1# SPDX-License-Identifier: GPL-2.0-only 2config CC_VERSION_TEXT 3 string 4 default "$(CC_VERSION_TEXT)" 5 help 6 This is used in unclear ways: 7 8 - Re-run Kconfig when the compiler is updated 9 The 'default' property references the environment variable, 10 CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd. 11 When the compiler is updated, Kconfig will be invoked. 12 13 - Ensure full rebuild when the compiler is updated 14 include/linux/compiler-version.h contains this option in the comment 15 line so fixdep adds include/config/CC_VERSION_TEXT into the 16 auto-generated dependency. When the compiler is updated, syncconfig 17 will touch it and then every file will be rebuilt. 18 19config CC_IS_GCC 20 def_bool $(success,test "$(cc-name)" = GCC) 21 22config GCC_VERSION 23 int 24 default $(cc-version) if CC_IS_GCC 25 default 0 26 27config CC_IS_CLANG 28 def_bool $(success,test "$(cc-name)" = Clang) 29 30config CLANG_VERSION 31 int 32 default $(cc-version) if CC_IS_CLANG 33 default 0 34 35config AS_IS_GNU 36 def_bool $(success,test "$(as-name)" = GNU) 37 38config AS_IS_LLVM 39 def_bool $(success,test "$(as-name)" = LLVM) 40 41config AS_VERSION 42 int 43 # Use clang version if this is the integrated assembler 44 default CLANG_VERSION if AS_IS_LLVM 45 default $(as-version) 46 47config LD_IS_BFD 48 def_bool $(success,test "$(ld-name)" = BFD) 49 50config LD_VERSION 51 int 52 default $(ld-version) if LD_IS_BFD 53 default 0 54 55config LD_IS_LLD 56 def_bool $(success,test "$(ld-name)" = LLD) 57 58config LLD_VERSION 59 int 60 default $(ld-version) if LD_IS_LLD 61 default 0 62 63config RUSTC_VERSION 64 int 65 default $(rustc-version) 66 help 67 It does not depend on `RUST` since that one may need to use the version 68 in a `depends on`. 69 70config RUST_IS_AVAILABLE 71 def_bool $(success,$(srctree)/scripts/rust_is_available.sh) 72 help 73 This shows whether a suitable Rust toolchain is available (found). 74 75 Please see Documentation/rust/quick-start.rst for instructions on how 76 to satisfy the build requirements of Rust support. 77 78 In particular, the Makefile target 'rustavailable' is useful to check 79 why the Rust toolchain is not being detected. 80 81config RUSTC_LLVM_VERSION 82 int 83 default $(rustc-llvm-version) 84 85config RUSTC_LLVM_MAJOR_VERSION 86 int 87 default $(shell,expr $(rustc-llvm-version) / 10000) 88 89config RUSTC_CLANG_LLVM_COMPATIBLE 90 bool 91 default y if CC_IS_CLANG && RUSTC_LLVM_MAJOR_VERSION = $(shell,expr $(cc-version) / 10000) 92 help 93 This indicates whether Rust and Clang use LLVM of the same major 94 version. 95 96 Operations involving handling LLVM IR or bitcode (e.g. cross-language 97 LTO) require the same LLVM major version to work properly. For best 98 compatibility it is recommended that the exact same LLVM is used. 99 100config ARCH_HAS_CC_CAN_LINK 101 bool 102 103config CC_CAN_LINK 104 bool 105 default ARCH_CC_CAN_LINK if ARCH_HAS_CC_CAN_LINK 106 default $(cc_can_link_user,$(m64-flag)) if 64BIT 107 default $(cc_can_link_user,$(m32-flag)) 108 109# Fixed in GCC 14, 13.3, 12.4 and 11.5 110# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 111config GCC_ASM_GOTO_OUTPUT_BROKEN 112 bool 113 depends on CC_IS_GCC 114 default y if GCC_VERSION < 110500 115 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400 116 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300 117 118config CC_HAS_ASM_GOTO_OUTPUT 119 def_bool y 120 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN 121 depends on $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null) 122 123config CC_HAS_ASM_GOTO_TIED_OUTPUT 124 depends on CC_HAS_ASM_GOTO_OUTPUT 125 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 126 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null) 127 128config TOOLS_SUPPORT_RELR 129 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 130 131config CC_HAS_ASM_INLINE 132 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 133 134config CC_HAS_ASSUME 135 bool 136 # clang needs to be at least 19.1.0 since the meaning of the assume 137 # attribute changed: 138 # https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17 139 default y if CC_IS_CLANG && CLANG_VERSION >= 190100 140 # supported since gcc 13.1.0 141 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654 142 default y if CC_IS_GCC && GCC_VERSION >= 130100 143 144config CC_HAS_NO_PROFILE_FN_ATTR 145 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 146 147config CC_HAS_COUNTED_BY 148 bool 149 # clang needs to be at least 20.1.0 to avoid potential crashes 150 # when building structures that contain __counted_by 151 # https://github.com/ClangBuiltLinux/linux/issues/2114 152 # https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489 153 default y if CC_IS_CLANG && CLANG_VERSION >= 200100 154 # supported since gcc 15.1.0 155 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 156 default y if CC_IS_GCC && GCC_VERSION >= 150100 157 158config CC_HAS_COUNTED_BY_PTR 159 bool 160 # supported since clang 22 161 default y if CC_IS_CLANG && CLANG_VERSION >= 220100 162 # supported since gcc 16.0.0 163 default y if CC_IS_GCC && GCC_VERSION >= 160000 164 165config CC_HAS_BROKEN_COUNTED_BY_REF 166 bool 167 # https://github.com/llvm/llvm-project/issues/182575 168 default y if CC_IS_CLANG && CLANG_VERSION < 220100 169 170config CC_HAS_ALLOC_TOKEN 171 def_bool $(cc-option,-falloc-token-max=123) 172 173config CC_HAS_MULTIDIMENSIONAL_NONSTRING 174 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 175 176config LD_CAN_USE_KEEP_IN_OVERLAY 177 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 178 # https://github.com/llvm/llvm-project/pull/130661 179 def_bool LD_IS_BFD || LLD_VERSION >= 210000 180 181config RUSTC_HAS_SPAN_FILE 182 def_bool RUSTC_VERSION >= 108800 183 184config RUSTC_HAS_UNNECESSARY_TRANSMUTES 185 def_bool RUSTC_VERSION >= 108800 186 187config RUSTC_HAS_FILE_WITH_NUL 188 def_bool RUSTC_VERSION >= 108900 189 190config RUSTC_HAS_FILE_AS_C_STR 191 def_bool RUSTC_VERSION >= 109100 192 193config RUSTC_HAS_SUSPICIOUS_RUNTIME_SYMBOL_DEFINITIONS 194 def_bool RUSTC_VERSION >= 109800 195 196config PAHOLE_VERSION 197 int 198 default "$(PAHOLE_VERSION)" 199 200config CONSTRUCTORS 201 bool 202 203config IRQ_WORK 204 def_bool y if SMP 205 206config BUILDTIME_TABLE_SORT 207 bool 208 209config THREAD_INFO_IN_TASK 210 bool 211 help 212 Select this to move thread_info off the stack into task_struct. To 213 make this work, an arch will need to remove all thread_info fields 214 except flags and fix any runtime bugs. 215 216 One subtle change that will be needed is to use try_get_task_stack() 217 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 218 219menu "General setup" 220 221config BROKEN 222 bool 223 help 224 This option allows you to choose whether you want to try to 225 compile (and fix) old drivers that haven't been updated to 226 new infrastructure. 227 228config BROKEN_ON_SMP 229 bool 230 depends on BROKEN || !SMP 231 default y 232 233config INIT_ENV_ARG_LIMIT 234 int 235 default 32 if !UML 236 default 128 if UML 237 help 238 Maximum of each of the number of arguments and environment 239 variables passed to init from the kernel command line. 240 241config COMPILE_TEST 242 bool "Compile also drivers which will not load" 243 depends on HAS_IOMEM 244 help 245 Some drivers can be compiled on a different platform than they are 246 intended to be run on. Despite they cannot be loaded there (or even 247 when they load they cannot be used due to missing HW support), 248 developers still, opposing to distributors, might want to build such 249 drivers to compile-test them. 250 251 If you are a developer and want to build everything available, say Y 252 here. If you are a user/distributor, say N here to exclude useless 253 drivers to be distributed. 254 255config WERROR 256 bool "Compile the kernel with warnings as errors" 257 default COMPILE_TEST 258 help 259 A kernel build should not cause any compiler warnings, and this 260 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 261 to enforce that rule by default. Certain warnings from other tools 262 such as the linker may be upgraded to errors with this option as 263 well. 264 265 However, if you have a new (or very old) compiler or linker with odd 266 and unusual warnings, or you have some architecture with problems, 267 you may need to disable this config option in order to 268 successfully build the kernel. 269 270 If in doubt, say Y. 271 272config UAPI_HEADER_TEST 273 bool "Compile test UAPI headers" 274 depends on HEADERS_INSTALL 275 help 276 Compile test headers exported to user-space to ensure they are 277 self-contained, i.e. compilable as standalone units. 278 279 If you are a developer or tester and want to ensure the exported 280 headers are self-contained, say Y here. Otherwise, choose N. 281 282config LOCALVERSION 283 string "Local version - append to kernel release" 284 help 285 Append an extra string to the end of your kernel version. 286 This will show up when you type uname, for example. 287 The string you set here will be appended after the contents of 288 any files with a filename matching localversion* in your 289 object and source tree, in that order. Your total string can 290 be a maximum of 64 characters. 291 292config LOCALVERSION_AUTO 293 bool "Automatically append version information to the version string" 294 default y 295 depends on !COMPILE_TEST 296 help 297 This will try to automatically determine if the current tree is a 298 release tree by looking for git tags that belong to the current 299 top of tree revision. 300 301 A string of the format -gxxxxxxxx will be added to the localversion 302 if a git-based tree is found. The string generated by this will be 303 appended after any matching localversion* files, and after the value 304 set in CONFIG_LOCALVERSION. 