forked from torvalds/linux
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathKconfig.debug
2820 lines (2315 loc) · 91.4 KB
/
Kconfig.debug
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
# SPDX-License-Identifier: GPL-2.0-only
menu "Kernel hacking"
menu "printk and dmesg options"
config PRINTK_TIME
bool "Show timing information on printks"
depends on PRINTK
help
Selecting this option causes time stamps of the printk()
messages to be added to the output of the syslog() system
call and at the console.
The timestamp is always recorded internally, and exported
to /dev/kmsg. This flag just specifies if the timestamp should
be included, not that the timestamp is recorded.
The behavior is also controlled by the kernel command line
parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
config PRINTK_CALLER
bool "Show caller information on printks"
depends on PRINTK
help
Selecting this option causes printk() to add a caller "thread id" (if
in task context) or a caller "processor id" (if not in task context)
to every message.
This option is intended for environments where multiple threads
concurrently call printk() for many times, for it is difficult to
interpret without knowing where these lines (or sometimes individual
line which was divided into multiple lines due to race) came from.
Since toggling after boot makes the code racy, currently there is
no option to enable/disable at the kernel command line parameter or
sysfs interface.
config STACKTRACE_BUILD_ID
bool "Show build ID information in stacktraces"
depends on PRINTK
help
Selecting this option adds build ID information for symbols in
stacktraces printed with the printk format '%p[SR]b'.
This option is intended for distros where debuginfo is not easily
accessible but can be downloaded given the build ID of the vmlinux or
kernel module where the function is located.
config CONSOLE_LOGLEVEL_DEFAULT
int "Default console loglevel (1-15)"
range 1 15
default "7"
help
Default loglevel to determine what will be printed on the console.
Setting a default here is equivalent to passing in loglevel=<x> in
the kernel bootargs. loglevel=<x> continues to override whatever
value is specified here as well.
Note: This does not affect the log level of un-prefixed printk()
usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
option.
config CONSOLE_LOGLEVEL_QUIET
int "quiet console loglevel (1-15)"
range 1 15
default "4"
help
loglevel to use when "quiet" is passed on the kernel commandline.
When "quiet" is passed on the kernel commandline this loglevel
will be used as the loglevel. IOW passing "quiet" will be the
equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
config MESSAGE_LOGLEVEL_DEFAULT
int "Default message log level (1-7)"
range 1 7
default "4"
help
Default log level for printk statements with no specified priority.
This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
that are auditing their logs closely may want to set it to a lower
priority.
Note: This does not affect what message level gets printed on the console
by default. To change that, use loglevel=<x> in the kernel bootargs,
or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
config BOOT_PRINTK_DELAY
bool "Delay each boot printk message by N milliseconds"
depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
help
This build option allows you to read kernel boot messages
by inserting a short delay after each one. The delay is
specified in milliseconds on the kernel command line,
using "boot_delay=N".
It is likely that you would also need to use "lpj=M" to preset
the "loops per jiffie" value.
See a previous boot log for the "lpj" value to use for your
system, and then set "lpj=M" before setting "boot_delay=N".
NOTE: Using this option may adversely affect SMP systems.
I.e., processors other than the first one may not boot up.
BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
what it believes to be lockup conditions.
config DYNAMIC_DEBUG
bool "Enable dynamic printk() support"
default n
depends on PRINTK
depends on (DEBUG_FS || PROC_FS)
select DYNAMIC_DEBUG_CORE
help
Compiles debug level messages into the kernel, which would not
otherwise be available at runtime. These messages can then be
enabled/disabled based on various levels of scope - per source file,
function, module, format string, and line number. This mechanism
implicitly compiles in all pr_debug() and dev_dbg() calls, which
enlarges the kernel text size by about 2%.
If a source file is compiled with DEBUG flag set, any
pr_debug() calls in it are enabled by default, but can be
disabled at runtime as below. Note that DEBUG flag is
turned on by many CONFIG_*DEBUG* options.
Usage:
Dynamic debugging is controlled via the 'dynamic_debug/control' file,
which is contained in the 'debugfs' filesystem or procfs.
Thus, the debugfs or procfs filesystem must first be mounted before
making use of this feature.
