1menu "printk and dmesg options"
   2
   3config PRINTK_TIME
   4	bool "Show timing information on printks"
   5	depends on PRINTK
   6	help
   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
  16	  parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
  17
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  18config 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
  29	  Note: This does not affect the log level of un-prefixed printk()
  30	  usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
  31	  option.
  32
 
 
 
 
 
 
 
 
 
 
 
  33config MESSAGE_LOGLEVEL_DEFAULT
  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
  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
  48config 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
  66config 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/admin-guide/dynamic-debug-howto.rst for additional
 134	  information.
 135
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 136endmenu # "printk and dmesg options"
 137
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 138menu "Compile-time checks and compiler options"
 139
 140config DEBUG_INFO
 141	bool "Compile the kernel with debug info"
 142	depends on DEBUG_KERNEL && !COMPILE_TEST
 143	help
 144          If you say Y here the resulting kernel image will include
 145	  debugging info resulting in a larger kernel image.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 146	  This adds debug symbols to the kernel and modules (gcc -g), and
 147	  is needed if you intend to use kernel crashdump or binary object
 148	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 149	  Say Y here only if you plan to debug the kernel.
 150
 151	  If unsure, say N.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 152
 153config DEBUG_INFO_REDUCED
 154	bool "Reduce debugging information"
 155	depends on DEBUG_INFO
 156	help
 157	  If you say Y here gcc is instructed to generate less debugging
 158	  information for structure types. This means that tools that
 159	  need full debugging information (like kgdb or systemtap) won't
 160	  be happy. But if you merely need debugging information to
 161	  resolve line numbers there is no loss. Advantage is that
 162	  build directory object sizes shrink dramatically over a full
 163	  DEBUG_INFO build and compile times are reduced too.
 164	  Only works with newer gcc versions.
 165
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 166config DEBUG_INFO_SPLIT
 167	bool "Produce split debuginfo in .dwo files"
 168	depends on DEBUG_INFO
 
 
 
 
 
 169	help
 170	  Generate debug info into separate .dwo files. This significantly
 171	  reduces the build directory size for builds with DEBUG_INFO,
 172	  because it stores the information only once on disk in .dwo
 173	  files instead of multiple times in object files and executables.
 174	  In addition the debug information is also compressed.
 175
 176	  Requires recent gcc (4.7+) and recent gdb/binutils.
 177	  Any tool that packages or reads debug information would need
 178	  to know about the .dwo files and include them.
 179	  Incompatible with older versions of ccache.
 180
 181config DEBUG_INFO_DWARF4
 182	bool "Generate dwarf4 debuginfo"
 183	depends on DEBUG_INFO
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 184	help
 185	  Generate dwarf4 debug info. This requires recent versions
 186	  of gcc and gdb. It makes the debug information larger.
 187	  But it significantly improves the success of resolving
 188	  variables in gdb on optimized code.
 
 
 
 
 
 
 
 189
 190config GDB_SCRIPTS
 191	bool "Provide GDB scripts for kernel debugging"
 192	depends on DEBUG_INFO
 193	help
 194	  This creates the required links to GDB helper scripts in the
 195	  build directory. If you load vmlinux into gdb, the helper
 196	  scripts will be automatically imported by gdb as well, and
 197	  additional functions are available to analyze a Linux kernel
 198	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
 199	  for further details.
 200
 201config ENABLE_WARN_DEPRECATED
 202	bool "Enable __deprecated logic"
 203	default y
 204	help
 205	  Enable the __deprecated logic in the kernel build.
 206	  Disable this to suppress the "warning: 'foo' is deprecated
 207	  (declared at kernel/power/somefile.c:1234)" messages.
 208
 209config ENABLE_MUST_CHECK
 210	bool "Enable __must_check logic"
 211	default y
 212	help
 213	  Enable the __must_check logic in the kernel build.  Disable this to
 214	  suppress the "warning: ignoring return value of 'foo', declared with
 215	  attribute warn_unused_result" messages.
 216
 217config FRAME_WARN
 218	int "Warn for stack frames larger than (needs gcc 4.4)"
 219	range 0 8192
 220	default 3072 if KASAN_EXTRA
 221	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
 222	default 1280 if (!64BIT && PARISC)
 223	default 1024 if (!64BIT && !PARISC)
 
 
 224	default 2048 if 64BIT
 225	help
 226	  Tell gcc to warn at build time for stack frames larger than this.
 227	  Setting this too low will cause a lot of warnings.
 228	  Setting it to 0 disables the warning.
 229	  Requires gcc 4.4
 230
 231config STRIP_ASM_SYMS
 232	bool "Strip assembler-generated symbols during link"
 233	default n
 234	help
 235	  Strip internal assembler-generated symbols during a link (symbols
 236	  that look like '.Lxxx') so they don't pollute the output of
 237	  get_wchan() and suchlike.
 238
 239config READABLE_ASM
 240        bool "Generate readable assembler code"
 241        depends on DEBUG_KERNEL
 242        help
 243          Disable some compiler optimizations that tend to generate human unreadable
 244          assembler output. This may make the kernel slightly slower, but it helps
 245          to keep kernel developers who have to stare a lot at assembler listings
 246          sane.
 247
 248config UNUSED_SYMBOLS
 249	bool "Enable unused/obsolete exported symbols"
 250	default y if X86
 251	help
 252	  Unused but exported symbols make the kernel needlessly bigger.  For
 253	  that reason most of these unused exports will soon be removed.  This
 254	  option is provided temporarily to provide a transition period in case
 255	  some external kernel module needs one of these symbols anyway. If you
 256	  encounter such a case in your module, consider if you are actually
 257	  using the right API.  (rationale: since nobody in the kernel is using
 258	  this in a module, there is a pretty good chance it's actually the
 259	  wrong interface to use).  If you really need the symbol, please send a
 260	  mail to the linux kernel mailing list mentioning the symbol and why
 261	  you really need it, and what the merge plan to the mainline kernel for
 262	  your module is.
 263
 264config PAGE_OWNER
 265	bool "Track page owner"
 266	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
 267	select DEBUG_FS
 268	select STACKTRACE
 269	select STACKDEPOT
 270	select PAGE_EXTENSION
 271	help
 272	  This keeps track of what call chain is the owner of a page, may
 273	  help to find bare alloc_page(s) leaks. Even if you include this
 274	  feature on your build, it is disabled in default. You should pass
 275	  "page_owner=on" to boot parameter in order to enable it. Eats
 276	  a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
 277	  for user-space helper.
 278
 279	  If unsure, say N.
 280
 281config DEBUG_FS
 282	bool "Debug Filesystem"
 283	help
 284	  debugfs is a virtual file system that kernel developers use to put
 285	  debugging files into.  Enable this option to be able to read and
 286	  write to these files.
 287
 288	  For detailed documentation on the debugfs API, see
 289	  Documentation/filesystems/.
 290
 291	  If unsure, say N.
 292
 293config HEADERS_CHECK
 294	bool "Run 'make headers_check' when building vmlinux"
 295	depends on !UML
 296	help
 297	  This option will extract the user-visible kernel headers whenever
 298	  building the kernel, and will run basic sanity checks on them to
 299	  ensure that exported files do not attempt to include files which
 300	  were not exported, etc.
 301
 302	  If you're making modifications to header files which are
 303	  relevant for userspace, say 'Y', and check the headers
 304	  exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 305	  your build tree), to make sure they're suitable.
 306
 307config DEBUG_SECTION_MISMATCH
 308	bool "Enable full Section mismatch analysis"
 
 309	help
 310	  The section mismatch analysis checks if there are illegal
 311	  references from one section to another section.
 312	  During linktime or runtime, some sections are dropped;
 313	  any use of code/data previously in these sections would
 314	  most likely result in an oops.
 315	  In the code, functions and variables are annotated with
 316	  __init,, etc. (see the full list in include/linux/init.h),
 317	  which results in the code/data being placed in specific sections.
 318	  The section mismatch analysis is always performed after a full
 319	  kernel build, and enabling this option causes the following
 320	  additional steps to occur:
 321	  - Add the option -fno-inline-functions-called-once to gcc commands.
 322	    When inlining a function annotated with __init in a non-init
 323	    function, we would lose the section information and thus
 324	    the analysis would not catch the illegal reference.
 325	    This option tells gcc to inline less (but it does result in
 326	    a larger kernel).
 327	  - Run the section mismatch analysis for each module/built-in.a file.
 328	    When we run the section mismatch analysis on vmlinux.o, we
 329	    lose valuable information about where the mismatch was
 330	    introduced.
 331	    Running the analysis for each module/built-in.a file
 332	    tells where the mismatch happens much closer to the
 333	    source. The drawback is that the same mismatch is
 334	    reported at least twice.
 335	  - Enable verbose reporting from modpost in order to help resolve
 336	    the section mismatches that are reported.
 337
 338config SECTION_MISMATCH_WARN_ONLY
 339	bool "Make section mismatch errors non-fatal"
 340	default y
 341	help
 342	  If you say N here, the build process will fail if there are any
 343	  section mismatch, instead of just throwing warnings.
 344
 345	  If unsure, say Y.
 346
 
