1menu "Kernel hacking" 2 3menu "printk and dmesg options" 4 5config PRINTK_TIME 6 bool "Show timing information on printks" 7 depends on PRINTK 8 help 9 Selecting this option causes time stamps of the printk() 10 messages to be added to the output of the syslog() system 11 call and at the console. 12 13 The timestamp is always recorded internally, and exported 14 to /dev/kmsg. This flag just specifies if the timestamp should 15 be included, not that the timestamp is recorded. 16 17 The behavior is also controlled by the kernel command line 18 parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst 19 20config PRINTK_CALLER 21 bool "Show caller information on printks" 22 depends on PRINTK 23 help 24 Selecting this option causes printk() to add a caller "thread id" (if 25 in task context) or a caller "processor id" (if not in task context) 26 to every message. 27 28 This option is intended for environments where multiple threads 29 concurrently call printk() for many times, for it is difficult to 30 interpret without knowing where these lines (or sometimes individual 31 line which was divided into multiple lines due to race) came from. 32 33 Since toggling after boot makes the code racy, currently there is 34 no option to enable/disable at the kernel command line parameter or 35 sysfs interface. 36 37config CONSOLE_LOGLEVEL_DEFAULT 38 int "Default console loglevel (1-15)" 39 range 1 15 40 default "7" 41 help 42 Default loglevel to determine what will be printed on the console. 43 44 Setting a default here is equivalent to passing in loglevel=<x> in 45 the kernel bootargs. loglevel=<x> continues to override whatever 46 value is specified here as well. 47 48 Note: This does not affect the log level of un-prefixed printk() 49 usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT 50 option. 51 52config CONSOLE_LOGLEVEL_QUIET 53 int "quiet console loglevel (1-15)" 54 range 1 15 55 default "4" 56 help 57 loglevel to use when "quiet" is passed on the kernel commandline. 58 59 When "quiet" is passed on the kernel commandline this loglevel 60 will be used as the loglevel. IOW passing "quiet" will be the 61 equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>" 62 63config MESSAGE_LOGLEVEL_DEFAULT 64 int "Default message log level (1-7)" 65 range 1 7 66 default "4" 67 help 68 Default log level for printk statements with no specified priority. 69 70 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks 71 that are auditing their logs closely may want to set it to a lower 72 priority. 73 74 Note: This does not affect what message level gets printed on the console 75 by default. To change that, use loglevel=<x> in the kernel bootargs, 76 or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value. 77 78config BOOT_PRINTK_DELAY 79 bool "Delay each boot printk message by N milliseconds" 80 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY 81 help 82 This build option allows you to read kernel boot messages 83 by inserting a short delay after each one. The delay is 84 specified in milliseconds on the kernel command line, 85 using "boot_delay=N". 86 87 It is likely that you would also need to use "lpj=M" to preset 88 the "loops per jiffie" value. 89 See a previous boot log for the "lpj" value to use for your 90 system, and then set "lpj=M" before setting "boot_delay=N". 91 NOTE: Using this option may adversely affect SMP systems. 92 I.e., processors other than the first one may not boot up. 93 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect 94 what it believes to be lockup conditions. 95 96config DYNAMIC_DEBUG 97 bool "Enable dynamic printk() support" 98 default n 99 depends on PRINTK 100 depends on DEBUG_FS 101 help 102 103 Compiles debug level messages into the kernel, which would not 104 otherwise be available at runtime. These messages can then be 105 enabled/disabled based on various levels of scope - per source file, 106 function, module, format string, and line number. This mechanism 107 implicitly compiles in all pr_debug() and dev_dbg() calls, which 108 enlarges the kernel text size by about 2%. 109 110 If a source file is compiled with DEBUG flag set, any 111 pr_debug() calls in it are enabled by default, but can be 112 disabled at runtime as below. Note that DEBUG flag is 113 turned on by many CONFIG_*DEBUG* options. 114 115 Usage: 116 117 Dynamic debugging is controlled via the 'dynamic_debug/control' file, 118 which is contained in the 'debugfs' filesystem. Thus, the debugfs 119 filesystem must first be mounted before making use of this feature. 120 We refer the control file as: <debugfs>/dynamic_debug/control. This 121 file contains a list of the debug statements that can be enabled. The 122 format for each line of the file is: 123 124 filename:lineno [module]function flags format 125 126 filename : source file of the debug statement 127 lineno : line number of the debug statement 128 module : module that contains the debug statement 129 function : function that contains the debug statement 130 flags : '=p' means the line is turned 'on' for printing 131 format : the format used for the debug statement 132 133 From a live system: 134 135 nullarbor:~ # cat <debugfs>/dynamic_debug/control 136 # filename:lineno [module]function flags format 137 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012" 138 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012" 139 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012" 140 141 Example usage: 142 143 // enable the message at line 1603 of file svcsock.c 144 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > 145 <debugfs>/dynamic_debug/control 146 147 // enable all the messages in file svcsock.c 148 nullarbor:~ # echo -n 'file svcsock.c +p' > 149 <debugfs>/dynamic_debug/control 150 151 // enable all the messages in the NFS server module 152 nullarbor:~ # echo -n 'module nfsd +p' > 153 <debugfs>/dynamic_debug/control 154 155 // enable all 12 messages in the function svc_process() 156 nullarbor:~ # echo -n 'func svc_process +p' > 157 <debugfs>/dynamic_debug/control 158 159 // disable all 12 messages in the function svc_process() 160 nullarbor:~ # echo -n 'func svc_process -p' > 161 <debugfs>/dynamic_debug/control 162 163 See Documentation/admin-guide/dynamic-debug-howto.rst for additional 164 information. 165 166endmenu # "printk and dmesg options" 167 168menu "Compile-time checks and compiler options" 169 170config DEBUG_INFO 171 bool "Compile the kernel with debug info" 172 depends on DEBUG_KERNEL && !COMPILE_TEST 173 help 174 If you say Y here the resulting kernel image will include 175 debugging info resulting in a larger kernel image. 176 This adds debug symbols to the kernel and modules (gcc -g), and 177 is needed if you intend to use kernel crashdump or binary object 178 tools like crash, kgdb, LKCD, gdb, etc on the kernel. 179 Say Y here only if you plan to debug the kernel. 180 181 If unsure, say N. 182 183config DEBUG_INFO_REDUCED 184 bool "Reduce debugging information" 185 depends on DEBUG_INFO 186 help 187 If you say Y here gcc is instructed to generate less debugging 188 information for structure types. This means that tools that 189 need full debugging information (like kgdb or systemtap) won't 190 be happy. But if you merely need debugging information to 191 resolve line numbers there is no loss. Advantage is that 192 build directory object sizes shrink dramatically over a full 193 DEBUG_INFO build and compile times are reduced too. 194 Only works with newer gcc versions. 195 196config DEBUG_INFO_SPLIT 197 bool "Produce split debuginfo in .dwo files" 198 depends on DEBUG_INFO 199 help 200 Generate debug info into separate .dwo files. This significantly 201 reduces the build directory size for builds with DEBUG_INFO, 202 because it stores the information only once on disk in .dwo 203 files instead of multiple times in object files and executables. 204 In addition the debug information is also compressed. 205 206 Requires recent gcc (4.7+) and recent gdb/binutils. 207 Any tool that packages or reads debug information would need 208 to know about the .dwo files and include them. 209 Incompatible with older versions of ccache. 210 211config DEBUG_INFO_DWARF4 212 bool "Generate dwarf4 debuginfo" 213 depends on DEBUG_INFO 214 help 215 Generate dwarf4 debug info. This requires recent versions 216 of gcc and gdb. It makes the debug information larger. 217 But it significantly improves the success of resolving 218 variables in gdb on optimized code. 219 220config GDB_SCRIPTS 221 bool "Provide GDB scripts for kernel debugging" 222 depends on DEBUG_INFO 223 help 224 This creates the required links to GDB helper scripts in the 225 build directory. If you load vmlinux into gdb, the helper 226 scripts will be automatically imported by gdb as well, and 227 additional functions are available to analyze a Linux kernel 228 instance. See Documentation/dev-tools/gdb-kernel-debugging.rst 229 for further details. 230 231config ENABLE_MUST_CHECK 232 bool "Enable __must_check logic" 233 default y 234 help 235 Enable the __must_check logic in the kernel build. Disable this to 236 suppress the "warning: ignoring return value of 'foo', declared with 237 attribute warn_unused_result" messages. 238 239config FRAME_WARN 240 int "Warn for stack frames larger than (needs gcc 4.4)" 241 range 0 8192 242 default 2048 if GCC_PLUGIN_LATENT_ENTROPY 243 default 1280 if (!64BIT && PARISC) 244 default 1024 if (!64BIT && !PARISC) 245 default 2048 if 64BIT 246 help 247 Tell gcc to warn at build time for stack frames larger than this. 248 Setting this too low will cause a lot of warnings. 249 Setting it to 0 disables the warning. 