We refer the control file as: <debugfs>/dynamic_debug/control. This
file contains a list of the debug statements that can be enabled. The
format for each line of the file is:
filename:lineno [module]function flags format
filename : source file of the debug statement
lineno : line number of the debug statement
module : module that contains the debug statement
function : function that contains the debug statement
flags : '=p' means the line is turned 'on' for printing
format : the format used for the debug statement
From a live system:
nullarbor:~ # cat <debugfs>/dynamic_debug/control
# filename:lineno [module]function flags format
fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
Example usage:
// enable the message at line 1603 of file svcsock.c
nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
<debugfs>/dynamic_debug/control
// enable all the messages in file svcsock.c
nullarbor:~ # echo -n 'file svcsock.c +p' >
<debugfs>/dynamic_debug/control
// enable all the messages in the NFS server module
nullarbor:~ # echo -n 'module nfsd +p' >
<debugfs>/dynamic_debug/control
// enable all 12 messages in the function svc_process()
nullarbor:~ # echo -n 'func svc_process +p' >
<debugfs>/dynamic_debug/control
// disable all 12 messages in the function svc_process()
nullarbor:~ # echo -n 'func svc_process -p' >
<debugfs>/dynamic_debug/control
See Documentation/admin-guide/dynamic-debug-howto.rst for additional
information.
config DYNAMIC_DEBUG_CORE
bool "Enable core function of dynamic debug support"
depends on PRINTK
depends on (DEBUG_FS || PROC_FS)
help
Enable core functional support of dynamic debug. It is useful
when you want to tie dynamic debug to your kernel modules with
DYNAMIC_DEBUG_MODULE defined for each of them, especially for
the case of embedded system where the kernel image size is
sensitive for people.
config SYMBOLIC_ERRNAME
bool "Support symbolic error names in printf"
default y if PRINTK
help
If you say Y here, the kernel's printf implementation will
be able to print symbolic error names such as ENOSPC instead
of the number 28. It makes the kernel image slightly larger
(about 3KB), but can make the kernel logs easier to read.
config DEBUG_BUGVERBOSE
bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
default y
help
Say Y here to make BUG() panics output the file name and line number
of the BUG call as well as the EIP and oops trace. This aids
debugging but costs about 70-100K of memory.
endmenu # "printk and dmesg options"
config DEBUG_KERNEL
bool "Kernel debugging"
help
Say Y here if you are developing drivers or trying to debug and
identify kernel problems.
config DEBUG_MISC
bool "Miscellaneous debug code"
default DEBUG_KERNEL
depends on DEBUG_KERNEL
help
Say Y here if you need to enable miscellaneous debug code that should
be under a more specific debug option but isn't.
menu "Compile-time checks and compiler options"
config DEBUG_INFO
bool
help
A kernel debug info option other than "None" has been selected
in the "Debug information" choice below, indicating that debug
information will be generated for build targets.
# Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which
# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
config AS_HAS_NON_CONST_LEB128
def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
choice
prompt "Debug information"
depends on DEBUG_KERNEL
help
Selecting something other than "None" results in a kernel image
that will include debugging info resulting in a larger kernel image.
This adds debug symbols to the kernel and modules (gcc -g), and
is needed if you intend to use kernel crashdump or binary object
tools like crash, kgdb, LKCD, gdb, etc on the kernel.
Choose which version of DWARF debug info to emit. If unsure,
select "Toolchain default".
config DEBUG_INFO_NONE
bool "Disable debug information"
help
Do not build the kernel with debugging information, which will
result in a faster and smaller build.
config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
bool "Rely on the toolchain's implicit default DWARF version"
select DEBUG_INFO
depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
help
The implicit default version of DWARF debug info produced by a
toolchain changes over time.
This can break consumers of the debug info that haven't upgraded to
support newer revisions, and prevent testing newer versions, but
those should be less common scenarios.
config DEBUG_INFO_DWARF4
bool "Generate DWARF Version 4 debuginfo"
select DEBUG_INFO
depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
help
Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
if using clang without clang's integrated assembler, and gdb 7.0+.
If you have consumers of DWARF debug info that are not ready for
newer revisions of DWARF, you may wish to choose this or have your
config select this.
config DEBUG_INFO_DWARF5
bool "Generate DWARF Version 5 debuginfo"
select DEBUG_INFO
depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
help
Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
5.0+ accepts the -gdwarf-5 flag but only had partial support for some
draft features until 7.0), and gdb 8.0+.