 
 
 
 
 
 
 
 
 
 
 
 
 347#
 348# Select this config option from the architecture Kconfig, if it
 349# is preferred to always offer frame pointers as a config
 350# option on the architecture (regardless of KERNEL_DEBUG):
 351#
 352config ARCH_WANT_FRAME_POINTERS
 353	bool
 354
 355config FRAME_POINTER
 356	bool "Compile the kernel with frame pointers"
 357	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
 358	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 359	help
 360	  If you say Y here the resulting kernel image will be slightly
 361	  larger and slower, but it gives very useful debugging information
 362	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
 363
 
 
 
 364config STACK_VALIDATION
 365	bool "Compile-time stack metadata validation"
 366	depends on HAVE_STACK_VALIDATION
 
 367	default n
 368	help
 369	  Add compile-time checks to validate stack metadata, including frame
 370	  pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
 371	  that runtime stack traces are more reliable.
 372
 373	  This is also a prerequisite for generation of ORC unwind data, which
 374	  is needed for CONFIG_UNWINDER_ORC.
 375
 376	  For more information, see
 377	  tools/objtool/Documentation/stack-validation.txt.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 378
 379config DEBUG_FORCE_WEAK_PER_CPU
 380	bool "Force weak per-cpu definitions"
 381	depends on DEBUG_KERNEL
 382	help
 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.
 387
 388	  1. percpu symbols must be unique whether static or not
 389	  2. percpu variables can't be defined inside a function
 390
 391	  To ensure that generic code follows the above rules, this
 392	  option forces all percpu variables to be defined as weak.
 393
 394endmenu # "Compiler options"
 395
 
 
 396config 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/admin-guide/sysrq.rst>.
 408	  Don't say Y unless you really know what this hack does.
 409
 410config 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/admin-guide/sysrq.rst.
 418
 419config MAGIC_SYSRQ_SERIAL
 420	bool "Enable magic SysRq key over serial"
 421	depends on MAGIC_SYSRQ
 422	default y
 423	help
 424	  Many embedded boards have a disconnected TTL level serial which can
 425	  generate some garbage that can lead to spurious false sysrq detects.
 426	  This option allows you to decide whether you want to enable the
 427	  magic SysRq key.
 428
 429config DEBUG_KERNEL
 430	bool "Kernel debugging"
 
 
 431	help
 432	  Say Y here if you are developing drivers or trying to debug and
 433	  identify kernel problems.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 434
 435menu "Memory Debugging"
 436
 437source mm/Kconfig.debug
 438
 439config DEBUG_OBJECTS
 440	bool "Debug object operations"
 441	depends on DEBUG_KERNEL
 442	help
 443	  If you say Y here, additional code will be inserted into the
 444	  kernel to track the life time of various objects and validate
 445	  the operations on those objects.
 446
 447config DEBUG_OBJECTS_SELFTEST
 448	bool "Debug objects selftest"
 449	depends on DEBUG_OBJECTS
 450	help
 451	  This enables the selftest of the object debug code.
 452
 453config DEBUG_OBJECTS_FREE
 454	bool "Debug objects in freed memory"
 455	depends on DEBUG_OBJECTS
 456	help
 457	  This enables checks whether a k/v free operation frees an area
 458	  which contains an object which has not been deactivated
 459	  properly. This can make kmalloc/kfree-intensive workloads
 460	  much slower.
 461
 462config DEBUG_OBJECTS_TIMERS
 463	bool "Debug timer objects"
 464	depends on DEBUG_OBJECTS
 465	help
 466	  If you say Y here, additional code will be inserted into the
 467	  timer routines to track the life time of timer objects and
 468	  validate the timer operations.
 469
 470config DEBUG_OBJECTS_WORK
 471	bool "Debug work objects"
 472	depends on DEBUG_OBJECTS
 473	help
 474	  If you say Y here, additional code will be inserted into the
 475	  work queue routines to track the life time of work objects and
 476	  validate the work operations.
 477
 478config DEBUG_OBJECTS_RCU_HEAD
 479	bool "Debug RCU callbacks objects"
 480	depends on DEBUG_OBJECTS
 481	help
 482	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 483
 484config DEBUG_OBJECTS_PERCPU_COUNTER
 485	bool "Debug percpu counter objects"
 486	depends on DEBUG_OBJECTS
 487	help
 488	  If you say Y here, additional code will be inserted into the
 489	  percpu counter routines to track the life time of percpu counter
 490	  objects and validate the percpu counter operations.
 491
 492config DEBUG_OBJECTS_ENABLE_DEFAULT
 493	int "debug_objects bootup default value (0-1)"
 494        range 0 1
 495        default "1"
 496        depends on DEBUG_OBJECTS
 497        help
 498          Debug objects boot parameter default value
 499
 500config DEBUG_SLAB
 501	bool "Debug slab memory allocations"
 502	depends on DEBUG_KERNEL && SLAB
 503	help
 504	  Say Y here to have the kernel do limited verification on memory
 505	  allocation as well as poisoning memory on free to catch use of freed
 506	  memory. This can make kmalloc/kfree-intensive workloads much slower.
 507
 508config DEBUG_SLAB_LEAK
 509	bool "Memory leak debugging"
 510	depends on DEBUG_SLAB
 511
 512config SLUB_DEBUG_ON
 513	bool "SLUB debugging on by default"
 514	depends on SLUB && SLUB_DEBUG
 515	default n
 516	help
 517	  Boot with debugging on by default. SLUB boots by default with
 518	  the runtime debug capabilities switched off. Enabling this is
 519	  equivalent to specifying the "slub_debug" parameter on boot.
 520	  There is no support for more fine grained debug control like
 521	  possible with slub_debug=xxx. SLUB debugging may be switched
 522	  off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 523	  "slub_debug=-".
 524
 525config SLUB_STATS
 526	default n
 527	bool "Enable SLUB performance statistics"
 528	depends on SLUB && SYSFS
 529	help
 530	  SLUB statistics are useful to debug SLUBs allocation behavior in
 531	  order find ways to optimize the allocator. This should never be
 532	  enabled for production use since keeping statistics slows down
 533	  the allocator by a few percentage points. The slabinfo command
 534	  supports the determination of the most active slabs to figure
 535	  out which slabs are relevant to a particular load.
 536	  Try running: slabinfo -DA
 537
 538config HAVE_DEBUG_KMEMLEAK
 539	bool
 540
 541config DEBUG_KMEMLEAK
 542	bool "Kernel memory leak detector"
 543	depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
 544	select DEBUG_FS
 545	select STACKTRACE if STACKTRACE_SUPPORT
 546	select KALLSYMS
 547	select CRC32
 548	help
 549	  Say Y here if you want to enable the memory leak
 550	  detector. The memory allocation/freeing is traced in a way
 551	  similar to the Boehm's conservative garbage collector, the
 552	  difference being that the orphan objects are not freed but
 553	  only shown in /sys/kernel/debug/kmemleak. Enabling this
 554	  feature will introduce an overhead to memory
 555	  allocations. See Documentation/dev-tools/kmemleak.rst for more
 556	  details.
 557
 558	  Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 559	  of finding leaks due to the slab objects poisoning.
 560
 561	  In order to access the kmemleak file, debugfs needs to be
 562	  mounted (usually at /sys/kernel/debug).
 563
 564config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 565	int "Maximum kmemleak early log entries"
 566	depends on DEBUG_KMEMLEAK
 567	range 200 40000
 568	default 400
 569	help
 570	  Kmemleak must track all the memory allocations to avoid
 571	  reporting false positives. Since memory may be allocated or
 572	  freed before kmemleak is initialised, an early log buffer is
 573	  used to store these actions. If kmemleak reports "early log
 574	  buffer exceeded", please increase this value.
 575
 576config DEBUG_KMEMLEAK_TEST
 577	tristate "Simple test for the kernel memory leak detector"
 578	depends on DEBUG_KMEMLEAK && m
 579	help
 580	  This option enables a module that explicitly leaks memory.
 581
 582	  If unsure, say N.
 583
 584config DEBUG_KMEMLEAK_DEFAULT_OFF
 585	bool "Default kmemleak to off"
 586	depends on DEBUG_KMEMLEAK
 587	help
 588	  Say Y here to disable kmemleak by default. It can then be enabled
 589	  on the command line via kmemleak=on.
 
 590
 591config DEBUG_STACK_USAGE
 592	bool "Stack utilization instrumentation"
 593	depends on DEBUG_KERNEL && !IA64
 594	help
 595	  Enables the display of the minimum amount of free stack which each
 596	  task has ever had available in the sysrq-T and sysrq-P debug output.
 