250 Requires gcc 4.4 251 252config STRIP_ASM_SYMS 253 bool "Strip assembler-generated symbols during link" 254 default n 255 help 256 Strip internal assembler-generated symbols during a link (symbols 257 that look like '.Lxxx') so they don't pollute the output of 258 get_wchan() and suchlike. 259 260config READABLE_ASM 261 bool "Generate readable assembler code" 262 depends on DEBUG_KERNEL 263 help 264 Disable some compiler optimizations that tend to generate human unreadable 265 assembler output. This may make the kernel slightly slower, but it helps 266 to keep kernel developers who have to stare a lot at assembler listings 267 sane. 268 269config UNUSED_SYMBOLS 270 bool "Enable unused/obsolete exported symbols" 271 default y if X86 272 help 273 Unused but exported symbols make the kernel needlessly bigger. For 274 that reason most of these unused exports will soon be removed. This 275 option is provided temporarily to provide a transition period in case 276 some external kernel module needs one of these symbols anyway. If you 277 encounter such a case in your module, consider if you are actually 278 using the right API. (rationale: since nobody in the kernel is using 279 this in a module, there is a pretty good chance it's actually the 280 wrong interface to use). If you really need the symbol, please send a 281 mail to the linux kernel mailing list mentioning the symbol and why 282 you really need it, and what the merge plan to the mainline kernel for 283 your module is. 284 285config DEBUG_FS 286 bool "Debug Filesystem" 287 help 288 debugfs is a virtual file system that kernel developers use to put 289 debugging files into. Enable this option to be able to read and 290 write to these files. 291 292 For detailed documentation on the debugfs API, see 293 Documentation/filesystems/. 294 295 If unsure, say N. 296 297config HEADERS_CHECK 298 bool "Run 'make headers_check' when building vmlinux" 299 depends on !UML 300 help 301 This option will extract the user-visible kernel headers whenever 302 building the kernel, and will run basic sanity checks on them to 303 ensure that exported files do not attempt to include files which 304 were not exported, etc. 305 306 If you're making modifications to header files which are 307 relevant for userspace, say 'Y', and check the headers 308 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in 309 your build tree), to make sure they're suitable. 310 311config DEBUG_SECTION_MISMATCH 312 bool "Enable full Section mismatch analysis" 313 help 314 The section mismatch analysis checks if there are illegal 315 references from one section to another section. 316 During linktime or runtime, some sections are dropped; 317 any use of code/data previously in these sections would 318 most likely result in an oops. 319 In the code, functions and variables are annotated with 320 __init,, etc. (see the full list in include/linux/init.h), 321 which results in the code/data being placed in specific sections. 322 The section mismatch analysis is always performed after a full 323 kernel build, and enabling this option causes the following 324 additional steps to occur: 325 - Add the option -fno-inline-functions-called-once to gcc commands. 326 When inlining a function annotated with __init in a non-init 327 function, we would lose the section information and thus 328 the analysis would not catch the illegal reference. 329 This option tells gcc to inline less (but it does result in 330 a larger kernel). 331 - Run the section mismatch analysis for each module/built-in.a file. 332 When we run the section mismatch analysis on vmlinux.o, we 333 lose valuable information about where the mismatch was 334 introduced. 335 Running the analysis for each module/built-in.a file 336 tells where the mismatch happens much closer to the 337 source. The drawback is that the same mismatch is 338 reported at least twice. 339 - Enable verbose reporting from modpost in order to help resolve 340 the section mismatches that are reported. 341 342config SECTION_MISMATCH_WARN_ONLY 343 bool "Make section mismatch errors non-fatal" 344 default y 345 help 346 If you say N here, the build process will fail if there are any 347 section mismatch, instead of just throwing warnings. 348 349 If unsure, say Y. 350 351# 352# Select this config option from the architecture Kconfig, if it 353# is preferred to always offer frame pointers as a config 354# option on the architecture (regardless of KERNEL_DEBUG): 355# 356config ARCH_WANT_FRAME_POINTERS 357 bool 358 359config FRAME_POINTER 360 bool "Compile the kernel with frame pointers" 361 depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS 362 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS 363 help 364 If you say Y here the resulting kernel image will be slightly 365 larger and slower, but it gives very useful debugging information 366 in case of kernel bugs. (precise oopses/stacktraces/warnings) 367 368config STACK_VALIDATION 369 bool "Compile-time stack metadata validation" 370 depends on HAVE_STACK_VALIDATION 371 default n 372 help 373 Add compile-time checks to validate stack metadata, including frame 374 pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure 375 that runtime stack traces are more reliable. 376 377 This is also a prerequisite for generation of ORC unwind data, which 378 is needed for CONFIG_UNWINDER_ORC. 379 380 For more information, see 381 tools/objtool/Documentation/stack-validation.txt. 382 383config DEBUG_FORCE_WEAK_PER_CPU 384 bool "Force weak per-cpu definitions" 385 depends on DEBUG_KERNEL 386 help 387 s390 and alpha require percpu variables in modules to be 388 defined weak to work around addressing range issue which 389 puts the following two restrictions on percpu variable 390 definitions. 391 392 1. percpu symbols must be unique whether static or not 393 2. percpu variables can't be defined inside a function 394 395 To ensure that generic code follows the above rules, this 396 option forces all percpu variables to be defined as weak. 397 398endmenu # "Compiler options" 399 400config MAGIC_SYSRQ 401 bool "Magic SysRq key" 402 depends on !UML 403 help 404 If you say Y here, you will have some control over the system even 405 if the system crashes for example during kernel debugging (e.g., you 406 will be able to flush the buffer cache to disk, reboot the system 407 immediately or dump some status information). This is accomplished 408 by pressing various keys while holding SysRq (Alt+PrintScreen). It 409 also works on a serial console (on PC hardware at least), if you 410 send a BREAK and then within 5 seconds a command keypress. The 411 keys are documented in <file:Documentation/admin-guide/sysrq.rst>. 412 Don't say Y unless you really know what this hack does. 413 414config MAGIC_SYSRQ_DEFAULT_ENABLE 415 hex "Enable magic SysRq key functions by default" 416 depends on MAGIC_SYSRQ 417 default 0x1 418 help 419 Specifies which SysRq key functions are enabled by default. 420 This may be set to 1 or 0 to enable or disable them all, or 421 to a bitmask as described in Documentation/admin-guide/sysrq.rst. 422 423config MAGIC_SYSRQ_SERIAL 424 bool "Enable magic SysRq key over serial" 425 depends on MAGIC_SYSRQ 426 default y 427 help 428 Many embedded boards have a disconnected TTL level serial which can 429 generate some garbage that can lead to spurious false sysrq detects. 430 This option allows you to decide whether you want to enable the 431 magic SysRq key. 432 433config DEBUG_KERNEL 434 bool "Kernel debugging" 435 help 436 Say Y here if you are developing drivers or trying to debug and 437 identify kernel problems. 438 439menu "Memory Debugging" 440 441source "mm/Kconfig.debug" 442 443config DEBUG_OBJECTS 444 bool "Debug object operations" 445 depends on DEBUG_KERNEL 446 help 447 If you say Y here, additional code will be inserted into the 448 kernel to track the life time of various objects and validate 449 the operations on those objects. 450 451config DEBUG_OBJECTS_SELFTEST 452 bool "Debug objects selftest" 453 depends on DEBUG_OBJECTS 454 help 455 This enables the selftest of the object debug code. 456 457config DEBUG_OBJECTS_FREE 458 bool "Debug objects in freed memory" 459 depends on DEBUG_OBJECTS 460 help 461 This enables checks whether a k/v free operation frees an area 462 which contains an object which has not been deactivated 463 properly. This can make kmalloc/kfree-intensive workloads 464 much slower. 465 466config DEBUG_OBJECTS_TIMERS 467 bool "Debug timer objects" 468 depends on DEBUG_OBJECTS 469 help 470 If you say Y here, additional code will be inserted into the 471 timer routines to track the life time of timer objects and 472 validate the timer operations. 473 474config DEBUG_OBJECTS_WORK 475 bool "Debug work objects" 476 depends on DEBUG_OBJECTS 477 help 478 If you say Y here, additional code will be inserted into the 479 work queue routines to track the life time of work objects and 480 validate the work operations. 481 482config DEBUG_OBJECTS_RCU_HEAD 483 bool "Debug RCU callbacks objects" 484 depends on DEBUG_OBJECTS 485 help 486 Enable this to turn on debugging of RCU list heads (call_rcu() usage). 487 488config DEBUG_OBJECTS_PERCPU_COUNTER 489 bool "Debug percpu counter objects" 490 depends on DEBUG_OBJECTS 491 help 492 If you say Y here, additional code will be inserted into the 493 percpu counter routines to track the life time of percpu counter 494 objects and validate the percpu counter operations. 