Changes to the structure of debug info in Version 5 allow for around
15-18% savings in resulting image and debug info section sizes as
compared to DWARF Version 4. DWARF Version 5 standardizes previous
extensions such as accelerators for symbol indexing and the format
for fission (.dwo/.dwp) files. Users may not want to select this
config if they rely on tooling that has not yet been updated to
support DWARF Version 5.
endchoice # "Debug information"
if DEBUG_INFO
config DEBUG_INFO_REDUCED
bool "Reduce debugging information"
help
If you say Y here gcc is instructed to generate less debugging
information for structure types. This means that tools that
need full debugging information (like kgdb or systemtap) won't
be happy. But if you merely need debugging information to
resolve line numbers there is no loss. Advantage is that
build directory object sizes shrink dramatically over a full
DEBUG_INFO build and compile times are reduced too.
Only works with newer gcc versions.
config DEBUG_INFO_COMPRESSED
bool "Compressed debugging information"
depends on $(cc-option,-gz=zlib)
depends on $(ld-option,--compress-debug-sections=zlib)
help
Compress the debug information using zlib. Requires GCC 5.0+ or Clang
5.0+, binutils 2.26+, and zlib.
Users of dpkg-deb via scripts/package/builddeb may find an increase in
size of their debug .deb packages with this config set, due to the
debug info being compressed with zlib, then the object files being
recompressed with a different compression scheme. But this is still
preferable to setting $KDEB_COMPRESS to "none" which would be even
larger.
config DEBUG_INFO_SPLIT
bool "Produce split debuginfo in .dwo files"
depends on $(cc-option,-gsplit-dwarf)
help
Generate debug info into separate .dwo files. This significantly
reduces the build directory size for builds with DEBUG_INFO,
because it stores the information only once on disk in .dwo
files instead of multiple times in object files and executables.
In addition the debug information is also compressed.
Requires recent gcc (4.7+) and recent gdb/binutils.
Any tool that packages or reads debug information would need
to know about the .dwo files and include them.
Incompatible with older versions of ccache.
config DEBUG_INFO_BTF
bool "Generate BTF typeinfo"
depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
depends on BPF_SYSCALL
depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
help
Generate deduplicated BTF type information from DWARF debug info.
Turning this on expects presence of pahole tool, which will convert
DWARF type info into equivalent deduplicated BTF type info.
config PAHOLE_HAS_SPLIT_BTF
def_bool PAHOLE_VERSION >= 119
config PAHOLE_HAS_BTF_TAG
def_bool PAHOLE_VERSION >= 123
depends on CC_IS_CLANG
help
Decide whether pahole emits btf_tag attributes (btf_type_tag and
btf_decl_tag) or not. Currently only clang compiler implements
these attributes, so make the config depend on CC_IS_CLANG.
config DEBUG_INFO_BTF_MODULES
def_bool y
depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
help
Generate compact split BTF type information for kernel modules.
config MODULE_ALLOW_BTF_MISMATCH
bool "Allow loading modules with non-matching BTF type info"
depends on DEBUG_INFO_BTF_MODULES
help
For modules whose split BTF does not match vmlinux, load without
BTF rather than refusing to load. The default behavior with
module BTF enabled is to reject modules with such mismatches;
this option will still load module BTF where possible but ignore
it when a mismatch is found.
config GDB_SCRIPTS
bool "Provide GDB scripts for kernel debugging"
help
This creates the required links to GDB helper scripts in the
build directory. If you load vmlinux into gdb, the helper
scripts will be automatically imported by gdb as well, and
additional functions are available to analyze a Linux kernel
instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
for further details.
endif # DEBUG_INFO
config FRAME_WARN
int "Warn for stack frames larger than"
range 0 8192
default 0 if KMSAN
default 2048 if GCC_PLUGIN_LATENT_ENTROPY
default 2048 if PARISC
default 1536 if (!64BIT && XTENSA)
default 1280 if KASAN && !64BIT
default 1024 if !64BIT
default 2048 if 64BIT
help
Tell the compiler to warn at build time for stack frames larger than this.
Setting this too low will cause a lot of warnings.
