENSION |
269 | help | |
270 | This keeps track of what call chain is the owner of a page, may | |
271 | help to find bare alloc_page(s) leaks. Even if you include this | |
272 | feature on your build, it is disabled in default. You should pass | |
273 | "page_owner=on" to boot parameter in order to enable it. Eats | |
274 | a fair amount of memory if enabled. See tools/vm/page_owner_sort.c | |
275 | for user-space helper. | |
276 | ||
277 | If unsure, say N. | |
278 | ||
bf4735a4 DM |
279 | config DEBUG_FS |
280 | bool "Debug Filesystem" | |
9fd4dcec | 281 | select SRCU |
bf4735a4 DM |
282 | help |
283 | debugfs is a virtual file system that kernel developers use to put | |
284 | debugging files into. Enable this option to be able to read and | |
285 | write to these files. | |
286 | ||
ff543332 RD |
287 | For detailed documentation on the debugfs API, see |
288 | Documentation/DocBook/filesystems. | |
289 | ||
bf4735a4 DM |
290 | If unsure, say N. |
291 | ||
292 | config HEADERS_CHECK | |
293 | bool "Run 'make headers_check' when building vmlinux" | |
294 | depends on !UML | |
295 | help | |
296 | This option will extract the user-visible kernel headers whenever | |
297 | building the kernel, and will run basic sanity checks on them to | |
298 | ensure that exported files do not attempt to include files which | |
299 | were not exported, etc. | |
300 | ||
301 | If you're making modifications to header files which are | |
302 | relevant for userspace, say 'Y', and check the headers | |
303 | exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in | |
304 | your build tree), to make sure they're suitable. | |
305 | ||
91341d4b SR |
306 | config DEBUG_SECTION_MISMATCH |
307 | bool "Enable full Section mismatch analysis" | |
91341d4b SR |
308 | help |
309 | The section mismatch analysis checks if there are illegal | |
310 | references from one section to another section. | |
e809ab01 MW |
311 | During linktime or runtime, some sections are dropped; |
312 | any use of code/data previously in these sections would | |
91341d4b | 313 | most likely result in an oops. |
e809ab01 | 314 | In the code, functions and variables are annotated with |
0db0628d | 315 | __init,, etc. (see the full list in include/linux/init.h), |
d6fbfa4f | 316 | which results in the code/data being placed in specific sections. |
e809ab01 MW |
317 | The section mismatch analysis is always performed after a full |
318 | kernel build, and enabling this option causes the following | |
319 | additional steps to occur: | |
320 | - Add the option -fno-inline-functions-called-once to gcc commands. | |
321 | When inlining a function annotated with __init in a non-init | |
322 | function, we would lose the section information and thus | |
91341d4b | 323 | the analysis would not catch the illegal reference. |
e809ab01 MW |
324 | This option tells gcc to inline less (but it does result in |
325 | a larger kernel). | |
326 | - Run the section mismatch analysis for each module/built-in.o file. | |
327 | When we run the section mismatch analysis on vmlinux.o, we | |
67797b92 | 328 | lose valuable information about where the mismatch was |
91341d4b SR |
329 | introduced. |
330 | Running the analysis for each module/built-in.o file | |
e809ab01 MW |
331 | tells where the mismatch happens much closer to the |
332 | source. The drawback is that the same mismatch is | |
333 | reported at least twice. | |
334 | - Enable verbose reporting from modpost in order to help resolve | |
335 | the section mismatches that are reported. | |
91341d4b | 336 | |
47490ec1 NB |
337 | config SECTION_MISMATCH_WARN_ONLY |
338 | bool "Make section mismatch errors non-fatal" | |
339 | default y | |
340 | help | |
341 | If you say N here, the build process will fail if there are any | |
342 | section mismatch, instead of just throwing warnings. | |
343 | ||
344 | If unsure, say Y. | |
345 | ||
6dfc0665 DH |
346 | # |
347 | # Select this config option from the architecture Kconfig, if it | |
348 | # is preferred to always offer frame pointers as a config | |
349 | # option on the architecture (regardless of KERNEL_DEBUG): | |
350 | # | |
351 | config ARCH_WANT_FRAME_POINTERS | |
352 | bool | |
f346f4b3 | 353 | help |
f346f4b3 | 354 | |
6dfc0665 DH |
355 | config FRAME_POINTER |
356 | bool "Compile the kernel with frame pointers" | |
357 | depends on DEBUG_KERNEL && \ | |
358 | (CRIS || M68K || FRV || UML || \ | |
359 | AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \ | |
360 | ARCH_WANT_FRAME_POINTERS | |
361 | default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS | |
a304e1b8 | 362 | help |
6dfc0665 DH |
363 | If you say Y here the resulting kernel image will be slightly |
364 | larger and slower, but it gives very useful debugging information | |
365 | in case of kernel bugs. (precise oopses/stacktraces/warnings) | |
a304e1b8 | 366 | |
b9ab5ebb JP |
367 | config STACK_VALIDATION |
368 | bool "Compile-time stack metadata validation" | |
369 | depends on HAVE_STACK_VALIDATION | |
370 | default n | |
371 | help | |
372 | Add compile-time checks to validate stack metadata, including frame | |
373 | pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure | |
374 | that runtime stack traces are more reliable. | |
375 | ||
376 | For more information, see | |
377 | tools/objtool/Documentation/stack-validation.txt. | |
378 | ||
6dfc0665 DH |
379 | config DEBUG_FORCE_WEAK_PER_CPU |
380 | bool "Force weak per-cpu definitions" | |
381 | depends on DEBUG_KERNEL | |
8446f1d3 | 382 | help |
6dfc0665 DH |
383 | s390 and alpha require percpu variables in modules to be |
384 | defined weak to work around addressing range issue which | |
385 | puts the following two restrictions on percpu variable | |
386 | definitions. | |
8446f1d3 | 387 | |
6dfc0665 DH |
388 | 1. percpu symbols must be unique whether static or not |
389 | 2. percpu variables can't be defined inside a function | |
8446f1d3 | 390 | |
6dfc0665 DH |
391 | To ensure that generic code follows the above rules, this |
392 | option forces all percpu variables to be defined as weak. | |
5f329089 | 393 | |
6dfc0665 | 394 | endmenu # "Compiler options" |
8446f1d3 | 395 | |
6dfc0665 DH |
396 | config MAGIC_SYSRQ |
397 | bool "Magic SysRq key" | |
398 | depends on !UML | |
399 | help | |
400 | If you say Y here, you will have some control over the system even | |
401 | if the system crashes for example during kernel debugging (e.g., you | |
402 | will be able to flush the buffer cache to disk, reboot the system | |
403 | immediately or dump some status information). This is accomplished | |
404 | by pressing various keys while holding SysRq (Alt+PrintScreen). It | |
405 | also works on a serial console (on PC hardware at least), if you | |
406 | send a BREAK and then within 5 seconds a command keypress. The | |
407 | keys are documented in <file:Documentation/sysrq.txt>. Don't say Y | |
408 | unless you really know what this hack does. | |
8446f1d3 | 409 | |
8eaede49 BH |
410 | config MAGIC_SYSRQ_DEFAULT_ENABLE |
411 | hex "Enable magic SysRq key functions by default" | |
412 | depends on MAGIC_SYSRQ | |
413 | default 0x1 | |
414 | help | |
415 | Specifies which SysRq key functions are enabled by default. | |
416 | This may be set to 1 or 0 to enable or disable them all, or | |
417 | to a bitmask as described in Documentation/sysrq.txt. | |
418 | ||
f346f4b3 AB |
419 | config DEBUG_KERNEL |
420 | bool "Kernel debugging" | |
fef2c9bc | 421 | help |
f346f4b3 AB |
422 | Say Y here if you are developing drivers or trying to debug and |
423 | identify kernel problems. | |
fef2c9bc | 424 | |
0610c8a8 | 425 | menu "Memory Debugging" |
fef2c9bc | 426 | |
0610c8a8 | 427 | source mm/Kconfig.debug |
fef2c9bc | 428 | |
0610c8a8 DH |
429 | config DEBUG_OBJECTS |
430 | bool "Debug object operations" | |
431 | depends on DEBUG_KERNEL | |
9c44bc03 | 432 | help |
0610c8a8 DH |
433 | If you say Y here, additional code will be inserted into the |
434 | kernel to track the life time of various objects and validate | |
435 | the operations on those objects. | |
9c44bc03 | 436 | |
0610c8a8 DH |
437 | config DEBUG_OBJECTS_SELFTEST |
438 | bool "Debug objects selftest" | |
439 | depends on DEBUG_OBJECTS | |
440 | help | |
441 | This enables the selftest of the object debug code. | |
9c44bc03 | 442 | |
0610c8a8 DH |
443 | config DEBUG_OBJECTS_FREE |
444 | bool "Debug objects in freed memory" | |
445 | depends on DEBUG_OBJECTS | |
446 | help | |
447 | This enables checks whether a k/v free operation frees an area | |
448 | which contains an object which has not been deactivated | |
449 | properly. This can make kmalloc/kfree-intensive workloads | |
450 | much slower. | |
3ac7fe5a | 451 | |
c6f3a97f TG |
452 | config DEBUG_OBJECTS_TIMERS |
453 | bool "Debug timer objects" | |
454 | depends on DEBUG_OBJECTS | |
455 | help | |
456 | If you say Y here, additional code will be inserted into the | |
457 | timer routines to track the life time of timer objects and | |
458 | validate the timer operations. | |
459 | ||
dc186ad7 TG |
460 | config DEBUG_OBJECTS_WORK |
461 | bool "Debug work objects" | |
462 | depends on DEBUG_OBJECTS | |
463 | help | |
464 | If you say Y here, additional code will be inserted into the | |
465 | work queue routines to track the life time of work objects and | |
466 | validate the work operations. | |
467 | ||
551d55a9 MD |
468 | config DEBUG_OBJECTS_RCU_HEAD |
469 | bool "Debug RCU callbacks objects" | |
fc2ecf7e | 470 | depends on DEBUG_OBJECTS |
551d55a9 MD |