 
 597
 598	  This option will slow down process creation somewhat.
 599
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 600config DEBUG_VM
 601	bool "Debug VM"
 602	depends on DEBUG_KERNEL
 603	help
 604	  Enable this to turn on extended checks in the virtual-memory system
 605          that may impact performance.
 
 
 
 
 
 
 
 
 
 
 606
 607	  If unsure, say N.
 608
 609config DEBUG_VM_VMACACHE
 610	bool "Debug VMA caching"
 611	depends on DEBUG_VM
 
 612	help
 613	  Enable this to turn on VMA caching debug information. Doing so
 614	  can cause significant overhead, so only enable it in non-production
 615	  environments.
 616
 617	  If unsure, say N.
 618
 619config DEBUG_VM_RB
 620	bool "Debug VM red-black trees"
 621	depends on DEBUG_VM
 622	help
 623	  Enable VM red-black tree debugging information and extra validations.
 624
 625	  If unsure, say N.
 626
 627config DEBUG_VM_PGFLAGS
 628	bool "Debug page-flags operations"
 629	depends on DEBUG_VM
 630	help
 631	  Enables extra validation on page flags operations.
 632
 633	  If unsure, say N.
 634
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 635config ARCH_HAS_DEBUG_VIRTUAL
 636	bool
 637
 638config DEBUG_VIRTUAL
 639	bool "Debug VM translations"
 640	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
 641	help
 642	  Enable some costly sanity checks in virtual to page code. This can
 643	  catch mistakes with virt_to_page() and friends.
 644
 645	  If unsure, say N.
 646
 647config DEBUG_NOMMU_REGIONS
 648	bool "Debug the global anon/private NOMMU mapping region tree"
 649	depends on DEBUG_KERNEL && !MMU
 650	help
 651	  This option causes the global tree of anonymous and private mapping
 652	  regions to be regularly checked for invalid topology.
 653
 654config DEBUG_MEMORY_INIT
 655	bool "Debug memory initialisation" if EXPERT
 656	default !EXPERT
 657	help
 658	  Enable this for additional checks during memory initialisation.
 659	  The sanity checks verify aspects of the VM such as the memory model
 660	  and other information provided by the architecture. Verbose
 661	  information will be printed at KERN_DEBUG loglevel depending
 662	  on the mminit_loglevel= command-line option.
 663
 664	  If unsure, say Y
 665
 666config MEMORY_NOTIFIER_ERROR_INJECT
 667	tristate "Memory hotplug notifier error injection module"
 668	depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
 669	help
 670	  This option provides the ability to inject artificial errors to
 671	  memory hotplug notifier chain callbacks.  It is controlled through
 672	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
 673
 674	  If the notifier call chain should be failed with some events
 675	  notified, write the error code to "actions/<notifier event>/error".
 676
 677	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
 678
 679	  # cd /sys/kernel/debug/notifier-error-inject/memory
 680	  # echo -12 > actions/MEM_GOING_OFFLINE/error
 681	  # echo offline > /sys/devices/system/memory/memoryXXX/state
 682	  bash: echo: write error: Cannot allocate memory
 683
 684	  To compile this code as a module, choose M here: the module will
 685	  be called memory-notifier-error-inject.
 686
 687	  If unsure, say N.
 688
 689config DEBUG_PER_CPU_MAPS
 690	bool "Debug access to per_cpu maps"
 691	depends on DEBUG_KERNEL
 692	depends on SMP
 693	help
 694	  Say Y to verify that the per_cpu map being accessed has
 695	  been set up. This adds a fair amount of code to kernel memory
 696	  and decreases performance.
 697
 698	  Say N if unsure.
 699
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 700config DEBUG_HIGHMEM
 701	bool "Highmem debugging"
 702	depends on DEBUG_KERNEL && HIGHMEM
 
 
 703	help
 704	  This option enables additional error checking for high memory
 705	  systems.  Disable for production systems.
 706
 707config HAVE_DEBUG_STACKOVERFLOW
 708	bool
 709
 710config DEBUG_STACKOVERFLOW
 711	bool "Check for stack overflows"
 712	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
 713	---help---
 714	  Say Y here if you want to check for overflows of kernel, IRQ
 715	  and exception stacks (if your architecture uses them). This
 716	  option will show detailed messages if free stack space drops
 717	  below a certain limit.
 718
 719	  These kinds of bugs usually occur when call-chains in the
 720	  kernel get too deep, especially when interrupts are
 721	  involved.
 722
 723	  Use this in cases where you see apparently random memory
 724	  corruption, especially if it appears in 'struct thread_info'
 725
 726	  If in doubt, say "N".
 727
 728source "lib/Kconfig.kasan"
 729
 730endmenu # "Memory Debugging"
 731
 732config ARCH_HAS_KCOV
 733	bool
 734	help
 735	  KCOV does not have any arch-specific code, but currently it is enabled
 736	  only for x86_64. KCOV requires testing on other archs, and most likely
 737	  disabling of instrumentation for some early boot code.
 738
 739config KCOV
 740	bool "Code coverage for fuzzing"
 741	depends on ARCH_HAS_KCOV
 742	select DEBUG_FS
 743	select GCC_PLUGINS if !COMPILE_TEST
 744	select GCC_PLUGIN_SANCOV if !COMPILE_TEST
 
 
 
 745	help
 746	  KCOV exposes kernel code coverage information in a form suitable
 747	  for coverage-guided fuzzing (randomized testing).
 
 748
 749	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
 750	  different machines and across reboots. If you need stable PC values,
 751	  disable RANDOMIZE_BASE.
 752
 753	  For more details, see Documentation/dev-tools/kcov.rst.
 754
 755config KCOV_ENABLE_COMPARISONS
 756	bool "Enable comparison operands collection by KCOV"
 757	depends on KCOV
 758	default n
 
 
 759	help
 760	  KCOV also exposes operands of every comparison in the instrumented
 761	  code along with operand sizes and PCs of the comparison instructions.
 762	  These operands can be used by fuzzing engines to improve the quality
 763	  of fuzzing coverage.
 764
 765config KCOV_INSTRUMENT_ALL
 766	bool "Instrument all code by default"
 767	depends on KCOV
 768	default y if KCOV
 769	help
 770	  If you are doing generic system call fuzzing (like e.g. syzkaller),
 771	  then you will want to instrument the whole kernel and you should
 772	  say y here. If you are doing more targeted fuzzing (like e.g.
 773	  filesystem fuzzing with AFL) then you will want to enable coverage
 774	  for more specific subsets of files, and should say n here.
 775
 776config DEBUG_SHIRQ
 777	bool "Debug shared IRQ handlers"
 778	depends on DEBUG_KERNEL
 779	help
 780	  Enable this to generate a spurious interrupt as soon as a shared
 781	  interrupt handler is registered, and just before one is deregistered.
 782	  Drivers ought to be able to handle interrupts coming in at those
 783	  points; some don't and need to be caught.
 
 
 
 
 
 
 
 
 
 784
 785menu "Debug Lockups and Hangs"
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 786
 787config LOCKUP_DETECTOR
 788	bool
 789
 790config SOFTLOCKUP_DETECTOR
 791	bool "Detect Soft Lockups"
 792	depends on DEBUG_KERNEL && !S390
 793	select LOCKUP_DETECTOR
 794	help
 795	  Say Y here to enable the kernel to act as a watchdog to detect
 796	  soft lockups.
 797
 798	  Softlockups are bugs that cause the kernel to loop in kernel
 799	  mode for more than 20 seconds, without giving other tasks a
 800	  chance to run.  The current stack trace is displayed upon
 801	  detection and the system will stay locked up.
 802
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 803config BOOTPARAM_SOFTLOCKUP_PANIC
 804	bool "Panic (Reboot) On Soft Lockups"
 805	depends on SOFTLOCKUP_DETECTOR
 806	help
 807	  Say Y here to enable the kernel to panic on "soft lockups",
 808	  which are bugs that cause the kernel to loop in kernel
 809	  mode for more than 20 seconds (configurable using the watchdog_thresh
 810	  sysctl), without giving other tasks a chance to run.
 811
 812	  The panic can be used in combination with panic_timeout,
 813	  to cause the system to reboot automatically after a
 814	  lockup has been detected. This feature is useful for
 815	  high-availability systems that have uptime guarantees and
 816	  where a lockup must be resolved ASAP.
 817
 818	  Say N if unsure.
 819
 820config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 821	int
 822	depends on SOFTLOCKUP_DETECTOR
 823	range 0 1
 824	default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 825	default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 826
 827config HARDLOCKUP_DETECTOR_PERF
 828	bool
 829	select SOFTLOCKUP_DETECTOR
 
 830
 831#
 832# Enables a timestamp based low pass filter to compensate for perf based
 833# hard lockup detection which runs too fast due to turbo modes.
 