305 306 (The actual string used here is the first 12 characters produced 307 by running the command: 308 309 $ git rev-parse --verify HEAD 310 311 which is done within the script "scripts/setlocalversion".) 312 313config BUILD_SALT 314 string "Build ID Salt" 315 default "" 316 help 317 The build ID is used to link binaries and their debug info. Setting 318 this option will use the value in the calculation of the build id. 319 This is mostly useful for distributions which want to ensure the 320 build is unique between builds. It's safe to leave the default. 321 322config HAVE_KERNEL_GZIP 323 bool 324 325config HAVE_KERNEL_BZIP2 326 bool 327 328config HAVE_KERNEL_LZMA 329 bool 330 331config HAVE_KERNEL_XZ 332 bool 333 334config HAVE_KERNEL_LZO 335 bool 336 337config HAVE_KERNEL_LZ4 338 bool 339 340config HAVE_KERNEL_ZSTD 341 bool 342 343config HAVE_KERNEL_UNCOMPRESSED 344 bool 345 346choice 347 prompt "Kernel compression mode" 348 default KERNEL_GZIP 349 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED 350 help 351 The linux kernel is a kind of self-extracting executable. 352 Several compression algorithms are available, which differ 353 in efficiency, compression and decompression speed. 354 Compression speed is only relevant when building a kernel. 355 Decompression speed is relevant at each boot. 356 357 If you have any problems with bzip2 or lzma compressed 358 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 359 version of this functionality (bzip2 only), for 2.4, was 360 supplied by Christian Ludwig) 361 362 High compression options are mostly useful for users, who 363 are low on disk space (embedded systems), but for whom ram 364 size matters less. 365 366 If in doubt, select 'gzip' 367 368config KERNEL_GZIP 369 bool "Gzip" 370 depends on HAVE_KERNEL_GZIP 371 help 372 The old and tried gzip compression. It provides a good balance 373 between compression ratio and decompression speed. 374 375config KERNEL_BZIP2 376 bool "Bzip2" 377 depends on HAVE_KERNEL_BZIP2 378 help 379 Its compression ratio and speed is intermediate. 380 Decompression speed is slowest among the choices. The kernel 381 size is about 10% smaller with bzip2, in comparison to gzip. 382 Bzip2 uses a large amount of memory. For modern kernels you 383 will need at least 8MB RAM or more for booting. 384 385config KERNEL_LZMA 386 bool "LZMA" 387 depends on HAVE_KERNEL_LZMA 388 help 389 This compression algorithm's ratio is best. Decompression speed 390 is between gzip and bzip2. Compression is slowest. 391 The kernel size is about 33% smaller with LZMA in comparison to gzip. 392 393config KERNEL_XZ 394 bool "XZ" 395 depends on HAVE_KERNEL_XZ 396 help 397 XZ uses the LZMA2 algorithm and instruction set specific 398 BCJ filters which can improve compression ratio of executable 399 code. The size of the kernel is about 30% smaller with XZ in 400 comparison to gzip. On architectures for which there is a BCJ 401 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 402 and SPARC), XZ will create a few percent smaller kernel than 403 plain LZMA. 404 405 The speed is about the same as with LZMA: The decompression 406 speed of XZ is better than that of bzip2 but worse than gzip 407 and LZO. Compression is slow. 408 409config KERNEL_LZO 410 bool "LZO" 411 depends on HAVE_KERNEL_LZO 412 help 413 Its compression ratio is the poorest among the choices. The kernel 414 size is about 10% bigger than gzip; however its speed 415 (both compression and decompression) is the fastest. 416 417config KERNEL_LZ4 418 bool "LZ4" 419 depends on HAVE_KERNEL_LZ4 420 help 421 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 422 A preliminary version of LZ4 de/compression tool is available at 423 <https://code.google.com/p/lz4/>. 424 425 Its compression ratio is worse than LZO. The size of the kernel 426 is about 8% bigger than LZO. But the decompression speed is 427 faster than LZO. 428 429config KERNEL_ZSTD 430 bool "ZSTD" 431 depends on HAVE_KERNEL_ZSTD 432 help 433 ZSTD is a compression algorithm targeting intermediate compression 434 with fast decompression speed. It will compress better than GZIP and 435 decompress around the same speed as LZO, but slower than LZ4. You 436 will need at least 192 KB RAM or more for booting. The zstd command 437 line tool is required for compression. 438 439config KERNEL_UNCOMPRESSED 440 bool "None" 441 depends on HAVE_KERNEL_UNCOMPRESSED 442 help 443 Produce uncompressed kernel image. This option is usually not what 444 you want. It is useful for debugging the kernel in slow simulation 445 environments, where decompressing and moving the kernel is awfully 446 slow. This option allows early boot code to skip the decompressor 447 and jump right at uncompressed kernel image. 448 449endchoice 450 451config DEFAULT_INIT 452 string "Default init path" 453 default "" 454 help 455 This option determines the default init for the system if no init= 456 option is passed on the kernel command line. If the requested path is 457 not present, we will still then move on to attempting further 458 locations (e.g. /sbin/init, etc). If this is empty, we will just use 459 the fallback list when init= is not passed. 460 461config DEFAULT_HOSTNAME 462 string "Default hostname" 463 default "(none)" 464 help 465 This option determines the default system hostname before userspace 466 calls sethostname(2). The kernel traditionally uses "(none)" here, 467 but you may wish to use a different default here to make a minimal 468 system more usable with less configuration. 469 470config SYSVIPC 471 bool "System V IPC" 472 help 473 Inter Process Communication is a suite of library functions and 474 system calls which let processes (running programs) synchronize and 475 exchange information. It is generally considered to be a good thing, 476 and some programs won't run unless you say Y here. In particular, if 477 you want to run the DOS emulator dosemu under Linux (read the 478 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 479 you'll need to say Y here. 480 481 You can find documentation about IPC with "info ipc" and also in 482 section 6.4 of the Linux Programmer's Guide, available from 483 <http://www.tldp.org/guides.html>. 484 485config SYSVIPC_SYSCTL 486 bool 487 depends on SYSVIPC 488 depends on SYSCTL 489 default y 490 491config SYSVIPC_COMPAT 492 def_bool y 493 depends on COMPAT && SYSVIPC 494 495config POSIX_MQUEUE 496 bool "POSIX Message Queues" 497 depends on NET 498 help 499 POSIX variant of message queues is a part of IPC. In POSIX message 500 queues every message has a priority which decides about succession 501 of receiving it by a process. If you want to compile and run 502 programs written e.g. for Solaris with use of its POSIX message 503 queues (functions mq_*) say Y here. 504 505 POSIX message queues are visible as a filesystem called 'mqueue' 506 and can be mounted somewhere if you want to do filesystem 507 operations on message queues. 508 509 If unsure, say Y. 510 511config POSIX_MQUEUE_SYSCTL 512 bool 513 depends on POSIX_MQUEUE 514 depends on SYSCTL 515 default y 516 517config WATCH_QUEUE 518 bool "General notification queue" 519 default n 520 help 521 522 This is a general notification queue for the kernel to pass events to 523 userspace by splicing them into pipes. It can be used in conjunction 524 with watches for key/keyring change notifications and device 525 notifications. 526 527 See Documentation/core-api/watch_queue.rst 528 529config CROSS_MEMORY_ATTACH 530 bool "Enable process_vm_readv/writev syscalls" 531 depends on MMU 532 default y 533 help 534 Enabling this option adds the system calls process_vm_readv and 535 process_vm_writev which allow a process with the correct privileges 536 to directly read from or write to another process' address space. 537 See the man page for more details. 538 539config AUDIT 540 bool "Auditing support" 541 depends on NET 542 help 543 Enable auditing infrastructure that can be used with another 544 kernel subsystem, such as SELinux (which requires this for 545 logging of avc messages output). System call auditing is included 546 on architectures which support it. 547 548config HAVE_ARCH_AUDITSYSCALL 549 bool 550 551config AUDITSYSCALL 552 def_bool y 553 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 554 select FSNOTIFY 555 556source "kernel/irq/Kconfig" 557source "kernel/time/Kconfig" 558source "kernel/bpf/Kconfig" 559source "kernel/Kconfig.preempt" 560 561menu "CPU/Task time and stats accounting" 562 563config VIRT_CPU_ACCOUNTING 564 bool 565 566choice 567 prompt "Cputime accounting" 568 default TICK_CPU_ACCOUNTING 569 570# Kind of a stub config for the pure tick based cputime accounting 571config TICK_CPU_ACCOUNTING 572 bool "Simple tick based cputime accounting" 573 depends on !S390 && !NO_HZ_FULL 574 help 575 This is the basic tick based cputime accounting that maintains 576 statistics about user, system and idle time spent on per jiffies 577 granularity. 578 579 If unsure, say Y. 580 581config VIRT_CPU_ACCOUNTING_NATIVE 582 bool "Deterministic task and CPU time accounting" 583 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 584 select VIRT_CPU_ACCOUNTING 585 help 586 Select this option to enable more accurate task and CPU time 587 accounting. This is done by reading a CPU counter on each 588 kernel entry and exit and on transitions within the kernel 589 between system, softirq and hardirq state, so there is a 590 small performance impact. In the case of s390 or IBM POWER > 5, 591 this also enables accounting of stolen time on logically-partitioned 592 systems. 593 594config VIRT_CPU_ACCOUNTING_GEN 595 bool "Full dynticks CPU time accounting" 596 depends on HAVE_CONTEXT_TRACKING_USER 597 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 598 depends on GENERIC_CLOCKEVENTS 599 select VIRT_CPU_ACCOUNTING 600 select CONTEXT_TRACKING_USER 601 help 602 Select this option to enable task and CPU time accounting on full 603 dynticks systems. This accounting is implemented by watching every 604 kernel-user boundaries using the context tracking subsystem. 