495 496config DEBUG_OBJECTS_ENABLE_DEFAULT 497 int "debug_objects bootup default value (0-1)" 498 range 0 1 499 default "1" 500 depends on DEBUG_OBJECTS 501 help 502 Debug objects boot parameter default value 503 504config DEBUG_SLAB 505 bool "Debug slab memory allocations" 506 depends on DEBUG_KERNEL && SLAB 507 help 508 Say Y here to have the kernel do limited verification on memory 509 allocation as well as poisoning memory on free to catch use of freed 510 memory. This can make kmalloc/kfree-intensive workloads much slower. 511 512config DEBUG_SLAB_LEAK 513 bool "Memory leak debugging" 514 depends on DEBUG_SLAB 515 516config SLUB_DEBUG_ON 517 bool "SLUB debugging on by default" 518 depends on SLUB && SLUB_DEBUG 519 default n 520 help 521 Boot with debugging on by default. SLUB boots by default with 522 the runtime debug capabilities switched off. Enabling this is 523 equivalent to specifying the "slub_debug" parameter on boot. 524 There is no support for more fine grained debug control like 525 possible with slub_debug=xxx. SLUB debugging may be switched 526 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying 527 "slub_debug=-". 528 529config SLUB_STATS 530 default n 531 bool "Enable SLUB performance statistics" 532 depends on SLUB && SYSFS 533 help 534 SLUB statistics are useful to debug SLUBs allocation behavior in 535 order find ways to optimize the allocator. This should never be 536 enabled for production use since keeping statistics slows down 537 the allocator by a few percentage points. The slabinfo command 538 supports the determination of the most active slabs to figure 539 out which slabs are relevant to a particular load. 540 Try running: slabinfo -DA 541 542config HAVE_DEBUG_KMEMLEAK 543 bool 544 545config DEBUG_KMEMLEAK 546 bool "Kernel memory leak detector" 547 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK 548 select DEBUG_FS 549 select STACKTRACE if STACKTRACE_SUPPORT 550 select KALLSYMS 551 select CRC32 552 help 553 Say Y here if you want to enable the memory leak 554 detector. The memory allocation/freeing is traced in a way 555 similar to the Boehm's conservative garbage collector, the 556 difference being that the orphan objects are not freed but 557 only shown in /sys/kernel/debug/kmemleak. Enabling this 558 feature will introduce an overhead to memory 559 allocations. See Documentation/dev-tools/kmemleak.rst for more 560 details. 561 562 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances 563 of finding leaks due to the slab objects poisoning. 564 565 In order to access the kmemleak file, debugfs needs to be 566 mounted (usually at /sys/kernel/debug). 567 568config DEBUG_KMEMLEAK_EARLY_LOG_SIZE 569 int "Maximum kmemleak early log entries" 570 depends on DEBUG_KMEMLEAK 571 range 200 40000 572 default 400 573 help 574 Kmemleak must track all the memory allocations to avoid 575 reporting false positives. Since memory may be allocated or 576 freed before kmemleak is initialised, an early log buffer is 577 used to store these actions. If kmemleak reports "early log 578 buffer exceeded", please increase this value. 579 580config DEBUG_KMEMLEAK_TEST 581 tristate "Simple test for the kernel memory leak detector" 582 depends on DEBUG_KMEMLEAK && m 583 help 584 This option enables a module that explicitly leaks memory. 585 586 If unsure, say N. 587 588config DEBUG_KMEMLEAK_DEFAULT_OFF 589 bool "Default kmemleak to off" 590 depends on DEBUG_KMEMLEAK 591 help 592 Say Y here to disable kmemleak by default. It can then be enabled 593 on the command line via kmemleak=on. 594 595config DEBUG_KMEMLEAK_AUTO_SCAN 596 bool "Enable kmemleak auto scan thread on boot up" 597 default y 598 depends on DEBUG_KMEMLEAK 599 help 600 Depending on the cpu, kmemleak scan may be cpu intensive and can 601 stall user tasks at times. This option enables/disables automatic 602 kmemleak scan at boot up. 603 604 Say N here to disable kmemleak auto scan thread to stop automatic 605 scanning. Disabling this option disables automatic reporting of 606 memory leaks. 607 608 If unsure, say Y. 609 610config DEBUG_STACK_USAGE 611 bool "Stack utilization instrumentation" 612 depends on DEBUG_KERNEL && !IA64 613 help 614 Enables the display of the minimum amount of free stack which each 615 task has ever had available in the sysrq-T and sysrq-P debug output. 616 617 This option will slow down process creation somewhat. 618 619config DEBUG_VM 620 bool "Debug VM" 621 depends on DEBUG_KERNEL 622 help 623 Enable this to turn on extended checks in the virtual-memory system 624 that may impact performance. 625 626 If unsure, say N. 627 628config DEBUG_VM_VMACACHE 629 bool "Debug VMA caching" 630 depends on DEBUG_VM 631 help 632 Enable this to turn on VMA caching debug information. Doing so 633 can cause significant overhead, so only enable it in non-production 634 environments. 635 636 If unsure, say N. 637 638config DEBUG_VM_RB 639 bool "Debug VM red-black trees" 640 depends on DEBUG_VM 641 help 642 Enable VM red-black tree debugging information and extra validations. 643 644 If unsure, say N. 645 646config DEBUG_VM_PGFLAGS 647 bool "Debug page-flags operations" 648 depends on DEBUG_VM 649 help 650 Enables extra validation on page flags operations. 651 652 If unsure, say N. 653 654config ARCH_HAS_DEBUG_VIRTUAL 655 bool 656 657config DEBUG_VIRTUAL 658 bool "Debug VM translations" 659 depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL 660 help 661 Enable some costly sanity checks in virtual to page code. This can 662 catch mistakes with virt_to_page() and friends. 663 664 If unsure, say N. 665 666config DEBUG_NOMMU_REGIONS 667 bool "Debug the global anon/private NOMMU mapping region tree" 668 depends on DEBUG_KERNEL && !MMU 669 help 670 This option causes the global tree of anonymous and private mapping 671 regions to be regularly checked for invalid topology. 672 673config DEBUG_MEMORY_INIT 674 bool "Debug memory initialisation" if EXPERT 675 default !EXPERT 676 help 677 Enable this for additional checks during memory initialisation. 678 The sanity checks verify aspects of the VM such as the memory model 679 and other information provided by the architecture. Verbose 680 information will be printed at KERN_DEBUG loglevel depending 681 on the mminit_loglevel= command-line option. 682 683 If unsure, say Y 684 685config MEMORY_NOTIFIER_ERROR_INJECT 686 tristate "Memory hotplug notifier error injection module" 687 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION 688 help 689 This option provides the ability to inject artificial errors to 690 memory hotplug notifier chain callbacks. It is controlled through 691 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory 692 693 If the notifier call chain should be failed with some events 694 notified, write the error code to "actions/<notifier event>/error". 695 696 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 697 698 # cd /sys/kernel/debug/notifier-error-inject/memory 699 # echo -12 > actions/MEM_GOING_OFFLINE/error 700 # echo offline > /sys/devices/system/memory/memoryXXX/state 701 bash: echo: write error: Cannot allocate memory 702 703 To compile this code as a module, choose M here: the module will 704 be called memory-notifier-error-inject. 705 706 If unsure, say N. 707 708config DEBUG_PER_CPU_MAPS 709 bool "Debug access to per_cpu maps" 710 depends on DEBUG_KERNEL 711 depends on SMP 712 help 713 Say Y to verify that the per_cpu map being accessed has 714 been set up. This adds a fair amount of code to kernel memory 715 and decreases performance. 716 717 Say N if unsure. 718 719config DEBUG_HIGHMEM 720 bool "Highmem debugging" 721 depends on DEBUG_KERNEL && HIGHMEM 722 help 723 This option enables additional error checking for high memory 724 systems. Disable for production systems. 725 726config HAVE_DEBUG_STACKOVERFLOW 727 bool 728 729config DEBUG_STACKOVERFLOW 730 bool "Check for stack overflows" 731 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW 732 ---help--- 733 Say Y here if you want to check for overflows of kernel, IRQ 734 and exception stacks (if your architecture uses them). This 735 option will show detailed messages if free stack space drops 736 below a certain limit. 737 738 These kinds of bugs usually occur when call-chains in the 739 kernel get too deep, especially when interrupts are 740 involved. 741 742 Use this in cases where you see apparently random memory 743 corruption, especially if it appears in 'struct thread_info' 744 745 If in doubt, say "N". 746 747source "lib/Kconfig.kasan" 748 749endmenu # "Memory Debugging" 750 751config ARCH_HAS_KCOV 752 bool 753 help 754 KCOV does not have any arch-specific code, but currently it is enabled 755 only for x86_64. KCOV requires testing on other archs, and most likely 756 disabling of instrumentation for some early boot code. 757 758config CC_HAS_SANCOV_TRACE_PC 759 def_bool $(cc-option,-fsanitize-coverage=trace-pc) 760 761config KCOV 762 bool "Code coverage for fuzzing" 763 depends on ARCH_HAS_KCOV 764 depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS 765 select DEBUG_FS 766 select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC 767 help 768 KCOV exposes kernel code coverage information in a form suitable 769 for coverage-guided fuzzing (randomized testing). 770 771 If RANDOMIZE_BASE is enabled, PC values will not be stable across 772 different machines and across reboots. If you need stable PC values, 773 disable RANDOMIZE_BASE. 774 775 For more details, see Documentation/dev-tools/kcov.rst. 776 777config KCOV_ENABLE_COMPARISONS 778 bool "Enable comparison operands collection by KCOV" 779 depends on KCOV 780 depends on $(cc-option,-fsanitize-coverage=trace-cmp) 781 help 782 KCOV also exposes operands of every comparison in the instrumented 783 code along with operand sizes and PCs of the comparison instructions. 