Setting it to 0 disables the warning.
config STRIP_ASM_SYMS
bool "Strip assembler-generated symbols during link"
default n
help
Strip internal assembler-generated symbols during a link (symbols
that look like '.Lxxx') so they don't pollute the output of
get_wchan() and suchlike.
config READABLE_ASM
bool "Generate readable assembler code"
depends on DEBUG_KERNEL
depends on CC_IS_GCC
help
Disable some compiler optimizations that tend to generate human unreadable
assembler output. This may make the kernel slightly slower, but it helps
to keep kernel developers who have to stare a lot at assembler listings
sane.
config HEADERS_INSTALL
bool "Install uapi headers to usr/include"
depends on !UML
help
This option will install uapi headers (headers exported to user-space)
into the usr/include directory for use during the kernel build.
This is unneeded for building the kernel itself, but needed for some
user-space program samples. It is also needed by some features such
as uapi header sanity checks.
config DEBUG_SECTION_MISMATCH
bool "Enable full Section mismatch analysis"
depends on CC_IS_GCC
help
The section mismatch analysis checks if there are illegal
references from one section to another section.
During linktime or runtime, some sections are dropped;
any use of code/data previously in these sections would
most likely result in an oops.
In the code, functions and variables are annotated with
__init,, etc. (see the full list in include/linux/init.h),
which results in the code/data being placed in specific sections.
The section mismatch analysis is always performed after a full
kernel build, and enabling this option causes the following
additional step to occur:
- Add the option -fno-inline-functions-called-once to gcc commands.
When inlining a function annotated with __init in a non-init
function, we would lose the section information and thus
the analysis would not catch the illegal reference.
This option tells gcc to inline less (but it does result in
a larger kernel).
config SECTION_MISMATCH_WARN_ONLY
bool "Make section mismatch errors non-fatal"
default y
help
If you say N here, the build process will fail if there are any
section mismatch, instead of just throwing warnings.
If unsure, say Y.
config DEBUG_FORCE_FUNCTION_ALIGN_64B
bool "Force all function address 64B aligned"
depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC)
help
There are cases that a commit from one domain changes the function
address alignment of other domains, and cause magic performance
bump (regression or improvement). Enable this option will help to
verify if the bump is caused by function alignment changes, while
it will slightly increase the kernel size and affect icache usage.
It is mainly for debug and performance tuning use.
#
# Select this config option from the architecture Kconfig, if it
# is preferred to always offer frame pointers as a config
# option on the architecture (regardless of KERNEL_DEBUG):
#
config ARCH_WANT_FRAME_POINTERS
bool
config FRAME_POINTER
bool "Compile the kernel with frame pointers"
depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
help
If you say Y here the resulting kernel image will be slightly
larger and slower, but it gives very useful debugging information
in case of kernel bugs. (precise oopses/stacktraces/warnings)
config OBJTOOL
bool
config STACK_VALIDATION
bool "Compile-time stack metadata validation"
depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
select OBJTOOL
default n
help
Validate frame pointer rules at compile-time. This helps ensure that
runtime stack traces are more reliable.
For more information, see
tools/objtool/Documentation/objtool.txt.
config NOINSTR_VALIDATION
bool
depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
select OBJTOOL
default y
config VMLINUX_MAP
bool "Generate vmlinux.map file when linking"
depends on EXPERT
help
Selecting this option will pass "-Map=vmlinux.map" to ld
when linking vmlinux. That file can be useful for verifying
and debugging magic section games, and for seeing which
pieces of code get eliminated with
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
config DEBUG_FORCE_WEAK_PER_CPU
bool "Force weak per-cpu definitions"
depends on DEBUG_KERNEL
help
s390 and alpha require percpu variables in modules to be
defined weak to work around addressing range issue which
puts the following two restrictions on percpu variable
definitions.
1. percpu symbols must be unique whether static or not
2. percpu variables can't be defined inside a function
To ensure that generic code follows the above rules, this
option forces all percpu variables to be defined as weak.
endmenu # "Compiler options"
menu "Generic Kernel Debugging Instruments"
config MAGIC_SYSRQ
bool "Magic SysRq key"
depends on !UML
help
If you say Y here, you will have some control over the system even
if the system crashes for example during kernel debugging (e.g., you
will be able to flush the buffer cache to disk, reboot the system
immediately or dump some status information). This is accomplished
by pressing various keys while holding SysRq (Alt+PrintScreen). It
also works on a serial console (on PC hardware at least), if you
send a BREAK and then within 5 seconds a command keypress. The
keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
Don't say Y unless you really know what this hack does.
config MAGIC_SYSRQ_DEFAULT_ENABLE
hex "Enable magic SysRq key functions by default"
depends on MAGIC_SYSRQ
default 0x1
help
Specifies which SysRq key functions are enabled by default.
