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 support present-but-inaccessible (PROT_NONE) page 952# table entries detectable via pte_protnone() / pmd_protnone(): 953# 954config ARCH_HAS_PTE_PROTNONE 955 bool 956 957# 958# For architectures that want to enable the support for NUMA-affine scheduler 959# balancing logic: 960# 961config ARCH_SUPPORTS_NUMA_BALANCING 962 bool 963 964# 965# For architectures that prefer to flush all TLBs after a number of pages 966# are unmapped instead of sending one IPI per page to flush. The architecture 967# must provide guarantees on what happens if a clean TLB cache entry is 968# written after the unmap. Details are in mm/rmap.c near the check for 969# should_defer_flush. The architecture should also consider if the full flush 970# and the refill costs are offset by the savings of sending fewer IPIs. 971config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 972 bool 973 974config CC_HAS_INT128 975 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 976 977config CC_IMPLICIT_FALLTHROUGH 978 string 979 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 980 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 981 982config CC_MS_EXTENSIONS 983 string 984 default "-fms-anonymous-structs" if $(cc-option,-fms-anonymous-structs) 985 default "-fms-extensions" 986 987# Currently, disable gcc-10+ array-bounds globally. 988# It's still broken in gcc-13, so no upper bound yet. 989config GCC10_NO_ARRAY_BOUNDS 990 def_bool y 991 992config CC_NO_ARRAY_BOUNDS 993 bool 994 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 995 996# Currently, disable -Wstringop-overflow for GCC globally. 997config GCC_NO_STRINGOP_OVERFLOW 998 def_bool y 999 1000config CC_NO_STRINGOP_OVERFLOW 1001 bool 1002 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 1003 1004config CC_STRINGOP_OVERFLOW 1005 bool 1006 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 1007 1008# 1009# For architectures that know their GCC __int128 support is sound 1010# 1011config ARCH_SUPPORTS_INT128 1012 bool 1013 1014# For architectures that (ab)use NUMA to represent different memory regions 1015# all cpu-local but of different latencies, such as SuperH. 1016# 1017config ARCH_WANT_NUMA_VARIABLE_LOCALITY 1018 bool 1019 1020config NUMA_BALANCING 1021 bool "Memory placement aware NUMA scheduler" 1022 depends on ARCH_SUPPORTS_NUMA_BALANCING 1023 depends on ARCH_HAS_PTE_PROTNONE 1024 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 1025 depends on SMP && NUMA_MIGRATION && !PREEMPT_RT 1026 help 1027 This option adds support for automatic NUMA aware memory/task placement. 1028 The mechanism is quite primitive and is based on migrating memory when 1029 it has references to the node the task is running on. 1030 1031 This system will be inactive on UMA systems. 1032 1033config SCHED_CACHE 1034 bool "Cache aware load balance" 1035 default y 1036 depends on SMP 1037 help 1038 When enabled, the scheduler will attempt to aggregate tasks from 1039 the same process onto a single Last Level Cache (LLC) domain when 1040 possible. This improves cache locality by keeping tasks that share 1041 resources within the same cache domain, reducing cache misses and 1042 lowering data access latency. 1043 1044config NUMA_BALANCING_DEFAULT_ENABLED 1045 bool "Automatically enable NUMA aware memory/task placement" 1046 default y 1047 depends on NUMA_BALANCING 1048 help 1049 If set, automatic NUMA balancing will be enabled if running on a NUMA 1050 machine. 1051 1052config SLAB_OBJ_EXT 1053 bool 1054 1055menuconfig CGROUPS 1056 bool "Control Group support" 1057 select KERNFS 1058 help 1059 This option adds support for grouping sets of processes together, for 1060 use with process control subsystems such as Cpusets, CFS, memory 1061 controls or device isolation. 1062 See 1063 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1064 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1065 and resource control) 1066 1067 Say N if unsure. 1068 1069if CGROUPS 1070 1071config PAGE_COUNTER 1072 bool 1073 1074config CGROUP_FAVOR_DYNMODS 1075 bool "Favor dynamic modification latency reduction by default" 1076 help 1077 This option enables the "favordynmods" mount option by default 1078 which reduces the latencies of dynamic cgroup modifications such 1079 as task migrations and controller on/offs at the cost of making 1080 hot path operations such as forks and exits more expensive. 1081 1082 Say N if unsure. 1083 1084config MEMCG 1085 bool "Memory controller" 1086 select PAGE_COUNTER 1087 select EVENTFD 1088 select SLAB_OBJ_EXT 1089 select VM_EVENT_COUNTERS 1090 help 1091 Provides control over the memory footprint of tasks in a cgroup. 1092 1093config MEMCG_NMI_UNSAFE 1094 bool 1095 depends on MEMCG 1096 depends on HAVE_NMI 1097 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1098 default y 1099 1100config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1101 bool 1102 depends on MEMCG 1103 depends on HAVE_NMI 1104 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1105 default y 1106 1107config MEMCG_V1 1108 bool "Legacy cgroup v1 memory controller" 1109 depends on MEMCG 1110 default n 1111 help 1112 Legacy cgroup v1 memory controller which has been deprecated by 1113 cgroup v2 implementation. The v1 is there for legacy applications 1114 which haven't migrated to the new cgroup v2 interface yet. If you 1115 do not have any such application then you are completely fine leaving 1116 this option disabled. 1117 1118 Please note that feature set of the legacy memory controller is likely 1119 going to shrink due to deprecation process. New deployments with v1 1120 controller are highly discouraged. 1121 1122 Say N if unsure. 1123 1124config BLK_CGROUP 1125 bool "IO controller" 1126 depends on BLOCK 1127 default n 1128 help 1129 Generic block IO controller cgroup interface. This is the common 1130 cgroup interface which should be used by various IO controlling 1131 policies. 