 834#
 835config HARDLOCKUP_CHECK_TIMESTAMP
 836	bool
 837
 838#
 839# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
 840# lockup detector rather than the perf based detector.
 841#
 842config HARDLOCKUP_DETECTOR
 843	bool "Detect Hard Lockups"
 844	depends on DEBUG_KERNEL && !S390
 845	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
 
 
 
 846	select LOCKUP_DETECTOR
 847	select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
 848	select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
 849	help
 850	  Say Y here to enable the kernel to act as a watchdog to detect
 851	  hard lockups.
 852
 853	  Hardlockups are bugs that cause the CPU to loop in kernel mode
 854	  for more than 10 seconds, without letting other interrupts have a
 855	  chance to run.  The current stack trace is displayed upon detection
 856	  and the system will stay locked up.
 857
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 858config BOOTPARAM_HARDLOCKUP_PANIC
 859	bool "Panic (Reboot) On Hard Lockups"
 860	depends on HARDLOCKUP_DETECTOR
 861	help
 862	  Say Y here to enable the kernel to panic on "hard lockups",
 863	  which are bugs that cause the kernel to loop in kernel
 864	  mode with interrupts disabled for more than 10 seconds (configurable
 865	  using the watchdog_thresh sysctl).
 866
 867	  Say N if unsure.
 868
 869config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 870	int
 871	depends on HARDLOCKUP_DETECTOR
 872	range 0 1
 873	default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
 874	default 1 if BOOTPARAM_HARDLOCKUP_PANIC
 875
 876config DETECT_HUNG_TASK
 877	bool "Detect Hung Tasks"
 878	depends on DEBUG_KERNEL
 879	default SOFTLOCKUP_DETECTOR
 880	help
 881	  Say Y here to enable the kernel to detect "hung tasks",
 882	  which are bugs that cause the task to be stuck in
 883	  uninterruptible "D" state indefinitely.
 884
 885	  When a hung task is detected, the kernel will print the
 886	  current stack trace (which you should report), but the
 887	  task will stay in uninterruptible state. If lockdep is
 888	  enabled then all held locks will also be reported. This
 889	  feature has negligible overhead.
 890
 891config DEFAULT_HUNG_TASK_TIMEOUT
 892	int "Default timeout for hung task detection (in seconds)"
 893	depends on DETECT_HUNG_TASK
 894	default 120
 895	help
 896	  This option controls the default timeout (in seconds) used
 897	  to determine when a task has become non-responsive and should
 898	  be considered hung.
 899
 900	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
 901	  sysctl or by writing a value to
 902	  /proc/sys/kernel/hung_task_timeout_secs.
 903
 904	  A timeout of 0 disables the check.  The default is two minutes.
 905	  Keeping the default should be fine in most cases.
 906
 907config BOOTPARAM_HUNG_TASK_PANIC
 908	bool "Panic (Reboot) On Hung Tasks"
 909	depends on DETECT_HUNG_TASK
 910	help
 911	  Say Y here to enable the kernel to panic on "hung tasks",
 912	  which are bugs that cause the kernel to leave a task stuck
 913	  in uninterruptible "D" state.
 914
 915	  The panic can be used in combination with panic_timeout,
 916	  to cause the system to reboot automatically after a
 917	  hung task has been detected. This feature is useful for
 918	  high-availability systems that have uptime guarantees and
 919	  where a hung tasks must be resolved ASAP.
 920
 921	  Say N if unsure.
 922
 923config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 924	int
 925	depends on DETECT_HUNG_TASK
 926	range 0 1
 927	default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 928	default 1 if BOOTPARAM_HUNG_TASK_PANIC
 929
 930config WQ_WATCHDOG
 931	bool "Detect Workqueue Stalls"
 932	depends on DEBUG_KERNEL
 933	help
 934	  Say Y here to enable stall detection on workqueues.  If a
 935	  worker pool doesn't make forward progress on a pending work
 936	  item for over a given amount of time, 30s by default, a
 937	  warning message is printed along with dump of workqueue
 938	  state.  This can be configured through kernel parameter
 939	  "workqueue.watchdog_thresh" and its sysfs counterpart.
 940
 941endmenu # "Debug lockups and hangs"
 
 
 
 
 
 
 
 
 
 
 
 942
 943config PANIC_ON_OOPS
 944	bool "Panic on Oops"
 
 945	help
 946	  Say Y here to enable the kernel to panic when it oopses. This
 947	  has the same effect as setting oops=panic on the kernel command
 948	  line.
 949
 950	  This feature is useful to ensure that the kernel does not do
 951	  anything erroneous after an oops which could result in data
 952	  corruption or other issues.
 953
 954	  Say N if unsure.
 955
 956config PANIC_ON_OOPS_VALUE
 957	int
 958	range 0 1
 959	default 0 if !PANIC_ON_OOPS
 960	default 1 if PANIC_ON_OOPS
 961
 962config PANIC_TIMEOUT
 963	int "panic timeout"
 964	default 0
 965	help
 966	  Set the timeout value (in seconds) until a reboot occurs when the
 967	  the kernel panics. If n = 0, then we wait forever. A timeout
 968	  value n > 0 will wait n seconds before rebooting, while a timeout
 969	  value n < 0 will reboot immediately.
 970
 971config SCHED_DEBUG
 972	bool "Collect scheduler debugging info"
 973	depends on DEBUG_KERNEL && PROC_FS
 974	default y
 975	help
 976	  If you say Y here, the /proc/sched_debug file will be provided
 977	  that can help debug the scheduler. The runtime overhead of this
 978	  option is minimal.
 979
 980config SCHED_INFO
 981	bool
 982	default n
 983
 984config SCHEDSTATS
 985	bool "Collect scheduler statistics"
 986	depends on DEBUG_KERNEL && PROC_FS
 987	select SCHED_INFO
 988	help
 989	  If you say Y here, additional code will be inserted into the
 990	  scheduler and related routines to collect statistics about
 991	  scheduler behavior and provide them in /proc/schedstat.  These
 992	  stats may be useful for both tuning and debugging the scheduler
 993	  If you aren't debugging the scheduler or trying to tune a specific
 994	  application, you can say N to avoid the very slight overhead
 995	  this adds.
 996
 997config SCHED_STACK_END_CHECK
 998	bool "Detect stack corruption on calls to schedule()"
 999	depends on DEBUG_KERNEL
1000	default n
1001	help
1002	  This option checks for a stack overrun on calls to schedule().
1003	  If the stack end location is found to be over written always panic as
1004	  the content of the corrupted region can no longer be trusted.
1005	  This is to ensure no erroneous behaviour occurs which could result in
1006	  data corruption or a sporadic crash at a later stage once the region
1007	  is examined. The runtime overhead introduced is minimal.
1008
1009config DEBUG_TIMEKEEPING
1010	bool "Enable extra timekeeping sanity checking"
1011	help
1012	  This option will enable additional timekeeping sanity checks
1013	  which may be helpful when diagnosing issues where timekeeping
1014	  problems are suspected.
1015
1016	  This may include checks in the timekeeping hotpaths, so this
1017	  option may have a (very small) performance impact to some
1018	  workloads.
1019
1020	  If unsure, say N.
1021
1022config DEBUG_PREEMPT
1023	bool "Debug preemptible kernel"
1024	depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1025	default y
1026	help
1027	  If you say Y here then the kernel will use a debug variant of the
1028	  commonly used smp_processor_id() function and will print warnings
1029	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1030	  will detect preemption count underflows.
1031
 
 
 
 
1032menu "Lock Debugging (spinlocks, mutexes, etc...)"
1033
1034config LOCK_DEBUGGING_SUPPORT
1035	bool
1036	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1037	default y
1038
1039config PROVE_LOCKING
1040	bool "Lock debugging: prove locking correctness"
1041	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1042	select LOCKDEP
1043	select DEBUG_SPINLOCK
1044	select DEBUG_MUTEXES
1045	select DEBUG_RT_MUTEXES if RT_MUTEXES
1046	select DEBUG_RWSEMS if RWSEM_SPIN_ON_OWNER
1047	select DEBUG_WW_MUTEX_SLOWPATH
1048	select DEBUG_LOCK_ALLOC
 
1049	select TRACE_IRQFLAGS
1050	default n
1051	help
1052	 This feature enables the kernel to prove that all locking
1053	 that occurs in the kernel runtime is mathematically
1054	 correct: that under no circumstance could an arbitrary (and
1055	 not yet triggered) combination of observed locking
1056	 sequences (on an arbitrary number of CPUs, running an
1057	 arbitrary number of tasks and interrupt contexts) cause a
1058	 deadlock.
1059
1060	 In short, this feature enables the kernel to report locking
1061	 related deadlocks before they actually occur.
1062
1063	 The proof does not depend on how hard and complex a
1064	 deadlock scenario would be to trigger: how many
1065	 participant CPUs, tasks and irq-contexts would be needed
1066	 for it to trigger. The proof also does not depend on
1067	 timing: if a race and a resulting deadlock is possible
1068	 theoretically (no matter how unlikely the race scenario
1069	 is), it will be proven so and will immediately be
1070	 reported by the kernel (once the event is observed that
1071	 makes the deadlock theoretically possible).
1072
1073	 If a deadlock is impossible (i.e. the locking rules, as
1074	 observed by the kernel, are mathematically correct), the
1075	 kernel reports nothing.
1076
1077	 NOTE: this feature can also be enabled for rwlocks, mutexes
1078	 and rwsems - in which case all dependencies between these
1079	 different locking variants are observed and mapped too, and
1080	 the proof of observed correctness is also maintained for an
1081	 arbitrary combination of these separate locking variants.
1082
1083	 For more details, see Documentation/locking/lockdep-design.txt.
 