605 The accounting is thus performed at the expense of some significant 606 overhead. 607 608 For now this is only useful if you are working on the full 609 dynticks subsystem development. 610 611 If unsure, say N. 612 613endchoice 614 615config IRQ_TIME_ACCOUNTING 616 bool "Fine granularity task level IRQ time accounting" 617 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 618 help 619 Select this option to enable fine granularity task irq time 620 accounting. This is done by reading a timestamp on each 621 transitions between softirq and hardirq state, so there can be a 622 small performance impact. 623 624 If in doubt, say N here. 625 626config HAVE_SCHED_AVG_IRQ 627 def_bool y 628 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 629 depends on SMP 630 631config SCHED_HW_PRESSURE 632 bool 633 default y if ARM && ARM_CPU_TOPOLOGY 634 default y if ARM64 635 depends on SMP 636 depends on CPU_FREQ_THERMAL 637 help 638 Select this option to enable HW pressure accounting in the 639 scheduler. HW pressure is the value conveyed to the scheduler 640 that reflects the reduction in CPU compute capacity resulted from 641 HW throttling. HW throttling occurs when the performance of 642 a CPU is capped due to high operating temperatures as an example. 643 644 If selected, the scheduler will be able to balance tasks accordingly, 645 i.e. put less load on throttled CPUs than on non/less throttled ones. 646 647 This requires the architecture to implement 648 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 649 650config BSD_PROCESS_ACCT 651 bool "BSD Process Accounting (DEPRECATED)" 652 depends on MULTIUSER 653 default n 654 help 655 If you say Y here, a user level program will be able to instruct the 656 kernel (via a special system call) to write process accounting 657 information to a file: whenever a process exits, information about 658 that process will be appended to the file by the kernel. The 659 information includes things such as creation time, owning user, 660 command name, memory usage, controlling terminal etc. (the complete 661 list is in the struct acct in <file:include/linux/acct.h>). It is 662 up to the user level program to do useful things with this 663 information. This mechanism is antiquated and has significant 664 scalability issues. You probably want to use eBPF instead. Say 665 N unless you really need this. 666 667config BSD_PROCESS_ACCT_V3 668 bool "BSD Process Accounting version 3 file format" 669 depends on BSD_PROCESS_ACCT 670 default n 671 help 672 If you say Y here, the process accounting information is written 673 in a new file format that also logs the process IDs of each 674 process and its parent. Note that this file format is incompatible 675 with previous v0/v1/v2 file formats, so you will need updated tools 676 for processing it. A preliminary version of these tools is available 677 at <http://www.gnu.org/software/acct/>. 678 679config TASKSTATS 680 bool "Export task/process statistics through netlink" 681 depends on NET 682 depends on MULTIUSER 683 default n 684 help 685 Export selected statistics for tasks/processes through the 686 generic netlink interface. Unlike BSD process accounting, the 687 statistics are available during the lifetime of tasks/processes as 688 responses to commands. Like BSD accounting, they are sent to user 689 space on task exit. 690 691 Say N if unsure. 692 693config TASK_DELAY_ACCT 694 bool "Enable per-task delay accounting" 695 depends on TASKSTATS 696 select SCHED_INFO 697 help 698 Collect information on time spent by a task waiting for system 699 resources like cpu, synchronous block I/O completion and swapping 700 in pages. Such statistics can help in setting a task's priorities 701 relative to other tasks for cpu, io, rss limits etc. 702 703 Say N if unsure. 704 705config TASK_XACCT 706 bool "Enable extended accounting over taskstats" 707 depends on TASKSTATS 708 help 709 Collect extended task accounting data and send the data 710 to userland for processing over the taskstats interface. 711 712 Say N if unsure. 713 714config TASK_IO_ACCOUNTING 715 bool "Enable per-task storage I/O accounting" 716 depends on TASK_XACCT 717 help 718 Collect information on the number of bytes of storage I/O which this 719 task has caused. 720 721 Say N if unsure. 722 723config PSI 724 bool "Pressure stall information tracking" 725 select KERNFS 726 help 727 Collect metrics that indicate how overcommitted the CPU, memory, 728 and IO capacity are in the system. 729 730 If you say Y here, the kernel will create /proc/pressure/ with the 731 pressure statistics files cpu, memory, and io. These will indicate 732 the share of walltime in which some or all tasks in the system are 733 delayed due to contention of the respective resource. 734 735 In kernels with cgroup support, cgroups (cgroup2 only) will 736 have cpu.pressure, memory.pressure, and io.pressure files, 737 which aggregate pressure stalls for the grouped tasks only. 738 739 For more details see Documentation/accounting/psi.rst. 740 741 Say N if unsure. 742 743config PSI_DEFAULT_DISABLED 744 bool "Require boot parameter to enable pressure stall information tracking" 745 default n 746 depends on PSI 747 help 748 If set, pressure stall information tracking will be disabled 749 per default but can be enabled through passing psi=1 on the 750 kernel commandline during boot. 751 752 This feature adds some code to the task wakeup and sleep 753 paths of the scheduler. The overhead is too low to affect 754 common scheduling-intense workloads in practice (such as 755 webservers, memcache), but it does show up in artificial 756 scheduler stress tests, such as hackbench. 757 758 If you are paranoid and not sure what the kernel will be 759 used for, say Y. 760 761 Say N if unsure. 762 763endmenu # "CPU/Task time and stats accounting" 764 765config CPU_ISOLATION 766 bool "CPU isolation" 767 depends on SMP 768 default y 769 help 770 Make sure that CPUs running critical tasks are not disturbed by 771 any source of "noise" such as unbound workqueues, timers, kthreads... 772 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 773 the "isolcpus=" boot parameter. 774 775 Say Y if unsure. 776 777source "kernel/rcu/Kconfig" 778 779config IKCONFIG 780 tristate "Kernel .config support" 781 help 782 This option enables the complete Linux kernel ".config" file 783 contents to be saved in the kernel. It provides documentation 784 of which kernel options are used in a running kernel or in an 785 on-disk kernel. This information can be extracted from the kernel 786 image file with the script scripts/extract-ikconfig and used as 787 input to rebuild the current kernel or to build another kernel. 788 It can also be extracted from a running kernel by reading 789 /proc/config.gz if enabled (below). 790 791config IKCONFIG_PROC 792 bool "Enable access to .config through /proc/config.gz" 793 depends on IKCONFIG && PROC_FS 794 help 795 This option enables access to the kernel configuration file 796 through /proc/config.gz. 797 798config IKHEADERS 799 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 800 depends on SYSFS 801 help 802 This option enables access to the in-kernel headers that are generated during 803 the build process. These can be used to build eBPF tracing programs, 804 or similar programs. If you build the headers as a module, a module called 805 kheaders.ko is built which can be loaded on-demand to get access to headers. 806 807config LOG_BUF_SHIFT 808 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 809 range 12 25 810 default 17 811 depends on PRINTK 812 help 813 Select the minimal kernel log buffer size as a power of 2. 814 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 815 parameter, see below. Any higher size also might be forced 816 by "log_buf_len" boot parameter. 817 818 Examples: 819 17 => 128 KB 820 16 => 64 KB 821 15 => 32 KB 822 14 => 16 KB 823 13 => 8 KB 824 12 => 4 KB 825 826config LOG_CPU_MAX_BUF_SHIFT 827 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 828 depends on SMP 829 range 0 21 830 default 0 if BASE_SMALL 831 default 12 832 depends on PRINTK 833 help 834 This option allows to increase the default ring buffer size 835 according to the number of CPUs. The value defines the contribution 836 of each CPU as a power of 2. The used space is typically only few 837 lines however it might be much more when problems are reported, 838 e.g. backtraces. 839 840 The increased size means that a new buffer has to be allocated and 841 the original static one is unused. It makes sense only on systems 842 with more CPUs. Therefore this value is used only when the sum of 843 contributions is greater than the half of the default kernel ring 844 buffer as defined by LOG_BUF_SHIFT. The default values are set 845 so that more than 16 CPUs are needed to trigger the allocation. 846 847 Also this option is ignored when "log_buf_len" kernel parameter is 848 used as it forces an exact (power of two) size of the ring buffer. 849 850 The number of possible CPUs is used for this computation ignoring 851 hotplugging making the computation optimal for the worst case 852 scenario while allowing a simple algorithm to be used from bootup. 853 854 Examples shift values and their meaning: 855 17 => 128 KB for each CPU 856 16 => 64 KB for each CPU 857 15 => 32 KB for each CPU 858 14 => 16 KB for each CPU 859 13 => 8 KB for each CPU 860 12 => 4 KB for each CPU 861 862config PRINTK_INDEX 863 bool "Printk indexing debugfs interface" 864 depends on PRINTK && DEBUG_FS 865 help 866 Add support for indexing of all printk formats known at compile time 867 at <debugfs>/printk/index/<module>. 868 869 This can be used as part of maintaining daemons which monitor 870 /dev/kmsg, as it permits auditing the printk formats present in a 871 kernel, allowing detection of cases where monitored printks are 872 changed or no longer present. 