1132 1133 Currently, CFQ IO scheduler uses it to recognize task groups and 1134 control disk bandwidth allocation (proportional time slice allocation) 1135 to such task groups. It is also used by bio throttling logic in 1136 block layer to implement upper limit in IO rates on a device. 1137 1138 This option only enables generic Block IO controller infrastructure. 1139 One needs to also enable actual IO controlling logic/policy. For 1140 enabling proportional weight division of disk bandwidth in CFQ, set 1141 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1142 CONFIG_BLK_DEV_THROTTLING=y. 1143 1144 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1145 1146config CGROUP_WRITEBACK 1147 bool 1148 depends on MEMCG && BLK_CGROUP 1149 default y 1150 1151menuconfig CGROUP_SCHED 1152 bool "CPU controller" 1153 default n 1154 help 1155 This feature lets CPU scheduler recognize task groups and control CPU 1156 bandwidth allocation to such task groups. It uses cgroups to group 1157 tasks. 1158 1159if CGROUP_SCHED 1160config GROUP_SCHED_WEIGHT 1161 def_bool n 1162 1163config GROUP_SCHED_BANDWIDTH 1164 def_bool n 1165 1166config FAIR_GROUP_SCHED 1167 bool "Group scheduling for SCHED_OTHER" 1168 depends on CGROUP_SCHED 1169 select GROUP_SCHED_WEIGHT 1170 default CGROUP_SCHED 1171 1172config CFS_BANDWIDTH 1173 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1174 depends on FAIR_GROUP_SCHED 1175 select GROUP_SCHED_BANDWIDTH 1176 default n 1177 help 1178 This option allows users to define CPU bandwidth rates (limits) for 1179 tasks running within the fair group scheduler. Groups with no limit 1180 set are considered to be unconstrained and will run with no 1181 restriction. 1182 See Documentation/scheduler/sched-bwc.rst for more information. 1183 1184config RT_GROUP_SCHED 1185 bool "Group scheduling for SCHED_RR/FIFO" 1186 depends on CGROUP_SCHED 1187 default n 1188 help 1189 This feature lets you explicitly allocate real CPU bandwidth 1190 to task groups. If enabled, it will also make it impossible to 1191 schedule realtime tasks for non-root users until you allocate 1192 realtime bandwidth for them. 1193 See Documentation/scheduler/sched-rt-group.rst for more information. 1194 1195config RT_GROUP_SCHED_DEFAULT_DISABLED 1196 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1197 depends on RT_GROUP_SCHED 1198 default n 1199 help 1200 When set, the RT group scheduling is disabled by default. The option 1201 is in inverted form so that mere RT_GROUP_SCHED enables the group 1202 scheduling. 1203 1204 Say N if unsure. 1205 1206config EXT_GROUP_SCHED 1207 bool 1208 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1209 select GROUP_SCHED_WEIGHT 1210 select GROUP_SCHED_BANDWIDTH 1211 default y 1212 1213endif #CGROUP_SCHED 1214 1215config EXT_SUB_SCHED 1216 def_bool y 1217 depends on SCHED_CLASS_EXT && CGROUPS 1218 1219config SCHED_MM_CID 1220 def_bool y 1221 depends on SMP && RSEQ 1222 1223config UCLAMP_TASK_GROUP 1224 bool "Utilization clamping per group of tasks" 1225 depends on CGROUP_SCHED 1226 depends on UCLAMP_TASK 1227 default n 1228 help 1229 This feature enables the scheduler to track the clamped utilization 1230 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1231 1232 When this option is enabled, the user can specify a min and max 1233 CPU bandwidth which is allowed for each single task in a group. 1234 The max bandwidth allows to clamp the maximum frequency a task 1235 can use, while the min bandwidth allows to define a minimum 1236 frequency a task will always use. 1237 1238 When task group based utilization clamping is enabled, an eventually 1239 specified task-specific clamp value is constrained by the cgroup 1240 specified clamp value. Both minimum and maximum task clamping cannot 1241 be bigger than the corresponding clamping defined at task group level. 1242 1243 If in doubt, say N. 1244 1245config CGROUP_PIDS 1246 bool "PIDs controller" 1247 help 1248 Provides enforcement of process number limits in the scope of a 1249 cgroup. Any attempt to fork more processes than is allowed in the 1250 cgroup will fail. PIDs are fundamentally a global resource because it 1251 is fairly trivial to reach PID exhaustion before you reach even a 1252 conservative kmemcg limit. As a result, it is possible to grind a 1253 system to halt without being limited by other cgroup policies. The 1254 PIDs controller is designed to stop this from happening. 1255 1256 It should be noted that organisational operations (such as attaching 1257 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1258 since the PIDs limit only affects a process's ability to fork, not to 1259 attach to a cgroup. 1260 1261config CGROUP_RDMA 1262 bool "RDMA controller" 1263 help 1264 Provides enforcement of RDMA resources defined by IB stack. 1265 It is fairly easy for consumers to exhaust RDMA resources, which 1266 can result into resource unavailability to other consumers. 1267 RDMA controller is designed to stop this from happening. 1268 Attaching processes with active RDMA resources to the cgroup 1269 hierarchy is allowed even if can cross the hierarchy's limit. 1270 1271config CGROUP_DMEM 1272 bool "Device memory controller (DMEM)" 1273 select PAGE_COUNTER 1274 help 1275 The DMEM controller allows compatible devices to restrict device 1276 memory usage based on the cgroup hierarchy. 1277 1278 As an example, it allows you to restrict VRAM usage for applications 1279 in the DRM subsystem. 1280 1281config CGROUP_FREEZER 1282 bool "Freezer controller" 1283 help 1284 Provides a way to freeze and unfreeze all tasks in a 1285 cgroup. 1286 1287 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1288 controller includes important in-kernel memory consumers per default. 