784 These operands can be used by fuzzing engines to improve the quality 785 of fuzzing coverage. 786 787config KCOV_INSTRUMENT_ALL 788 bool "Instrument all code by default" 789 depends on KCOV 790 default y 791 help 792 If you are doing generic system call fuzzing (like e.g. syzkaller), 793 then you will want to instrument the whole kernel and you should 794 say y here. If you are doing more targeted fuzzing (like e.g. 795 filesystem fuzzing with AFL) then you will want to enable coverage 796 for more specific subsets of files, and should say n here. 797 798config DEBUG_SHIRQ 799 bool "Debug shared IRQ handlers" 800 depends on DEBUG_KERNEL 801 help 802 Enable this to generate a spurious interrupt as soon as a shared 803 interrupt handler is registered, and just before one is deregistered. 804 Drivers ought to be able to handle interrupts coming in at those 805 points; some don't and need to be caught. 806 807menu "Debug Lockups and Hangs" 808 809config LOCKUP_DETECTOR 810 bool 811 812config SOFTLOCKUP_DETECTOR 813 bool "Detect Soft Lockups" 814 depends on DEBUG_KERNEL && !S390 815 select LOCKUP_DETECTOR 816 help 817 Say Y here to enable the kernel to act as a watchdog to detect 818 soft lockups. 819 820 Softlockups are bugs that cause the kernel to loop in kernel 821 mode for more than 20 seconds, without giving other tasks a 822 chance to run. The current stack trace is displayed upon 823 detection and the system will stay locked up. 824 825config BOOTPARAM_SOFTLOCKUP_PANIC 826 bool "Panic (Reboot) On Soft Lockups" 827 depends on SOFTLOCKUP_DETECTOR 828 help 829 Say Y here to enable the kernel to panic on "soft lockups", 830 which are bugs that cause the kernel to loop in kernel 831 mode for more than 20 seconds (configurable using the watchdog_thresh 832 sysctl), without giving other tasks a chance to run. 833 834 The panic can be used in combination with panic_timeout, 835 to cause the system to reboot automatically after a 836 lockup has been detected. This feature is useful for 837 high-availability systems that have uptime guarantees and 838 where a lockup must be resolved ASAP. 839 840 Say N if unsure. 841 842config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE 843 int 844 depends on SOFTLOCKUP_DETECTOR 845 range 0 1 846 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC 847 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC 848 849config HARDLOCKUP_DETECTOR_PERF 850 bool 851 select SOFTLOCKUP_DETECTOR 852 853# 854# Enables a timestamp based low pass filter to compensate for perf based 855# hard lockup detection which runs too fast due to turbo modes. 856# 857config HARDLOCKUP_CHECK_TIMESTAMP 858 bool 859 860# 861# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard 862# lockup detector rather than the perf based detector. 863# 864config HARDLOCKUP_DETECTOR 865 bool "Detect Hard Lockups" 866 depends on DEBUG_KERNEL && !S390 867 depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH 868 select LOCKUP_DETECTOR 869 select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF 870 select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH 871 help 872 Say Y here to enable the kernel to act as a watchdog to detect 873 hard lockups. 874 875 Hardlockups are bugs that cause the CPU to loop in kernel mode 876 for more than 10 seconds, without letting other interrupts have a 877 chance to run. The current stack trace is displayed upon detection 878 and the system will stay locked up. 879 880config BOOTPARAM_HARDLOCKUP_PANIC 881 bool "Panic (Reboot) On Hard Lockups" 882 depends on HARDLOCKUP_DETECTOR 883 help 884 Say Y here to enable the kernel to panic on "hard lockups", 885 which are bugs that cause the kernel to loop in kernel 886 mode with interrupts disabled for more than 10 seconds (configurable 887 using the watchdog_thresh sysctl). 888 889 Say N if unsure. 890 891config BOOTPARAM_HARDLOCKUP_PANIC_VALUE 892 int 893 depends on HARDLOCKUP_DETECTOR 894 range 0 1 895 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC 896 default 1 if BOOTPARAM_HARDLOCKUP_PANIC 897 898config DETECT_HUNG_TASK 899 bool "Detect Hung Tasks" 900 depends on DEBUG_KERNEL 901 default SOFTLOCKUP_DETECTOR 902 help 903 Say Y here to enable the kernel to detect "hung tasks", 904 which are bugs that cause the task to be stuck in 905 uninterruptible "D" state indefinitely. 906 907 When a hung task is detected, the kernel will print the 908 current stack trace (which you should report), but the 909 task will stay in uninterruptible state. If lockdep is 910 enabled then all held locks will also be reported. This 911 feature has negligible overhead. 912 913config DEFAULT_HUNG_TASK_TIMEOUT 914 int "Default timeout for hung task detection (in seconds)" 915 depends on DETECT_HUNG_TASK 916 default 120 917 help 918 This option controls the default timeout (in seconds) used 919 to determine when a task has become non-responsive and should 920 be considered hung. 921 922 It can be adjusted at runtime via the kernel.hung_task_timeout_secs 923 sysctl or by writing a value to 924 /proc/sys/kernel/hung_task_timeout_secs. 925 926 A timeout of 0 disables the check. The default is two minutes. 927 Keeping the default should be fine in most cases. 928 929config BOOTPARAM_HUNG_TASK_PANIC 930 bool "Panic (Reboot) On Hung Tasks" 931 depends on DETECT_HUNG_TASK 932 help 933 Say Y here to enable the kernel to panic on "hung tasks", 934 which are bugs that cause the kernel to leave a task stuck 935 in uninterruptible "D" state. 936 937 The panic can be used in combination with panic_timeout, 938 to cause the system to reboot automatically after a 939 hung task has been detected. This feature is useful for 940 high-availability systems that have uptime guarantees and 941 where a hung tasks must be resolved ASAP. 942 943 Say N if unsure. 944 945config BOOTPARAM_HUNG_TASK_PANIC_VALUE 946 int 947 depends on DETECT_HUNG_TASK 948 range 0 1 949 default 0 if !BOOTPARAM_HUNG_TASK_PANIC 950 default 1 if BOOTPARAM_HUNG_TASK_PANIC 951 952config WQ_WATCHDOG 953 bool "Detect Workqueue Stalls" 954 depends on DEBUG_KERNEL 955 help 956 Say Y here to enable stall detection on workqueues. If a 957 worker pool doesn't make forward progress on a pending work 958 item for over a given amount of time, 30s by default, a 959 warning message is printed along with dump of workqueue 960 state. This can be configured through kernel parameter 961 "workqueue.watchdog_thresh" and its sysfs counterpart. 962 963endmenu # "Debug lockups and hangs" 964 965config PANIC_ON_OOPS 966 bool "Panic on Oops" 967 help 968 Say Y here to enable the kernel to panic when it oopses. This 969 has the same effect as setting oops=panic on the kernel command 970 line. 971 972 This feature is useful to ensure that the kernel does not do 973 anything erroneous after an oops which could result in data 974 corruption or other issues. 975 976 Say N if unsure. 977 978config PANIC_ON_OOPS_VALUE 979 int 980 range 0 1 981 default 0 if !PANIC_ON_OOPS 982 default 1 if PANIC_ON_OOPS 983 984config PANIC_TIMEOUT 985 int "panic timeout" 986 default 0 987 help 988 Set the timeout value (in seconds) until a reboot occurs when the 989 the kernel panics. If n = 0, then we wait forever. A timeout 990 value n > 0 will wait n seconds before rebooting, while a timeout 991 value n < 0 will reboot immediately. 992 993config SCHED_DEBUG 994 bool "Collect scheduler debugging info" 995 depends on DEBUG_KERNEL && PROC_FS 996 default y 997 help 998 If you say Y here, the /proc/sched_debug file will be provided 999 that can help debug the scheduler. The runtime overhead of this 1000 option is minimal. 1001 1002config SCHED_INFO 1003 bool 1004 default n 1005 1006config SCHEDSTATS 1007 bool "Collect scheduler statistics" 1008 depends on DEBUG_KERNEL && PROC_FS 1009 select SCHED_INFO 1010 help 1011 If you say Y here, additional code will be inserted into the 1012 scheduler and related routines to collect statistics about 1013 scheduler behavior and provide them in /proc/schedstat. These 1014 stats may be useful for both tuning and debugging the scheduler 1015 If you aren't debugging the scheduler or trying to tune a specific 1016 application, you can say N to avoid the very slight overhead 1017 this adds. 1018 1019config SCHED_STACK_END_CHECK 1020 bool "Detect stack corruption on calls to schedule()" 1021 depends on DEBUG_KERNEL 1022 default n 1023 help 1024 This option checks for a stack overrun on calls to schedule(). 1025 If the stack end location is found to be over written always panic as 1026 the content of the corrupted region can no longer be trusted. 1027 This is to ensure no erroneous behaviour occurs which could result in 1028 data corruption or a sporadic crash at a later stage once the region 1029 is examined. The runtime overhead introduced is minimal. 1030 1031config DEBUG_TIMEKEEPING 1032 bool "Enable extra timekeeping sanity checking" 1033 help 1034 This option will enable additional timekeeping sanity checks 1035 which may be helpful when diagnosing issues where timekeeping 1036 problems are suspected. 1037 1038 This may include checks in the timekeeping hotpaths, so this 1039 option may have a (very small) performance impact to some 1040 workloads. 1041 1042 If unsure, say N. 1043 1044config DEBUG_PREEMPT 1045 bool "Debug preemptible kernel" 1046 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT 1047 default y 1048 help 1049 If you say Y here then the kernel will use a debug variant of the 1050 commonly used smp_processor_id() function and will print warnings 1051 if kernel code uses it in a preemption-unsafe way. Also, the kernel 1052 will detect preemption count underflows. 