873 874 There is no additional runtime cost to printk with this enabled. 875 876# 877# Architectures with an unreliable sched_clock() should select this: 878# 879config HAVE_UNSTABLE_SCHED_CLOCK 880 bool 881 882config GENERIC_SCHED_CLOCK 883 bool 884 885menu "Scheduler features" 886 887config UCLAMP_TASK 888 bool "Enable utilization clamping for RT/FAIR tasks" 889 depends on CPU_FREQ_GOV_SCHEDUTIL 890 help 891 This feature enables the scheduler to track the clamped utilization 892 of each CPU based on RUNNABLE tasks scheduled on that CPU. 893 894 With this option, the user can specify the min and max CPU 895 utilization allowed for RUNNABLE tasks. The max utilization defines 896 the maximum frequency a task should use while the min utilization 897 defines the minimum frequency it should use. 898 899 Both min and max utilization clamp values are hints to the scheduler, 900 aiming at improving its frequency selection policy, but they do not 901 enforce or grant any specific bandwidth for tasks. 902 903 If in doubt, say N. 904 905config UCLAMP_BUCKETS_COUNT 906 int "Number of supported utilization clamp buckets" 907 range 5 20 908 default 5 909 depends on UCLAMP_TASK 910 help 911 Defines the number of clamp buckets to use. The range of each bucket 912 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 913 number of clamp buckets the finer their granularity and the higher 914 the precision of clamping aggregation and tracking at run-time. 915 916 For example, with the minimum configuration value we will have 5 917 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 918 be refcounted in the [20..39]% bucket and will set the bucket clamp 919 effective value to 25%. 920 If a second 30% boosted task should be co-scheduled on the same CPU, 921 that task will be refcounted in the same bucket of the first task and 922 it will boost the bucket clamp effective value to 30%. 923 The clamp effective value of a bucket is reset to its nominal value 924 (20% in the example above) when there are no more tasks refcounted in 925 that bucket. 926 927 An additional boost/capping margin can be added to some tasks. In the 928 example above the 25% task will be boosted to 30% until it exits the 929 CPU. If that should be considered not acceptable on certain systems, 930 it's always possible to reduce the margin by increasing the number of 931 clamp buckets to trade off used memory for run-time tracking 932 precision. 933 934 If in doubt, use the default value. 935 936config SCHED_PROXY_EXEC 937 bool "Proxy Execution" 938 # Avoid some build failures w/ PREEMPT_RT until it can be fixed 939 depends on !PREEMPT_RT 940 # Need to investigate how to inform sched_ext of split contexts 941 depends on !SCHED_CLASS_EXT 942 # Not particularly useful until we get to multi-rq proxying 943 depends on EXPERT 944 help 945 This option enables proxy execution, a mechanism for mutex-owning 946 tasks to inherit the scheduling context of higher priority waiters. 947 948endmenu 949 950# 951# For architectures that want to enable the support for NUMA-affine scheduler 952# balancing logic: 953# 954config ARCH_SUPPORTS_NUMA_BALANCING 955 bool 956 957# 958# For architectures that prefer to flush all TLBs after a number of pages 959# are unmapped instead of sending one IPI per page to flush. The architecture 960# must provide guarantees on what happens if a clean TLB cache entry is 961# written after the unmap. Details are in mm/rmap.c near the check for 962# should_defer_flush. The architecture should also consider if the full flush 963# and the refill costs are offset by the savings of sending fewer IPIs. 964config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 965 bool 966 967config CC_HAS_INT128 968 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 969 970config CC_IMPLICIT_FALLTHROUGH 971 string 972 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 973 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 974 975config CC_MS_EXTENSIONS 976 string 977 default "-fms-anonymous-structs" if $(cc-option,-fms-anonymous-structs) 978 default "-fms-extensions" 979 980# Currently, disable gcc-10+ array-bounds globally. 981# It's still broken in gcc-13, so no upper bound yet. 982config GCC10_NO_ARRAY_BOUNDS 983 def_bool y 984 985config CC_NO_ARRAY_BOUNDS 986 bool 987 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 988 989# Currently, disable -Wstringop-overflow for GCC globally. 990config GCC_NO_STRINGOP_OVERFLOW 991 def_bool y 992 993config CC_NO_STRINGOP_OVERFLOW 994 bool 995 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 996 997config CC_STRINGOP_OVERFLOW 998 bool 999 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 1000 1001# 1002# For architectures that know their GCC __int128 support is sound 1003# 1004config ARCH_SUPPORTS_INT128 1005 bool 1006 1007# For architectures that (ab)use NUMA to represent different memory regions 1008# all cpu-local but of different latencies, such as SuperH. 1009# 1010config ARCH_WANT_NUMA_VARIABLE_LOCALITY 1011 bool 1012 1013config NUMA_BALANCING 1014 bool "Memory placement aware NUMA scheduler" 1015 depends on ARCH_SUPPORTS_NUMA_BALANCING 1016 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 1017 depends on SMP && NUMA_MIGRATION && !PREEMPT_RT 1018 help 1019 This option adds support for automatic NUMA aware memory/task placement. 1020 The mechanism is quite primitive and is based on migrating memory when 1021 it has references to the node the task is running on. 1022 1023 This system will be inactive on UMA systems. 1024 1025config SCHED_CACHE 1026 bool "Cache aware load balance" 1027 default y 1028 depends on SMP 1029 help 1030 When enabled, the scheduler will attempt to aggregate tasks from 1031 the same process onto a single Last Level Cache (LLC) domain when 1032 possible. This improves cache locality by keeping tasks that share 1033 resources within the same cache domain, reducing cache misses and 1034 lowering data access latency. 1035 1036config NUMA_BALANCING_DEFAULT_ENABLED 1037 bool "Automatically enable NUMA aware memory/task placement" 1038 default y 1039 depends on NUMA_BALANCING 1040 help 1041 If set, automatic NUMA balancing will be enabled if running on a NUMA 1042 machine. 1043 1044config SLAB_OBJ_EXT 1045 bool 1046 1047menuconfig CGROUPS 1048 bool "Control Group support" 1049 select KERNFS 1050 help 1051 This option adds support for grouping sets of processes together, for 1052 use with process control subsystems such as Cpusets, CFS, memory 1053 controls or device isolation. 1054 See 1055 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1056 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1057 and resource control) 1058 1059 Say N if unsure. 1060 1061if CGROUPS 1062 1063config PAGE_COUNTER 1064 bool 1065 1066config CGROUP_FAVOR_DYNMODS 1067 bool "Favor dynamic modification latency reduction by default" 1068 help 1069 This option enables the "favordynmods" mount option by default 1070 which reduces the latencies of dynamic cgroup modifications such 1071 as task migrations and controller on/offs at the cost of making 1072 hot path operations such as forks and exits more expensive. 1073 1074 Say N if unsure. 1075 1076config MEMCG 1077 bool "Memory controller" 1078 select PAGE_COUNTER 1079 select EVENTFD 1080 select SLAB_OBJ_EXT 1081 select VM_EVENT_COUNTERS 1082 help 1083 Provides control over the memory footprint of tasks in a cgroup. 1084 1085config MEMCG_NMI_UNSAFE 1086 bool 1087 depends on MEMCG 1088 depends on HAVE_NMI 1089 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1090 default y 1091 1092config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1093 bool 1094 depends on MEMCG 1095 depends on HAVE_NMI 1096 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1097 default y 1098 1099config MEMCG_V1 1100 bool "Legacy cgroup v1 memory controller" 1101 depends on MEMCG 1102 default n 1103 help 1104 Legacy cgroup v1 memory controller which has been deprecated by 1105 cgroup v2 implementation. The v1 is there for legacy applications 1106 which haven't migrated to the new cgroup v2 interface yet. If you 1107 do not have any such application then you are completely fine leaving 1108 this option disabled. 1109 1110 Please note that feature set of the legacy memory controller is likely 1111 going to shrink due to deprecation process. New deployments with v1 1112 controller are highly discouraged. 1113 1114 Say N if unsure. 1115 1116config BLK_CGROUP 1117 bool "IO controller" 1118 depends on BLOCK 1119 default n 1120 help 1121 Generic block IO controller cgroup interface. This is the common 1122 cgroup interface which should be used by various IO controlling 1123 policies. 1124 1125 Currently, CFQ IO scheduler uses it to recognize task groups and 1126 control disk bandwidth allocation (proportional time slice allocation) 1127 to such task groups. It is also used by bio throttling logic in 1128 block layer to implement upper limit in IO rates on a device. 1129 1130 This option only enables generic Block IO controller infrastructure. 1131 One needs to also enable actual IO controlling logic/policy. For 1132 enabling proportional weight division of disk bandwidth in CFQ, set 1133 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1134 CONFIG_BLK_DEV_THROTTLING=y. 1135 1136 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1137 1138config CGROUP_WRITEBACK 1139 bool 1140 depends on MEMCG && BLK_CGROUP 1141 default y 1142 1143menuconfig CGROUP_SCHED 1144 bool "CPU controller" 1145 default n 1146 help 1147 This feature lets CPU scheduler recognize task groups and control CPU 1148 bandwidth allocation to such task groups. It uses cgroups to group 1149 tasks. 