1289 1290 If you're using cgroup2, say N. 1291 1292config CGROUP_HUGETLB 1293 bool "HugeTLB controller" 1294 depends on HUGETLB_PAGE 1295 select PAGE_COUNTER 1296 default n 1297 help 1298 Provides a cgroup controller for HugeTLB pages. 1299 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1300 The limit is enforced during page fault. Since HugeTLB doesn't 1301 support page reclaim, enforcing the limit at page fault time implies 1302 that, the application will get SIGBUS signal if it tries to access 1303 HugeTLB pages beyond its limit. This requires the application to know 1304 beforehand how much HugeTLB pages it would require for its use. The 1305 control group is tracked in the third page lru pointer. This means 1306 that we cannot use the controller with huge page less than 3 pages. 1307 1308config CPUSETS 1309 bool "Cpuset controller" 1310 depends on SMP 1311 select UNION_FIND 1312 select CPU_ISOLATION 1313 help 1314 This option will let you create and manage CPUSETs which 1315 allow dynamically partitioning a system into sets of CPUs and 1316 Memory Nodes and assigning tasks to run only within those sets. 1317 This is primarily useful on large SMP or NUMA systems. 1318 1319 Say N if unsure. 1320 1321config CPUSETS_V1 1322 bool "Legacy cgroup v1 cpusets controller" 1323 depends on CPUSETS 1324 default n 1325 help 1326 Legacy cgroup v1 cpusets controller which has been deprecated by 1327 cgroup v2 implementation. The v1 is there for legacy applications 1328 which haven't migrated to the new cgroup v2 interface yet. Legacy 1329 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1330 do not have any such application then you are completely fine leaving 1331 this option disabled. 1332 1333 Say N if unsure. 1334 1335config PROC_PID_CPUSET 1336 bool "Include legacy /proc/<pid>/cpuset file" 1337 depends on CPUSETS_V1 1338 default y 1339 1340config CGROUP_DEVICE 1341 bool "Device controller" 1342 help 1343 Provides a cgroup controller implementing whitelists for 1344 devices which a process in the cgroup can mknod or open. 1345 1346config CGROUP_CPUACCT 1347 bool "Simple CPU accounting controller" 1348 help 1349 Provides a simple controller for monitoring the 1350 total CPU consumed by the tasks in a cgroup. 1351 1352config CGROUP_PERF 1353 bool "Perf controller" 1354 depends on PERF_EVENTS 1355 help 1356 This option extends the perf per-cpu mode to restrict monitoring 1357 to threads which belong to the cgroup specified and run on the 1358 designated cpu. Or this can be used to have cgroup ID in samples 1359 so that it can monitor performance events among cgroups. 1360 1361 Say N if unsure. 1362 1363config CGROUP_BPF 1364 bool "Support for eBPF programs attached to cgroups" 1365 depends on BPF_SYSCALL 1366 select SOCK_CGROUP_DATA 1367 help 1368 Allow attaching eBPF programs to a cgroup using the bpf(2) 1369 syscall command BPF_PROG_ATTACH. 1370 1371 In which context these programs are accessed depends on the type 1372 of attachment. For instance, programs that are attached using 1373 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1374 inet sockets. 1375 1376config CGROUP_MISC 1377 bool "Misc resource controller" 1378 default n 1379 help 1380 Provides a controller for miscellaneous resources on a host. 1381 1382 Miscellaneous scalar resources are the resources on the host system 1383 which cannot be abstracted like the other cgroups. This controller 1384 tracks and limits the miscellaneous resources used by a process 1385 attached to a cgroup hierarchy. 1386 1387 For more information, please check misc cgroup section in 1388 /Documentation/admin-guide/cgroup-v2.rst. 1389 1390config CGROUP_DEBUG 1391 bool "Debug controller" 1392 default n 1393 depends on DEBUG_KERNEL 1394 help 1395 This option enables a simple controller that exports 1396 debugging information about the cgroups framework. This 1397 controller is for control cgroup debugging only. Its 1398 interfaces are not stable. 1399 1400 Say N. 1401 1402config SOCK_CGROUP_DATA 1403 bool 1404 default n 1405 1406endif # CGROUPS 1407 1408menuconfig NAMESPACES 1409 bool "Namespaces support" if EXPERT 1410 depends on MULTIUSER 1411 default !EXPERT 1412 help 1413 Provides the way to make tasks work with different objects using 1414 the same id. For example same IPC id may refer to different objects 1415 or same user id or pid may refer to different tasks when used in 1416 different namespaces. 1417 1418if NAMESPACES 1419 1420config UTS_NS 1421 bool "UTS namespace" 1422 default y 1423 help 1424 In this namespace tasks see different info provided with the 1425 uname() system call 1426 1427config TIME_NS 1428 bool "TIME namespace" 1429 default y 1430 help 1431 In this namespace boottime and monotonic clocks can be set. 1432 The time will keep going with the same pace. 1433 1434config TIME_NS_VDSO 1435 def_bool TIME_NS && GENERIC_GETTIMEOFDAY 1436 1437config IPC_NS 1438 bool "IPC namespace" 1439 depends on (SYSVIPC || POSIX_MQUEUE) 1440 default y 1441 help 1442 In this namespace tasks work with IPC ids which correspond to 1443 different IPC objects in different namespaces. 1444 1445config USER_NS 1446 bool "User namespace" 1447 default n 1448 help 1449 This allows containers, i.e. vservers, to use user namespaces 1450 to provide different user info for different servers. 1451 1452 When user namespaces are enabled in the kernel it is 1453 recommended that the MEMCG option also be enabled and that 1454 user-space use the memory control groups to limit the amount 1455 of memory a memory unprivileged users can use. 1456 1457 If unsure, say N. 1458 1459config PID_NS 1460 bool "PID Namespaces" 1461 default y 1462 help 1463 Support process id namespaces. This allows having multiple 1464 processes with the same pid as long as they are in different 1465 pid namespaces. This is a building block of containers. 