1053 1054menu "Lock Debugging (spinlocks, mutexes, etc...)" 1055 1056config LOCK_DEBUGGING_SUPPORT 1057 bool 1058 depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT 1059 default y 1060 1061config PROVE_LOCKING 1062 bool "Lock debugging: prove locking correctness" 1063 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1064 select LOCKDEP 1065 select DEBUG_SPINLOCK 1066 select DEBUG_MUTEXES 1067 select DEBUG_RT_MUTEXES if RT_MUTEXES 1068 select DEBUG_RWSEMS if RWSEM_SPIN_ON_OWNER 1069 select DEBUG_WW_MUTEX_SLOWPATH 1070 select DEBUG_LOCK_ALLOC 1071 select TRACE_IRQFLAGS 1072 default n 1073 help 1074 This feature enables the kernel to prove that all locking 1075 that occurs in the kernel runtime is mathematically 1076 correct: that under no circumstance could an arbitrary (and 1077 not yet triggered) combination of observed locking 1078 sequences (on an arbitrary number of CPUs, running an 1079 arbitrary number of tasks and interrupt contexts) cause a 1080 deadlock. 1081 1082 In short, this feature enables the kernel to report locking 1083 related deadlocks before they actually occur. 1084 1085 The proof does not depend on how hard and complex a 1086 deadlock scenario would be to trigger: how many 1087 participant CPUs, tasks and irq-contexts would be needed 1088 for it to trigger. The proof also does not depend on 1089 timing: if a race and a resulting deadlock is possible 1090 theoretically (no matter how unlikely the race scenario 1091 is), it will be proven so and will immediately be 1092 reported by the kernel (once the event is observed that 1093 makes the deadlock theoretically possible). 1094 1095 If a deadlock is impossible (i.e. the locking rules, as 1096 observed by the kernel, are mathematically correct), the 1097 kernel reports nothing. 1098 1099 NOTE: this feature can also be enabled for rwlocks, mutexes 1100 and rwsems - in which case all dependencies between these 1101 different locking variants are observed and mapped too, and 1102 the proof of observed correctness is also maintained for an 1103 arbitrary combination of these separate locking variants. 1104 1105 For more details, see Documentation/locking/lockdep-design.txt. 1106 1107config LOCK_STAT 1108 bool "Lock usage statistics" 1109 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1110 select LOCKDEP 1111 select DEBUG_SPINLOCK 1112 select DEBUG_MUTEXES 1113 select DEBUG_RT_MUTEXES if RT_MUTEXES 1114 select DEBUG_LOCK_ALLOC 1115 default n 1116 help 1117 This feature enables tracking lock contention points 1118 1119 For more details, see Documentation/locking/lockstat.txt 1120 1121 This also enables lock events required by "perf lock", 1122 subcommand of perf. 1123 If you want to use "perf lock", you also need to turn on 1124 CONFIG_EVENT_TRACING. 1125 1126 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events. 1127 (CONFIG_LOCKDEP defines "acquire" and "release" events.) 1128 1129config DEBUG_RT_MUTEXES 1130 bool "RT Mutex debugging, deadlock detection" 1131 depends on DEBUG_KERNEL && RT_MUTEXES 1132 help 1133 This allows rt mutex semantics violations and rt mutex related 1134 deadlocks (lockups) to be detected and reported automatically. 1135 1136config DEBUG_SPINLOCK 1137 bool "Spinlock and rw-lock debugging: basic checks" 1138 depends on DEBUG_KERNEL 1139 select UNINLINE_SPIN_UNLOCK 1140 help 1141 Say Y here and build SMP to catch missing spinlock initialization 1142 and certain other kinds of spinlock errors commonly made. This is 1143 best used in conjunction with the NMI watchdog so that spinlock 1144 deadlocks are also debuggable. 1145 1146config DEBUG_MUTEXES 1147 bool "Mutex debugging: basic checks" 1148 depends on DEBUG_KERNEL 1149 help 1150 This feature allows mutex semantics violations to be detected and 1151 reported. 1152 1153config DEBUG_WW_MUTEX_SLOWPATH 1154 bool "Wait/wound mutex debugging: Slowpath testing" 1155 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1156 select DEBUG_LOCK_ALLOC 1157 select DEBUG_SPINLOCK 1158 select DEBUG_MUTEXES 1159 help 1160 This feature enables slowpath testing for w/w mutex users by 1161 injecting additional -EDEADLK wound/backoff cases. Together with 1162 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this 1163 will test all possible w/w mutex interface abuse with the 1164 exception of simply not acquiring all the required locks. 1165 Note that this feature can introduce significant overhead, so 1166 it really should not be enabled in a production or distro kernel, 1167 even a debug kernel. If you are a driver writer, enable it. If 1168 you are a distro, do not. 1169 1170config DEBUG_RWSEMS 1171 bool "RW Semaphore debugging: basic checks" 1172 depends on DEBUG_KERNEL && RWSEM_SPIN_ON_OWNER 1173 help 1174 This debugging feature allows mismatched rw semaphore locks and unlocks 1175 to be detected and reported. 1176 1177config DEBUG_LOCK_ALLOC 1178 bool "Lock debugging: detect incorrect freeing of live locks" 1179 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1180 select DEBUG_SPINLOCK 1181 select DEBUG_MUTEXES 1182 select DEBUG_RT_MUTEXES if RT_MUTEXES 1183 select LOCKDEP 1184 help 1185 This feature will check whether any held lock (spinlock, rwlock, 1186 mutex or rwsem) is incorrectly freed by the kernel, via any of the 1187 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(), 1188 vfree(), etc.), whether a live lock is incorrectly reinitialized via 1189 spin_lock_init()/mutex_init()/etc., or whether there is any lock 1190 held during task exit. 1191 1192config LOCKDEP 1193 bool 1194 depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT 1195 select STACKTRACE 1196 select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 1197 select KALLSYMS 1198 select KALLSYMS_ALL 1199 1200config LOCKDEP_SMALL 1201 bool 1202 1203config DEBUG_LOCKDEP 1204 bool "Lock dependency engine debugging" 1205 depends on DEBUG_KERNEL && LOCKDEP 1206 help 1207 If you say Y here, the lock dependency engine will do 1208 additional runtime checks to debug itself, at the price 1209 of more runtime overhead. 1210 1211config DEBUG_ATOMIC_SLEEP 1212 bool "Sleep inside atomic section checking" 1213 select PREEMPT_COUNT 1214 depends on DEBUG_KERNEL 1215 depends on !ARCH_NO_PREEMPT 1216 help 1217 If you say Y here, various routines which may sleep will become very 1218 noisy if they are called inside atomic sections: when a spinlock is 1219 held, inside an rcu read side critical section, inside preempt disabled 1220 sections, inside an interrupt, etc... 1221 1222config DEBUG_LOCKING_API_SELFTESTS 1223 bool "Locking API boot-time self-tests" 1224 depends on DEBUG_KERNEL 1225 help 1226 Say Y here if you want the kernel to run a short self-test during 1227 bootup. The self-test checks whether common types of locking bugs 1228 are detected by debugging mechanisms or not. (if you disable 1229 lock debugging then those bugs wont be detected of course.) 1230 The following locking APIs are covered: spinlocks, rwlocks, 1231 mutexes and rwsems. 1232 1233config LOCK_TORTURE_TEST 1234 tristate "torture tests for locking" 1235 depends on DEBUG_KERNEL 1236 select TORTURE_TEST 1237 help 1238 This option provides a kernel module that runs torture tests 1239 on kernel locking primitives. The kernel module may be built 1240 after the fact on the running kernel to be tested, if desired. 1241 1242 Say Y here if you want kernel locking-primitive torture tests 1243 to be built into the kernel. 1244 Say M if you want these torture tests to build as a module. 1245 Say N if you are unsure. 1246 1247config WW_MUTEX_SELFTEST 1248 tristate "Wait/wound mutex selftests" 1249 help 1250 This option provides a kernel module that runs tests on the 1251 on the struct ww_mutex locking API. 1252 1253 It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction 1254 with this test harness. 1255 1256 Say M if you want these self tests to build as a module. 1257 Say N if you are unsure. 1258 1259endmenu # lock debugging 1260 1261config TRACE_IRQFLAGS 1262 bool 1263 help 1264 Enables hooks to interrupt enabling and disabling for 1265 either tracing or lock debugging. 1266 1267config STACKTRACE 1268 bool "Stack backtrace support" 1269 depends on STACKTRACE_SUPPORT 1270 help 1271 This option causes the kernel to create a /proc/pid/stack for 1272 every process, showing its current stack trace. 1273 It is also used by various kernel debugging features that require 1274 stack trace generation. 1275 1276config WARN_ALL_UNSEEDED_RANDOM 1277 bool "Warn for all uses of unseeded randomness" 1278 default n 1279 help 1280 Some parts of the kernel contain bugs relating to their use of 1281 cryptographically secure random numbers before it's actually possible 1282 to generate those numbers securely. This setting ensures that these 1283 flaws don't go unnoticed, by enabling a message, should this ever 1284 occur. This will allow people with obscure setups to know when things 1285 are going wrong, so that they might contact developers about fixing 1286 it. 1287 1288 Unfortunately, on some models of some architectures getting 1289 a fully seeded CRNG is extremely difficult, and so this can 1290 result in dmesg getting spammed for a surprisingly long 1291 time. This is really bad from a security perspective, and 1292 so architecture maintainers really need to do what they can 1293 to get the CRNG seeded sooner after the system is booted. 1294 However, since users cannot do anything actionable to 1295 address this, by default the kernel will issue only a single 1296 warning for the first use of unseeded randomness. 