1150 1151if CGROUP_SCHED 1152config GROUP_SCHED_WEIGHT 1153 def_bool n 1154 1155config GROUP_SCHED_BANDWIDTH 1156 def_bool n 1157 1158config FAIR_GROUP_SCHED 1159 bool "Group scheduling for SCHED_OTHER" 1160 depends on CGROUP_SCHED 1161 select GROUP_SCHED_WEIGHT 1162 default CGROUP_SCHED 1163 1164config CFS_BANDWIDTH 1165 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1166 depends on FAIR_GROUP_SCHED 1167 select GROUP_SCHED_BANDWIDTH 1168 default n 1169 help 1170 This option allows users to define CPU bandwidth rates (limits) for 1171 tasks running within the fair group scheduler. Groups with no limit 1172 set are considered to be unconstrained and will run with no 1173 restriction. 1174 See Documentation/scheduler/sched-bwc.rst for more information. 1175 1176config RT_GROUP_SCHED 1177 bool "Group scheduling for SCHED_RR/FIFO" 1178 depends on CGROUP_SCHED 1179 default n 1180 help 1181 This feature lets you explicitly allocate real CPU bandwidth 1182 to task groups. If enabled, it will also make it impossible to 1183 schedule realtime tasks for non-root users until you allocate 1184 realtime bandwidth for them. 1185 See Documentation/scheduler/sched-rt-group.rst for more information. 1186 1187config RT_GROUP_SCHED_DEFAULT_DISABLED 1188 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1189 depends on RT_GROUP_SCHED 1190 default n 1191 help 1192 When set, the RT group scheduling is disabled by default. The option 1193 is in inverted form so that mere RT_GROUP_SCHED enables the group 1194 scheduling. 1195 1196 Say N if unsure. 1197 1198config EXT_GROUP_SCHED 1199 bool 1200 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1201 select GROUP_SCHED_WEIGHT 1202 select GROUP_SCHED_BANDWIDTH 1203 default y 1204 1205endif #CGROUP_SCHED 1206 1207config EXT_SUB_SCHED 1208 def_bool y 1209 depends on SCHED_CLASS_EXT && CGROUPS 1210 1211config SCHED_MM_CID 1212 def_bool y 1213 depends on SMP && RSEQ 1214 1215config UCLAMP_TASK_GROUP 1216 bool "Utilization clamping per group of tasks" 1217 depends on CGROUP_SCHED 1218 depends on UCLAMP_TASK 1219 default n 1220 help 1221 This feature enables the scheduler to track the clamped utilization 1222 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1223 1224 When this option is enabled, the user can specify a min and max 1225 CPU bandwidth which is allowed for each single task in a group. 1226 The max bandwidth allows to clamp the maximum frequency a task 1227 can use, while the min bandwidth allows to define a minimum 1228 frequency a task will always use. 1229 1230 When task group based utilization clamping is enabled, an eventually 1231 specified task-specific clamp value is constrained by the cgroup 1232 specified clamp value. Both minimum and maximum task clamping cannot 1233 be bigger than the corresponding clamping defined at task group level. 1234 1235 If in doubt, say N. 1236 1237config CGROUP_PIDS 1238 bool "PIDs controller" 1239 help 1240 Provides enforcement of process number limits in the scope of a 1241 cgroup. Any attempt to fork more processes than is allowed in the 1242 cgroup will fail. PIDs are fundamentally a global resource because it 1243 is fairly trivial to reach PID exhaustion before you reach even a 1244 conservative kmemcg limit. As a result, it is possible to grind a 1245 system to halt without being limited by other cgroup policies. The 1246 PIDs controller is designed to stop this from happening. 1247 1248 It should be noted that organisational operations (such as attaching 1249 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1250 since the PIDs limit only affects a process's ability to fork, not to 1251 attach to a cgroup. 1252 1253config CGROUP_RDMA 1254 bool "RDMA controller" 1255 help 1256 Provides enforcement of RDMA resources defined by IB stack. 1257 It is fairly easy for consumers to exhaust RDMA resources, which 1258 can result into resource unavailability to other consumers. 1259 RDMA controller is designed to stop this from happening. 1260 Attaching processes with active RDMA resources to the cgroup 1261 hierarchy is allowed even if can cross the hierarchy's limit. 1262 1263config CGROUP_DMEM 1264 bool "Device memory controller (DMEM)" 1265 select PAGE_COUNTER 1266 help 1267 The DMEM controller allows compatible devices to restrict device 1268 memory usage based on the cgroup hierarchy. 1269 1270 As an example, it allows you to restrict VRAM usage for applications 1271 in the DRM subsystem. 1272 1273config CGROUP_FREEZER 1274 bool "Freezer controller" 1275 help 1276 Provides a way to freeze and unfreeze all tasks in a 1277 cgroup. 1278 1279 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1280 controller includes important in-kernel memory consumers per default. 1281 1282 If you're using cgroup2, say N. 1283 1284config CGROUP_HUGETLB 1285 bool "HugeTLB controller" 1286 depends on HUGETLB_PAGE 1287 select PAGE_COUNTER 1288 default n 1289 help 1290 Provides a cgroup controller for HugeTLB pages. 1291 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1292 The limit is enforced during page fault. Since HugeTLB doesn't 1293 support page reclaim, enforcing the limit at page fault time implies 1294 that, the application will get SIGBUS signal if it tries to access 1295 HugeTLB pages beyond its limit. This requires the application to know 1296 beforehand how much HugeTLB pages it would require for its use. The 1297 control group is tracked in the third page lru pointer. This means 1298 that we cannot use the controller with huge page less than 3 pages. 1299 1300config CPUSETS 1301 bool "Cpuset controller" 1302 depends on SMP 1303 select UNION_FIND 1304 select CPU_ISOLATION 1305 help 1306 This option will let you create and manage CPUSETs which 1307 allow dynamically partitioning a system into sets of CPUs and 1308 Memory Nodes and assigning tasks to run only within those sets. 1309 This is primarily useful on large SMP or NUMA systems. 1310 1311 Say N if unsure. 1312 1313config CPUSETS_V1 1314 bool "Legacy cgroup v1 cpusets controller" 1315 depends on CPUSETS 1316 default n 1317 help 1318 Legacy cgroup v1 cpusets controller which has been deprecated by 1319 cgroup v2 implementation. The v1 is there for legacy applications 1320 which haven't migrated to the new cgroup v2 interface yet. Legacy 1321 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1322 do not have any such application then you are completely fine leaving 1323 this option disabled. 1324 1325 Say N if unsure. 1326 1327config PROC_PID_CPUSET 1328 bool "Include legacy /proc/<pid>/cpuset file" 1329 depends on CPUSETS_V1 1330 default y 1331 1332config CGROUP_DEVICE 1333 bool "Device controller" 1334 help 1335 Provides a cgroup controller implementing whitelists for 1336 devices which a process in the cgroup can mknod or open. 1337 1338config CGROUP_CPUACCT 1339 bool "Simple CPU accounting controller" 1340 help 1341 Provides a simple controller for monitoring the 1342 total CPU consumed by the tasks in a cgroup. 1343 1344config CGROUP_PERF 1345 bool "Perf controller" 1346 depends on PERF_EVENTS 1347 help 1348 This option extends the perf per-cpu mode to restrict monitoring 1349 to threads which belong to the cgroup specified and run on the 1350 designated cpu. Or this can be used to have cgroup ID in samples 1351 so that it can monitor performance events among cgroups. 1352 1353 Say N if unsure. 1354 1355config CGROUP_BPF 1356 bool "Support for eBPF programs attached to cgroups" 1357 depends on BPF_SYSCALL 1358 select SOCK_CGROUP_DATA 1359 help 1360 Allow attaching eBPF programs to a cgroup using the bpf(2) 1361 syscall command BPF_PROG_ATTACH. 1362 1363 In which context these programs are accessed depends on the type 1364 of attachment. For instance, programs that are attached using 1365 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1366 inet sockets. 1367 1368config CGROUP_MISC 1369 bool "Misc resource controller" 1370 default n 1371 help 1372 Provides a controller for miscellaneous resources on a host. 1373 1374 Miscellaneous scalar resources are the resources on the host system 1375 which cannot be abstracted like the other cgroups. This controller 1376 tracks and limits the miscellaneous resources used by a process 1377 attached to a cgroup hierarchy. 1378 1379 For more information, please check misc cgroup section in 1380 /Documentation/admin-guide/cgroup-v2.rst. 1381 1382config CGROUP_DEBUG 1383 bool "Debug controller" 1384 default n 1385 depends on DEBUG_KERNEL 1386 help 1387 This option enables a simple controller that exports 1388 debugging information about the cgroups framework. This 1389 controller is for control cgroup debugging only. Its 1390 interfaces are not stable. 1391 1392 Say N. 1393 1394config SOCK_CGROUP_DATA 1395 bool 1396 default n 1397 1398endif # CGROUPS 1399 1400menuconfig NAMESPACES 1401 bool "Namespaces support" if EXPERT 1402 depends on MULTIUSER 1403 default !EXPERT 1404 help 1405 Provides the way to make tasks work with different objects using 1406 the same id. For example same IPC id may refer to different objects 1407 or same user id or pid may refer to different tasks when used in 1408 different namespaces. 1409 1410if NAMESPACES 1411 1412config UTS_NS 1413 bool "UTS namespace" 1414 default y 1415 help 1416 In this namespace tasks see different info provided with the 1417 uname() system call 1418 1419config TIME_NS 1420 bool "TIME namespace" 1421 default y 1422 help 1423 In this namespace boottime and monotonic clocks can be set. 1424 The time will keep going with the same pace. 1425 1426config TIME_NS_VDSO 1427 def_bool TIME_NS && GENERIC_GETTIMEOFDAY 1428 1429config IPC_NS 1430 bool "IPC namespace" 1431 depends on (SYSVIPC || POSIX_MQUEUE) 1432 default y 1433 help 1434 In this namespace tasks work with IPC ids which correspond to 1435 different IPC objects in different namespaces. 1436 1437config USER_NS 1438 bool "User namespace" 1439 default n 1440 help 1441 This allows containers, i.e. vservers, to use user namespaces 1442 to provide different user info for different servers. 