1466 1467config NET_NS 1468 bool "Network namespace" 1469 depends on NET 1470 default y 1471 help 1472 Allow user space to create what appear to be multiple instances 1473 of the network stack. 1474 1475endif # NAMESPACES 1476 1477config CHECKPOINT_RESTORE 1478 bool "Checkpoint/restore support" 1479 depends on PROC_FS 1480 select PROC_CHILDREN 1481 select KCMP 1482 default n 1483 help 1484 Enables additional kernel features in a sake of checkpoint/restore. 1485 In particular it adds auxiliary prctl codes to setup process text, 1486 data and heap segment sizes, and a few additional /proc filesystem 1487 entries. 1488 1489 If unsure, say N here. 1490 1491config SCHED_AUTOGROUP 1492 bool "Automatic process group scheduling" 1493 select CGROUPS 1494 select CGROUP_SCHED 1495 select FAIR_GROUP_SCHED 1496 help 1497 This option optimizes the scheduler for common desktop workloads by 1498 automatically creating and populating task groups. This separation 1499 of workloads isolates aggressive CPU burners (like build jobs) from 1500 desktop applications. Task group autogeneration is currently based 1501 upon task session. 1502 1503config RELAY 1504 bool "Kernel->user space relay support (formerly relayfs)" 1505 select IRQ_WORK 1506 help 1507 This option enables support for relay interface support in 1508 certain file systems (such as debugfs). 1509 It is designed to provide an efficient mechanism for tools and 1510 facilities to relay large amounts of data from kernel space to 1511 user space. 1512 1513 If unsure, say N. 1514 1515config BLK_DEV_INITRD 1516 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1517 help 1518 The initial RAM filesystem is a ramfs which is loaded by the 1519 boot loader (loadlin or lilo) and that is mounted as root 1520 before the normal boot procedure. It is typically used to 1521 load modules needed to mount the "real" root file system, 1522 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1523 1524 If RAM disk support (BLK_DEV_RAM) is also included, this 1525 also enables initial RAM disk (initrd) support and adds 1526 15 Kbytes (more on some other architectures) to the kernel size. 1527 1528 If unsure say Y. 1529 1530if BLK_DEV_INITRD 1531 1532source "usr/Kconfig" 1533 1534endif 1535 1536config BOOT_CONFIG 1537 bool "Boot config support" 1538 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1539 help 1540 Extra boot config allows system admin to pass a config file as 1541 complemental extension of kernel cmdline when booting. 1542 The boot config file must be attached at the end of initramfs 1543 with checksum, size and magic word. 1544 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1545 1546 If unsure, say Y. 1547 1548config BOOT_CONFIG_FORCE 1549 bool "Force unconditional bootconfig processing" 1550 depends on BOOT_CONFIG 1551 default y if BOOT_CONFIG_EMBED 1552 help 1553 With this Kconfig option set, BOOT_CONFIG processing is carried 1554 out even when the "bootconfig" kernel-boot parameter is omitted. 1555 In fact, with this Kconfig option set, there is no way to 1556 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1557 parameters. 1558 1559 If unsure, say N. 1560 1561config BOOT_CONFIG_EMBED 1562 bool "Embed bootconfig file in the kernel" 1563 depends on BOOT_CONFIG 1564 help 1565 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1566 kernel. Usually, the bootconfig file is loaded with the initrd 1567 image. But if the system doesn't support initrd, this option will 1568 help you by embedding a bootconfig file while building the kernel. 1569 1570 If unsure, say N. 1571 1572config BOOT_CONFIG_EMBED_FILE 1573 string "Embedded bootconfig file path" 1574 depends on BOOT_CONFIG_EMBED 1575 help 1576 Specify a bootconfig file which will be embedded to the kernel. 1577 This bootconfig will be used if there is no initrd or no other 1578 bootconfig in the initrd. 1579 1580config CMDLINE_LOG_WRAP_IDEAL_LEN 1581 int "Length to try to wrap the cmdline when logged at boot" 1582 default 1021 1583 range 0 1021 1584 help 1585 At boot time, the kernel command line is logged to the console. 1586 The log message will start with the prefix "Kernel command line: ". 1587 The log message will attempt to be wrapped (split into multiple log 1588 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters. 1589 If wrapping happens, each log message will start with the prefix and 1590 all but the last message will end with " \". Messages may exceed the 1591 ideal length if a place to wrap isn't found before the specified 1592 number of characters. 1593 1594 A value of 0 disables wrapping, though be warned that the maximum 1595 length of a log message (1021 characters) may cause the cmdline to 1596 be truncated. 1597 1598config INITRAMFS_PRESERVE_MTIME 1599 bool "Preserve cpio archive mtimes in initramfs" 1600 depends on BLK_DEV_INITRD 1601 default y 1602 help 1603 Each entry in an initramfs cpio archive carries an mtime value. When 1604 enabled, extracted cpio items take this mtime, with directory mtime 1605 setting deferred until after creation of any child entries. 1606 1607 If unsure, say Y. 1608 1609config INITRAMFS_TEST 1610 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1611 depends on BLK_DEV_INITRD && KUNIT=y 1612 default KUNIT_ALL_TESTS 1613 help 1614 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1615 1616choice 1617 prompt "Compiler optimization level" 1618 default CC_OPTIMIZE_FOR_PERFORMANCE 1619 1620config CC_OPTIMIZE_FOR_PERFORMANCE 1621 bool "Optimize for performance (-O2)" 1622 help 1623 This is the default optimization level for the kernel, building 1624 with the "-O2" compiler flag for best performance and most 1625 helpful compile-time warnings. 1626 1627config CC_OPTIMIZE_FOR_SIZE 1628 bool "Optimize for size (-Os)" 1629 help 1630 Choosing this option will pass "-Os" to your compiler resulting 1631 in a smaller kernel. 