471 | help |
472 | Enable this to turn on debugging of RCU list heads (call_rcu() usage). | |
473 | ||
e2852ae8 TH |
474 | config DEBUG_OBJECTS_PERCPU_COUNTER |
475 | bool "Debug percpu counter objects" | |
476 | depends on DEBUG_OBJECTS | |
477 | help | |
478 | If you say Y here, additional code will be inserted into the | |
479 | percpu counter routines to track the life time of percpu counter | |
480 | objects and validate the percpu counter operations. | |
481 | ||
3ae70205 IM |
482 | config DEBUG_OBJECTS_ENABLE_DEFAULT |
483 | int "debug_objects bootup default value (0-1)" | |
484 | range 0 1 | |
485 | default "1" | |
486 | depends on DEBUG_OBJECTS | |
487 | help | |
488 | Debug objects boot parameter default value | |
489 | ||
1da177e4 | 490 | config DEBUG_SLAB |
4a2f0acf | 491 | bool "Debug slab memory allocations" |
7d46d9e6 | 492 | depends on DEBUG_KERNEL && SLAB && !KMEMCHECK |
1da177e4 LT |
493 | help |
494 | Say Y here to have the kernel do limited verification on memory | |
495 | allocation as well as poisoning memory on free to catch use of freed | |
496 | memory. This can make kmalloc/kfree-intensive workloads much slower. | |
497 | ||
871751e2 AV |
498 | config DEBUG_SLAB_LEAK |
499 | bool "Memory leak debugging" | |
500 | depends on DEBUG_SLAB | |
501 | ||
f0630fff CL |
502 | config SLUB_DEBUG_ON |
503 | bool "SLUB debugging on by default" | |
7d46d9e6 | 504 | depends on SLUB && SLUB_DEBUG && !KMEMCHECK |
f0630fff CL |
505 | default n |
506 | help | |
507 | Boot with debugging on by default. SLUB boots by default with | |
508 | the runtime debug capabilities switched off. Enabling this is | |
509 | equivalent to specifying the "slub_debug" parameter on boot. | |
510 | There is no support for more fine grained debug control like | |
511 | possible with slub_debug=xxx. SLUB debugging may be switched | |
512 | off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying | |
513 | "slub_debug=-". | |
514 | ||
8ff12cfc CL |
515 | config SLUB_STATS |
516 | default n | |
517 | bool "Enable SLUB performance statistics" | |
ab4d5ed5 | 518 | depends on SLUB && SYSFS |
8ff12cfc CL |
519 | help |
520 | SLUB statistics are useful to debug SLUBs allocation behavior in | |
521 | order find ways to optimize the allocator. This should never be | |
522 | enabled for production use since keeping statistics slows down | |
523 | the allocator by a few percentage points. The slabinfo command | |
524 | supports the determination of the most active slabs to figure | |
525 | out which slabs are relevant to a particular load. | |
526 | Try running: slabinfo -DA | |
527 | ||
b69ec42b CM |
528 | config HAVE_DEBUG_KMEMLEAK |
529 | bool | |
530 | ||
3bba00d7 CM |
531 | config DEBUG_KMEMLEAK |
532 | bool "Kernel memory leak detector" | |
525c1f92 | 533 | depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK |
79e0d9bd | 534 | select DEBUG_FS |
3bba00d7 CM |
535 | select STACKTRACE if STACKTRACE_SUPPORT |
536 | select KALLSYMS | |
b60e26a2 | 537 | select CRC32 |
3bba00d7 CM |
538 | help |
539 | Say Y here if you want to enable the memory leak | |
540 | detector. The memory allocation/freeing is traced in a way | |
541 | similar to the Boehm's conservative garbage collector, the | |
542 | difference being that the orphan objects are not freed but | |
543 | only shown in /sys/kernel/debug/kmemleak. Enabling this | |
544 | feature will introduce an overhead to memory | |
700199b0 | 545 | allocations. See Documentation/dev-tools/kmemleak.rst for more |
3bba00d7 CM |
546 | details. |
547 | ||
0610c8a8 DH |
548 | Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances |
549 | of finding leaks due to the slab objects poisoning. | |
550 | ||
551 | In order to access the kmemleak file, debugfs needs to be | |
552 | mounted (usually at /sys/kernel/debug). | |
553 | ||
554 | config DEBUG_KMEMLEAK_EARLY_LOG_SIZE | |
555 | int "Maximum kmemleak early log entries" | |
556 | depends on DEBUG_KMEMLEAK | |
557 | range 200 40000 | |
558 | default 400 | |
559 | help | |
560 | Kmemleak must track all the memory allocations to avoid | |
561 | reporting false positives. Since memory may be allocated or | |
562 | freed before kmemleak is initialised, an early log buffer is | |
563 | used to store these actions. If kmemleak reports "early log | |
564 | buffer exceeded", please increase this value. | |
565 | ||
566 | config DEBUG_KMEMLEAK_TEST | |
567 | tristate "Simple test for the kernel memory leak detector" | |
568 | depends on DEBUG_KMEMLEAK && m | |
569 | help | |
570 | This option enables a module that explicitly leaks memory. | |
571 | ||
572 | If unsure, say N. | |
573 | ||
574 | config DEBUG_KMEMLEAK_DEFAULT_OFF | |
575 | bool "Default kmemleak to off" | |
576 | depends on DEBUG_KMEMLEAK | |
577 | help | |
578 | Say Y here to disable kmemleak by default. It can then be enabled | |
579 | on the command line via kmemleak=on. | |
580 | ||
581 | config DEBUG_STACK_USAGE | |
582 | bool "Stack utilization instrumentation" | |
6c31da34 | 583 | depends on DEBUG_KERNEL && !IA64 |
0610c8a8 DH |
584 | help |
585 | Enables the display of the minimum amount of free stack which each | |
586 | task has ever had available in the sysrq-T and sysrq-P debug output. | |
587 | ||
588 | This option will slow down process creation somewhat. | |
589 | ||
590 | config DEBUG_VM | |
591 | bool "Debug VM" | |
592 | depends on DEBUG_KERNEL | |
593 | help | |
594 | Enable this to turn on extended checks in the virtual-memory system | |
595 | that may impact performance. | |
596 | ||
597 | If unsure, say N. | |
598 | ||
4f115147 DB |
599 | config DEBUG_VM_VMACACHE |
600 | bool "Debug VMA caching" | |
601 | depends on DEBUG_VM | |
602 | help | |
603 | Enable this to turn on VMA caching debug information. Doing so | |
604 | can cause significant overhead, so only enable it in non-production | |
605 | environments. | |
606 | ||
607 | If unsure, say N. | |
608 | ||
0610c8a8 DH |
609 | config DEBUG_VM_RB |
610 | bool "Debug VM red-black trees" | |
611 | depends on DEBUG_VM | |
612 | help | |
a663dad6 | 613 | Enable VM red-black tree debugging information and extra validations. |
0610c8a8 DH |
614 | |
615 | If unsure, say N. | |
616 | ||
95ad9755 KS |
617 | config DEBUG_VM_PGFLAGS |
618 | bool "Debug page-flags operations" | |
619 | depends on DEBUG_VM | |
620 | help | |
621 | Enables extra validation on page flags operations. | |
622 | ||
623 | If unsure, say N. | |
624 | ||
0610c8a8 DH |
625 | config DEBUG_VIRTUAL |
626 | bool "Debug VM translations" | |
627 | depends on DEBUG_KERNEL && X86 | |
628 | help | |
629 | Enable some costly sanity checks in virtual to page code. This can | |
630 | catch mistakes with virt_to_page() and friends. | |
631 | ||
632 | If unsure, say N. | |
633 | ||
634 | config DEBUG_NOMMU_REGIONS | |
635 | bool "Debug the global anon/private NOMMU mapping region tree" | |
636 | depends on DEBUG_KERNEL && !MMU | |
637 | help | |
638 | This option causes the global tree of anonymous and private mapping | |
639 | regions to be regularly checked for invalid topology. | |
640 | ||
641 | config DEBUG_MEMORY_INIT | |
642 | bool "Debug memory initialisation" if EXPERT | |
643 | default !EXPERT | |
644 | help | |
645 | Enable this for additional checks during memory initialisation. | |
646 | The sanity checks verify aspects of the VM such as the memory model | |
647 | and other information provided by the architecture. Verbose | |
648 | information will be printed at KERN_DEBUG loglevel depending | |
649 | on the mminit_loglevel= command-line option. | |
650 | ||
651 | If unsure, say Y | |
652 | ||
653 | config MEMORY_NOTIFIER_ERROR_INJECT | |
654 | tristate "Memory hotplug notifier error injection module" | |
655 | depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION | |
656 | help | |
657 | This option provides the ability to inject artificial errors to | |
658 | memory hotplug notifier chain callbacks. It is controlled through | |
659 | debugfs interface under /sys/kernel/debug/notifier-error-inject/memory | |
660 | ||
661 | If the notifier call chain should be failed with some events | |
662 | notified, write the error code to "actions/<notifier event>/error". | |
663 | ||
664 | Example: Inject memory hotplug offline error (-12 == -ENOMEM) | |
665 | ||
666 | # cd /sys/kernel/debug/notifier-error-inject/memory | |
667 | # echo -12 > actions/MEM_GOING_OFFLINE/error | |
668 | # echo offline > /sys/devices/system/memory/memoryXXX/state | |
669 | bash: echo: write error: Cannot allocate memory | |
670 | ||
671 | To compile this code as a module, choose M here: the module will | |
672 | be called memory-notifier-error-inject. | |
673 | ||
674 | If unsure, say N. | |
675 | ||
676 | config DEBUG_PER_CPU_MAPS | |
677 | bool "Debug access to per_cpu maps" | |
678 | depends on DEBUG_KERNEL | |
679 | depends on SMP | |
680 | help | |
681 | Say Y to verify that the per_cpu map being accessed has | |
682 | been set up. This adds a fair amount of code to kernel memory | |
683 | and decreases performance. | |
684 | ||
685 | Say N if unsure. | |
686 | ||
687 | config DEBUG_HIGHMEM | |
688 | bool "Highmem debugging" | |
689 | depends on DEBUG_KERNEL && HIGHMEM | |
690 | help | |
b1357c9f GU |
691 | This option enables additional error checking for high memory |
692 | systems. Disable for production systems. | |
0610c8a8 DH |
693 | |
694 | config HAVE_DEBUG_STACKOVERFLOW | |
695 | bool | |
696 | ||
697 | config DEBUG_STACKOVERFLOW | |
698 | bool "Check for stack overflows" | |
