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