 
 
 
 
 
 
 
 
1084
1085config LOCK_STAT
1086	bool "Lock usage statistics"
1087	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1088	select LOCKDEP
1089	select DEBUG_SPINLOCK
1090	select DEBUG_MUTEXES
1091	select DEBUG_RT_MUTEXES if RT_MUTEXES
1092	select DEBUG_LOCK_ALLOC
1093	default n
1094	help
1095	 This feature enables tracking lock contention points
1096
1097	 For more details, see Documentation/locking/lockstat.txt
1098
1099	 This also enables lock events required by "perf lock",
1100	 subcommand of perf.
1101	 If you want to use "perf lock", you also need to turn on
1102	 CONFIG_EVENT_TRACING.
1103
1104	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1105	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1106
1107config DEBUG_RT_MUTEXES
1108	bool "RT Mutex debugging, deadlock detection"
1109	depends on DEBUG_KERNEL && RT_MUTEXES
1110	help
1111	 This allows rt mutex semantics violations and rt mutex related
1112	 deadlocks (lockups) to be detected and reported automatically.
1113
1114config DEBUG_SPINLOCK
1115	bool "Spinlock and rw-lock debugging: basic checks"
1116	depends on DEBUG_KERNEL
1117	select UNINLINE_SPIN_UNLOCK
1118	help
1119	  Say Y here and build SMP to catch missing spinlock initialization
1120	  and certain other kinds of spinlock errors commonly made.  This is
1121	  best used in conjunction with the NMI watchdog so that spinlock
1122	  deadlocks are also debuggable.
1123
1124config DEBUG_MUTEXES
1125	bool "Mutex debugging: basic checks"
1126	depends on DEBUG_KERNEL
1127	help
1128	 This feature allows mutex semantics violations to be detected and
1129	 reported.
1130
1131config DEBUG_WW_MUTEX_SLOWPATH
1132	bool "Wait/wound mutex debugging: Slowpath testing"
1133	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1134	select DEBUG_LOCK_ALLOC
1135	select DEBUG_SPINLOCK
1136	select DEBUG_MUTEXES
 
1137	help
1138	 This feature enables slowpath testing for w/w mutex users by
1139	 injecting additional -EDEADLK wound/backoff cases. Together with
1140	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1141	 will test all possible w/w mutex interface abuse with the
1142	 exception of simply not acquiring all the required locks.
1143	 Note that this feature can introduce significant overhead, so
1144	 it really should not be enabled in a production or distro kernel,
1145	 even a debug kernel.  If you are a driver writer, enable it.  If
1146	 you are a distro, do not.
1147
1148config DEBUG_RWSEMS
1149	bool "RW Semaphore debugging: basic checks"
1150	depends on DEBUG_KERNEL && RWSEM_SPIN_ON_OWNER
1151	help
1152	  This debugging feature allows mismatched rw semaphore locks and unlocks
1153	  to be detected and reported.
1154
1155config DEBUG_LOCK_ALLOC
1156	bool "Lock debugging: detect incorrect freeing of live locks"
1157	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1158	select DEBUG_SPINLOCK
1159	select DEBUG_MUTEXES
1160	select DEBUG_RT_MUTEXES if RT_MUTEXES
1161	select LOCKDEP
1162	help
1163	 This feature will check whether any held lock (spinlock, rwlock,
1164	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1165	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1166	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1167	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1168	 held during task exit.
1169
1170config LOCKDEP
1171	bool
1172	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1173	select STACKTRACE
1174	select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !X86
1175	select KALLSYMS
1176	select KALLSYMS_ALL
1177
1178config LOCKDEP_SMALL
1179	bool
1180
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1181config DEBUG_LOCKDEP
1182	bool "Lock dependency engine debugging"
1183	depends on DEBUG_KERNEL && LOCKDEP
 
1184	help
1185	  If you say Y here, the lock dependency engine will do
1186	  additional runtime checks to debug itself, at the price
1187	  of more runtime overhead.
1188
1189config DEBUG_ATOMIC_SLEEP
1190	bool "Sleep inside atomic section checking"
1191	select PREEMPT_COUNT
1192	depends on DEBUG_KERNEL
 
1193	help
1194	  If you say Y here, various routines which may sleep will become very
1195	  noisy if they are called inside atomic sections: when a spinlock is
1196	  held, inside an rcu read side critical section, inside preempt disabled
1197	  sections, inside an interrupt, etc...
1198
1199config DEBUG_LOCKING_API_SELFTESTS
1200	bool "Locking API boot-time self-tests"
1201	depends on DEBUG_KERNEL
1202	help
1203	  Say Y here if you want the kernel to run a short self-test during
1204	  bootup. The self-test checks whether common types of locking bugs
1205	  are detected by debugging mechanisms or not. (if you disable
1206	  lock debugging then those bugs wont be detected of course.)
1207	  The following locking APIs are covered: spinlocks, rwlocks,
1208	  mutexes and rwsems.
1209
1210config LOCK_TORTURE_TEST
1211	tristate "torture tests for locking"
1212	depends on DEBUG_KERNEL
1213	select TORTURE_TEST
1214	default n
1215	help
1216	  This option provides a kernel module that runs torture tests
1217	  on kernel locking primitives.  The kernel module may be built
1218	  after the fact on the running kernel to be tested, if desired.
1219
1220	  Say Y here if you want kernel locking-primitive torture tests
1221	  to be built into the kernel.
1222	  Say M if you want these torture tests to build as a module.
1223	  Say N if you are unsure.
1224
1225config WW_MUTEX_SELFTEST
1226	tristate "Wait/wound mutex selftests"
1227	help
1228	  This option provides a kernel module that runs tests on the
1229	  on the struct ww_mutex locking API.
1230
1231	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1232	  with this test harness.
1233
1234	  Say M if you want these self tests to build as a module.
1235	  Say N if you are unsure.
1236
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1237endmenu # lock debugging
1238
1239config TRACE_IRQFLAGS
 
1240	bool
1241	help
1242	  Enables hooks to interrupt enabling and disabling for
1243	  either tracing or lock debugging.
1244
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1245config STACKTRACE
1246	bool "Stack backtrace support"
1247	depends on STACKTRACE_SUPPORT
1248	help
1249	  This option causes the kernel to create a /proc/pid/stack for
1250	  every process, showing its current stack trace.
1251	  It is also used by various kernel debugging features that require
1252	  stack trace generation.
1253
1254config WARN_ALL_UNSEEDED_RANDOM
1255	bool "Warn for all uses of unseeded randomness"
1256	default n
1257	help
1258	  Some parts of the kernel contain bugs relating to their use of
1259	  cryptographically secure random numbers before it's actually possible
1260	  to generate those numbers securely. This setting ensures that these
1261	  flaws don't go unnoticed, by enabling a message, should this ever
1262	  occur. This will allow people with obscure setups to know when things
1263	  are going wrong, so that they might contact developers about fixing
1264	  it.
1265
1266	  Unfortunately, on some models of some architectures getting
1267	  a fully seeded CRNG is extremely difficult, and so this can
1268	  result in dmesg getting spammed for a surprisingly long
1269	  time.  This is really bad from a security perspective, and
1270	  so architecture maintainers really need to do what they can
1271	  to get the CRNG seeded sooner after the system is booted.
1272	  However, since users can not do anything actionble to
1273	  address this, by default the kernel will issue only a single
1274	  warning for the first use of unseeded randomness.
1275
1276	  Say Y here if you want to receive warnings for all uses of
1277	  unseeded randomness.  This will be of use primarily for
1278	  those developers interersted in improving the security of
1279	  Linux kernels running on their architecture (or
1280	  subarchitecture).
1281
1282config DEBUG_KOBJECT
1283	bool "kobject debugging"
1284	depends on DEBUG_KERNEL
1285	help
1286	  If you say Y here, some extra kobject debugging messages will be sent
1287	  to the syslog. 
1288
1289config DEBUG_KOBJECT_RELEASE
1290	bool "kobject release debugging"
1291	depends on DEBUG_OBJECTS_TIMERS
1292	help
1293	  kobjects are reference counted objects.  This means that their
1294	  last reference count put is not predictable, and the kobject can
1295	  live on past the point at which a driver decides to drop it's
1296	  initial reference to the kobject gained on allocation.  An
1297	  example of this would be a struct device which has just been
1298	  unregistered.
1299
1300	  However, some buggy drivers assume that after such an operation,
1301	  the memory backing the kobject can be immediately freed.  This
1302	  goes completely against the principles of a refcounted object.
1303
1304	  If you say Y here, the kernel will delay the release of kobjects
1305	  on the last reference count to improve the visibility of this
1306	  kind of kobject release bug.
1307
1308config HAVE_DEBUG_BUGVERBOSE
1309	bool
1310
1311config DEBUG_BUGVERBOSE
1312	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1313	depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1314	default y
1315	help
1316	  Say Y here to make BUG() panics output the file name and line number
1317	  of the BUG call as well as the EIP and oops trace.  This aids
1318	  debugging but costs about 70-100K of memory.
1319
1320config DEBUG_LIST
1321	bool "Debug linked list manipulation"
1322	depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
 
1323	help
1324	  Enable this to turn on extended checks in the linked-list
1325	  walking routines.
 