699 | depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW | |
700 | ---help--- | |
701 | Say Y here if you want to check for overflows of kernel, IRQ | |
edb0ec07 | 702 | and exception stacks (if your architecture uses them). This |
0610c8a8 DH |
703 | option will show detailed messages if free stack space drops |
704 | below a certain limit. | |
705 | ||
706 | These kinds of bugs usually occur when call-chains in the | |
707 | kernel get too deep, especially when interrupts are | |
708 | involved. | |
709 | ||
710 | Use this in cases where you see apparently random memory | |
711 | corruption, especially if it appears in 'struct thread_info' | |
712 | ||
713 | If in doubt, say "N". | |
714 | ||
715 | source "lib/Kconfig.kmemcheck" | |
716 | ||
0b24becc AR |
717 | source "lib/Kconfig.kasan" |
718 | ||
0610c8a8 DH |
719 | endmenu # "Memory Debugging" |
720 | ||
5c9a8750 DV |
721 | config ARCH_HAS_KCOV |
722 | bool | |
723 | help | |
724 | KCOV does not have any arch-specific code, but currently it is enabled | |
725 | only for x86_64. KCOV requires testing on other archs, and most likely | |
726 | disabling of instrumentation for some early boot code. | |
727 | ||
728 | config KCOV | |
729 | bool "Code coverage for fuzzing" | |
730 | depends on ARCH_HAS_KCOV | |
731 | select DEBUG_FS | |
a519167e KC |
732 | select GCC_PLUGINS if !COMPILE_TEST |
733 | select GCC_PLUGIN_SANCOV if !COMPILE_TEST | |
5c9a8750 DV |
734 | help |
735 | KCOV exposes kernel code coverage information in a form suitable | |
736 | for coverage-guided fuzzing (randomized testing). | |
737 | ||
738 | If RANDOMIZE_BASE is enabled, PC values will not be stable across | |
739 | different machines and across reboots. If you need stable PC values, | |
740 | disable RANDOMIZE_BASE. | |
741 | ||
700199b0 | 742 | For more details, see Documentation/dev-tools/kcov.rst. |
5c9a8750 | 743 | |
a4691dea VN |
744 | config KCOV_INSTRUMENT_ALL |
745 | bool "Instrument all code by default" | |
746 | depends on KCOV | |
747 | default y if KCOV | |
748 | help | |
749 | If you are doing generic system call fuzzing (like e.g. syzkaller), | |
750 | then you will want to instrument the whole kernel and you should | |
751 | say y here. If you are doing more targeted fuzzing (like e.g. | |
752 | filesystem fuzzing with AFL) then you will want to enable coverage | |
753 | for more specific subsets of files, and should say n here. | |
754 | ||
a304e1b8 DW |
755 | config DEBUG_SHIRQ |
756 | bool "Debug shared IRQ handlers" | |
0244ad00 | 757 | depends on DEBUG_KERNEL |
a304e1b8 DW |
758 | help |
759 | Enable this to generate a spurious interrupt as soon as a shared | |
760 | interrupt handler is registered, and just before one is deregistered. | |
761 | Drivers ought to be able to handle interrupts coming in at those | |
762 | points; some don't and need to be caught. | |
763 | ||
92aef8fb DH |
764 | menu "Debug Lockups and Hangs" |
765 | ||
58687acb DZ |
766 | config LOCKUP_DETECTOR |
767 | bool "Detect Hard and Soft Lockups" | |
dea20a3f | 768 | depends on DEBUG_KERNEL && !S390 |
8446f1d3 | 769 | help |
58687acb DZ |
770 | Say Y here to enable the kernel to act as a watchdog to detect |
771 | hard and soft lockups. | |
772 | ||
773 | Softlockups are bugs that cause the kernel to loop in kernel | |
5f329089 | 774 | mode for more than 20 seconds, without giving other tasks a |
58687acb DZ |
775 | chance to run. The current stack trace is displayed upon |
776 | detection and the system will stay locked up. | |
8446f1d3 | 777 | |
58687acb | 778 | Hardlockups are bugs that cause the CPU to loop in kernel mode |
5f329089 | 779 | for more than 10 seconds, without letting other interrupts have a |
58687acb DZ |
780 | chance to run. The current stack trace is displayed upon detection |
781 | and the system will stay locked up. | |
8446f1d3 | 782 | |
58687acb | 783 | The overhead should be minimal. A periodic hrtimer runs to |
5f329089 FLVC |
784 | generate interrupts and kick the watchdog task every 4 seconds. |
785 | An NMI is generated every 10 seconds or so to check for hardlockups. | |
786 | ||
787 | The frequency of hrtimer and NMI events and the soft and hard lockup | |
788 | thresholds can be controlled through the sysctl watchdog_thresh. | |
8446f1d3 | 789 | |
23637d47 | 790 | config HARDLOCKUP_DETECTOR |
8f1f66ed JB |
791 | def_bool y |
792 | depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG | |
793 | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI | |
8446f1d3 | 794 | |
fef2c9bc DZ |
795 | config BOOTPARAM_HARDLOCKUP_PANIC |
796 | bool "Panic (Reboot) On Hard Lockups" | |
8f1f66ed | 797 | depends on HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
798 | help |
799 | Say Y here to enable the kernel to panic on "hard lockups", | |
800 | which are bugs that cause the kernel to loop in kernel | |
5f329089 FLVC |
801 | mode with interrupts disabled for more than 10 seconds (configurable |
802 | using the watchdog_thresh sysctl). | |
fef2c9bc DZ |
803 | |
804 | Say N if unsure. | |
805 | ||
806 | config BOOTPARAM_HARDLOCKUP_PANIC_VALUE | |
807 | int | |
8f1f66ed | 808 | depends on HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
809 | range 0 1 |
810 | default 0 if !BOOTPARAM_HARDLOCKUP_PANIC | |
811 | default 1 if BOOTPARAM_HARDLOCKUP_PANIC | |
812 | ||
9c44bc03 IM |
813 | config BOOTPARAM_SOFTLOCKUP_PANIC |
814 | bool "Panic (Reboot) On Soft Lockups" | |
89d7ce2a | 815 | depends on LOCKUP_DETECTOR |
9c44bc03 IM |
816 | help |
817 | Say Y here to enable the kernel to panic on "soft lockups", | |
818 | which are bugs that cause the kernel to loop in kernel | |
5f329089 FLVC |
819 | mode for more than 20 seconds (configurable using the watchdog_thresh |
820 | sysctl), without giving other tasks a chance to run. | |
9c44bc03 IM |
821 | |
822 | The panic can be used in combination with panic_timeout, | |
823 | to cause the system to reboot automatically after a | |
824 | lockup has been detected. This feature is useful for | |
825 | high-availability systems that have uptime guarantees and | |
826 | where a lockup must be resolved ASAP. | |
827 | ||
828 | Say N if unsure. | |
829 | ||
830 | config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE | |
831 | int | |
e16bb1d7 | 832 | depends on LOCKUP_DETECTOR |
9c44bc03 IM |
833 | range 0 1 |
834 | default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC | |
835 | default 1 if BOOTPARAM_SOFTLOCKUP_PANIC | |
836 | ||
e162b39a MSB |
837 | config DETECT_HUNG_TASK |
838 | bool "Detect Hung Tasks" | |
839 | depends on DEBUG_KERNEL | |
8edbb83e | 840 | default LOCKUP_DETECTOR |
e162b39a | 841 | help |
0610c8a8 DH |
842 | Say Y here to enable the kernel to detect "hung tasks", |
843 | which are bugs that cause the task to be stuck in | |
96b03ab8 | 844 | uninterruptible "D" state indefinitely. |
1da177e4 | 845 | |
0610c8a8 DH |
846 | When a hung task is detected, the kernel will print the |
847 | current stack trace (which you should report), but the | |
848 | task will stay in uninterruptible state. If lockdep is | |
849 | enabled then all held locks will also be reported. This | |
850 | feature has negligible overhead. | |
871751e2 | 851 | |
0610c8a8 DH |
852 | config DEFAULT_HUNG_TASK_TIMEOUT |
853 | int "Default timeout for hung task detection (in seconds)" | |
854 | depends on DETECT_HUNG_TASK | |
855 | default 120 | |
f0630fff | 856 | help |
0610c8a8 DH |
857 | This option controls the default timeout (in seconds) used |
858 | to determine when a task has become non-responsive and should | |
859 | be considered hung. | |
f0630fff | 860 | |
0610c8a8 DH |
861 | It can be adjusted at runtime via the kernel.hung_task_timeout_secs |
862 | sysctl or by writing a value to | |
863 | /proc/sys/kernel/hung_task_timeout_secs. | |
8ff12cfc | 864 | |
0610c8a8 DH |
865 | A timeout of 0 disables the check. The default is two minutes. |
866 | Keeping the default should be fine in most cases. | |
b69ec42b | 867 | |
0610c8a8 DH |
868 | config BOOTPARAM_HUNG_TASK_PANIC |
869 | bool "Panic (Reboot) On Hung Tasks" | |
870 | depends on DETECT_HUNG_TASK | |
3bba00d7 | 871 | help |
0610c8a8 DH |
872 | Say Y here to enable the kernel to panic on "hung tasks", |
873 | which are bugs that cause the kernel to leave a task stuck | |
874 | in uninterruptible "D" state. | |
3bba00d7 | 875 | |
0610c8a8 DH |
876 | The panic can be used in combination with panic_timeout, |
877 | to cause the system to reboot automatically after a | |
878 | hung task has been detected. This feature is useful for | |
879 | high-availability systems that have uptime guarantees and | |
880 | where a hung tasks must be resolved ASAP. | |
bf96d1e3 | 881 | |
0610c8a8 | 882 | Say N if unsure. |
bf96d1e3 | 883 | |
0610c8a8 DH |
884 | config BOOTPARAM_HUNG_TASK_PANIC_VALUE |
885 | int | |
886 | depends on DETECT_HUNG_TASK | |
887 | range 0 1 | |
888 | default 0 if !BOOTPARAM_HUNG_TASK_PANIC | |
889 | default 1 if BOOTPARAM_HUNG_TASK_PANIC | |
3bba00d7 | 890 | |
82607adc TH |
891 | config WQ_WATCHDOG |
892 | bool "Detect Workqueue Stalls" | |
893 | depends on DEBUG_KERNEL | |
894 | help | |
895 | Say Y here to enable stall detection on workqueues. If a | |
896 | worker pool doesn't make forward progress on a pending work | |
897 | item for over a given amount of time, 30s by default, a | |
898 | warning message is printed along with dump of workqueue | |
899 | state. This can be configured through kernel parameter | |
900 | "workqueue.watchdog_thresh" and its sysfs counterpart. | |