1297 1298 Say Y here if you want to receive warnings for all uses of 1299 unseeded randomness. This will be of use primarily for 1300 those developers interested in improving the security of 1301 Linux kernels running on their architecture (or 1302 subarchitecture). 1303 1304config DEBUG_KOBJECT 1305 bool "kobject debugging" 1306 depends on DEBUG_KERNEL 1307 help 1308 If you say Y here, some extra kobject debugging messages will be sent 1309 to the syslog. 1310 1311config DEBUG_KOBJECT_RELEASE 1312 bool "kobject release debugging" 1313 depends on DEBUG_OBJECTS_TIMERS 1314 help 1315 kobjects are reference counted objects. This means that their 1316 last reference count put is not predictable, and the kobject can 1317 live on past the point at which a driver decides to drop it's 1318 initial reference to the kobject gained on allocation. An 1319 example of this would be a struct device which has just been 1320 unregistered. 1321 1322 However, some buggy drivers assume that after such an operation, 1323 the memory backing the kobject can be immediately freed. This 1324 goes completely against the principles of a refcounted object. 1325 1326 If you say Y here, the kernel will delay the release of kobjects 1327 on the last reference count to improve the visibility of this 1328 kind of kobject release bug. 1329 1330config HAVE_DEBUG_BUGVERBOSE 1331 bool 1332 1333config DEBUG_BUGVERBOSE 1334 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT 1335 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE) 1336 default y 1337 help 1338 Say Y here to make BUG() panics output the file name and line number 1339 of the BUG call as well as the EIP and oops trace. This aids 1340 debugging but costs about 70-100K of memory. 1341 1342config DEBUG_LIST 1343 bool "Debug linked list manipulation" 1344 depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION 1345 help 1346 Enable this to turn on extended checks in the linked-list 1347 walking routines. 1348 1349 If unsure, say N. 1350 1351config DEBUG_PI_LIST 1352 bool "Debug priority linked list manipulation" 1353 depends on DEBUG_KERNEL 1354 help 1355 Enable this to turn on extended checks in the priority-ordered 1356 linked-list (plist) walking routines. This checks the entire 1357 list multiple times during each manipulation. 1358 1359 If unsure, say N. 1360 1361config DEBUG_SG 1362 bool "Debug SG table operations" 1363 depends on DEBUG_KERNEL 1364 help 1365 Enable this to turn on checks on scatter-gather tables. This can 1366 help find problems with drivers that do not properly initialize 1367 their sg tables. 1368 1369 If unsure, say N. 1370 1371config DEBUG_NOTIFIERS 1372 bool "Debug notifier call chains" 1373 depends on DEBUG_KERNEL 1374 help 1375 Enable this to turn on sanity checking for notifier call chains. 1376 This is most useful for kernel developers to make sure that 1377 modules properly unregister themselves from notifier chains. 1378 This is a relatively cheap check but if you care about maximum 1379 performance, say N. 1380 1381config DEBUG_CREDENTIALS 1382 bool "Debug credential management" 1383 depends on DEBUG_KERNEL 1384 help 1385 Enable this to turn on some debug checking for credential 1386 management. The additional code keeps track of the number of 1387 pointers from task_structs to any given cred struct, and checks to 1388 see that this number never exceeds the usage count of the cred 1389 struct. 1390 1391 Furthermore, if SELinux is enabled, this also checks that the 1392 security pointer in the cred struct is never seen to be invalid. 1393 1394 If unsure, say N. 1395 1396source "kernel/rcu/Kconfig.debug" 1397 1398config DEBUG_WQ_FORCE_RR_CPU 1399 bool "Force round-robin CPU selection for unbound work items" 1400 depends on DEBUG_KERNEL 1401 default n 1402 help 1403 Workqueue used to implicitly guarantee that work items queued 1404 without explicit CPU specified are put on the local CPU. This 1405 guarantee is no longer true and while local CPU is still 1406 preferred work items may be put on foreign CPUs. Kernel 1407 parameter "workqueue.debug_force_rr_cpu" is added to force 1408 round-robin CPU selection to flush out usages which depend on the 1409 now broken guarantee. This config option enables the debug 1410 feature by default. When enabled, memory and cache locality will 1411 be impacted. 1412 1413config DEBUG_BLOCK_EXT_DEVT 1414 bool "Force extended block device numbers and spread them" 1415 depends on DEBUG_KERNEL 1416 depends on BLOCK 1417 default n 1418 help 1419 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON 1420 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT 1421 YOU ARE DOING. Distros, please enable this and fix whatever 1422 is broken. 1423 1424 Conventionally, block device numbers are allocated from 1425 predetermined contiguous area. However, extended block area 1426 may introduce non-contiguous block device numbers. This 1427 option forces most block device numbers to be allocated from 1428 the extended space and spreads them to discover kernel or 1429 userland code paths which assume predetermined contiguous 1430 device number allocation. 1431 1432 Note that turning on this debug option shuffles all the 1433 device numbers for all IDE and SCSI devices including libata 1434 ones, so root partition specified using device number 1435 directly (via rdev or root=MAJ:MIN) won't work anymore. 1436 Textual device names (root=/dev/sdXn) will continue to work. 1437 1438 Say N if you are unsure. 1439 1440config CPU_HOTPLUG_STATE_CONTROL 1441 bool "Enable CPU hotplug state control" 1442 depends on DEBUG_KERNEL 1443 depends on HOTPLUG_CPU 1444 default n 1445 help 1446 Allows to write steps between "offline" and "online" to the CPUs 1447 sysfs target file so states can be stepped granular. This is a debug 1448 option for now as the hotplug machinery cannot be stopped and 1449 restarted at arbitrary points yet. 1450 1451 Say N if your are unsure. 1452 1453config NOTIFIER_ERROR_INJECTION 1454 tristate "Notifier error injection" 1455 depends on DEBUG_KERNEL 1456 select DEBUG_FS 1457 help 1458 This option provides the ability to inject artificial errors to 1459 specified notifier chain callbacks. It is useful to test the error 1460 handling of notifier call chain failures. 1461 1462 Say N if unsure. 1463 1464config PM_NOTIFIER_ERROR_INJECT 1465 tristate "PM notifier error injection module" 1466 depends on PM && NOTIFIER_ERROR_INJECTION 1467 default m if PM_DEBUG 1468 help 1469 This option provides the ability to inject artificial errors to 1470 PM notifier chain callbacks. It is controlled through debugfs 1471 interface /sys/kernel/debug/notifier-error-inject/pm 1472 1473 If the notifier call chain should be failed with some events 1474 notified, write the error code to "actions/<notifier event>/error". 1475 1476 Example: Inject PM suspend error (-12 = -ENOMEM) 1477 1478 # cd /sys/kernel/debug/notifier-error-inject/pm/ 1479 # echo -12 > actions/PM_SUSPEND_PREPARE/error 1480 # echo mem > /sys/power/state 1481 bash: echo: write error: Cannot allocate memory 1482 1483 To compile this code as a module, choose M here: the module will 1484 be called pm-notifier-error-inject. 1485 1486 If unsure, say N. 1487 1488config OF_RECONFIG_NOTIFIER_ERROR_INJECT 1489 tristate "OF reconfig notifier error injection module" 1490 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION 1491 help 1492 This option provides the ability to inject artificial errors to 1493 OF reconfig notifier chain callbacks. It is controlled 1494 through debugfs interface under 1495 /sys/kernel/debug/notifier-error-inject/OF-reconfig/ 1496 1497 If the notifier call chain should be failed with some events 1498 notified, write the error code to "actions/<notifier event>/error". 1499 1500 To compile this code as a module, choose M here: the module will 1501 be called of-reconfig-notifier-error-inject. 1502 1503 If unsure, say N. 1504 1505config NETDEV_NOTIFIER_ERROR_INJECT 1506 tristate "Netdev notifier error injection module" 1507 depends on NET && NOTIFIER_ERROR_INJECTION 1508 help 1509 This option provides the ability to inject artificial errors to 1510 netdevice notifier chain callbacks. It is controlled through debugfs 1511 interface /sys/kernel/debug/notifier-error-inject/netdev 1512 1513 If the notifier call chain should be failed with some events 1514 notified, write the error code to "actions/<notifier event>/error". 1515 1516 Example: Inject netdevice mtu change error (-22 = -EINVAL) 1517 1518 # cd /sys/kernel/debug/notifier-error-inject/netdev 1519 # echo -22 > actions/NETDEV_CHANGEMTU/error 1520 # ip link set eth0 mtu 1024 1521 RTNETLINK answers: Invalid argument 1522 1523 To compile this code as a module, choose M here: the module will 1524 be called netdev-notifier-error-inject. 1525 1526 If unsure, say N. 1527 1528config FUNCTION_ERROR_INJECTION 1529 def_bool y 1530 depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES 1531 1532config FAULT_INJECTION 1533 bool "Fault-injection framework" 1534 depends on DEBUG_KERNEL 1535 help 1536 Provide fault-injection framework. 1537 For more details, see Documentation/fault-injection/. 1538 1539config FAILSLAB 1540 bool "Fault-injection capability for kmalloc" 1541 depends on FAULT_INJECTION 1542 depends on SLAB || SLUB 1543 help 1544 Provide fault-injection capability for kmalloc. 1545 1546config FAIL_PAGE_ALLOC 1547 bool "Fault-injection capabilitiy for alloc_pages()" 1548 depends on FAULT_INJECTION 1549 help 1550 Provide fault-injection capability for alloc_pages(). 