1632 1633endchoice 1634 1635config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1636 bool 1637 help 1638 This requires that the arch annotates or otherwise protects 1639 its external entry points from being discarded. Linker scripts 1640 must also merge .text.*, .data.*, and .bss.* correctly into 1641 output sections. Care must be taken not to pull in unrelated 1642 sections (e.g., '.text.init'). Typically '.' in section names 1643 is used to distinguish them from label names / C identifiers. 1644 1645config LD_DEAD_CODE_DATA_ELIMINATION 1646 bool "Dead code and data elimination (EXPERIMENTAL)" 1647 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1648 depends on EXPERT 1649 depends on $(cc-option,-ffunction-sections -fdata-sections) 1650 depends on $(ld-option,--gc-sections) 1651 help 1652 Enable this if you want to do dead code and data elimination with 1653 the linker by compiling with -ffunction-sections -fdata-sections, 1654 and linking with --gc-sections. 1655 1656 This can reduce on disk and in-memory size of the kernel 1657 code and static data, particularly for small configs and 1658 on small systems. This has the possibility of introducing 1659 silently broken kernel if the required annotations are not 1660 present. This option is not well tested yet, so use at your 1661 own risk. 1662 1663config LD_ORPHAN_WARN 1664 def_bool y 1665 depends on ARCH_WANT_LD_ORPHAN_WARN 1666 depends on $(ld-option,--orphan-handling=warn) 1667 depends on $(ld-option,--orphan-handling=error) 1668 1669config LD_ORPHAN_WARN_LEVEL 1670 string 1671 depends on LD_ORPHAN_WARN 1672 default "error" if WERROR 1673 default "warn" 1674 1675config SYSCTL 1676 bool 1677 1678config HAVE_UID16 1679 bool 1680 1681config SYSCTL_EXCEPTION_TRACE 1682 bool 1683 help 1684 Enable support for /proc/sys/debug/exception-trace. 1685 1686config SYSCTL_ARCH_UNALIGN_NO_WARN 1687 bool 1688 help 1689 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1690 Allows arch to define/use @no_unaligned_warning to possibly warn 1691 about unaligned access emulation going on under the hood. 1692 1693config SYSCTL_ARCH_UNALIGN_ALLOW 1694 bool 1695 help 1696 Enable support for /proc/sys/kernel/unaligned-trap 1697 Allows arches to define/use @unaligned_enabled to runtime toggle 1698 the unaligned access emulation. 1699 see arch/parisc/kernel/unaligned.c for reference 1700 1701config SYSFS_SYSCALL 1702 bool "Sysfs syscall support" 1703 default n 1704 help 1705 sys_sysfs is an obsolete system call no longer supported in libc. 1706 Note that disabling this option is more secure but might break 1707 compatibility with some systems. 1708 1709 If unsure say N here. 1710 1711config HAVE_PCSPKR_PLATFORM 1712 bool 1713 1714menuconfig EXPERT 1715 bool "Configure standard kernel features (expert users)" 1716 # Unhide debug options, to make the on-by-default options visible 1717 select DEBUG_KERNEL 1718 help 1719 This option allows certain base kernel options and settings 1720 to be disabled or tweaked. This is for specialized 1721 environments which can tolerate a "non-standard" kernel. 1722 Only use this if you really know what you are doing. 1723 1724config UID16 1725 bool "Enable 16-bit UID system calls" if EXPERT 1726 depends on HAVE_UID16 && MULTIUSER 1727 default y 1728 help 1729 This enables the legacy 16-bit UID syscall wrappers. 1730 1731config MULTIUSER 1732 bool "Multiple users, groups and capabilities support" if EXPERT 1733 default y 1734 help 1735 This option enables support for non-root users, groups and 1736 capabilities. 1737 1738 If you say N here, all processes will run with UID 0, GID 0, and all 1739 possible capabilities. Saying N here also compiles out support for 1740 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1741 setgid, and capset. 1742 1743 If unsure, say Y here. 1744 1745config SGETMASK_SYSCALL 1746 bool "sgetmask/ssetmask syscalls support" if EXPERT 1747 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1748 help 1749 sys_sgetmask and sys_ssetmask are obsolete system calls 1750 no longer supported in libc but still enabled by default in some 1751 architectures. 1752 1753 If unsure, leave the default option here. 1754 1755config FHANDLE 1756 bool "open by fhandle syscalls" if EXPERT 1757 select EXPORTFS 1758 default y 1759 help 1760 If you say Y here, a user level program will be able to map 1761 file names to handle and then later use the handle for 1762 different file system operations. This is useful in implementing 1763 userspace file servers, which now track files using handles instead 1764 of names. The handle would remain the same even if file names 1765 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1766 syscalls. 1767 1768config POSIX_TIMERS 1769 bool "Posix Clocks & timers" if EXPERT 1770 default y 1771 help 1772 This includes native support for POSIX timers to the kernel. 1773 Some embedded systems have no use for them and therefore they 1774 can be configured out to reduce the size of the kernel image. 1775 1776 When this option is disabled, the following syscalls won't be 1777 available: timer_create, timer_gettime: timer_getoverrun, 1778 timer_settime, timer_delete, clock_adjtime, getitimer, 1779 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1780 clock_getres and clock_nanosleep syscalls will be limited to 1781 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1782 1783 If unsure say y. 1784 1785config PRINTK 1786 default y 1787 bool "Enable support for printk" if EXPERT 1788 select IRQ_WORK 1789 help 1790 This option enables normal printk support. Removing it 1791 eliminates most of the message strings from the kernel image 1792 and makes the kernel more or less silent. As this makes it 1793 very difficult to diagnose system problems, saying N here is 1794 strongly discouraged. 