901 | ||
92aef8fb DH |
902 | endmenu # "Debug lockups and hangs" |
903 | ||
904 | config PANIC_ON_OOPS | |
905 | bool "Panic on Oops" | |
a9d9058a | 906 | help |
92aef8fb DH |
907 | Say Y here to enable the kernel to panic when it oopses. This |
908 | has the same effect as setting oops=panic on the kernel command | |
909 | line. | |
a9d9058a | 910 | |
92aef8fb DH |
911 | This feature is useful to ensure that the kernel does not do |
912 | anything erroneous after an oops which could result in data | |
913 | corruption or other issues. | |
914 | ||
915 | Say N if unsure. | |
916 | ||
917 | config PANIC_ON_OOPS_VALUE | |
918 | int | |
919 | range 0 1 | |
920 | default 0 if !PANIC_ON_OOPS | |
921 | default 1 if PANIC_ON_OOPS | |
922 | ||
5800dc3c JB |
923 | config PANIC_TIMEOUT |
924 | int "panic timeout" | |
925 | default 0 | |
926 | help | |
927 | Set the timeout value (in seconds) until a reboot occurs when the | |
928 | the kernel panics. If n = 0, then we wait forever. A timeout | |
929 | value n > 0 will wait n seconds before rebooting, while a timeout | |
930 | value n < 0 will reboot immediately. | |
931 | ||
0610c8a8 DH |
932 | config SCHED_DEBUG |
933 | bool "Collect scheduler debugging info" | |
934 | depends on DEBUG_KERNEL && PROC_FS | |
935 | default y | |
0822ee4a | 936 | help |
0610c8a8 DH |
937 | If you say Y here, the /proc/sched_debug file will be provided |
938 | that can help debug the scheduler. The runtime overhead of this | |
939 | option is minimal. | |
0822ee4a | 940 | |
f6db8347 NR |
941 | config SCHED_INFO |
942 | bool | |
943 | default n | |
944 | ||
0610c8a8 DH |
945 | config SCHEDSTATS |
946 | bool "Collect scheduler statistics" | |
947 | depends on DEBUG_KERNEL && PROC_FS | |
f6db8347 | 948 | select SCHED_INFO |
0610c8a8 DH |
949 | help |
950 | If you say Y here, additional code will be inserted into the | |
951 | scheduler and related routines to collect statistics about | |
952 | scheduler behavior and provide them in /proc/schedstat. These | |
953 | stats may be useful for both tuning and debugging the scheduler | |
954 | If you aren't debugging the scheduler or trying to tune a specific | |
955 | application, you can say N to avoid the very slight overhead | |
956 | this adds. | |
0822ee4a | 957 | |
0d9e2632 AT |
958 | config SCHED_STACK_END_CHECK |
959 | bool "Detect stack corruption on calls to schedule()" | |
960 | depends on DEBUG_KERNEL | |
961 | default n | |
962 | help | |
963 | This option checks for a stack overrun on calls to schedule(). | |
964 | If the stack end location is found to be over written always panic as | |
965 | the content of the corrupted region can no longer be trusted. | |
966 | This is to ensure no erroneous behaviour occurs which could result in | |
967 | data corruption or a sporadic crash at a later stage once the region | |
968 | is examined. The runtime overhead introduced is minimal. | |
969 | ||
3c17ad19 JS |
970 | config DEBUG_TIMEKEEPING |
971 | bool "Enable extra timekeeping sanity checking" | |
972 | help | |
973 | This option will enable additional timekeeping sanity checks | |
974 | which may be helpful when diagnosing issues where timekeeping | |
975 | problems are suspected. | |
976 | ||
977 | This may include checks in the timekeeping hotpaths, so this | |
978 | option may have a (very small) performance impact to some | |
979 | workloads. | |
980 | ||
981 | If unsure, say N. | |
982 | ||
0610c8a8 DH |
983 | config TIMER_STATS |
984 | bool "Collect kernel timers statistics" | |
985 | depends on DEBUG_KERNEL && PROC_FS | |
ab0155a2 | 986 | help |
0610c8a8 DH |
987 | If you say Y here, additional code will be inserted into the |
988 | timer routines to collect statistics about kernel timers being | |
989 | reprogrammed. The statistics can be read from /proc/timer_stats. | |
990 | The statistics collection is started by writing 1 to /proc/timer_stats, | |
991 | writing 0 stops it. This feature is useful to collect information | |
992 | about timer usage patterns in kernel and userspace. This feature | |
993 | is lightweight if enabled in the kernel config but not activated | |
994 | (it defaults to deactivated on bootup and will only be activated | |
995 | if some application like powertop activates it explicitly). | |
ab0155a2 | 996 | |
1da177e4 LT |
997 | config DEBUG_PREEMPT |
998 | bool "Debug preemptible kernel" | |
01deab98 | 999 | depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT |
1da177e4 LT |
1000 | default y |
1001 | help | |
1002 | If you say Y here then the kernel will use a debug variant of the | |
1003 | commonly used smp_processor_id() function and will print warnings | |
1004 | if kernel code uses it in a preemption-unsafe way. Also, the kernel | |
1005 | will detect preemption count underflows. | |
1006 | ||
9eade16b DH |
1007 | menu "Lock Debugging (spinlocks, mutexes, etc...)" |
1008 | ||
e7eebaf6 IM |
1009 | config DEBUG_RT_MUTEXES |
1010 | bool "RT Mutex debugging, deadlock detection" | |
e7eebaf6 IM |
1011 | depends on DEBUG_KERNEL && RT_MUTEXES |
1012 | help | |
1013 | This allows rt mutex semantics violations and rt mutex related | |
1014 | deadlocks (lockups) to be detected and reported automatically. | |
1015 | ||
1da177e4 | 1016 | config DEBUG_SPINLOCK |
4d9f34ad | 1017 | bool "Spinlock and rw-lock debugging: basic checks" |
1da177e4 | 1018 | depends on DEBUG_KERNEL |
e335e3eb | 1019 | select UNINLINE_SPIN_UNLOCK |
1da177e4 LT |
1020 | help |
1021 | Say Y here and build SMP to catch missing spinlock initialization | |
1022 | and certain other kinds of spinlock errors commonly made. This is | |
1023 | best used in conjunction with the NMI watchdog so that spinlock | |
1024 | deadlocks are also debuggable. | |
1025 | ||
4d9f34ad IM |
1026 | config DEBUG_MUTEXES |
1027 | bool "Mutex debugging: basic checks" | |
1028 | depends on DEBUG_KERNEL | |
1029 | help | |
1030 | This feature allows mutex semantics violations to be detected and | |
1031 | reported. | |
1032 | ||
23010027 DV |
1033 | config DEBUG_WW_MUTEX_SLOWPATH |
1034 | bool "Wait/wound mutex debugging: Slowpath testing" | |
1035 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT | |
1036 | select DEBUG_LOCK_ALLOC | |
1037 | select DEBUG_SPINLOCK | |
1038 | select DEBUG_MUTEXES | |
1039 | help | |
1040 | This feature enables slowpath testing for w/w mutex users by | |
1041 | injecting additional -EDEADLK wound/backoff cases. Together with | |
1042 | the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this | |
1043 | will test all possible w/w mutex interface abuse with the | |
1044 | exception of simply not acquiring all the required locks. | |
4d692373 RC |
1045 | Note that this feature can introduce significant overhead, so |
1046 | it really should not be enabled in a production or distro kernel, | |
1047 | even a debug kernel. If you are a driver writer, enable it. If | |
1048 | you are a distro, do not. | |
23010027 | 1049 | |
4d9f34ad IM |
1050 | config DEBUG_LOCK_ALLOC |
1051 | bool "Lock debugging: detect incorrect freeing of live locks" | |
517e7aa5 | 1052 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
1053 | select DEBUG_SPINLOCK |
1054 | select DEBUG_MUTEXES | |
4d9f34ad IM |
1055 | select LOCKDEP |
1056 | help | |
1057 | This feature will check whether any held lock (spinlock, rwlock, | |
1058 | mutex or rwsem) is incorrectly freed by the kernel, via any of the | |
1059 | memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), | |
1060 | vfree(), etc.), whether a live lock is incorrectly reinitialized via | |
1061 | spin_lock_init()/mutex_init()/etc., or whether there is any lock | |
1062 | held during task exit. | |
1063 | ||
1064 | config PROVE_LOCKING | |
1065 | bool "Lock debugging: prove locking correctness" | |
517e7aa5 | 1066 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad IM |
1067 | select LOCKDEP |
1068 | select DEBUG_SPINLOCK | |
1069 | select DEBUG_MUTEXES | |
4d9f34ad | 1070 | select DEBUG_LOCK_ALLOC |
46b93b74 | 1071 | select TRACE_IRQFLAGS |
4d9f34ad IM |
1072 | default n |
1073 | help | |
1074 | This feature enables the kernel to prove that all locking | |
1075 | that occurs in the kernel runtime is mathematically | |
1076 | correct: that under no circumstance could an arbitrary (and | |
1077 | not yet triggered) combination of observed locking | |
1078 | sequences (on an arbitrary number of CPUs, running an | |
1079 | arbitrary number of tasks and interrupt contexts) cause a | |
1080 | deadlock. | |
1081 | ||
1082 | In short, this feature enables the kernel to report locking | |
1083 | related deadlocks before they actually occur. | |
1084 | ||
1085 | The proof does not depend on how hard and complex a | |
1086 | deadlock scenario would be to trigger: how many | |
1087 | participant CPUs, tasks and irq-contexts would be needed | |
1088 | for it to trigger. The proof also does not depend on | |
1089 | timing: if a race and a resulting deadlock is possible | |
1090 | theoretically (no matter how unlikely the race scenario | |
1091 | is), it will be proven so and will immediately be | |
1092 | reported by the kernel (once the event is observed that | |
1093 | makes the deadlock theoretically possible). | |
1094 | ||
1095 | If a deadlock is impossible (i.e. the locking rules, as | |
1096 | observed by the kernel, are mathematically correct), the | |
1097 | kernel reports nothing. | |
1098 | ||
1099 | NOTE: this feature can also be enabled for rwlocks, mutexes | |
1100 | and rwsems - in which case all dependencies between these | |