1443 1444 When user namespaces are enabled in the kernel it is 1445 recommended that the MEMCG option also be enabled and that 1446 user-space use the memory control groups to limit the amount 1447 of memory a memory unprivileged users can use. 1448 1449 If unsure, say N. 1450 1451config PID_NS 1452 bool "PID Namespaces" 1453 default y 1454 help 1455 Support process id namespaces. This allows having multiple 1456 processes with the same pid as long as they are in different 1457 pid namespaces. This is a building block of containers. 1458 1459config NET_NS 1460 bool "Network namespace" 1461 depends on NET 1462 default y 1463 help 1464 Allow user space to create what appear to be multiple instances 1465 of the network stack. 1466 1467endif # NAMESPACES 1468 1469config CHECKPOINT_RESTORE 1470 bool "Checkpoint/restore support" 1471 depends on PROC_FS 1472 select PROC_CHILDREN 1473 select KCMP 1474 default n 1475 help 1476 Enables additional kernel features in a sake of checkpoint/restore. 1477 In particular it adds auxiliary prctl codes to setup process text, 1478 data and heap segment sizes, and a few additional /proc filesystem 1479 entries. 1480 1481 If unsure, say N here. 1482 1483config SCHED_AUTOGROUP 1484 bool "Automatic process group scheduling" 1485 select CGROUPS 1486 select CGROUP_SCHED 1487 select FAIR_GROUP_SCHED 1488 help 1489 This option optimizes the scheduler for common desktop workloads by 1490 automatically creating and populating task groups. This separation 1491 of workloads isolates aggressive CPU burners (like build jobs) from 1492 desktop applications. Task group autogeneration is currently based 1493 upon task session. 1494 1495config RELAY 1496 bool "Kernel->user space relay support (formerly relayfs)" 1497 select IRQ_WORK 1498 help 1499 This option enables support for relay interface support in 1500 certain file systems (such as debugfs). 1501 It is designed to provide an efficient mechanism for tools and 1502 facilities to relay large amounts of data from kernel space to 1503 user space. 1504 1505 If unsure, say N. 1506 1507config BLK_DEV_INITRD 1508 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1509 help 1510 The initial RAM filesystem is a ramfs which is loaded by the 1511 boot loader (loadlin or lilo) and that is mounted as root 1512 before the normal boot procedure. It is typically used to 1513 load modules needed to mount the "real" root file system, 1514 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1515 1516 If RAM disk support (BLK_DEV_RAM) is also included, this 1517 also enables initial RAM disk (initrd) support and adds 1518 15 Kbytes (more on some other architectures) to the kernel size. 1519 1520 If unsure say Y. 1521 1522if BLK_DEV_INITRD 1523 1524source "usr/Kconfig" 1525 1526endif 1527 1528config BOOT_CONFIG 1529 bool "Boot config support" 1530 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1531 help 1532 Extra boot config allows system admin to pass a config file as 1533 complemental extension of kernel cmdline when booting. 1534 The boot config file must be attached at the end of initramfs 1535 with checksum, size and magic word. 1536 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1537 1538 If unsure, say Y. 1539 1540config BOOT_CONFIG_FORCE 1541 bool "Force unconditional bootconfig processing" 1542 depends on BOOT_CONFIG 1543 default y if BOOT_CONFIG_EMBED 1544 help 1545 With this Kconfig option set, BOOT_CONFIG processing is carried 1546 out even when the "bootconfig" kernel-boot parameter is omitted. 1547 In fact, with this Kconfig option set, there is no way to 1548 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1549 parameters. 1550 1551 If unsure, say N. 1552 1553config BOOT_CONFIG_EMBED 1554 bool "Embed bootconfig file in the kernel" 1555 depends on BOOT_CONFIG 1556 help 1557 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1558 kernel. Usually, the bootconfig file is loaded with the initrd 1559 image. But if the system doesn't support initrd, this option will 1560 help you by embedding a bootconfig file while building the kernel. 1561 1562 If unsure, say N. 1563 1564config BOOT_CONFIG_EMBED_FILE 1565 string "Embedded bootconfig file path" 1566 depends on BOOT_CONFIG_EMBED 1567 help 1568 Specify a bootconfig file which will be embedded to the kernel. 1569 This bootconfig will be used if there is no initrd or no other 1570 bootconfig in the initrd. 1571 1572config CMDLINE_LOG_WRAP_IDEAL_LEN 1573 int "Length to try to wrap the cmdline when logged at boot" 1574 default 1021 1575 range 0 1021 1576 help 1577 At boot time, the kernel command line is logged to the console. 1578 The log message will start with the prefix "Kernel command line: ". 1579 The log message will attempt to be wrapped (split into multiple log 1580 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters. 1581 If wrapping happens, each log message will start with the prefix and 1582 all but the last message will end with " \". Messages may exceed the 1583 ideal length if a place to wrap isn't found before the specified 1584 number of characters. 1585 1586 A value of 0 disables wrapping, though be warned that the maximum 1587 length of a log message (1021 characters) may cause the cmdline to 1588 be truncated. 1589 1590config INITRAMFS_PRESERVE_MTIME 1591 bool "Preserve cpio archive mtimes in initramfs" 1592 depends on BLK_DEV_INITRD 1593 default y 1594 help 1595 Each entry in an initramfs cpio archive carries an mtime value. When 1596 enabled, extracted cpio items take this mtime, with directory mtime 1597 setting deferred until after creation of any child entries. 1598 1599 If unsure, say Y. 1600 1601config INITRAMFS_TEST 1602 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1603 depends on BLK_DEV_INITRD && KUNIT=y 1604 default KUNIT_ALL_TESTS 1605 help 1606 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1607 1608choice 1609 prompt "Compiler optimization level" 1610 default CC_OPTIMIZE_FOR_PERFORMANCE 1611 1612config CC_OPTIMIZE_FOR_PERFORMANCE 1613 bool "Optimize for performance (-O2)" 1614 help 1615 This is the default optimization level for the kernel, building 1616 with the "-O2" compiler flag for best performance and most 1617 helpful compile-time warnings. 1618 1619config CC_OPTIMIZE_FOR_SIZE 1620 bool "Optimize for size (-Os)" 1621 help 1622 Choosing this option will pass "-Os" to your compiler resulting 1623 in a smaller kernel. 1624 1625endchoice 1626 1627config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1628 bool 1629 help 1630 This requires that the arch annotates or otherwise protects 1631 its external entry points from being discarded. Linker scripts 1632 must also merge .text.*, .data.*, and .bss.* correctly into 1633 output sections. Care must be taken not to pull in unrelated 1634 sections (e.g., '.text.init'). Typically '.' in section names 1635 is used to distinguish them from label names / C identifiers. 1636 1637config LD_DEAD_CODE_DATA_ELIMINATION 1638 bool "Dead code and data elimination (EXPERIMENTAL)" 1639 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1640 depends on EXPERT 1641 depends on $(cc-option,-ffunction-sections -fdata-sections) 1642 depends on $(ld-option,--gc-sections) 1643 help 1644 Enable this if you want to do dead code and data elimination with 1645 the linker by compiling with -ffunction-sections -fdata-sections, 1646 and linking with --gc-sections. 1647 1648 This can reduce on disk and in-memory size of the kernel 1649 code and static data, particularly for small configs and 1650 on small systems. This has the possibility of introducing 1651 silently broken kernel if the required annotations are not 1652 present. This option is not well tested yet, so use at your 1653 own risk. 1654 1655config LD_ORPHAN_WARN 1656 def_bool y 1657 depends on ARCH_WANT_LD_ORPHAN_WARN 1658 depends on $(ld-option,--orphan-handling=warn) 1659 depends on $(ld-option,--orphan-handling=error) 1660 1661config LD_ORPHAN_WARN_LEVEL 1662 string 1663 depends on LD_ORPHAN_WARN 1664 default "error" if WERROR 1665 default "warn" 1666 1667config SYSCTL 1668 bool 1669 1670config HAVE_UID16 1671 bool 1672 1673config SYSCTL_EXCEPTION_TRACE 1674 bool 1675 help 1676 Enable support for /proc/sys/debug/exception-trace. 1677 1678config SYSCTL_ARCH_UNALIGN_NO_WARN 1679 bool 1680 help 1681 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1682 Allows arch to define/use @no_unaligned_warning to possibly warn 1683 about unaligned access emulation going on under the hood. 1684 1685config SYSCTL_ARCH_UNALIGN_ALLOW 1686 bool 1687 help 1688 Enable support for /proc/sys/kernel/unaligned-trap 1689 Allows arches to define/use @unaligned_enabled to runtime toggle 1690 the unaligned access emulation. 1691 see arch/parisc/kernel/unaligned.c for reference 1692 1693config SYSFS_SYSCALL 1694 bool "Sysfs syscall support" 1695 default n 1696 help 1697 sys_sysfs is an obsolete system call no longer supported in libc. 1698 Note that disabling this option is more secure but might break 1699 compatibility with some systems. 1700 1701 If unsure say N here. 1702 1703config HAVE_PCSPKR_PLATFORM 1704 bool 1705 1706menuconfig EXPERT 1707 bool "Configure standard kernel features (expert users)" 1708 # Unhide debug options, to make the on-by-default options visible 1709 select DEBUG_KERNEL 1710 help 1711 This option allows certain base kernel options and settings 1712 to be disabled or tweaked. This is for specialized 1713 environments which can tolerate a "non-standard" kernel. 1714 Only use this if you really know what you are doing. 1715 1716config UID16 1717 bool "Enable 16-bit UID system calls" if EXPERT 1718 depends on HAVE_UID16 && MULTIUSER 1719 default y 1720 help 1721 This enables the legacy 16-bit UID syscall wrappers. 1722 1723config MULTIUSER 1724 bool "Multiple users, groups and capabilities support" if EXPERT 1725 default y 1726 help 1727 This option enables support for non-root users, groups and 1728 capabilities. 