This may be set to 1 or 0 to enable or disable them all, or
to a bitmask as described in Documentation/admin-guide/sysrq.rst.
config MAGIC_SYSRQ_SERIAL
bool "Enable magic SysRq key over serial"
depends on MAGIC_SYSRQ
default y
help
Many embedded boards have a disconnected TTL level serial which can
generate some garbage that can lead to spurious false sysrq detects.
This option allows you to decide whether you want to enable the
magic SysRq key.
config MAGIC_SYSRQ_SERIAL_SEQUENCE
string "Char sequence that enables magic SysRq over serial"
depends on MAGIC_SYSRQ_SERIAL
default ""
help
Specifies a sequence of characters that can follow BREAK to enable
SysRq on a serial console.
If unsure, leave an empty string and the option will not be enabled.
config DEBUG_FS
bool "Debug Filesystem"
help
debugfs is a virtual file system that kernel developers use to put
debugging files into. Enable this option to be able to read and
write to these files.
For detailed documentation on the debugfs API, see
Documentation/filesystems/.
If unsure, say N.
choice
prompt "Debugfs default access"
depends on DEBUG_FS
default DEBUG_FS_ALLOW_ALL
help
This selects the default access restrictions for debugfs.
It can be overridden with kernel command line option
debugfs=[on,no-mount,off]. The restrictions apply for API access
and filesystem registration.
config DEBUG_FS_ALLOW_ALL
bool "Access normal"
help
No restrictions apply. Both API and filesystem registration
is on. This is the normal default operation.
config DEBUG_FS_DISALLOW_MOUNT
bool "Do not register debugfs as filesystem"
help
The API is open but filesystem is not loaded. Clients can still do
their work and read with debug tools that do not need
debugfs filesystem.
config DEBUG_FS_ALLOW_NONE
bool "No access"
help
Access is off. Clients get -PERM when trying to create nodes in
debugfs tree and debugfs is not registered as a filesystem.
Client can then back-off or continue without debugfs access.
endchoice
source "lib/Kconfig.kgdb"
source "lib/Kconfig.ubsan"
source "lib/Kconfig.kcsan"
endmenu
menu "Networking Debugging"
source "net/Kconfig.debug"
endmenu # "Networking Debugging"
menu "Memory Debugging"
source "mm/Kconfig.debug"
config DEBUG_OBJECTS
bool "Debug object operations"
depends on DEBUG_KERNEL
help
If you say Y here, additional code will be inserted into the
kernel to track the life time of various objects and validate
the operations on those objects.
config DEBUG_OBJECTS_SELFTEST
bool "Debug objects selftest"
depends on DEBUG_OBJECTS
help
This enables the selftest of the object debug code.
config DEBUG_OBJECTS_FREE
bool "Debug objects in freed memory"
depends on DEBUG_OBJECTS
help
This enables checks whether a k/v free operation frees an area
which contains an object which has not been deactivated
properly. This can make kmalloc/kfree-intensive workloads
much slower.
config DEBUG_OBJECTS_TIMERS
bool "Debug timer objects"
depends on DEBUG_OBJECTS
help
If you say Y here, additional code will be inserted into the
timer routines to track the life time of timer objects and
validate the timer operations.
config DEBUG_OBJECTS_WORK
bool "Debug work objects"
depends on DEBUG_OBJECTS
help
If you say Y here, additional code will be inserted into the
work queue routines to track the life time of work objects and
validate the work operations.
config DEBUG_OBJECTS_RCU_HEAD
bool "Debug RCU callbacks objects"
depends on DEBUG_OBJECTS
help
Enable this to turn on debugging of RCU list heads (call_rcu() usage).
config DEBUG_OBJECTS_PERCPU_COUNTER
bool "Debug percpu counter objects"
depends on DEBUG_OBJECTS
help
If you say Y here, additional code will be inserted into the
percpu counter routines to track the life time of percpu counter
objects and validate the percpu counter operations.
config DEBUG_OBJECTS_ENABLE_DEFAULT
int "debug_objects bootup default value (0-1)"
range 0 1
default "1"
depends on DEBUG_OBJECTS
help
Debug objects boot parameter default value
config SHRINKER_DEBUG
bool "Enable shrinker debugging support"
depends on DEBUG_FS
help
Say Y to enable the shrinker debugfs interface which provides
visibility into the kernel memory shrinkers subsystem.