1101 | different locking variants are observed and mapped too, and | |
1102 | the proof of observed correctness is also maintained for an | |
1103 | arbitrary combination of these separate locking variants. | |
1104 | ||
214e0aed | 1105 | For more details, see Documentation/locking/lockdep-design.txt. |
4d9f34ad | 1106 | |
e6b5f1be BM |
1107 | config PROVE_LOCKING_SMALL |
1108 | bool | |
1109 | ||
4d9f34ad IM |
1110 | config LOCKDEP |
1111 | bool | |
517e7aa5 | 1112 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
4d9f34ad | 1113 | select STACKTRACE |
df2e1ef6 | 1114 | select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE |
4d9f34ad IM |
1115 | select KALLSYMS |
1116 | select KALLSYMS_ALL | |
1117 | ||
f20786ff | 1118 | config LOCK_STAT |
fdfb870f | 1119 | bool "Lock usage statistics" |
f20786ff PZ |
1120 | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT |
1121 | select LOCKDEP | |
1122 | select DEBUG_SPINLOCK | |
1123 | select DEBUG_MUTEXES | |
1124 | select DEBUG_LOCK_ALLOC | |
1125 | default n | |
1126 | help | |
1127 | This feature enables tracking lock contention points | |
1128 | ||
214e0aed | 1129 | For more details, see Documentation/locking/lockstat.txt |
a560aa48 | 1130 | |
dd8b1cf6 FW |
1131 | This also enables lock events required by "perf lock", |
1132 | subcommand of perf. | |
1133 | If you want to use "perf lock", you also need to turn on | |
1134 | CONFIG_EVENT_TRACING. | |
84c6f88f HM |
1135 | |
1136 | CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. | |
dd8b1cf6 | 1137 | (CONFIG_LOCKDEP defines "acquire" and "release" events.) |
84c6f88f | 1138 | |
4d9f34ad IM |
1139 | config DEBUG_LOCKDEP |
1140 | bool "Lock dependency engine debugging" | |
517e7aa5 | 1141 | depends on DEBUG_KERNEL && LOCKDEP |
4d9f34ad IM |
1142 | help |
1143 | If you say Y here, the lock dependency engine will do | |
1144 | additional runtime checks to debug itself, at the price | |
1145 | of more runtime overhead. | |
1146 | ||
d902db1e FW |
1147 | config DEBUG_ATOMIC_SLEEP |
1148 | bool "Sleep inside atomic section checking" | |
e8f7c70f | 1149 | select PREEMPT_COUNT |
1da177e4 LT |
1150 | depends on DEBUG_KERNEL |
1151 | help | |
1152 | If you say Y here, various routines which may sleep will become very | |
d902db1e FW |
1153 | noisy if they are called inside atomic sections: when a spinlock is |
1154 | held, inside an rcu read side critical section, inside preempt disabled | |
1155 | sections, inside an interrupt, etc... | |
1da177e4 | 1156 | |
cae2ed9a IM |
1157 | config DEBUG_LOCKING_API_SELFTESTS |
1158 | bool "Locking API boot-time self-tests" | |
1159 | depends on DEBUG_KERNEL | |
1160 | help | |
1161 | Say Y here if you want the kernel to run a short self-test during | |
1162 | bootup. The self-test checks whether common types of locking bugs | |
1163 | are detected by debugging mechanisms or not. (if you disable | |
1164 | lock debugging then those bugs wont be detected of course.) | |
1165 | The following locking APIs are covered: spinlocks, rwlocks, | |
1166 | mutexes and rwsems. | |
1167 | ||
0af3fe1e PM |
1168 | config LOCK_TORTURE_TEST |
1169 | tristate "torture tests for locking" | |
1170 | depends on DEBUG_KERNEL | |
1171 | select TORTURE_TEST | |
1172 | default n | |
1173 | help | |
1174 | This option provides a kernel module that runs torture tests | |
1175 | on kernel locking primitives. The kernel module may be built | |
1176 | after the fact on the running kernel to be tested, if desired. | |
1177 | ||
1178 | Say Y here if you want kernel locking-primitive torture tests | |
1179 | to be built into the kernel. | |
1180 | Say M if you want these torture tests to build as a module. | |
1181 | Say N if you are unsure. | |
1182 | ||
9eade16b | 1183 | endmenu # lock debugging |
8637c099 | 1184 | |
9eade16b DH |
1185 | config TRACE_IRQFLAGS |
1186 | bool | |
5ca43f6c | 1187 | help |
9eade16b DH |
1188 | Enables hooks to interrupt enabling and disabling for |
1189 | either tracing or lock debugging. | |
5ca43f6c | 1190 | |
8637c099 | 1191 | config STACKTRACE |
0c38e1fe | 1192 | bool "Stack backtrace support" |
8637c099 | 1193 | depends on STACKTRACE_SUPPORT |
0c38e1fe DJ |
1194 | help |
1195 | This option causes the kernel to create a /proc/pid/stack for | |
1196 | every process, showing its current stack trace. | |
1197 | It is also used by various kernel debugging features that require | |
1198 | stack trace generation. | |
5ca43f6c | 1199 | |
1da177e4 LT |
1200 | config DEBUG_KOBJECT |
1201 | bool "kobject debugging" | |
1202 | depends on DEBUG_KERNEL | |
1203 | help | |
1204 | If you say Y here, some extra kobject debugging messages will be sent | |
1205 | to the syslog. | |
1206 | ||
c817a67e RK |
1207 | config DEBUG_KOBJECT_RELEASE |
1208 | bool "kobject release debugging" | |
2a999aa0 | 1209 | depends on DEBUG_OBJECTS_TIMERS |
c817a67e RK |
1210 | help |
1211 | kobjects are reference counted objects. This means that their | |
1212 | last reference count put is not predictable, and the kobject can | |
1213 | live on past the point at which a driver decides to drop it's | |
1214 | initial reference to the kobject gained on allocation. An | |
1215 | example of this would be a struct device which has just been | |
1216 | unregistered. | |
1217 | ||
1218 | However, some buggy drivers assume that after such an operation, | |
1219 | the memory backing the kobject can be immediately freed. This | |
1220 | goes completely against the principles of a refcounted object. | |
1221 | ||
1222 | If you say Y here, the kernel will delay the release of kobjects | |
1223 | on the last reference count to improve the visibility of this | |
1224 | kind of kobject release bug. | |
1225 | ||
9b2a60c4 CM |
1226 | config HAVE_DEBUG_BUGVERBOSE |
1227 | bool | |
1228 | ||
1da177e4 | 1229 | config DEBUG_BUGVERBOSE |
6a108a14 | 1230 | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT |
9b2a60c4 | 1231 | depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) |
8420e7ef | 1232 | default y |
1da177e4 LT |
1233 | help |
1234 | Say Y here to make BUG() panics output the file name and line number | |
1235 | of the BUG call as well as the EIP and oops trace. This aids | |
1236 | debugging but costs about 70-100K of memory. | |
1237 | ||
199a9afc DJ |
1238 | config DEBUG_LIST |
1239 | bool "Debug linked list manipulation" | |
4520bcb2 | 1240 | depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION |
199a9afc DJ |
1241 | help |
1242 | Enable this to turn on extended checks in the linked-list | |
1243 | walking routines. | |
1244 | ||
1245 | If unsure, say N. | |
1246 | ||
b8cfff68 DS |
1247 | config DEBUG_PI_LIST |
1248 | bool "Debug priority linked list manipulation" | |
1249 | depends on DEBUG_KERNEL | |
1250 | help | |
1251 | Enable this to turn on extended checks in the priority-ordered | |
1252 | linked-list (plist) walking routines. This checks the entire | |
1253 | list multiple times during each manipulation. | |
1254 | ||
1255 | If unsure, say N. | |
1256 | ||
d6ec0842 JA |
1257 | config DEBUG_SG |
1258 | bool "Debug SG table operations" | |
1259 | depends on DEBUG_KERNEL | |
1260 | help | |
1261 | Enable this to turn on checks on scatter-gather tables. This can | |
1262 | help find problems with drivers that do not properly initialize | |
1263 | their sg tables. | |
1264 | ||
1265 | If unsure, say N. | |
1266 | ||
1b2439db AV |
1267 | config DEBUG_NOTIFIERS |
1268 | bool "Debug notifier call chains" | |
1269 | depends on DEBUG_KERNEL | |
1270 | help | |
1271 | Enable this to turn on sanity checking for notifier call chains. | |
1272 | This is most useful for kernel developers to make sure that | |
1273 | modules properly unregister themselves from notifier chains. | |
1274 | This is a relatively cheap check but if you care about maximum | |
1275 | performance, say N. | |
1276 | ||
e0e81739 DH |
1277 | config DEBUG_CREDENTIALS |
1278 | bool "Debug credential management" | |
1279 | depends on DEBUG_KERNEL | |
1280 | help | |
1281 | Enable this to turn on some debug checking for credential | |
1282 | management. The additional code keeps track of the number of | |
1283 | pointers from task_structs to any given cred struct, and checks to | |
1284 | see that this number never exceeds the usage count of the cred | |
1285 | struct. | |
1286 | ||
1287 | Furthermore, if SELinux is enabled, this also checks that the | |
1288 | security pointer in the cred struct is never seen to be invalid. | |
1289 | ||
1290 | If unsure, say N. | |
1291 | ||
2f03e3ca DH |
1292 | menu "RCU Debugging" |
1293 | ||
1294 | config PROVE_RCU | |
9bae6592 | 1295 | def_bool PROVE_LOCKING |
2f03e3ca DH |
1296 | |
1297 | config PROVE_RCU_REPEATEDLY | |
1298 | bool "RCU debugging: don't disable PROVE_RCU on first splat" | |
1299 | depends on PROVE_RCU | |
1300 | default n | |
1301 | help | |
1302 | By itself, PROVE_RCU will disable checking upon issuing the | |
1303 | first warning (or "splat"). This feature prevents such | |
1304 | disabling, allowing multiple RCU-lockdep warnings to be printed | |
1305 | on a single reboot. | |
1306 | ||
1307 | Say Y to allow multiple RCU-lockdep warnings per boot. | |
1308 | ||
1309 | Say N if you are unsure. | |
1310 | ||
2f03e3ca DH |
1311 | config SPARSE_RCU_POINTER |
1312 | bool "RCU debugging: sparse-based checks for pointer usage" | |
1313 | default n | |
1314 | help | |
1315 | This feature enables the __rcu sparse annotation for | |
1316 | RCU-protected pointers. This annotation will cause sparse | |