1729 1730 If you say N here, all processes will run with UID 0, GID 0, and all 1731 possible capabilities. Saying N here also compiles out support for 1732 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1733 setgid, and capset. 1734 1735 If unsure, say Y here. 1736 1737config SGETMASK_SYSCALL 1738 bool "sgetmask/ssetmask syscalls support" if EXPERT 1739 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1740 help 1741 sys_sgetmask and sys_ssetmask are obsolete system calls 1742 no longer supported in libc but still enabled by default in some 1743 architectures. 1744 1745 If unsure, leave the default option here. 1746 1747config FHANDLE 1748 bool "open by fhandle syscalls" if EXPERT 1749 select EXPORTFS 1750 default y 1751 help 1752 If you say Y here, a user level program will be able to map 1753 file names to handle and then later use the handle for 1754 different file system operations. This is useful in implementing 1755 userspace file servers, which now track files using handles instead 1756 of names. The handle would remain the same even if file names 1757 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1758 syscalls. 1759 1760config POSIX_TIMERS 1761 bool "Posix Clocks & timers" if EXPERT 1762 default y 1763 help 1764 This includes native support for POSIX timers to the kernel. 1765 Some embedded systems have no use for them and therefore they 1766 can be configured out to reduce the size of the kernel image. 1767 1768 When this option is disabled, the following syscalls won't be 1769 available: timer_create, timer_gettime: timer_getoverrun, 1770 timer_settime, timer_delete, clock_adjtime, getitimer, 1771 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1772 clock_getres and clock_nanosleep syscalls will be limited to 1773 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1774 1775 If unsure say y. 1776 1777config PRINTK 1778 default y 1779 bool "Enable support for printk" if EXPERT 1780 select IRQ_WORK 1781 help 1782 This option enables normal printk support. Removing it 1783 eliminates most of the message strings from the kernel image 1784 and makes the kernel more or less silent. As this makes it 1785 very difficult to diagnose system problems, saying N here is 1786 strongly discouraged. 1787 1788config PRINTK_RINGBUFFER_KUNIT_TEST 1789 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1790 depends on PRINTK && KUNIT 1791 default KUNIT_ALL_TESTS 1792 help 1793 This builds the printk ringbuffer KUnit test suite. 1794 1795 For more information on KUnit and unit tests in general, please refer 1796 to the KUnit documentation. 1797 1798 If unsure, say N. 1799 1800config BUG 1801 bool "BUG() support" if EXPERT 1802 default y 1803 help 1804 Disabling this option eliminates support for BUG and WARN, reducing 1805 the size of your kernel image and potentially quietly ignoring 1806 numerous fatal conditions. You should only consider disabling this 1807 option for embedded systems with no facilities for reporting errors. 1808 Just say Y. 1809 1810config ELF_CORE 1811 depends on COREDUMP 1812 default y 1813 bool "Enable ELF core dumps" if EXPERT 1814 help 1815 Enable support for generating core dumps. Disabling saves about 4k. 1816 1817 1818config PCSPKR_PLATFORM 1819 bool "Enable PC-Speaker support" if EXPERT 1820 depends on HAVE_PCSPKR_PLATFORM 1821 select I8253_LOCK 1822 default y 1823 help 1824 This option allows to disable the internal PC-Speaker 1825 support, saving some memory. 1826 1827config BASE_SMALL 1828 bool "Enable smaller-sized data structures for core" if EXPERT 1829 help 1830 Enabling this option reduces the size of miscellaneous core 1831 kernel data structures. This saves memory on small machines, 1832 but may reduce performance. 1833 1834config FUTEX 1835 bool "Enable futex support" if EXPERT 1836 depends on !(SPARC32 && SMP) 1837 default y 1838 imply RT_MUTEXES 1839 help 1840 Disabling this option will cause the kernel to be built without 1841 support for "fast userspace mutexes". The resulting kernel may not 1842 run glibc-based applications correctly. 1843 1844config FUTEX_PI 1845 bool 1846 depends on FUTEX && RT_MUTEXES 1847 default y 1848 1849config FUTEX_PRIVATE_HASH 1850 bool 1851 depends on FUTEX && !BASE_SMALL && MMU 1852 default y 1853 1854config FUTEX_MPOL 1855 bool 1856 depends on FUTEX && NUMA 1857 default y 1858 1859config HAVE_FUTEX_ROBUST_UNLOCK 1860 bool 1861 1862config FUTEX_ROBUST_UNLOCK 1863 def_bool FUTEX && HAVE_GENERIC_VDSO && GENERIC_IRQ_ENTRY && RSEQ && HAVE_FUTEX_ROBUST_UNLOCK 1864 1865config EPOLL 1866 bool "Enable eventpoll support" if EXPERT 1867 default y 1868 help 1869 Disabling this option will cause the kernel to be built without 1870 support for epoll family of system calls. 1871 1872config SIGNALFD 1873 bool "Enable signalfd() system call" if EXPERT 1874 default y 1875 help 1876 Enable the signalfd() system call that allows to receive signals 1877 on a file descriptor. 1878 1879 If unsure, say Y. 1880 1881config TIMERFD 1882 bool "Enable timerfd() system call" if EXPERT 1883 default y 1884 help 1885 Enable the timerfd() system call that allows to receive timer 1886 events on a file descriptor. 1887 1888 If unsure, say Y. 1889 1890config EVENTFD 1891 bool "Enable eventfd() system call" if EXPERT 1892 default y 1893 help 1894 Enable the eventfd() system call that allows to receive both 1895 kernel notification (ie. KAIO) or userspace notifications. 1896 1897 If unsure, say Y. 1898 1899config SHMEM 1900 bool "Use full shmem filesystem" if EXPERT 1901 default y 1902 depends on MMU 1903 help 1904 The shmem is an internal filesystem used to manage shared memory. 1905 It is backed by swap and manages resource limits. It is also exported 1906 to userspace as tmpfs if TMPFS is enabled. Disabling this 1907 option replaces shmem and tmpfs with the much simpler ramfs code, 1908 which may be appropriate on small systems without swap. 1909 1910config AIO 1911 bool "Enable AIO support" if EXPERT 1912 default y 1913 help 1914 This option enables POSIX asynchronous I/O which may by used 1915 by some high performance threaded applications. Disabling 1916 this option saves about 7k. 1917 1918config IO_URING 1919 bool "Enable IO uring support" if EXPERT 1920 select IO_WQ 1921 default y 1922 help 1923 This option enables support for the io_uring interface, enabling 1924 applications to submit and complete IO through submission and 1925 completion rings that are shared between the kernel and application. 1926 1927config GCOV_PROFILE_URING 1928 bool "Enable GCOV profiling on the io_uring subsystem" 1929 depends on IO_URING && GCOV_KERNEL 1930 help 1931 Enable GCOV profiling on the io_uring subsystem, to facilitate 1932 code coverage testing. 1933 1934 If unsure, say N. 1935 1936 Note that this will have a negative impact on the performance of 1937 the io_uring subsystem, hence this should only be enabled for 1938 specific test purposes. 1939 1940config IO_URING_MOCK_FILE 1941 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1942 default n 1943 depends on IO_URING 1944 help 1945 Enable mock files for io_uring subsystem testing. The ABI might 1946 still change, so it's still experimental and should only be enabled 1947 for specific test purposes. 1948 1949 If unsure, say N. 1950 1951config ADVISE_SYSCALLS 1952 bool "Enable madvise/fadvise syscalls" if EXPERT 1953 default y 1954 help 1955 This option enables the madvise and fadvise syscalls, used by 1956 applications to advise the kernel about their future memory or file 1957 usage, improving performance. If building an embedded system where no 1958 applications use these syscalls, you can disable this option to save 1959 space. 1960 1961config MEMBARRIER 1962 bool "Enable membarrier() system call" if EXPERT 1963 default y 1964 help 1965 Enable the membarrier() system call that allows issuing memory 1966 barriers across all running threads, which can be used to distribute 1967 the cost of user-space memory barriers asymmetrically by transforming 1968 pairs of memory barriers into pairs consisting of membarrier() and a 1969 compiler barrier. 1970 1971 If unsure, say Y. 1972 1973config KCMP 1974 bool "Enable kcmp() system call" if EXPERT 1975 help 1976 Enable the kernel resource comparison system call. It provides 1977 user-space with the ability to compare two processes to see if they 1978 share a common resource, such as a file descriptor or even virtual 1979 memory space. 1980 1981 If unsure, say N. 1982 1983config RSEQ 1984 bool "Enable rseq() system call" if EXPERT 1985 default y 1986 depends on HAVE_RSEQ 1987 select MEMBARRIER 1988 help 1989 Enable the restartable sequences system call. It provides a 1990 user-space cache for the current CPU number value, which 1991 speeds up getting the current CPU number from user-space, 1992 as well as an ABI to speed up user-space operations on 1993 per-CPU data. 1994 1995 If unsure, say Y. 1996 1997config RSEQ_SLICE_EXTENSION 1998 bool "Enable rseq-based time slice extension mechanism" 1999 depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS 2000 help 2001 Allows userspace to request a limited time slice extension when 2002 returning from an interrupt to user space via the RSEQ shared 2003 data ABI. If granted, that allows to complete a critical section, 2004 so that other threads are not stuck on a conflicted resource, 2005 while the task is scheduled out. 2006 2007 If unsure, say N. 2008 2009config RSEQ_STATS 2010 default n 2011 bool "Enable lightweight statistics of restartable sequences" if EXPERT 2012 depends on RSEQ && DEBUG_FS 2013 help 2014 Enable lightweight counters which expose information about the 2015 frequency of RSEQ operations via debugfs. Mostly interesting for 2016 kernel debugging or performance analysis. While lightweight it's 2017 still adding code into the user/kernel mode transitions. 