 
 
 
1326
1327	  If unsure, say N.
1328
1329config DEBUG_PI_LIST
1330	bool "Debug priority linked list manipulation"
1331	depends on DEBUG_KERNEL
1332	help
1333	  Enable this to turn on extended checks in the priority-ordered
1334	  linked-list (plist) walking routines.  This checks the entire
1335	  list multiple times during each manipulation.
1336
1337	  If unsure, say N.
1338
1339config DEBUG_SG
1340	bool "Debug SG table operations"
1341	depends on DEBUG_KERNEL
1342	help
1343	  Enable this to turn on checks on scatter-gather tables. This can
1344	  help find problems with drivers that do not properly initialize
1345	  their sg tables.
1346
1347	  If unsure, say N.
1348
1349config DEBUG_NOTIFIERS
1350	bool "Debug notifier call chains"
1351	depends on DEBUG_KERNEL
1352	help
1353	  Enable this to turn on sanity checking for notifier call chains.
1354	  This is most useful for kernel developers to make sure that
1355	  modules properly unregister themselves from notifier chains.
1356	  This is a relatively cheap check but if you care about maximum
1357	  performance, say N.
1358
1359config DEBUG_CREDENTIALS
1360	bool "Debug credential management"
1361	depends on DEBUG_KERNEL
 
1362	help
1363	  Enable this to turn on some debug checking for credential
1364	  management.  The additional code keeps track of the number of
1365	  pointers from task_structs to any given cred struct, and checks to
1366	  see that this number never exceeds the usage count of the cred
1367	  struct.
1368
1369	  Furthermore, if SELinux is enabled, this also checks that the
1370	  security pointer in the cred struct is never seen to be invalid.
 
 
 
1371
1372	  If unsure, say N.
1373
 
 
1374source "kernel/rcu/Kconfig.debug"
1375
1376config DEBUG_WQ_FORCE_RR_CPU
1377	bool "Force round-robin CPU selection for unbound work items"
1378	depends on DEBUG_KERNEL
1379	default n
1380	help
1381	  Workqueue used to implicitly guarantee that work items queued
1382	  without explicit CPU specified are put on the local CPU.  This
1383	  guarantee is no longer true and while local CPU is still
1384	  preferred work items may be put on foreign CPUs.  Kernel
1385	  parameter "workqueue.debug_force_rr_cpu" is added to force
1386	  round-robin CPU selection to flush out usages which depend on the
1387	  now broken guarantee.  This config option enables the debug
1388	  feature by default.  When enabled, memory and cache locality will
1389	  be impacted.
1390
1391config DEBUG_BLOCK_EXT_DEVT
1392        bool "Force extended block device numbers and spread them"
1393	depends on DEBUG_KERNEL
1394	depends on BLOCK
1395	default n
1396	help
1397	  BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1398	  SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1399	  YOU ARE DOING.  Distros, please enable this and fix whatever
1400	  is broken.
1401
1402	  Conventionally, block device numbers are allocated from
1403	  predetermined contiguous area.  However, extended block area
1404	  may introduce non-contiguous block device numbers.  This
1405	  option forces most block device numbers to be allocated from
1406	  the extended space and spreads them to discover kernel or
1407	  userland code paths which assume predetermined contiguous
1408	  device number allocation.
1409
1410	  Note that turning on this debug option shuffles all the
1411	  device numbers for all IDE and SCSI devices including libata
1412	  ones, so root partition specified using device number
1413	  directly (via rdev or root=MAJ:MIN) won't work anymore.
1414	  Textual device names (root=/dev/sdXn) will continue to work.
1415
1416	  Say N if you are unsure.
1417
1418config CPU_HOTPLUG_STATE_CONTROL
1419	bool "Enable CPU hotplug state control"
1420	depends on DEBUG_KERNEL
1421	depends on HOTPLUG_CPU
1422	default n
1423	help
1424	  Allows to write steps between "offline" and "online" to the CPUs
1425	  sysfs target file so states can be stepped granular. This is a debug
1426	  option for now as the hotplug machinery cannot be stopped and
1427	  restarted at arbitrary points yet.
1428
1429	  Say N if your are unsure.
1430
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1431config NOTIFIER_ERROR_INJECTION
1432	tristate "Notifier error injection"
1433	depends on DEBUG_KERNEL
1434	select DEBUG_FS
1435	help
1436	  This option provides the ability to inject artificial errors to
1437	  specified notifier chain callbacks. It is useful to test the error
1438	  handling of notifier call chain failures.
1439
1440	  Say N if unsure.
1441
1442config PM_NOTIFIER_ERROR_INJECT
1443	tristate "PM notifier error injection module"
1444	depends on PM && NOTIFIER_ERROR_INJECTION
1445	default m if PM_DEBUG
1446	help
1447	  This option provides the ability to inject artificial errors to
1448	  PM notifier chain callbacks.  It is controlled through debugfs
1449	  interface /sys/kernel/debug/notifier-error-inject/pm
1450
1451	  If the notifier call chain should be failed with some events
1452	  notified, write the error code to "actions/<notifier event>/error".
1453
1454	  Example: Inject PM suspend error (-12 = -ENOMEM)
1455
1456	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1457	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1458	  # echo mem > /sys/power/state
1459	  bash: echo: write error: Cannot allocate memory
1460
1461	  To compile this code as a module, choose M here: the module will
1462	  be called pm-notifier-error-inject.
1463
1464	  If unsure, say N.
1465
1466config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1467	tristate "OF reconfig notifier error injection module"
1468	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1469	help
1470	  This option provides the ability to inject artificial errors to
1471	  OF reconfig notifier chain callbacks.  It is controlled
1472	  through debugfs interface under
1473	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1474
1475	  If the notifier call chain should be failed with some events
1476	  notified, write the error code to "actions/<notifier event>/error".
1477
1478	  To compile this code as a module, choose M here: the module will
1479	  be called of-reconfig-notifier-error-inject.
1480
1481	  If unsure, say N.
1482
1483config NETDEV_NOTIFIER_ERROR_INJECT
1484	tristate "Netdev notifier error injection module"
1485	depends on NET && NOTIFIER_ERROR_INJECTION
1486	help
1487	  This option provides the ability to inject artificial errors to
1488	  netdevice notifier chain callbacks.  It is controlled through debugfs
1489	  interface /sys/kernel/debug/notifier-error-inject/netdev
1490
1491	  If the notifier call chain should be failed with some events
1492	  notified, write the error code to "actions/<notifier event>/error".
1493
1494	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1495
1496	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1497	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1498	  # ip link set eth0 mtu 1024
1499	  RTNETLINK answers: Invalid argument
1500
1501	  To compile this code as a module, choose M here: the module will
1502	  be called netdev-notifier-error-inject.
1503
1504	  If unsure, say N.
1505
 
 
 
 
 
 
 
 
 
 
1506config FAULT_INJECTION
1507	bool "Fault-injection framework"
1508	depends on DEBUG_KERNEL
1509	help
1510	  Provide fault-injection framework.
1511	  For more details, see Documentation/fault-injection/.
1512
1513config FUNCTION_ERROR_INJECTION
1514	def_bool y
1515	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1516
1517config FAILSLAB
1518	bool "Fault-injection capability for kmalloc"
1519	depends on FAULT_INJECTION
1520	depends on SLAB || SLUB
1521	help
1522	  Provide fault-injection capability for kmalloc.
1523
1524config FAIL_PAGE_ALLOC
1525	bool "Fault-injection capabilitiy for alloc_pages()"
1526	depends on FAULT_INJECTION
1527	help
1528	  Provide fault-injection capability for alloc_pages().
1529
 
 
 
 
 
 
 