1317 | to flag any non-RCU used of annotated pointers. This can be | |
1318 | helpful when debugging RCU usage. Please note that this feature | |
1319 | is not intended to enforce code cleanliness; it is instead merely | |
1320 | a debugging aid. | |
1321 | ||
1322 | Say Y to make sparse flag questionable use of RCU-protected pointers | |
1323 | ||
1324 | Say N if you are unsure. | |
1325 | ||
51b1130e PM |
1326 | config TORTURE_TEST |
1327 | tristate | |
1328 | default n | |
1329 | ||
8704baab PM |
1330 | config RCU_PERF_TEST |
1331 | tristate "performance tests for RCU" | |
1332 | depends on DEBUG_KERNEL | |
1333 | select TORTURE_TEST | |
1334 | select SRCU | |
1335 | select TASKS_RCU | |
1336 | default n | |
1337 | help | |
1338 | This option provides a kernel module that runs performance | |
1339 | tests on the RCU infrastructure. The kernel module may be built | |
1340 | after the fact on the running kernel to be tested, if desired. | |
1341 | ||
1342 | Say Y here if you want RCU performance tests to be built into | |
1343 | the kernel. | |
1344 | Say M if you want the RCU performance tests to build as a module. | |
1345 | Say N if you are unsure. | |
1346 | ||
a241ec65 PM |
1347 | config RCU_TORTURE_TEST |
1348 | tristate "torture tests for RCU" | |
1349 | depends on DEBUG_KERNEL | |
51b1130e | 1350 | select TORTURE_TEST |
83fe27ea | 1351 | select SRCU |
82d0f4c0 | 1352 | select TASKS_RCU |
a241ec65 PM |
1353 | default n |
1354 | help | |
1355 | This option provides a kernel module that runs torture tests | |
1356 | on the RCU infrastructure. The kernel module may be built | |
1357 | after the fact on the running kernel to be tested, if desired. | |
1358 | ||
31a72bce PM |
1359 | Say Y here if you want RCU torture tests to be built into |
1360 | the kernel. | |
a241ec65 PM |
1361 | Say M if you want the RCU torture tests to build as a module. |
1362 | Say N if you are unsure. | |
8bb31b9d | 1363 | |
0f41c0dd PM |
1364 | config RCU_TORTURE_TEST_SLOW_PREINIT |
1365 | bool "Slow down RCU grace-period pre-initialization to expose races" | |
1366 | depends on RCU_TORTURE_TEST | |
1367 | help | |
1368 | This option delays grace-period pre-initialization (the | |
1369 | propagation of CPU-hotplug changes up the rcu_node combining | |
1370 | tree) for a few jiffies between initializing each pair of | |
1371 | consecutive rcu_node structures. This helps to expose races | |
1372 | involving grace-period pre-initialization, in other words, it | |
1373 | makes your kernel less stable. It can also greatly increase | |
1374 | grace-period latency, especially on systems with large numbers | |
1375 | of CPUs. This is useful when torture-testing RCU, but in | |
1376 | almost no other circumstance. | |
1377 | ||
1378 | Say Y here if you want your system to crash and hang more often. | |
1379 | Say N if you want a sane system. | |
1380 | ||
1381 | config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY | |
1382 | int "How much to slow down RCU grace-period pre-initialization" | |
1383 | range 0 5 | |
1384 | default 3 | |
1385 | depends on RCU_TORTURE_TEST_SLOW_PREINIT | |
1386 | help | |
1387 | This option specifies the number of jiffies to wait between | |
1388 | each rcu_node structure pre-initialization step. | |
1389 | ||
37745d28 PM |
1390 | config RCU_TORTURE_TEST_SLOW_INIT |
1391 | bool "Slow down RCU grace-period initialization to expose races" | |
1392 | depends on RCU_TORTURE_TEST | |
1393 | help | |
0f41c0dd PM |
1394 | This option delays grace-period initialization for a few |
1395 | jiffies between initializing each pair of consecutive | |
37745d28 PM |
1396 | rcu_node structures. This helps to expose races involving |
1397 | grace-period initialization, in other words, it makes your | |
1398 | kernel less stable. It can also greatly increase grace-period | |
1399 | latency, especially on systems with large numbers of CPUs. | |
1400 | This is useful when torture-testing RCU, but in almost no | |
1401 | other circumstance. | |
1402 | ||
1403 | Say Y here if you want your system to crash and hang more often. | |
1404 | Say N if you want a sane system. | |
1405 | ||
1406 | config RCU_TORTURE_TEST_SLOW_INIT_DELAY | |
1407 | int "How much to slow down RCU grace-period initialization" | |
1408 | range 0 5 | |
186bea5d | 1409 | default 3 |
8d7dc928 | 1410 | depends on RCU_TORTURE_TEST_SLOW_INIT |
37745d28 PM |
1411 | help |
1412 | This option specifies the number of jiffies to wait between | |
1413 | each rcu_node structure initialization. | |
1414 | ||
0f41c0dd PM |
1415 | config RCU_TORTURE_TEST_SLOW_CLEANUP |
1416 | bool "Slow down RCU grace-period cleanup to expose races" | |
1417 | depends on RCU_TORTURE_TEST | |
1418 | help | |
1419 | This option delays grace-period cleanup for a few jiffies | |
1420 | between cleaning up each pair of consecutive rcu_node | |
1421 | structures. This helps to expose races involving grace-period | |
1422 | cleanup, in other words, it makes your kernel less stable. | |
1423 | It can also greatly increase grace-period latency, especially | |
1424 | on systems with large numbers of CPUs. This is useful when | |
1425 | torture-testing RCU, but in almost no other circumstance. | |
1426 | ||
1427 | Say Y here if you want your system to crash and hang more often. | |
1428 | Say N if you want a sane system. | |
1429 | ||
1430 | config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY | |
1431 | int "How much to slow down RCU grace-period cleanup" | |
1432 | range 0 5 | |
1433 | default 3 | |
1434 | depends on RCU_TORTURE_TEST_SLOW_CLEANUP | |
1435 | help | |
1436 | This option specifies the number of jiffies to wait between | |
1437 | each rcu_node structure cleanup operation. | |
1438 | ||
b163760e PM |
1439 | config RCU_CPU_STALL_TIMEOUT |
1440 | int "RCU CPU stall timeout in seconds" | |
6bfc09e2 | 1441 | depends on RCU_STALL_COMMON |
b163760e | 1442 | range 3 300 |
c896054f | 1443 | default 21 |
b163760e PM |
1444 | help |
1445 | If a given RCU grace period extends more than the specified | |
1446 | number of seconds, a CPU stall warning is printed. If the | |
1447 | RCU grace period persists, additional CPU stall warnings are | |
1448 | printed at more widely spaced intervals. | |
1449 | ||
5c8806a0 PM |
1450 | config RCU_TRACE |
1451 | bool "Enable tracing for RCU" | |
6dab2778 | 1452 | depends on DEBUG_KERNEL |
52494535 | 1453 | select TRACE_CLOCK |
6dab2778 | 1454 | help |
5c8806a0 | 1455 | This option provides tracing in RCU which presents stats |
f2151a0a NB |
1456 | in debugfs for debugging RCU implementation. It also enables |
1457 | additional tracepoints for ftrace-style event tracing. | |
ad118c54 | 1458 | |
5c8806a0 | 1459 | Say Y here if you want to enable RCU tracing |
6dab2778 AV |
1460 | Say N if you are unsure. |
1461 | ||
1ce46ee5 | 1462 | config RCU_EQS_DEBUG |
eb6d5b0a | 1463 | bool "Provide debugging asserts for adding NO_HZ support to an arch" |
1ce46ee5 PM |
1464 | depends on DEBUG_KERNEL |
1465 | help | |
1466 | This option provides consistency checks in RCU's handling of | |
1467 | NO_HZ. These checks have proven quite helpful in detecting | |
1468 | bugs in arch-specific NO_HZ code. | |
1469 | ||
1470 | Say N here if you need ultimate kernel/user switch latencies | |
1471 | Say Y if you are unsure | |
1472 | ||
2f03e3ca DH |
1473 | endmenu # "RCU Debugging" |
1474 | ||
f303fccb TH |
1475 | config DEBUG_WQ_FORCE_RR_CPU |
1476 | bool "Force round-robin CPU selection for unbound work items" | |
1477 | depends on DEBUG_KERNEL | |
1478 | default n | |
1479 | help | |
1480 | Workqueue used to implicitly guarantee that work items queued | |
1481 | without explicit CPU specified are put on the local CPU. This | |
1482 | guarantee is no longer true and while local CPU is still | |
1483 | preferred work items may be put on foreign CPUs. Kernel | |
1484 | parameter "workqueue.debug_force_rr_cpu" is added to force | |
1485 | round-robin CPU selection to flush out usages which depend on the | |
1486 | now broken guarantee. This config option enables the debug | |
1487 | feature by default. When enabled, memory and cache locality will | |
1488 | be impacted. | |
1489 | ||
870d6656 TH |
1490 | config DEBUG_BLOCK_EXT_DEVT |
1491 | bool "Force extended block device numbers and spread them" | |
1492 | depends on DEBUG_KERNEL | |
1493 | depends on BLOCK | |
759f8ca3 | 1494 | default n |
870d6656 | 1495 | help |
0e11e342 TH |
1496 | BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON |
1497 | SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT | |
1498 | YOU ARE DOING. Distros, please enable this and fix whatever | |
1499 | is broken. | |
1500 | ||
870d6656 TH |
1501 | Conventionally, block device numbers are allocated from |
1502 | predetermined contiguous area. However, extended block area | |
1503 | may introduce non-contiguous block device numbers. This | |
1504 | option forces most block device numbers to be allocated from | |
1505 | the extended space and spreads them to discover kernel or | |
1506 | userland code paths which assume predetermined contiguous | |
1507 | device number allocation. | |
1508 | ||
55dc7db7 TH |
1509 | Note that turning on this debug option shuffles all the |
1510 | device numbers for all IDE and SCSI devices including libata | |
1511 | ones, so root partition specified using device number | |
1512 | directly (via rdev or root=MAJ:MIN) won't work anymore. | |
1513 | Textual device names (root=/dev/sdXn) will continue to work. | |
1514 | ||