2018 2019 If unsure, say N. 2020 2021config RSEQ_DEBUG_DEFAULT_ENABLE 2022 default n 2023 bool "Enable restartable sequences debug mode by default" if EXPERT 2024 depends on RSEQ 2025 help 2026 This enables the static branch for debug mode of restartable 2027 sequences. 2028 2029 This also can be controlled on the kernel command line via the 2030 command line parameter "rseq_debug=0/1" and through debugfs. 2031 2032 If unsure, say N. 2033 2034config DEBUG_RSEQ 2035 default n 2036 bool "Enable debugging of rseq() system call" if EXPERT 2037 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY 2038 select RSEQ_DEBUG_DEFAULT_ENABLE 2039 help 2040 Enable extra debugging checks for the rseq system call. 2041 2042 If unsure, say N. 2043 2044config CACHESTAT_SYSCALL 2045 bool "Enable cachestat() system call" if EXPERT 2046 default y 2047 help 2048 Enable the cachestat system call, which queries the page cache 2049 statistics of a file (number of cached pages, dirty pages, 2050 pages marked for writeback, (recently) evicted pages). 2051 2052 If unsure say Y here. 2053 2054config KALLSYMS 2055 bool "Load all symbols for debugging/ksymoops" if EXPERT 2056 default y 2057 help 2058 Say Y here to let the kernel print out symbolic crash information and 2059 symbolic stack backtraces. This increases the size of the kernel 2060 somewhat, as all symbols have to be loaded into the kernel image. 2061 2062config KALLSYMS_SELFTEST 2063 bool "Test the basic functions and performance of kallsyms" 2064 depends on KALLSYMS 2065 default n 2066 help 2067 Test the basic functions and performance of some interfaces, such as 2068 kallsyms_lookup_name. It also calculates the compression rate of the 2069 kallsyms compression algorithm for the current symbol set. 2070 2071 Start self-test automatically after system startup. Suggest executing 2072 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 2073 displayed in the last line, indicating that the test is complete. 2074 2075config KALLSYMS_ALL 2076 bool "Include all symbols in kallsyms" 2077 depends on DEBUG_KERNEL && KALLSYMS 2078 help 2079 Normally kallsyms only contains the symbols of functions for nicer 2080 OOPS messages and backtraces (i.e., symbols from the text and inittext 2081 sections). This is sufficient for most cases. And only if you want to 2082 enable kernel live patching, or other less common use cases (e.g., 2083 when a debugger is used) all symbols are required (i.e., names of 2084 variables from the data sections, etc). 2085 2086 This option makes sure that all symbols are loaded into the kernel 2087 image (i.e., symbols from all sections) in cost of increased kernel 2088 size (depending on the kernel configuration, it may be 300KiB or 2089 something like this). 2090 2091 Say N unless you really need all symbols, or kernel live patching. 2092 2093# end of the "standard kernel features (expert users)" menu 2094 2095config ARCH_HAS_MEMBARRIER_CALLBACKS 2096 bool 2097 2098config ARCH_HAS_MEMBARRIER_SYNC_CORE 2099 bool 2100 2101config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 2102 bool 2103 help 2104 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 2105 2106 A 64-bit kernel is required for the memory sealing feature. 2107 No specific hardware features from the CPU are needed. 2108 2109 To enable this feature, the architecture needs to update their 2110 special mappings calls to include the sealing flag and confirm 2111 that it doesn't unmap/remap system mappings during the life 2112 time of the process. The existence of this flag for an architecture 2113 implies that it does not require the remapping of the system 2114 mappings during process lifetime, so sealing these mappings is safe 2115 from a kernel perspective. 2116 2117 After the architecture enables this, a distribution can set 2118 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 2119 2120 For complete descriptions of memory sealing, please see 2121 Documentation/userspace-api/mseal.rst 2122 2123config HAVE_PERF_EVENTS 2124 bool 2125 help 2126 See tools/perf/design.txt for details. 2127 2128config GUEST_PERF_EVENTS 2129 bool 2130 depends on HAVE_PERF_EVENTS 2131 2132config PERF_GUEST_MEDIATED_PMU 2133 bool 2134 depends on GUEST_PERF_EVENTS 2135 2136config PERF_USE_VMALLOC 2137 bool 2138 help 2139 See tools/perf/design.txt for details 2140 2141menu "Kernel Performance Events And Counters" 2142 2143config PERF_EVENTS 2144 bool "Kernel performance events and counters" 2145 default y if PROFILING 2146 depends on HAVE_PERF_EVENTS 2147 select IRQ_WORK 2148 help 2149 Enable kernel support for various performance events provided 2150 by software and hardware. 2151 2152 Software events are supported either built-in or via the 2153 use of generic tracepoints. 2154 2155 Most modern CPUs support performance events via performance 2156 counter registers. These registers count the number of certain 2157 types of hw events: such as instructions executed, cachemisses 2158 suffered, or branches mis-predicted - without slowing down the 2159 kernel or applications. These registers can also trigger interrupts 2160 when a threshold number of events have passed - and can thus be 2161 used to profile the code that runs on that CPU. 2162 2163 The Linux Performance Event subsystem provides an abstraction of 2164 these software and hardware event capabilities, available via a 2165 system call and used by the "perf" utility in tools/perf/. It 2166 provides per task and per CPU counters, and it provides event 2167 capabilities on top of those. 2168 2169 Say Y if unsure. 2170 2171config DEBUG_PERF_USE_VMALLOC 2172 default n 2173 bool "Debug: use vmalloc to back perf mmap() buffers" 2174 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2175 select PERF_USE_VMALLOC 2176 help 2177 Use vmalloc memory to back perf mmap() buffers. 2178 2179 Mostly useful for debugging the vmalloc code on platforms 2180 that don't require it. 2181 2182 Say N if unsure. 2183 2184endmenu 2185 2186config SYSTEM_DATA_VERIFICATION 2187 def_bool n 2188 select SYSTEM_TRUSTED_KEYRING 2189 select KEYS 2190 select CRYPTO 2191 select CRYPTO_RSA 2192 select ASYMMETRIC_KEY_TYPE 2193 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2194 select ASN1 2195 select OID_REGISTRY 2196 select X509_CERTIFICATE_PARSER 2197 select PKCS7_MESSAGE_PARSER 2198 help 2199 Provide PKCS#7 message verification using the contents of the system 2200 trusted keyring to provide public keys. This then can be used for 2201 module verification, kexec image verification and firmware blob 2202 verification. 2203 2204config PROFILING 2205 bool "Profiling support" 2206 help 2207 Say Y here to enable the extended profiling support mechanisms used 2208 by profilers. 2209 2210config RUST 2211 bool "Rust support" 2212 depends on HAVE_RUST 2213 depends on RUST_IS_AVAILABLE 2214 select EXTENDED_MODVERSIONS if MODVERSIONS 2215 depends on !MODVERSIONS || GENDWARFKSYMS 2216 depends on !GCC_PLUGIN_RANDSTRUCT 2217 depends on !RANDSTRUCT 2218 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2219 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2220 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2221 depends on !KASAN || CC_IS_CLANG 2222 depends on !KASAN_SW_TAGS || RUSTC_VERSION >= 109600 2223 help 2224 Enables Rust support in the kernel. 2225 2226 This allows other Rust-related options, like drivers written in Rust, 2227 to be selected. 2228 2229 It is also required to be able to load external kernel modules 2230 written in Rust. 2231 2232 See Documentation/rust/ for more information. 2233 2234 If unsure, say N. 2235 2236source "rust/kernel/Kconfig.test" 2237 2238config RUSTC_VERSION_TEXT 2239 string 2240 depends on RUST 2241 default "$(RUSTC_VERSION_TEXT)" 2242 help 2243 See `CC_VERSION_TEXT`. 2244 2245config BINDGEN_VERSION_TEXT 2246 string 2247 depends on RUST 2248 default "$(shell,$(BINDGEN) --version 2>/dev/null)" 2249 2250# 2251# Place an empty function call at each tracepoint site. Can be 2252# dynamically changed for a probe function. 2253# 2254config TRACEPOINTS 2255 bool 2256 select TASKS_TRACE_RCU 2257 2258source "kernel/Kconfig.kexec" 2259 2260source "kernel/liveupdate/Kconfig" 2261 2262endmenu # General setup 2263 2264source "arch/Kconfig" 2265 2266config RT_MUTEXES 2267 bool 2268 default y if PREEMPT_RT 2269 2270config MODULE_SIG_FORMAT 2271 def_bool n 2272 select SYSTEM_DATA_VERIFICATION 2273 2274source "kernel/module/Kconfig" 2275 2276config INIT_ALL_POSSIBLE 2277 bool 2278 help 2279 Back when each arch used to define their own cpu_online_mask and 2280 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2281 with all 1s, and others with all 0s. When they were centralised, 2282 it was better to provide this option than to break all the archs 2283 and have several arch maintainers pursuing me down dark alleys. 2284 2285source "block/Kconfig" 2286 2287config PREEMPT_NOTIFIERS 2288 bool 2289 2290config PADATA 2291 depends on SMP 2292 bool 2293 2294config ASN1 2295 tristate 2296 help 2297 Build a simple ASN.1 grammar compiler that produces a bytecode output 2298 that can be interpreted by the ASN.1 stream decoder and used to 2299 inform it as to what tags are to be expected in a stream and what 2300 functions to call on what tags. 2301 2302source "kernel/Kconfig.locks" 2303 2304config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2305 bool 2306 2307config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2308 bool 2309 2310config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2311 bool 2312 2313# It may be useful for an architecture to override the definitions of the 2314# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2315# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2316# different calling convention for syscalls. They can also override the 2317# macros for not-implemented syscalls in kernel/sys_ni.c and 2318# kernel/time/posix-stubs.c. All these overrides need to be available in 2319# <asm/syscall_wrapper.h>. 2320config ARCH_HAS_SYSCALL_WRAPPER 2321 def_bool n 2322