1530config FAIL_MAKE_REQUEST
1531	bool "Fault-injection capability for disk IO"
1532	depends on FAULT_INJECTION && BLOCK
1533	help
1534	  Provide fault-injection capability for disk IO.
1535
1536config FAIL_IO_TIMEOUT
1537	bool "Fault-injection capability for faking disk interrupts"
1538	depends on FAULT_INJECTION && BLOCK
1539	help
1540	  Provide fault-injection capability on end IO handling. This
1541	  will make the block layer "forget" an interrupt as configured,
1542	  thus exercising the error handling.
1543
1544	  Only works with drivers that use the generic timeout handling,
1545	  for others it wont do anything.
1546
1547config FAIL_MMC_REQUEST
1548	bool "Fault-injection capability for MMC IO"
1549	depends on FAULT_INJECTION_DEBUG_FS && MMC
1550	help
1551	  Provide fault-injection capability for MMC IO.
1552	  This will make the mmc core return data errors. This is
1553	  useful to test the error handling in the mmc block device
1554	  and to test how the mmc host driver handles retries from
1555	  the block device.
1556
1557config FAIL_FUTEX
1558	bool "Fault-injection capability for futexes"
1559	select DEBUG_FS
1560	depends on FAULT_INJECTION && FUTEX
1561	help
1562	  Provide fault-injection capability for futexes.
1563
 
 
 
 
 
 
1564config FAIL_FUNCTION
1565	bool "Fault-injection capability for functions"
1566	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1567	help
1568	  Provide function-based fault-injection capability.
1569	  This will allow you to override a specific function with a return
1570	  with given return value. As a result, function caller will see
1571	  an error value and have to handle it. This is useful to test the
1572	  error handling in various subsystems.
1573
1574config FAULT_INJECTION_DEBUG_FS
1575	bool "Debugfs entries for fault-injection capabilities"
1576	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1577	help
1578	  Enable configuration of fault-injection capabilities via debugfs.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1579
1580config FAULT_INJECTION_STACKTRACE_FILTER
1581	bool "stacktrace filter for fault-injection capabilities"
1582	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1583	depends on !X86_64
1584	select STACKTRACE
1585	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !X86
1586	help
1587	  Provide stacktrace filter for fault-injection capabilities
1588
1589config LATENCYTOP
1590	bool "Latency measuring infrastructure"
1591	depends on DEBUG_KERNEL
1592	depends on STACKTRACE_SUPPORT
1593	depends on PROC_FS
1594	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !X86
1595	select KALLSYMS
1596	select KALLSYMS_ALL
1597	select STACKTRACE
1598	select SCHEDSTATS
1599	select SCHED_DEBUG
1600	help
1601	  Enable this option if you want to use the LatencyTOP tool
1602	  to find out which userspace is blocking on what kernel operations.
 
1603
1604source kernel/trace/Kconfig
 
1605
1606config PROVIDE_OHCI1394_DMA_INIT
1607	bool "Remote debugging over FireWire early on boot"
1608	depends on PCI && X86
 
 
 
 
 
 
 
1609	help
1610	  If you want to debug problems which hang or crash the kernel early
1611	  on boot and the crashing machine has a FireWire port, you can use
1612	  this feature to remotely access the memory of the crashed machine
1613	  over FireWire. This employs remote DMA as part of the OHCI1394
1614	  specification which is now the standard for FireWire controllers.
1615
1616	  With remote DMA, you can monitor the printk buffer remotely using
1617	  firescope and access all memory below 4GB using fireproxy from gdb.
1618	  Even controlling a kernel debugger is possible using remote DMA.
1619
1620	  Usage:
 
 
 
 
 
 
 
 
1621
1622	  If ohci1394_dma=early is used as boot parameter, it will initialize
1623	  all OHCI1394 controllers which are found in the PCI config space.
 
 
 
 
 
 
 
 
1624
1625	  As all changes to the FireWire bus such as enabling and disabling
1626	  devices cause a bus reset and thereby disable remote DMA for all
1627	  devices, be sure to have the cable plugged and FireWire enabled on
1628	  the debugging host before booting the debug target for debugging.
 
 
 
 
1629
1630	  This code (~1k) is freed after boot. By then, the firewire stack
1631	  in charge of the OHCI-1394 controllers should be used instead.
 
 
 
 
 
1632
1633	  See Documentation/debugging-via-ohci1394.txt for more information.
 
 
1634
1635config DMA_API_DEBUG
1636	bool "Enable debugging of DMA-API usage"
1637	depends on HAVE_DMA_API_DEBUG
1638	help
1639	  Enable this option to debug the use of the DMA API by device drivers.
1640	  With this option you will be able to detect common bugs in device
1641	  drivers like double-freeing of DMA mappings or freeing mappings that
1642	  were never allocated.
1643
1644	  This also attempts to catch cases where a page owned by DMA is
1645	  accessed by the cpu in a way that could cause data corruption.  For
1646	  example, this enables cow_user_page() to check that the source page is
1647	  not undergoing DMA.
1648
1649	  This option causes a performance degradation.  Use only if you want to
1650	  debug device drivers and dma interactions.
 
 
 
 
 
 
1651
1652	  If unsure, say N.
 
 
1653
1654menuconfig RUNTIME_TESTING_MENU
1655	bool "Runtime Testing"
1656	def_bool y
1657
1658if RUNTIME_TESTING_MENU
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1659
1660config LKDTM
1661	tristate "Linux Kernel Dump Test Tool Module"
1662	depends on DEBUG_FS
1663	depends on BLOCK
1664	default n
1665	help
1666	This module enables testing of the different dumping mechanisms by
1667	inducing system failures at predefined crash points.
1668	If you don't need it: say N
1669	Choose M here to compile this code as a module. The module will be
1670	called lkdtm.
1671
1672	Documentation on how to use the module can be found in
1673	Documentation/fault-injection/provoke-crashes.txt
 
 
 
 
 
 
 
 
 
 
 
 
1674
1675config TEST_LIST_SORT
1676	tristate "Linked list sorting test"
1677	depends on DEBUG_KERNEL || m
 
1678	help
1679	  Enable this to turn on 'list_sort()' function test. This test is
1680	  executed only once during system boot (so affects only boot time),
1681	  or at module load time.
1682
1683	  If unsure, say N.
1684
1685config TEST_SORT
1686	tristate "Array-based sort test"
1687	depends on DEBUG_KERNEL || m
 
 
 
 
 
 
 
 
 
 
 
 
1688	help
1689	  This option enables the self-test function of 'sort()' at boot,
1690	  or at module load time.
1691
1692	  If unsure, say N.
1693
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1694config KPROBES_SANITY_TEST
1695	bool "Kprobes sanity tests"
1696	depends on DEBUG_KERNEL
1697	depends on KPROBES
1698	default n
 
 
1699	help
1700	  This option provides for testing basic kprobes functionality on
1701	  boot. A sample kprobe, jprobe and kretprobe are inserted and
1702	  verified for functionality.
1703
1704	  Say N if you are unsure.
1705
 
 
 
 
 
 
 
 
 
 
 
 
1706config BACKTRACE_SELF_TEST
1707	tristate "Self test for the backtrace code"
1708	depends on DEBUG_KERNEL
1709	default n
1710	help
1711	  This option provides a kernel module that can be used to test
1712	  the kernel stack backtrace code. This option is not useful
1713	  for distributions or general kernels, but only for kernel
1714	  developers working on architecture code.
1715
1716	  Note that if you want to also test saved backtraces, you will
1717	  have to enable STACKTRACE as well.
1718
1719	  Say N if you are unsure.
1720
 
 
 
 
 
 
 
 
 
 
1721config RBTREE_TEST
1722	tristate "Red-Black tree test"
1723	depends on DEBUG_KERNEL
1724	help
1725	  A benchmark measuring the performance of the rbtree library.
1726	  Also includes rbtree invariant checks.
1727
 
 
 
 
 
 
 
 
 
 
 
 
1728config INTERVAL_TREE_TEST
1729	tristate "Interval tree test"
1730	depends on DEBUG_KERNEL
1731	select INTERVAL_TREE
1732	help
1733	  A benchmark measuring the performance of the interval tree library
1734
1735config PERCPU_TEST
1736	tristate "Per cpu operations test"
1737	depends on m && DEBUG_KERNEL
1738	help
1739	  Enable this option to build test module which validates per-cpu
1740	  operations.
1741
1742	  If unsure, say N.
1743
1744config ATOMIC64_SELFTEST
1745	tristate "Perform an atomic64_t self-test"
1746	help
1747	  Enable this option to test the atomic64_t functions at boot or
1748	  at module load time.
1749
1750	  If unsure, say N.
1751
1752config ASYNC_RAID6_TEST
1753	tristate "Self test for hardware accelerated raid6 recovery"
1754	depends on ASYNC_RAID6_RECOV
1755	select ASYNC_MEMCPY
1756	---help---
1757	  This is a one-shot self test that permutes through the
1758	  recovery of all the possible two disk failure scenarios for a
1759	  N-disk array.  Recovery is performed with the asynchronous
1760	  raid6 recovery routines, and will optionally use an offload
1761	  engine if one is available.
1762
1763	  If unsure, say N.
1764
1765config TEST_HEXDUMP
1766	tristate "Test functions located in the hexdump module at runtime"
1767
1768config TEST_STRING_HELPERS
1769	tristate "Test functions located in the string_helpers module at runtime"
 