870d6656 TH |
1515 | Say N if you are unsure. |
1516 | ||
757c989b TG |
1517 | config CPU_HOTPLUG_STATE_CONTROL |
1518 | bool "Enable CPU hotplug state control" | |
1519 | depends on DEBUG_KERNEL | |
1520 | depends on HOTPLUG_CPU | |
1521 | default n | |
1522 | help | |
1523 | Allows to write steps between "offline" and "online" to the CPUs | |
1524 | sysfs target file so states can be stepped granular. This is a debug | |
1525 | option for now as the hotplug machinery cannot be stopped and | |
1526 | restarted at arbitrary points yet. | |
1527 | ||
1528 | Say N if your are unsure. | |
1529 | ||
8d438288 AM |
1530 | config NOTIFIER_ERROR_INJECTION |
1531 | tristate "Notifier error injection" | |
1532 | depends on DEBUG_KERNEL | |
1533 | select DEBUG_FS | |
1534 | help | |
e41e85cc | 1535 | This option provides the ability to inject artificial errors to |
8d438288 AM |
1536 | specified notifier chain callbacks. It is useful to test the error |
1537 | handling of notifier call chain failures. | |
1538 | ||
1539 | Say N if unsure. | |
1540 | ||
048b9c35 AM |
1541 | config 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 | |
e41e85cc | 1546 | This option provides the ability to inject artificial errors to |
048b9c35 AM |
1547 | 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 | ||
d526e85f BH |
1565 | config OF_RECONFIG_NOTIFIER_ERROR_INJECT |
1566 | tristate "OF reconfig notifier error injection module" | |
1567 | depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION | |
08dfb4dd | 1568 | help |
e41e85cc | 1569 | This option provides the ability to inject artificial errors to |
d526e85f | 1570 | OF reconfig notifier chain callbacks. It is controlled |
08dfb4dd | 1571 | through debugfs interface under |
d526e85f | 1572 | /sys/kernel/debug/notifier-error-inject/OF-reconfig/ |
08dfb4dd AM |
1573 | |
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 | |
e12a95f4 | 1578 | be called of-reconfig-notifier-error-inject. |
08dfb4dd AM |
1579 | |
1580 | If unsure, say N. | |
1581 | ||
02fff96a NA |
1582 | config 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 | ||
6ff1cb35 | 1605 | config FAULT_INJECTION |
1ab8509a AM |
1606 | bool "Fault-injection framework" |
1607 | depends on DEBUG_KERNEL | |
329409ae AM |
1608 | help |
1609 | Provide fault-injection framework. | |
1610 | For more details, see Documentation/fault-injection/. | |
6ff1cb35 | 1611 | |
8a8b6502 | 1612 | config FAILSLAB |
1ab8509a AM |
1613 | bool "Fault-injection capability for kmalloc" |
1614 | depends on FAULT_INJECTION | |
773ff60e | 1615 | depends on SLAB || SLUB |
8a8b6502 | 1616 | help |
1ab8509a | 1617 | Provide fault-injection capability for kmalloc. |
8a8b6502 | 1618 | |
933e312e AM |
1619 | config FAIL_PAGE_ALLOC |
1620 | bool "Fault-injection capabilitiy for alloc_pages()" | |
1ab8509a | 1621 | depends on FAULT_INJECTION |
933e312e | 1622 | help |
1ab8509a | 1623 | Provide fault-injection capability for alloc_pages(). |
933e312e | 1624 | |
c17bb495 | 1625 | config FAIL_MAKE_REQUEST |
86327d19 | 1626 | bool "Fault-injection capability for disk IO" |
581d4e28 | 1627 | depends on FAULT_INJECTION && BLOCK |
c17bb495 | 1628 | help |
1ab8509a | 1629 | Provide fault-injection capability for disk IO. |
c17bb495 | 1630 | |
581d4e28 | 1631 | config FAIL_IO_TIMEOUT |
f4d01439 | 1632 | bool "Fault-injection capability for faking disk interrupts" |
581d4e28 JA |
1633 | 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 | ||
1b676f70 PF |
1642 | config FAIL_MMC_REQUEST |
1643 | bool "Fault-injection capability for MMC IO" | |
28ff4fda | 1644 | depends on FAULT_INJECTION_DEBUG_FS && MMC |
1b676f70 PF |
1645 | 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 | ||
ab51fbab DB |
1652 | config 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 | ||
6ff1cb35 AM |
1659 | config FAULT_INJECTION_DEBUG_FS |
1660 | bool "Debugfs entries for fault-injection capabilities" | |
1ab8509a | 1661 | depends on FAULT_INJECTION && SYSFS && DEBUG_FS |
6ff1cb35 | 1662 | help |
1ab8509a | 1663 | Enable configuration of fault-injection capabilities via debugfs. |
1df49008 AM |
1664 | |
1665 | config FAULT_INJECTION_STACKTRACE_FILTER | |
1666 | bool "stacktrace filter for fault-injection capabilities" | |
1667 | depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT | |
6d690dca | 1668 | depends on !X86_64 |
1df49008 | 1669 | select STACKTRACE |
df2e1ef6 | 1670 | select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE |
1df49008 AM |
1671 | help |
1672 | Provide stacktrace filter for fault-injection capabilities | |
267c4025 | 1673 | |
9745512c AV |
1674 | config LATENCYTOP |
1675 | bool "Latency measuring infrastructure" | |
625fdcaa RD |
1676 | depends on DEBUG_KERNEL |
1677 | depends on STACKTRACE_SUPPORT | |
1678 | depends on PROC_FS | |
cc80ae38 | 1679 | select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC |
9745512c AV |
1680 | select KALLSYMS |
1681 | select KALLSYMS_ALL | |
1682 | select STACKTRACE | |
1683 | select SCHEDSTATS | |
1684 | select SCHED_DEBUG | |
9745512c AV |
1685 | 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 | ||
16444a8a ACM |
1689 | source kernel/trace/Kconfig |
1690 | ||
881c5149 DH |
1691 | menu "Runtime Testing" |
1692 | ||
1693 | config LKDTM | |
1694 | tristate "Linux Kernel Dump Test Tool Module" | |
1695 | depends on DEBUG_FS | |
1696 | depends on BLOCK | |
1697 | default n | |
1698 | help | |
1699 | This module enables testing of the different dumping mechanisms by | |
1700 | inducing system failures at predefined crash points. | |
1701 | If you don't need it: say N | |
1702 | Choose M here to compile this code as a module. The module will be | |
1703 | called lkdtm. | |
1704 | ||
1705 | Documentation on how to use the module can be found in | |
1706 | Documentation/fault-injection/provoke-crashes.txt | |
1707 | ||
1708 | config TEST_LIST_SORT | |
1709 | bool "Linked list sorting test" | |
1710 | depends on DEBUG_KERNEL | |
1711 | help | |
1712 | Enable this to turn on 'list_sort()' function test. This test is | |
1713 | executed only once during system boot, so affects only boot time. | |
1714 | ||
1715 | If unsure, say N. | |
1716 | ||
1717 | config KPROBES_SANITY_TEST | |
1718 | bool "Kprobes sanity tests" | |
1719 | depends on DEBUG_KERNEL | |
1720 | depends on KPROBES | |
1721 | default n | |
1722 | help | |
1723 | This option provides for testing basic kprobes functionality on | |
1724 | boot. A sample kprobe, jprobe and kretprobe are inserted and | |
1725 | verified for functionality. | |
1726 | ||
1727 | Say N if you are unsure. | |
1728 | ||
1729 | config BACKTRACE_SELF_TEST | |
1730 | tristate "Self test for the backtrace code" | |
1731 | depends on DEBUG_KERNEL | |
1732 | default n | |
1733 | help | |
1734 | This option provides a kernel module that can be used to test | |
1735 | the kernel stack backtrace code. This option is not useful | |
1736 | for distributions or general kernels, but only for kernel | |
1737 | developers working on architecture code. | |
1738 | ||
1739 | Note that if you want to also test saved backtraces, you will | |
1740 | have to enable STACKTRACE as well. | |
1741 | ||
1742 | Say N if you are unsure. | |
1743 | ||
910a742d ML |
1744 | config RBTREE_TEST |
1745 | tristate "Red-Black tree test" | |
7c993e11 | 1746 | depends on DEBUG_KERNEL |
910a742d ML |
1747 | help |
1748 | A benchmark measuring the performance of the rbtree library. | |
1749 | Also includes rbtree invariant checks. | |
1750 | ||
fff3fd8a ML |
1751 | config INTERVAL_TREE_TEST |
1752 | tristate "Interval tree test" | |
1753 | depends on m && DEBUG_KERNEL | |
a88cc108 | 1754 | select INTERVAL_TREE |
fff3fd8a ML |
1755 | help |
1756 | A benchmark measuring the performance of the interval tree library | |
1757 | ||
623fd807 GT |
1758 | config PERCPU_TEST |
1759 | tristate "Per cpu operations test" | |
1760 | depends on m && DEBUG_KERNEL | |
1761 | help | |
1762 | Enable this option to build test module which validates per-cpu | |
1763 | operations. | |
1764 | ||
1765 | If unsure, say N. | |
1766 | ||
881c5149 DH |
1767 | config ATOMIC64_SELFTEST |
1768 | bool "Perform an atomic64_t self-test at boot" | |
1769 | help | |
1770 | Enable this option to test the atomic64_t functions at boot. | |
1771 | ||
1772 | If unsure, say N. | |
1773 | ||
1774 | config ASYNC_RAID6_TEST | |
1775 | tristate "Self test for hardware accelerated raid6 recovery" | |
1776 | depends on ASYNC_RAID6_RECOV | |
1777 | select ASYNC_MEMCPY | |
1778 | ---help--- | |
1779 | This is a one-shot self test that permutes through the | |
1780 | recovery of all the possible two disk failure scenarios for a | |
1781 | N-disk array. Recovery is performed with the asynchronous | |
1782 | raid6 recovery routines, and will optionally use an offload | |
1783 | engine if one is available. | |
1784 | ||
1785 | If unsure, say N. | |
1786 | ||
64d1d77a AS |
1787 | config TEST_HEXDUMP |
1788 | tristate "Test functions located in the hexdump module at runtime" | |
1789 | ||
881c5149 DH |
1790 | config TEST_STRING_HELPERS |
1791 | tristate "Test functions located in the string_helpers module at runtime" | |
1792 | ||
1793 | config TEST_KSTRTOX | |
1794 | tristate "Test kstrto*() family of functions at runtime" | |
1795 | ||
707cc728 RV |
1796 | config TEST_PRINTF |
1797 | tristate "Test printf() family of functions at runtime" | |
1798 | ||
5fd003f5 DD |
1799 | config TEST_BITMAP |
1800 | tristate "Test bitmap_*() family of functions at runtime" | |
1801 | default n | |