1795 1796config PRINTK_RINGBUFFER_KUNIT_TEST 1797 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1798 depends on PRINTK && KUNIT 1799 default KUNIT_ALL_TESTS 1800 help 1801 This builds the printk ringbuffer KUnit test suite. 1802 1803 For more information on KUnit and unit tests in general, please refer 1804 to the KUnit documentation. 1805 1806 If unsure, say N. 1807 1808config BUG 1809 bool "BUG() support" if EXPERT 1810 default y 1811 help 1812 Disabling this option eliminates support for BUG and WARN, reducing 1813 the size of your kernel image and potentially quietly ignoring 1814 numerous fatal conditions. You should only consider disabling this 1815 option for embedded systems with no facilities for reporting errors. 1816 Just say Y. 1817 1818config ELF_CORE 1819 depends on COREDUMP 1820 default y 1821 bool "Enable ELF core dumps" if EXPERT 1822 help 1823 Enable support for generating core dumps. Disabling saves about 4k. 1824 1825 1826config PCSPKR_PLATFORM 1827 bool "Enable PC-Speaker support" if EXPERT 1828 depends on HAVE_PCSPKR_PLATFORM 1829 select I8253_LOCK 1830 default y 1831 help 1832 This option allows to disable the internal PC-Speaker 1833 support, saving some memory. 1834 1835config BASE_SMALL 1836 bool "Enable smaller-sized data structures for core" if EXPERT 1837 help 1838 Enabling this option reduces the size of miscellaneous core 1839 kernel data structures. This saves memory on small machines, 1840 but may reduce performance. 1841 1842config FUTEX 1843 bool "Enable futex support" if EXPERT 1844 depends on !(SPARC32 && SMP) 1845 default y 1846 imply RT_MUTEXES 1847 help 1848 Disabling this option will cause the kernel to be built without 1849 support for "fast userspace mutexes". The resulting kernel may not 1850 run glibc-based applications correctly. 1851 1852config FUTEX_PI 1853 bool 1854 depends on FUTEX && RT_MUTEXES 1855 default y 1856 1857config FUTEX_PRIVATE_HASH 1858 bool 1859 depends on FUTEX && !BASE_SMALL && MMU 1860 default y 1861 1862config FUTEX_MPOL 1863 bool 1864 depends on FUTEX && NUMA 1865 default y 1866 1867config HAVE_FUTEX_ROBUST_UNLOCK 1868 bool 1869 1870config FUTEX_ROBUST_UNLOCK 1871 def_bool FUTEX && HAVE_GENERIC_VDSO && GENERIC_IRQ_ENTRY && RSEQ && HAVE_FUTEX_ROBUST_UNLOCK 1872 1873config EPOLL 1874 bool "Enable eventpoll support" if EXPERT 1875 default y 1876 help 1877 Disabling this option will cause the kernel to be built without 1878 support for epoll family of system calls. 1879 1880config SIGNALFD 1881 bool "Enable signalfd() system call" if EXPERT 1882 default y 1883 help 1884 Enable the signalfd() system call that allows to receive signals 1885 on a file descriptor. 1886 1887 If unsure, say Y. 1888 1889config TIMERFD 1890 bool "Enable timerfd() system call" if EXPERT 1891 default y 1892 help 1893 Enable the timerfd() system call that allows to receive timer 1894 events on a file descriptor. 1895 1896 If unsure, say Y. 1897 1898config EVENTFD 1899 bool "Enable eventfd() system call" if EXPERT 1900 default y 1901 help 1902 Enable the eventfd() system call that allows to receive both 1903 kernel notification (ie. KAIO) or userspace notifications. 1904 1905 If unsure, say Y. 1906 1907config SHMEM 1908 bool "Use full shmem filesystem" if EXPERT 1909 default y 1910 depends on MMU 1911 help 1912 The shmem is an internal filesystem used to manage shared memory. 1913 It is backed by swap and manages resource limits. It is also exported 1914 to userspace as tmpfs if TMPFS is enabled. Disabling this 1915 option replaces shmem and tmpfs with the much simpler ramfs code, 1916 which may be appropriate on small systems without swap. 1917 1918config AIO 1919 bool "Enable AIO support" if EXPERT 1920 default y 1921 help 1922 This option enables POSIX asynchronous I/O which may by used 1923 by some high performance threaded applications. Disabling 1924 this option saves about 7k. 1925 1926config IO_URING 1927 bool "Enable IO uring support" if EXPERT 1928 select IO_WQ 1929 default y 1930 help 1931 This option enables support for the io_uring interface, enabling 1932 applications to submit and complete IO through submission and 1933 completion rings that are shared between the kernel and application. 1934 1935config GCOV_PROFILE_URING 1936 bool "Enable GCOV profiling on the io_uring subsystem" 1937 depends on IO_URING && GCOV_KERNEL 1938 help 1939 Enable GCOV profiling on the io_uring subsystem, to facilitate 1940 code coverage testing. 1941 1942 If unsure, say N. 1943 1944 Note that this will have a negative impact on the performance of 1945 the io_uring subsystem, hence this should only be enabled for 1946 specific test purposes. 1947 1948config IO_URING_MOCK_FILE 1949 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1950 default n 1951 depends on IO_URING 1952 help 1953 Enable mock files for io_uring subsystem testing. The ABI might 1954 still change, so it's still experimental and should only be enabled 1955 for specific test purposes. 1956 1957 If unsure, say N. 1958 1959config ADVISE_SYSCALLS 1960 bool "Enable madvise/fadvise syscalls" if EXPERT 1961 default y 1962 help 1963 This option enables the madvise and fadvise syscalls, used by 1964 applications to advise the kernel about their future memory or file 1965 usage, improving performance. If building an embedded system where no 1966 applications use these syscalls, you can disable this option to save 1967 space. 1968 1969config MEMBARRIER 1970 bool "Enable membarrier() system call" if EXPERT 1971 default y 1972 help 1973 Enable the membarrier() system call that allows issuing memory 1974 barriers across all running threads, which can be used to distribute 1975 the cost of user-space memory barriers asymmetrically by transforming 1976 pairs of memory barriers into pairs consisting of membarrier() and a 1977 compiler barrier. 