Disable it to avoid an extra memory footprint.
config HAVE_DEBUG_KMEMLEAK
bool
config DEBUG_KMEMLEAK
bool "Kernel memory leak detector"
depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
select DEBUG_FS
select STACKTRACE if STACKTRACE_SUPPORT
select KALLSYMS
select CRC32
help
Say Y here if you want to enable the memory leak
detector. The memory allocation/freeing is traced in a way
similar to the Boehm's conservative garbage collector, the
difference being that the orphan objects are not freed but
only shown in /sys/kernel/debug/kmemleak. Enabling this
feature will introduce an overhead to memory
allocations. See Documentation/dev-tools/kmemleak.rst for more
details.
Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
of finding leaks due to the slab objects poisoning.
In order to access the kmemleak file, debugfs needs to be
mounted (usually at /sys/kernel/debug).
config DEBUG_KMEMLEAK_MEM_POOL_SIZE
int "Kmemleak memory pool size"
depends on DEBUG_KMEMLEAK
range 200 1000000
default 16000
help
Kmemleak must track all the memory allocations to avoid
reporting false positives. Since memory may be allocated or
freed before kmemleak is fully initialised, use a static pool
of metadata objects to track such callbacks. After kmemleak is
fully initialised, this memory pool acts as an emergency one
if slab allocations fail.
config DEBUG_KMEMLEAK_TEST
tristate "Simple test for the kernel memory leak detector"
depends on DEBUG_KMEMLEAK && m
help
This option enables a module that explicitly leaks memory.
If unsure, say N.
config DEBUG_KMEMLEAK_DEFAULT_OFF
bool "Default kmemleak to off"
depends on DEBUG_KMEMLEAK
help
Say Y here to disable kmemleak by default. It can then be enabled
on the command line via kmemleak=on.
config DEBUG_KMEMLEAK_AUTO_SCAN
bool "Enable kmemleak auto scan thread on boot up"
default y
depends on DEBUG_KMEMLEAK
help
Depending on the cpu, kmemleak scan may be cpu intensive and can
stall user tasks at times. This option enables/disables automatic
kmemleak scan at boot up.
Say N here to disable kmemleak auto scan thread to stop automatic
scanning. Disabling this option disables automatic reporting of
memory leaks.
If unsure, say Y.
config DEBUG_STACK_USAGE
bool "Stack utilization instrumentation"
depends on DEBUG_KERNEL && !IA64
help
Enables the display of the minimum amount of free stack which each
task has ever had available in the sysrq-T and sysrq-P debug output.
This option will slow down process creation somewhat.
config SCHED_STACK_END_CHECK
bool "Detect stack corruption on calls to schedule()"
depends on DEBUG_KERNEL
default n
help
This option checks for a stack overrun on calls to schedule().
If the stack end location is found to be over written always panic as
the content of the corrupted region can no longer be trusted.
This is to ensure no erroneous behaviour occurs which could result in
data corruption or a sporadic crash at a later stage once the region
is examined. The runtime overhead introduced is minimal.
config ARCH_HAS_DEBUG_VM_PGTABLE
bool
help
An architecture should select this when it can successfully
build and run DEBUG_VM_PGTABLE.
config DEBUG_VM_IRQSOFF
def_bool DEBUG_VM && !PREEMPT_RT
config DEBUG_VM
bool "Debug VM"
depends on DEBUG_KERNEL
help
Enable this to turn on extended checks in the virtual-memory system
that may impact performance.
If unsure, say N.
config DEBUG_VM_MAPLE_TREE
bool "Debug VM maple trees"
depends on DEBUG_VM
select DEBUG_MAPLE_TREE
help
Enable VM maple tree debugging information and extra validations.
If unsure, say N.
config DEBUG_VM_RB
bool "Debug VM red-black trees"
depends on DEBUG_VM
help
Enable VM red-black tree debugging information and extra validations.
If unsure, say N.
config DEBUG_VM_PGFLAGS
bool "Debug page-flags operations"
depends on DEBUG_VM
help
Enables extra validation on page flags operations.