1802 | help | |
1803 | Enable this option to test the bitmap functions at boot. | |
1804 | ||
1805 | If unsure, say N. | |
1806 | ||
cfaff0e5 AS |
1807 | config TEST_UUID |
1808 | tristate "Test functions located in the uuid module at runtime" | |
1809 | ||
7e1e7763 | 1810 | config TEST_RHASHTABLE |
9d6dbe1b | 1811 | tristate "Perform selftest on resizable hash table" |
7e1e7763 TG |
1812 | default n |
1813 | help | |
1814 | Enable this option to test the rhashtable functions at boot. | |
1815 | ||
1816 | If unsure, say N. | |
1817 | ||
468a9428 GS |
1818 | config TEST_HASH |
1819 | tristate "Perform selftest on hash functions" | |
1820 | default n | |
1821 | help | |
1822 | Enable this option to test the kernel's integer (<linux/hash,h>) | |
1823 | and string (<linux/stringhash.h>) hash functions on boot | |
1824 | (or module load). | |
1825 | ||
1826 | This is intended to help people writing architecture-specific | |
1827 | optimized versions. If unsure, say N. | |
1828 | ||
881c5149 DH |
1829 | endmenu # runtime tests |
1830 | ||
f212ec4b | 1831 | config PROVIDE_OHCI1394_DMA_INIT |
080de8c2 | 1832 | bool "Remote debugging over FireWire early on boot" |
f212ec4b BK |
1833 | depends on PCI && X86 |
1834 | help | |
1835 | If you want to debug problems which hang or crash the kernel early | |
1836 | on boot and the crashing machine has a FireWire port, you can use | |
1837 | this feature to remotely access the memory of the crashed machine | |
1838 | over FireWire. This employs remote DMA as part of the OHCI1394 | |
1839 | specification which is now the standard for FireWire controllers. | |
1840 | ||
1841 | With remote DMA, you can monitor the printk buffer remotely using | |
1842 | firescope and access all memory below 4GB using fireproxy from gdb. | |
1843 | Even controlling a kernel debugger is possible using remote DMA. | |
1844 | ||
1845 | Usage: | |
1846 | ||
1847 | If ohci1394_dma=early is used as boot parameter, it will initialize | |
1848 | all OHCI1394 controllers which are found in the PCI config space. | |
1849 | ||
1850 | As all changes to the FireWire bus such as enabling and disabling | |
1851 | devices cause a bus reset and thereby disable remote DMA for all | |
1852 | devices, be sure to have the cable plugged and FireWire enabled on | |
1853 | the debugging host before booting the debug target for debugging. | |
1854 | ||
1855 | This code (~1k) is freed after boot. By then, the firewire stack | |
1856 | in charge of the OHCI-1394 controllers should be used instead. | |
1857 | ||
1858 | See Documentation/debugging-via-ohci1394.txt for more information. | |
9745512c | 1859 | |
5ee00bd4 JR |
1860 | config DMA_API_DEBUG |
1861 | bool "Enable debugging of DMA-API usage" | |
1862 | depends on HAVE_DMA_API_DEBUG | |
1863 | help | |
1864 | Enable this option to debug the use of the DMA API by device drivers. | |
1865 | With this option you will be able to detect common bugs in device | |
1866 | drivers like double-freeing of DMA mappings or freeing mappings that | |
1867 | were never allocated. | |
0abdd7a8 DW |
1868 | |
1869 | This also attempts to catch cases where a page owned by DMA is | |
1870 | accessed by the cpu in a way that could cause data corruption. For | |
1871 | example, this enables cow_user_page() to check that the source page is | |
1872 | not undergoing DMA. | |
1873 | ||
1874 | This option causes a performance degradation. Use only if you want to | |
1875 | debug device drivers and dma interactions. | |
1876 | ||
1877 | If unsure, say N. | |
346e15be | 1878 | |
8a6f0b47 | 1879 | config TEST_LKM |
93e9ef83 KC |
1880 | tristate "Test module loading with 'hello world' module" |
1881 | default n | |
1882 | depends on m | |
1883 | help | |
1884 | This builds the "test_module" module that emits "Hello, world" | |
1885 | on printk when loaded. It is designed to be used for basic | |
1886 | evaluation of the module loading subsystem (for example when | |
1887 | validating module verification). It lacks any extra dependencies, | |
1888 | and will not normally be loaded by the system unless explicitly | |
1889 | requested by name. | |
1890 | ||
1891 | If unsure, say N. | |
1892 | ||
3e2a4c18 KC |
1893 | config TEST_USER_COPY |
1894 | tristate "Test user/kernel boundary protections" | |
1895 | default n | |
1896 | depends on m | |
1897 | help | |
1898 | This builds the "test_user_copy" module that runs sanity checks | |
1899 | on the copy_to/from_user infrastructure, making sure basic | |
1900 | user/kernel boundary testing is working. If it fails to load, | |
1901 | a regression has been detected in the user/kernel memory boundary | |
1902 | protections. | |
1903 | ||
1904 | If unsure, say N. | |
1905 | ||
64a8946b AS |
1906 | config TEST_BPF |
1907 | tristate "Test BPF filter functionality" | |
1908 | default n | |
98920ba6 | 1909 | depends on m && NET |
64a8946b AS |
1910 | help |
1911 | This builds the "test_bpf" module that runs various test vectors | |
1912 | against the BPF interpreter or BPF JIT compiler depending on the | |
1913 | current setting. This is in particular useful for BPF JIT compiler | |
1914 | development, but also to run regression tests against changes in | |
3c731eba AS |
1915 | the interpreter code. It also enables test stubs for eBPF maps and |
1916 | verifier used by user space verifier testsuite. | |
64a8946b AS |
1917 | |
1918 | If unsure, say N. | |
1919 | ||
0a8adf58 KC |
1920 | config TEST_FIRMWARE |
1921 | tristate "Test firmware loading via userspace interface" | |
1922 | default n | |
1923 | depends on FW_LOADER | |
1924 | help | |
1925 | This builds the "test_firmware" module that creates a userspace | |
1926 | interface for testing firmware loading. This can be used to | |
1927 | control the triggering of firmware loading without needing an | |
1928 | actual firmware-using device. The contents can be rechecked by | |
1929 | userspace. | |
1930 | ||
1931 | If unsure, say N. | |
1932 | ||
e704f93a DR |
1933 | config TEST_UDELAY |
1934 | tristate "udelay test driver" | |
1935 | default n | |
1936 | help | |
1937 | This builds the "udelay_test" module that helps to make sure | |
1938 | that udelay() is working properly. | |
1939 | ||
1940 | If unsure, say N. | |
1941 | ||
4a20799d VM |
1942 | config MEMTEST |
1943 | bool "Memtest" | |
1944 | depends on HAVE_MEMBLOCK | |
1945 | ---help--- | |
1946 | This option adds a kernel parameter 'memtest', which allows memtest | |
1947 | to be set. | |
1948 | memtest=0, mean disabled; -- default | |
1949 | memtest=1, mean do 1 test pattern; | |
1950 | ... | |
8d8cfb47 | 1951 | memtest=17, mean do 17 test patterns. |
4a20799d VM |
1952 | If you are unsure how to answer this question, answer N. |
1953 | ||
2bf9e0ab IM |
1954 | config TEST_STATIC_KEYS |
1955 | tristate "Test static keys" | |
579e1acb JB |
1956 | default n |
1957 | depends on m | |
1958 | help | |
2bf9e0ab | 1959 | Test the static key interfaces. |
579e1acb JB |
1960 | |
1961 | If unsure, say N. | |
1962 | ||
de54ebbe KC |
1963 | config BUG_ON_DATA_CORRUPTION |
1964 | bool "Trigger a BUG when data corruption is detected" | |
91a6cee6 | 1965 | select DEBUG_LIST |
de54ebbe KC |
1966 | help |
1967 | Select this option if the kernel should BUG when it encounters | |
1968 | data corruption in kernel memory structures when they get checked | |
1969 | for validity. | |
1970 | ||
1971 | If unsure, say N. | |
1972 | ||
267c4025 | 1973 | source "samples/Kconfig" |
dc7d5527 JW |
1974 | |
1975 | source "lib/Kconfig.kgdb" | |
0a4af3b0 | 1976 | |
c6d30853 AR |
1977 | source "lib/Kconfig.ubsan" |
1978 | ||
21266be9 DW |
1979 | config ARCH_HAS_DEVMEM_IS_ALLOWED |
1980 | bool | |
1981 | ||
1982 | config STRICT_DEVMEM | |
1983 | bool "Filter access to /dev/mem" | |
6b2a65c7 | 1984 | depends on MMU && DEVMEM |
21266be9 DW |
1985 | depends on ARCH_HAS_DEVMEM_IS_ALLOWED |
1986 | default y if TILE || PPC | |
1987 | ---help--- | |
1988 | If this option is disabled, you allow userspace (root) access to all | |
1989 | of memory, including kernel and userspace memory. Accidental | |
1990 | access to this is obviously disastrous, but specific access can | |
1991 | be used by people debugging the kernel. Note that with PAT support | |
1992 | enabled, even in this case there are restrictions on /dev/mem | |
1993 | use due to the cache aliasing requirements. | |
1994 | ||
90a545e9 DW |
1995 | If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem |
1996 | file only allows userspace access to PCI space and the BIOS code and | |
1997 | data regions. This is sufficient for dosemu and X and all common | |
1998 | users of /dev/mem. | |
1999 | ||
2000 | If in doubt, say Y. | |
2001 | ||
2002 | config IO_STRICT_DEVMEM | |
2003 | bool "Filter I/O access to /dev/mem" | |
2004 | depends on STRICT_DEVMEM | |
90a545e9 DW |
2005 | ---help--- |
2006 | If this option is disabled, you allow userspace (root) access to all | |
2007 | io-memory regardless of whether a driver is actively using that | |
2008 | range. Accidental access to this is obviously disastrous, but | |
2009 | specific access can be used by people debugging kernel drivers. | |
2010 | ||
21266be9 | 2011 | If this option is switched on, the /dev/mem file only allows |
90a545e9 DW |
2012 | userspace access to *idle* io-memory ranges (see /proc/iomem) This |
2013 | may break traditional users of /dev/mem (dosemu, legacy X, etc...) | |
2014 | if the driver using a given range cannot be disabled. | |
21266be9 DW |
2015 | |
2016 | If in doubt, say Y. |