1978 1979 If unsure, say Y. 1980 1981config KCMP 1982 bool "Enable kcmp() system call" if EXPERT 1983 help 1984 Enable the kernel resource comparison system call. It provides 1985 user-space with the ability to compare two processes to see if they 1986 share a common resource, such as a file descriptor or even virtual 1987 memory space. 1988 1989 If unsure, say N. 1990 1991config RSEQ 1992 bool "Enable rseq() system call" if EXPERT 1993 default y 1994 depends on HAVE_RSEQ 1995 select MEMBARRIER 1996 help 1997 Enable the restartable sequences system call. It provides a 1998 user-space cache for the current CPU number value, which 1999 speeds up getting the current CPU number from user-space, 2000 as well as an ABI to speed up user-space operations on 2001 per-CPU data. 2002 2003 If unsure, say Y. 2004 2005config RSEQ_SLICE_EXTENSION 2006 bool "Enable rseq-based time slice extension mechanism" 2007 depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS 2008 help 2009 Allows userspace to request a limited time slice extension when 2010 returning from an interrupt to user space via the RSEQ shared 2011 data ABI. If granted, that allows to complete a critical section, 2012 so that other threads are not stuck on a conflicted resource, 2013 while the task is scheduled out. 2014 2015 If unsure, say N. 2016 2017config RSEQ_STATS 2018 default n 2019 bool "Enable lightweight statistics of restartable sequences" if EXPERT 2020 depends on RSEQ && DEBUG_FS 2021 help 2022 Enable lightweight counters which expose information about the 2023 frequency of RSEQ operations via debugfs. Mostly interesting for 2024 kernel debugging or performance analysis. While lightweight it's 2025 still adding code into the user/kernel mode transitions. 2026 2027 If unsure, say N. 2028 2029config RSEQ_DEBUG_DEFAULT_ENABLE 2030 default n 2031 bool "Enable restartable sequences debug mode by default" if EXPERT 2032 depends on RSEQ 2033 help 2034 This enables the static branch for debug mode of restartable 2035 sequences. 2036 2037 This also can be controlled on the kernel command line via the 2038 command line parameter "rseq_debug=0/1" and through debugfs. 2039 2040 If unsure, say N. 2041 2042config DEBUG_RSEQ 2043 default n 2044 bool "Enable debugging of rseq() system call" if EXPERT 2045 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY 2046 select RSEQ_DEBUG_DEFAULT_ENABLE 2047 help 2048 Enable extra debugging checks for the rseq system call. 2049 2050 If unsure, say N. 2051 2052config CACHESTAT_SYSCALL 2053 bool "Enable cachestat() system call" if EXPERT 2054 default y 2055 help 2056 Enable the cachestat system call, which queries the page cache 2057 statistics of a file (number of cached pages, dirty pages, 2058 pages marked for writeback, (recently) evicted pages). 2059 2060 If unsure say Y here. 2061 2062config KALLSYMS 2063 bool "Load all symbols for debugging/ksymoops" if EXPERT 2064 default y 2065 help 2066 Say Y here to let the kernel print out symbolic crash information and 2067 symbolic stack backtraces. This increases the size of the kernel 2068 somewhat, as all symbols have to be loaded into the kernel image. 2069 2070config KALLSYMS_SELFTEST 2071 bool "Test the basic functions and performance of kallsyms" 2072 depends on KALLSYMS 2073 default n 2074 help 2075 Test the basic functions and performance of some interfaces, such as 2076 kallsyms_lookup_name. It also calculates the compression rate of the 2077 kallsyms compression algorithm for the current symbol set. 2078 2079 Start self-test automatically after system startup. Suggest executing 2080 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 2081 displayed in the last line, indicating that the test is complete. 2082 2083config KALLSYMS_ALL 2084 bool "Include all symbols in kallsyms" 2085 depends on DEBUG_KERNEL && KALLSYMS 2086 help 2087 Normally kallsyms only contains the symbols of functions for nicer 2088 OOPS messages and backtraces (i.e., symbols from the text and inittext 2089 sections). This is sufficient for most cases. And only if you want to 2090 enable kernel live patching, or other less common use cases (e.g., 2091 when a debugger is used) all symbols are required (i.e., names of 2092 variables from the data sections, etc). 2093 2094 This option makes sure that all symbols are loaded into the kernel 2095 image (i.e., symbols from all sections) in cost of increased kernel 2096 size (depending on the kernel configuration, it may be 300KiB or 2097 something like this). 2098 2099 Say N unless you really need all symbols, or kernel live patching. 2100 2101# end of the "standard kernel features (expert users)" menu 2102 2103config ARCH_HAS_MEMBARRIER_CALLBACKS 2104 bool 2105 2106config ARCH_HAS_MEMBARRIER_SYNC_CORE 2107 bool 2108 2109config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 2110 bool 2111 help 2112 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 2113 2114 A 64-bit kernel is required for the memory sealing feature. 2115 No specific hardware features from the CPU are needed. 2116 2117 To enable this feature, the architecture needs to update their 2118 special mappings calls to include the sealing flag and confirm 2119 that it doesn't unmap/remap system mappings during the life 2120 time of the process. The existence of this flag for an architecture 2121 implies that it does not require the remapping of the system 2122 mappings during process lifetime, so sealing these mappings is safe 2123 from a kernel perspective. 2124 2125 After the architecture enables this, a distribution can set 2126 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 2127 2128 For complete descriptions of memory sealing, please see 2129 Documentation/userspace-api/mseal.rst 2130 2131config HAVE_PERF_EVENTS 2132 bool 2133 help 2134 See tools/perf/design.txt for details. 