 
 
 
 
 
 
1770
1771config TEST_KSTRTOX
1772	tristate "Test kstrto*() family of functions at runtime"
1773
1774config TEST_PRINTF
1775	tristate "Test printf() family of functions at runtime"
1776
 
 
 
1777config TEST_BITMAP
1778	tristate "Test bitmap_*() family of functions at runtime"
1779	default n
1780	help
1781	  Enable this option to test the bitmap functions at boot.
1782
1783	  If unsure, say N.
1784
1785config TEST_UUID
1786	tristate "Test functions located in the uuid module at runtime"
1787
 
 
 
 
 
 
 
 
 
 
 
 
1788config TEST_RHASHTABLE
1789	tristate "Perform selftest on resizable hash table"
1790	default n
1791	help
1792	  Enable this option to test the rhashtable functions at boot.
1793
1794	  If unsure, say N.
1795
1796config TEST_HASH
1797	tristate "Perform selftest on hash functions"
1798	default n
1799	help
1800	  Enable this option to test the kernel's integer (<linux/hash.h>),
1801	  string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1802	  hash functions on boot (or module load).
1803
1804	  This is intended to help people writing architecture-specific
1805	  optimized versions.  If unsure, say N.
1806
1807config TEST_PARMAN
1808	tristate "Perform selftest on priority array manager"
1809	default n
1810	depends on PARMAN
1811	help
1812	  Enable this option to test priority array manager on boot
1813	  (or module load).
1814
1815	  If unsure, say N.
1816
 
 
 
 
 
 
 
 
1817config TEST_LKM
1818	tristate "Test module loading with 'hello world' module"
1819	default n
1820	depends on m
1821	help
1822	  This builds the "test_module" module that emits "Hello, world"
1823	  on printk when loaded. It is designed to be used for basic
1824	  evaluation of the module loading subsystem (for example when
1825	  validating module verification). It lacks any extra dependencies,
1826	  and will not normally be loaded by the system unless explicitly
1827	  requested by name.
1828
1829	  If unsure, say N.
1830
1831config TEST_USER_COPY
1832	tristate "Test user/kernel boundary protections"
 
 
 
 
 
 
 
 
 
 
 
 
1833	default n
 
1834	depends on m
1835	help
1836	  This builds the "test_user_copy" module that runs sanity checks
1837	  on the copy_to/from_user infrastructure, making sure basic
1838	  user/kernel boundary testing is working. If it fails to load,
1839	  a regression has been detected in the user/kernel memory boundary
1840	  protections.
1841
1842	  If unsure, say N.
1843
1844config TEST_BPF
1845	tristate "Test BPF filter functionality"
1846	default n
1847	depends on m && NET
1848	help
1849	  This builds the "test_bpf" module that runs various test vectors
1850	  against the BPF interpreter or BPF JIT compiler depending on the
1851	  current setting. This is in particular useful for BPF JIT compiler
1852	  development, but also to run regression tests against changes in
1853	  the interpreter code. It also enables test stubs for eBPF maps and
1854	  verifier used by user space verifier testsuite.
1855
1856	  If unsure, say N.
1857
 
 
 
 
 
 
 
 
 
1858config FIND_BIT_BENCHMARK
1859	tristate "Test find_bit functions"
1860	default n
1861	help
1862	  This builds the "test_find_bit" module that measure find_*_bit()
1863	  functions performance.
1864
1865	  If unsure, say N.
1866
1867config TEST_FIRMWARE
1868	tristate "Test firmware loading via userspace interface"
1869	default n
1870	depends on FW_LOADER
1871	help
1872	  This builds the "test_firmware" module that creates a userspace
1873	  interface for testing firmware loading. This can be used to
1874	  control the triggering of firmware loading without needing an
1875	  actual firmware-using device. The contents can be rechecked by
1876	  userspace.
1877
1878	  If unsure, say N.
1879
1880config TEST_SYSCTL
1881	tristate "sysctl test driver"
1882	default n
1883	depends on PROC_SYSCTL
1884	help
1885	  This builds the "test_sysctl" module. This driver enables to test the
1886	  proc sysctl interfaces available to drivers safely without affecting
1887	  production knobs which might alter system functionality.
1888
1889	  If unsure, say N.
1890
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1891config TEST_UDELAY
1892	tristate "udelay test driver"
1893	default n
1894	help
1895	  This builds the "udelay_test" module that helps to make sure
1896	  that udelay() is working properly.
1897
1898	  If unsure, say N.
1899
1900config TEST_STATIC_KEYS
1901	tristate "Test static keys"
1902	default n
1903	depends on m
1904	help
1905	  Test the static key interfaces.
1906
1907	  If unsure, say N.
1908
 
 
 
 
 
 
 
 
 
 
1909config TEST_KMOD
1910	tristate "kmod stress tester"
1911	default n
1912	depends on m
1913	depends on BLOCK && (64BIT || LBDAF)	  # for XFS, BTRFS
1914	depends on NETDEVICES && NET_CORE && INET # for TUN
 
 
1915	select TEST_LKM
1916	select XFS_FS
1917	select TUN
1918	select BTRFS_FS
1919	help
1920	  Test the kernel's module loading mechanism: kmod. kmod implements
1921	  support to load modules using the Linux kernel's usermode helper.
1922	  This test provides a series of tests against kmod.
1923
1924	  Although technically you can either build test_kmod as a module or
1925	  into the kernel we disallow building it into the kernel since
1926	  it stress tests request_module() and this will very likely cause
1927	  some issues by taking over precious threads available from other
1928	  module load requests, ultimately this could be fatal.
1929
1930	  To run tests run:
1931
1932	  tools/testing/selftests/kmod/kmod.sh --help
1933
1934	  If unsure, say N.
1935
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1936config TEST_DEBUG_VIRTUAL
1937	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
1938	depends on DEBUG_VIRTUAL
1939	help
1940	  Test the kernel's ability to detect incorrect calls to
1941	  virt_to_phys() done against the non-linear part of the
1942	  kernel's virtual address map.
1943
1944	  If unsure, say N.
1945
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1946endif # RUNTIME_TESTING_MENU
1947
 
 
 
 
 
 
1948config MEMTEST
1949	bool "Memtest"
1950	depends on HAVE_MEMBLOCK
1951	---help---
1952	  This option adds a kernel parameter 'memtest', which allows memtest
1953	  to be set.
1954	        memtest=0, mean disabled; -- default
1955	        memtest=1, mean do 1 test pattern;
1956	        ...
1957	        memtest=17, mean do 17 test patterns.
1958	  If you are unsure how to answer this question, answer N.
1959
1960config BUG_ON_DATA_CORRUPTION
1961	bool "Trigger a BUG when data corruption is detected"
1962	select DEBUG_LIST
1963	help
1964	  Select this option if the kernel should BUG when it encounters
1965	  data corruption in kernel memory structures when they get checked
1966	  for validity.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1967
1968	  If unsure, say N.
1969
1970source "samples/Kconfig"
 
 
 
 
 
1971
1972source "lib/Kconfig.kgdb"
 
 
1973
1974source "lib/Kconfig.ubsan"
1975
1976config ARCH_HAS_DEVMEM_IS_ALLOWED
1977	bool
1978
1979config STRICT_DEVMEM
1980	bool "Filter access to /dev/mem"
1981	depends on MMU && DEVMEM
1982	depends on ARCH_HAS_DEVMEM_IS_ALLOWED
1983	default y if PPC || X86 || ARM64
1984	---help---
1985	  If this option is disabled, you allow userspace (root) access to all
1986	  of memory, including kernel and userspace memory. Accidental
1987	  access to this is obviously disastrous, but specific access can
1988	  be used by people debugging the kernel. Note that with PAT support
1989	  enabled, even in this case there are restrictions on /dev/mem
1990	  use due to the cache aliasing requirements.
1991
1992	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1993	  file only allows userspace access to PCI space and the BIOS code and
1994	  data regions.  This is sufficient for dosemu and X and all common
1995	  users of /dev/mem.
1996
1997	  If in doubt, say Y.
 
 
 
1998
1999config IO_STRICT_DEVMEM
2000	bool "Filter I/O access to /dev/mem"
2001	depends on STRICT_DEVMEM
2002	---help---
2003	  If this option is disabled, you allow userspace (root) access to all
2004	  io-memory regardless of whether a driver is actively using that
2005	  range.  Accidental access to this is obviously disastrous, but
2006	  specific access can be used by people debugging kernel drivers.
2007
2008	  If this option is switched on, the /dev/mem file only allows
2009	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
2010	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2011	  if the driver using a given range cannot be disabled.
 
 
 
2012
2013	  If in doubt, say Y.