1551 1552config FAIL_MAKE_REQUEST 1553 bool "Fault-injection capability for disk IO" 1554 depends on FAULT_INJECTION && BLOCK 1555 help 1556 Provide fault-injection capability for disk IO. 1557 1558config FAIL_IO_TIMEOUT 1559 bool "Fault-injection capability for faking disk interrupts" 1560 depends on FAULT_INJECTION && BLOCK 1561 help 1562 Provide fault-injection capability on end IO handling. This 1563 will make the block layer "forget" an interrupt as configured, 1564 thus exercising the error handling. 1565 1566 Only works with drivers that use the generic timeout handling, 1567 for others it wont do anything. 1568 1569config FAIL_FUTEX 1570 bool "Fault-injection capability for futexes" 1571 select DEBUG_FS 1572 depends on FAULT_INJECTION && FUTEX 1573 help 1574 Provide fault-injection capability for futexes. 1575 1576config FAULT_INJECTION_DEBUG_FS 1577 bool "Debugfs entries for fault-injection capabilities" 1578 depends on FAULT_INJECTION && SYSFS && DEBUG_FS 1579 help 1580 Enable configuration of fault-injection capabilities via debugfs. 1581 1582config FAIL_FUNCTION 1583 bool "Fault-injection capability for functions" 1584 depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION 1585 help 1586 Provide function-based fault-injection capability. 1587 This will allow you to override a specific function with a return 1588 with given return value. As a result, function caller will see 1589 an error value and have to handle it. This is useful to test the 1590 error handling in various subsystems. 1591 1592config FAIL_MMC_REQUEST 1593 bool "Fault-injection capability for MMC IO" 1594 depends on FAULT_INJECTION_DEBUG_FS && MMC 1595 help 1596 Provide fault-injection capability for MMC IO. 1597 This will make the mmc core return data errors. This is 1598 useful to test the error handling in the mmc block device 1599 and to test how the mmc host driver handles retries from 1600 the block device. 1601 1602config FAULT_INJECTION_STACKTRACE_FILTER 1603 bool "stacktrace filter for fault-injection capabilities" 1604 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT 1605 depends on !X86_64 1606 select STACKTRACE 1607 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1608 help 1609 Provide stacktrace filter for fault-injection capabilities 1610 1611config LATENCYTOP 1612 bool "Latency measuring infrastructure" 1613 depends on DEBUG_KERNEL 1614 depends on STACKTRACE_SUPPORT 1615 depends on PROC_FS 1616 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86 1617 select KALLSYMS 1618 select KALLSYMS_ALL 1619 select STACKTRACE 1620 select SCHEDSTATS 1621 select SCHED_DEBUG 1622 help 1623 Enable this option if you want to use the LatencyTOP tool 1624 to find out which userspace is blocking on what kernel operations. 1625 1626source "kernel/trace/Kconfig" 1627 1628config PROVIDE_OHCI1394_DMA_INIT 1629 bool "Remote debugging over FireWire early on boot" 1630 depends on PCI && X86 1631 help 1632 If you want to debug problems which hang or crash the kernel early 1633 on boot and the crashing machine has a FireWire port, you can use 1634 this feature to remotely access the memory of the crashed machine 1635 over FireWire. This employs remote DMA as part of the OHCI1394 1636 specification which is now the standard for FireWire controllers. 1637 1638 With remote DMA, you can monitor the printk buffer remotely using 1639 firescope and access all memory below 4GB using fireproxy from gdb. 1640 Even controlling a kernel debugger is possible using remote DMA. 1641 1642 Usage: 1643 1644 If ohci1394_dma=early is used as boot parameter, it will initialize 1645 all OHCI1394 controllers which are found in the PCI config space. 1646 1647 As all changes to the FireWire bus such as enabling and disabling 1648 devices cause a bus reset and thereby disable remote DMA for all 1649 devices, be sure to have the cable plugged and FireWire enabled on 1650 the debugging host before booting the debug target for debugging. 1651 1652 This code (~1k) is freed after boot. By then, the firewire stack 1653 in charge of the OHCI-1394 controllers should be used instead. 1654 1655 See Documentation/debugging-via-ohci1394.txt for more information. 1656 1657config DMA_API_DEBUG 1658 bool "Enable debugging of DMA-API usage" 1659 select NEED_DMA_MAP_STATE 1660 help 1661 Enable this option to debug the use of the DMA API by device drivers. 1662 With this option you will be able to detect common bugs in device 1663 drivers like double-freeing of DMA mappings or freeing mappings that 1664 were never allocated. 1665 1666 This also attempts to catch cases where a page owned by DMA is 1667 accessed by the cpu in a way that could cause data corruption. For 1668 example, this enables cow_user_page() to check that the source page is 1669 not undergoing DMA. 1670 1671 This option causes a performance degradation. Use only if you want to 1672 debug device drivers and dma interactions. 1673 1674 If unsure, say N. 1675 1676config DMA_API_DEBUG_SG 1677 bool "Debug DMA scatter-gather usage" 1678 default y 1679 depends on DMA_API_DEBUG 1680 help 1681 Perform extra checking that callers of dma_map_sg() have respected the 1682 appropriate segment length/boundary limits for the given device when 1683 preparing DMA scatterlists. 1684 1685 This is particularly likely to have been overlooked in cases where the 1686 dma_map_sg() API is used for general bulk mapping of pages rather than 1687 preparing literal scatter-gather descriptors, where there is a risk of 1688 unexpected behaviour from DMA API implementations if the scatterlist 1689 is technically out-of-spec. 1690 1691 If unsure, say N. 1692 1693menuconfig RUNTIME_TESTING_MENU 1694 bool "Runtime Testing" 1695 def_bool y 1696 1697if RUNTIME_TESTING_MENU 1698 1699config LKDTM 1700 tristate "Linux Kernel Dump Test Tool Module" 1701 depends on DEBUG_FS 1702 help 1703 This module enables testing of the different dumping mechanisms by 1704 inducing system failures at predefined crash points. 1705 If you don't need it: say N 1706 Choose M here to compile this code as a module. The module will be 1707 called lkdtm. 1708 1709 Documentation on how to use the module can be found in 1710 Documentation/fault-injection/provoke-crashes.txt 1711 1712config TEST_LIST_SORT 1713 tristate "Linked list sorting test" 1714 depends on DEBUG_KERNEL || m 1715 help 1716 Enable this to turn on 'list_sort()' function test. This test is 1717 executed only once during system boot (so affects only boot time), 1718 or at module load time. 1719 1720 If unsure, say N. 1721 1722config TEST_SORT 1723 tristate "Array-based sort test" 1724 depends on DEBUG_KERNEL || m 1725 help 1726 This option enables the self-test function of 'sort()' at boot, 1727 or at module load time. 1728 1729 If unsure, say N. 1730 1731config KPROBES_SANITY_TEST 1732 bool "Kprobes sanity tests" 1733 depends on DEBUG_KERNEL 1734 depends on KPROBES 1735 help 1736 This option provides for testing basic kprobes functionality on 1737 boot. Samples of kprobe and kretprobe are inserted and 1738 verified for functionality. 1739 1740 Say N if you are unsure. 1741 1742config BACKTRACE_SELF_TEST 1743 tristate "Self test for the backtrace code" 1744 depends on DEBUG_KERNEL 1745 help 1746 This option provides a kernel module that can be used to test 1747 the kernel stack backtrace code. This option is not useful 1748 for distributions or general kernels, but only for kernel 1749 developers working on architecture code. 1750 1751 Note that if you want to also test saved backtraces, you will 1752 have to enable STACKTRACE as well. 1753 1754 Say N if you are unsure. 1755 1756config RBTREE_TEST 1757 tristate "Red-Black tree test" 1758 depends on DEBUG_KERNEL 1759 help 1760 A benchmark measuring the performance of the rbtree library. 1761 Also includes rbtree invariant checks. 1762 1763config INTERVAL_TREE_TEST 1764 tristate "Interval tree test" 1765 depends on DEBUG_KERNEL 1766 select INTERVAL_TREE 1767 help 1768 A benchmark measuring the performance of the interval tree library 1769 1770config PERCPU_TEST 1771 tristate "Per cpu operations test" 1772 depends on m && DEBUG_KERNEL 1773 help 1774 Enable this option to build test module which validates per-cpu 1775 operations. 1776 1777 If unsure, say N. 1778 1779config ATOMIC64_SELFTEST 1780 tristate "Perform an atomic64_t self-test" 1781 help 1782 Enable this option to test the atomic64_t functions at boot or 1783 at module load time. 1784 1785 If unsure, say N. 1786 1787config ASYNC_RAID6_TEST 1788 tristate "Self test for hardware accelerated raid6 recovery" 1789 depends on ASYNC_RAID6_RECOV 1790 select ASYNC_MEMCPY 1791 ---help--- 1792 This is a one-shot self test that permutes through the 1793 recovery of all the possible two disk failure scenarios for a 1794 N-disk array. Recovery is performed with the asynchronous 1795 raid6 recovery routines, and will optionally use an offload 1796 engine if one is available. 1797 1798 If unsure, say N. 1799 1800config TEST_HEXDUMP 1801 tristate "Test functions located in the hexdump module at runtime" 1802 1803config TEST_STRING_HELPERS 1804 tristate "Test functions located in the string_helpers module at runtime" 1805 1806config TEST_KSTRTOX 1807 tristate "Test kstrto*() family of functions at runtime" 1808 1809config TEST_PRINTF 1810 tristate "Test printf() family of functions at runtime" 1811 1812config TEST_BITMAP 1813 tristate "Test bitmap_*() family of functions at runtime" 1814 help 1815 Enable this option to test the bitmap functions at boot. 1816 1817 If unsure, say N. 1818 1819config TEST_BITFIELD 1820 tristate "Test bitfield functions at runtime" 1821 help 1822 Enable this option to test the bitfield functions at boot. 1823 1824 If unsure, say N. 1825 1826config TEST_UUID 1827 tristate "Test functions located in the uuid module at runtime" 1828 1829config TEST_XARRAY 1830 tristate "Test the XArray code at runtime" 1831 1832config TEST_OVERFLOW 1833 tristate "Test check_*_overflow() functions at runtime" 1834 1835config TEST_RHASHTABLE 1836 tristate "Perform selftest on resizable hash table" 1837 help 1838 Enable this option to test the rhashtable functions at boot. 1839 1840 If unsure, say N. 1841 1842config TEST_HASH 1843 tristate "Perform selftest on hash functions" 1844 help 1845 Enable this option to test the kernel's integer (<linux/hash.h>), 1846 string (<linux/stringhash.h>), and siphash (<linux/siphash.h>) 1847 hash functions on boot (or module load). 