2135 2136config GUEST_PERF_EVENTS 2137 bool 2138 depends on HAVE_PERF_EVENTS 2139 2140config PERF_GUEST_MEDIATED_PMU 2141 bool 2142 depends on GUEST_PERF_EVENTS 2143 2144config PERF_USE_VMALLOC 2145 bool 2146 help 2147 See tools/perf/design.txt for details 2148 2149menu "Kernel Performance Events And Counters" 2150 2151config PERF_EVENTS 2152 bool "Kernel performance events and counters" 2153 default y if PROFILING 2154 depends on HAVE_PERF_EVENTS 2155 select IRQ_WORK 2156 help 2157 Enable kernel support for various performance events provided 2158 by software and hardware. 2159 2160 Software events are supported either built-in or via the 2161 use of generic tracepoints. 2162 2163 Most modern CPUs support performance events via performance 2164 counter registers. These registers count the number of certain 2165 types of hw events: such as instructions executed, cachemisses 2166 suffered, or branches mis-predicted - without slowing down the 2167 kernel or applications. These registers can also trigger interrupts 2168 when a threshold number of events have passed - and can thus be 2169 used to profile the code that runs on that CPU. 2170 2171 The Linux Performance Event subsystem provides an abstraction of 2172 these software and hardware event capabilities, available via a 2173 system call and used by the "perf" utility in tools/perf/. It 2174 provides per task and per CPU counters, and it provides event 2175 capabilities on top of those. 2176 2177 Say Y if unsure. 2178 2179config DEBUG_PERF_USE_VMALLOC 2180 default n 2181 bool "Debug: use vmalloc to back perf mmap() buffers" 2182 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2183 select PERF_USE_VMALLOC 2184 help 2185 Use vmalloc memory to back perf mmap() buffers. 2186 2187 Mostly useful for debugging the vmalloc code on platforms 2188 that don't require it. 2189 2190 Say N if unsure. 2191 2192endmenu 2193 2194config SYSTEM_DATA_VERIFICATION 2195 def_bool n 2196 select SYSTEM_TRUSTED_KEYRING 2197 select KEYS 2198 select CRYPTO 2199 select CRYPTO_RSA 2200 select ASYMMETRIC_KEY_TYPE 2201 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2202 select ASN1 2203 select OID_REGISTRY 2204 select X509_CERTIFICATE_PARSER 2205 select PKCS7_MESSAGE_PARSER 2206 help 2207 Provide PKCS#7 message verification using the contents of the system 2208 trusted keyring to provide public keys. This then can be used for 2209 module verification, kexec image verification and firmware blob 2210 verification. 2211 2212config PROFILING 2213 bool "Profiling support" 2214 help 2215 Say Y here to enable the extended profiling support mechanisms used 2216 by profilers. 2217 2218config RUST 2219 bool "Rust support" 2220 depends on HAVE_RUST 2221 depends on RUST_IS_AVAILABLE 2222 select EXTENDED_MODVERSIONS if MODVERSIONS 2223 depends on !MODVERSIONS || GENDWARFKSYMS 2224 depends on !GCC_PLUGIN_RANDSTRUCT 2225 depends on !RANDSTRUCT 2226 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2227 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2228 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2229 depends on !KASAN || CC_IS_CLANG 2230 depends on !KASAN_SW_TAGS || RUSTC_VERSION >= 109600 2231 help 2232 Enables Rust support in the kernel. 2233 2234 This allows other Rust-related options, like drivers written in Rust, 2235 to be selected. 2236 2237 It is also required to be able to load external kernel modules 2238 written in Rust. 2239 2240 See Documentation/rust/ for more information. 2241 2242 If unsure, say N. 2243 2244source "rust/kernel/Kconfig.test" 2245 2246config RUSTC_VERSION_TEXT 2247 string 2248 depends on RUST 2249 default "$(RUSTC_VERSION_TEXT)" 2250 help 2251 See `CC_VERSION_TEXT`. 2252 2253config BINDGEN_VERSION_TEXT 2254 string 2255 depends on RUST 2256 default "$(shell,$(BINDGEN) --version 2>/dev/null)" 2257 2258# 2259# Place an empty function call at each tracepoint site. Can be 2260# dynamically changed for a probe function. 2261# 2262config TRACEPOINTS 2263 bool 2264 select TASKS_TRACE_RCU 2265 2266source "kernel/Kconfig.kexec" 2267 2268source "kernel/liveupdate/Kconfig" 2269 2270endmenu # General setup 2271 2272source "arch/Kconfig" 2273 2274config RT_MUTEXES 2275 bool 2276 default y if PREEMPT_RT 2277 2278config MODULE_SIG_FORMAT 2279 def_bool n 2280 select SYSTEM_DATA_VERIFICATION 2281 2282source "kernel/module/Kconfig" 2283 2284config INIT_ALL_POSSIBLE 2285 bool 2286 help 2287 Back when each arch used to define their own cpu_online_mask and 2288 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2289 with all 1s, and others with all 0s. When they were centralised, 2290 it was better to provide this option than to break all the archs 2291 and have several arch maintainers pursuing me down dark alleys. 2292 2293source "block/Kconfig" 2294 2295config PREEMPT_NOTIFIERS 2296 bool 2297 2298config PADATA 2299 depends on SMP 2300 bool 2301 2302config ASN1 2303 tristate 2304 help 2305 Build a simple ASN.1 grammar compiler that produces a bytecode output 2306 that can be interpreted by the ASN.1 stream decoder and used to 2307 inform it as to what tags are to be expected in a stream and what 2308 functions to call on what tags. 2309 2310source "kernel/Kconfig.locks" 2311 2312config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2313 bool 2314 2315config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2316 bool 2317 2318config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2319 bool 2320 2321# It may be useful for an architecture to override the definitions of the 2322# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2323# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2324# different calling convention for syscalls. They can also override the 2325# macros for not-implemented syscalls in kernel/sys_ni.c and 2326# kernel/time/posix-stubs.c. All these overrides need to be available in 2327# <asm/syscall_wrapper.h>. 2328config ARCH_HAS_SYSCALL_WRAPPER 2329 def_bool n 2330