If unsure, say N.
config DEBUG_VM_PGTABLE
bool "Debug arch page table for semantics compliance"
depends on MMU
depends on ARCH_HAS_DEBUG_VM_PGTABLE
default y if DEBUG_VM
help
This option provides a debug method which can be used to test
architecture page table helper functions on various platforms in
verifying if they comply with expected generic MM semantics. This
will help architecture code in making sure that any changes or
new additions of these helpers still conform to expected
semantics of the generic MM. Platforms will have to opt in for
this through ARCH_HAS_DEBUG_VM_PGTABLE.
If unsure, say N.
config ARCH_HAS_DEBUG_VIRTUAL
bool
config DEBUG_VIRTUAL
bool "Debug VM translations"
depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
help
Enable some costly sanity checks in virtual to page code. This can
catch mistakes with virt_to_page() and friends.
If unsure, say N.
config DEBUG_NOMMU_REGIONS
bool "Debug the global anon/private NOMMU mapping region tree"
depends on DEBUG_KERNEL && !MMU
help
This option causes the global tree of anonymous and private mapping
regions to be regularly checked for invalid topology.
config DEBUG_MEMORY_INIT
bool "Debug memory initialisation" if EXPERT
default !EXPERT
help
Enable this for additional checks during memory initialisation.
The sanity checks verify aspects of the VM such as the memory model
and other information provided by the architecture. Verbose
information will be printed at KERN_DEBUG loglevel depending
on the mminit_loglevel= command-line option.
If unsure, say Y
config MEMORY_NOTIFIER_ERROR_INJECT
tristate "Memory hotplug notifier error injection module"
depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
help
This option provides the ability to inject artificial errors to
memory hotplug notifier chain callbacks. It is controlled through
debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
Example: Inject memory hotplug offline error (-12 == -ENOMEM)
# cd /sys/kernel/debug/notifier-error-inject/memory
# echo -12 > actions/MEM_GOING_OFFLINE/error
# echo offline > /sys/devices/system/memory/memoryXXX/state
bash: echo: write error: Cannot allocate memory
To compile this code as a module, choose M here: the module will
be called memory-notifier-error-inject.
If unsure, say N.
config DEBUG_PER_CPU_MAPS
bool "Debug access to per_cpu maps"
depends on DEBUG_KERNEL
depends on SMP
help
Say Y to verify that the per_cpu map being accessed has
been set up. This adds a fair amount of code to kernel memory
and decreases performance.
Say N if unsure.
config DEBUG_KMAP_LOCAL
bool "Debug kmap_local temporary mappings"
depends on DEBUG_KERNEL && KMAP_LOCAL
help
This option enables additional error checking for the kmap_local
infrastructure. Disable for production use.
config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
bool
config DEBUG_KMAP_LOCAL_FORCE_MAP
bool "Enforce kmap_local temporary mappings"
depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
select KMAP_LOCAL
select DEBUG_KMAP_LOCAL
help
This option enforces temporary mappings through the kmap_local
mechanism for non-highmem pages and on non-highmem systems.
Disable this for production systems!
config DEBUG_HIGHMEM
bool "Highmem debugging"
depends on DEBUG_KERNEL && HIGHMEM
select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
select DEBUG_KMAP_LOCAL
help
This option enables additional error checking for high memory
systems. Disable for production systems.
config HAVE_DEBUG_STACKOVERFLOW
bool
config DEBUG_STACKOVERFLOW
bool "Check for stack overflows"
depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
help
Say Y here if you want to check for overflows of kernel, IRQ
and exception stacks (if your architecture uses them). This
option will show detailed messages if free stack space drops
below a certain limit.
These kinds of bugs usually occur when call-chains in the
kernel get too deep, especially when interrupts are
involved.
Use this in cases where you see apparently random memory
corruption, especially if it appears in 'struct thread_info'
If in doubt, say "N".
source "lib/Kconfig.kasan"
source "lib/Kconfig.kfence"
source "lib/Kconfig.kmsan"
endmenu # "Memory Debugging"
config DEBUG_SHIRQ
bool "Debug shared IRQ handlers"
depends on DEBUG_KERNEL
help
Enable this to generate a spurious interrupt just before a shared
interrupt handler is deregistered (generating one when registering
is currently disabled). Drivers need to handle this correctly. Some
don't and need to be caught.
menu "Debug Oops, Lockups and Hangs"