1848 1849 This is intended to help people writing architecture-specific 1850 optimized versions. If unsure, say N. 1851 1852config TEST_IDA 1853 tristate "Perform selftest on IDA functions" 1854 1855config TEST_PARMAN 1856 tristate "Perform selftest on priority array manager" 1857 depends on PARMAN 1858 help 1859 Enable this option to test priority array manager on boot 1860 (or module load). 1861 1862 If unsure, say N. 1863 1864config TEST_LKM 1865 tristate "Test module loading with 'hello world' module" 1866 depends on m 1867 help 1868 This builds the "test_module" module that emits "Hello, world" 1869 on printk when loaded. It is designed to be used for basic 1870 evaluation of the module loading subsystem (for example when 1871 validating module verification). It lacks any extra dependencies, 1872 and will not normally be loaded by the system unless explicitly 1873 requested by name. 1874 1875 If unsure, say N. 1876 1877config TEST_VMALLOC 1878 tristate "Test module for stress/performance analysis of vmalloc allocator" 1879 default n 1880 depends on MMU 1881 depends on m 1882 help 1883 This builds the "test_vmalloc" module that should be used for 1884 stress and performance analysis. So, any new change for vmalloc 1885 subsystem can be evaluated from performance and stability point 1886 of view. 1887 1888 If unsure, say N. 1889 1890config TEST_USER_COPY 1891 tristate "Test user/kernel boundary protections" 1892 depends on m 1893 help 1894 This builds the "test_user_copy" module that runs sanity checks 1895 on the copy_to/from_user infrastructure, making sure basic 1896 user/kernel boundary testing is working. If it fails to load, 1897 a regression has been detected in the user/kernel memory boundary 1898 protections. 1899 1900 If unsure, say N. 1901 1902config TEST_BPF 1903 tristate "Test BPF filter functionality" 1904 depends on m && NET 1905 help 1906 This builds the "test_bpf" module that runs various test vectors 1907 against the BPF interpreter or BPF JIT compiler depending on the 1908 current setting. This is in particular useful for BPF JIT compiler 1909 development, but also to run regression tests against changes in 1910 the interpreter code. It also enables test stubs for eBPF maps and 1911 verifier used by user space verifier testsuite. 1912 1913 If unsure, say N. 1914 1915config FIND_BIT_BENCHMARK 1916 tristate "Test find_bit functions" 1917 help 1918 This builds the "test_find_bit" module that measure find_*_bit() 1919 functions performance. 1920 1921 If unsure, say N. 1922 1923config TEST_FIRMWARE 1924 tristate "Test firmware loading via userspace interface" 1925 depends on FW_LOADER 1926 help 1927 This builds the "test_firmware" module that creates a userspace 1928 interface for testing firmware loading. This can be used to 1929 control the triggering of firmware loading without needing an 1930 actual firmware-using device. The contents can be rechecked by 1931 userspace. 1932 1933 If unsure, say N. 1934 1935config TEST_SYSCTL 1936 tristate "sysctl test driver" 1937 depends on PROC_SYSCTL 1938 help 1939 This builds the "test_sysctl" module. This driver enables to test the 1940 proc sysctl interfaces available to drivers safely without affecting 1941 production knobs which might alter system functionality. 1942 1943 If unsure, say N. 1944 1945config TEST_UDELAY 1946 tristate "udelay test driver" 1947 help 1948 This builds the "udelay_test" module that helps to make sure 1949 that udelay() is working properly. 1950 1951 If unsure, say N. 1952 1953config TEST_STATIC_KEYS 1954 tristate "Test static keys" 1955 depends on m 1956 help 1957 Test the static key interfaces. 1958 1959 If unsure, say N. 1960 1961config TEST_KMOD 1962 tristate "kmod stress tester" 1963 depends on m 1964 depends on BLOCK && (64BIT || LBDAF) # for XFS, BTRFS 1965 depends on NETDEVICES && NET_CORE && INET # for TUN 1966 select TEST_LKM 1967 select XFS_FS 1968 select TUN 1969 select BTRFS_FS 1970 help 1971 Test the kernel's module loading mechanism: kmod. kmod implements 1972 support to load modules using the Linux kernel's usermode helper. 1973 This test provides a series of tests against kmod. 1974 1975 Although technically you can either build test_kmod as a module or 1976 into the kernel we disallow building it into the kernel since 1977 it stress tests request_module() and this will very likely cause 1978 some issues by taking over precious threads available from other 1979 module load requests, ultimately this could be fatal. 1980 1981 To run tests run: 1982 1983 tools/testing/selftests/kmod/kmod.sh --help 1984 1985 If unsure, say N. 1986 1987config TEST_DEBUG_VIRTUAL 1988 tristate "Test CONFIG_DEBUG_VIRTUAL feature" 1989 depends on DEBUG_VIRTUAL 1990 help 1991 Test the kernel's ability to detect incorrect calls to 1992 virt_to_phys() done against the non-linear part of the 1993 kernel's virtual address map. 1994 1995 If unsure, say N. 1996 1997config TEST_MEMCAT_P 1998 tristate "Test memcat_p() helper function" 1999 help 2000 Test the memcat_p() helper for correctly merging two 2001 pointer arrays together. 2002 2003 If unsure, say N. 2004 2005config TEST_LIVEPATCH 2006 tristate "Test livepatching" 2007 default n 2008 depends on DYNAMIC_DEBUG 2009 depends on LIVEPATCH 2010 depends on m 2011 help 2012 Test kernel livepatching features for correctness. The tests will 2013 load test modules that will be livepatched in various scenarios. 2014 2015 To run all the livepatching tests: 2016 2017 make -C tools/testing/selftests TARGETS=livepatch run_tests 2018 2019 Alternatively, individual tests may be invoked: 2020 2021 tools/testing/selftests/livepatch/test-callbacks.sh 2022 tools/testing/selftests/livepatch/test-livepatch.sh 2023 tools/testing/selftests/livepatch/test-shadow-vars.sh 2024 2025 If unsure, say N. 2026 2027config TEST_OBJAGG 2028 tristate "Perform selftest on object aggreration manager" 2029 default n 2030 depends on OBJAGG 2031 help 2032 Enable this option to test object aggregation manager on boot 2033 (or module load). 2034 2035 2036config TEST_STACKINIT 2037 tristate "Test level of stack variable initialization" 2038 help 2039 Test if the kernel is zero-initializing stack variables and 2040 padding. Coverage is controlled by compiler flags, 2041 CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, 2042 or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. 2043 2044 If unsure, say N. 2045 2046endif # RUNTIME_TESTING_MENU 2047 2048config MEMTEST 2049 bool "Memtest" 2050 ---help--- 2051 This option adds a kernel parameter 'memtest', which allows memtest 2052 to be set. 2053 memtest=0, mean disabled; -- default 2054 memtest=1, mean do 1 test pattern; 2055 ... 2056 memtest=17, mean do 17 test patterns. 2057 If you are unsure how to answer this question, answer N. 2058 2059config BUG_ON_DATA_CORRUPTION 2060 bool "Trigger a BUG when data corruption is detected" 2061 select DEBUG_LIST 2062 help 2063 Select this option if the kernel should BUG when it encounters 2064 data corruption in kernel memory structures when they get checked 2065 for validity. 2066 2067 If unsure, say N. 2068 2069source "samples/Kconfig" 2070 2071source "lib/Kconfig.kgdb" 2072 2073source "lib/Kconfig.ubsan" 2074 2075config ARCH_HAS_DEVMEM_IS_ALLOWED 2076 bool 2077 2078config STRICT_DEVMEM 2079 bool "Filter access to /dev/mem" 2080 depends on MMU && DEVMEM 2081 depends on ARCH_HAS_DEVMEM_IS_ALLOWED 2082 default y if PPC || X86 || ARM64 2083 ---help--- 2084 If this option is disabled, you allow userspace (root) access to all 2085 of memory, including kernel and userspace memory. Accidental 2086 access to this is obviously disastrous, but specific access can 2087 be used by people debugging the kernel. Note that with PAT support 2088 enabled, even in this case there are restrictions on /dev/mem 2089 use due to the cache aliasing requirements. 2090 2091 If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem 2092 file only allows userspace access to PCI space and the BIOS code and 2093 data regions. This is sufficient for dosemu and X and all common 2094 users of /dev/mem. 2095 2096 If in doubt, say Y. 2097 2098config IO_STRICT_DEVMEM 2099 bool "Filter I/O access to /dev/mem" 2100 depends on STRICT_DEVMEM 2101 ---help--- 2102 If this option is disabled, you allow userspace (root) access to all 2103 io-memory regardless of whether a driver is actively using that 2104 range. Accidental access to this is obviously disastrous, but 2105 specific access can be used by people debugging kernel drivers. 2106 2107 If this option is switched on, the /dev/mem file only allows 2108 userspace access to *idle* io-memory ranges (see /proc/iomem) This 2109 may break traditional users of /dev/mem (dosemu, legacy X, etc...) 2110 if the driver using a given range cannot be disabled. 2111 2112 If in doubt, say Y. 2113 2114source "arch/$(SRCARCH)/Kconfig.debug" 2115 2116endmenu # Kernel hacking 2117