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 VIRT_CPU_ACCOUNTING_GEN if NO_HZ_FULL 569 default TICK_CPU_ACCOUNTING 570 571# Kind of a stub config for the pure tick based cputime accounting 572config TICK_CPU_ACCOUNTING 573 bool "Simple tick based cputime accounting" 574 depends on !S390 && !NO_HZ_FULL 575 help 576 This is the basic tick based cputime accounting that maintains 577 statistics about user, system and idle time spent on per jiffies 578 granularity. 579 580 If unsure, say Y. 581 582config VIRT_CPU_ACCOUNTING_NATIVE 583 bool "Deterministic task and CPU time accounting" 584 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 585 select VIRT_CPU_ACCOUNTING 586 help 587 Select this option to enable more accurate task and CPU time 588 accounting. This is done by reading a CPU counter on each 589 kernel entry and exit and on transitions within the kernel 590 between system, softirq and hardirq state, so there is a 591 small performance impact. In the case of s390 or IBM POWER > 5, 592 this also enables accounting of stolen time on logically-partitioned 593 systems. 594 595config VIRT_CPU_ACCOUNTING_GEN 596 bool "Full dynticks CPU time accounting" 597 depends on HAVE_CONTEXT_TRACKING_USER 598 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 599 depends on GENERIC_CLOCKEVENTS 600 select VIRT_CPU_ACCOUNTING 601 select CONTEXT_TRACKING_USER 602 help 603 Select this option to enable task and CPU time accounting on full 604 dynticks systems. This accounting is implemented by watching every 605 kernel-user boundaries using the context tracking subsystem. 606 The accounting is thus performed at the expense of some significant 607 overhead. 608 609 For now this is only useful if you are working on the full 610 dynticks subsystem development. 611 612 If unsure, say N. 613 614endchoice 615 616config IRQ_TIME_ACCOUNTING 617 bool "Fine granularity task level IRQ time accounting" 618 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 619 help 620 Select this option to enable fine granularity task irq time 621 accounting. This is done by reading a timestamp on each 622 transitions between softirq and hardirq state, so there can be a 623 small performance impact. 624 625 If in doubt, say N here. 626 627config HAVE_SCHED_AVG_IRQ 628 def_bool y 629 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 630 depends on SMP 631 632config SCHED_HW_PRESSURE 633 bool 634 default y if ARM && ARM_CPU_TOPOLOGY 635 default y if ARM64 636 depends on SMP 637 depends on CPU_FREQ_THERMAL 638 help 639 Select this option to enable HW pressure accounting in the 640 scheduler. HW pressure is the value conveyed to the scheduler 641 that reflects the reduction in CPU compute capacity resulted from 642 HW throttling. HW throttling occurs when the performance of 643 a CPU is capped due to high operating temperatures as an example. 644 645 If selected, the scheduler will be able to balance tasks accordingly, 646 i.e. put less load on throttled CPUs than on non/less throttled ones. 647 648 This requires the architecture to implement 649 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 650 651config BSD_PROCESS_ACCT 652 bool "BSD Process Accounting (DEPRECATED)" 653 depends on MULTIUSER 654 default n 655 help 656 If you say Y here, a user level program will be able to instruct the 657 kernel (via a special system call) to write process accounting 658 information to a file: whenever a process exits, information about 659 that process will be appended to the file by the kernel. The 660 information includes things such as creation time, owning user, 661 command name, memory usage, controlling terminal etc. (the complete 662 list is in the struct acct in <file:include/linux/acct.h>). It is 663 up to the user level program to do useful things with this 664 information. This mechanism is antiquated and has significant 665 scalability issues. You probably want to use eBPF instead. Say 666 N unless you really need this. 667 668config BSD_PROCESS_ACCT_V3 669 bool "BSD Process Accounting version 3 file format" 670 depends on BSD_PROCESS_ACCT 671 default n 672 help 673 If you say Y here, the process accounting information is written 674 in a new file format that also logs the process IDs of each 675 process and its parent. Note that this file format is incompatible 676 with previous v0/v1/v2 file formats, so you will need updated tools 677 for processing it. A preliminary version of these tools is available 678 at <http://www.gnu.org/software/acct/>. 679 680config TASKSTATS 681 bool "Export task/process statistics through netlink" 682 depends on NET 683 depends on MULTIUSER 684 default n 685 help 686 Export selected statistics for tasks/processes through the 687 generic netlink interface. Unlike BSD process accounting, the 688 statistics are available during the lifetime of tasks/processes as 689 responses to commands. Like BSD accounting, they are sent to user 690 space on task exit. 691 692 Say N if unsure. 693 694config TASK_DELAY_ACCT 695 bool "Enable per-task delay accounting" 696 depends on TASKSTATS 697 select SCHED_INFO 698 help 699 Collect information on time spent by a task waiting for system 700 resources like cpu, synchronous block I/O completion and swapping 701 in pages. Such statistics can help in setting a task's priorities 702 relative to other tasks for cpu, io, rss limits etc. 703 704 Say N if unsure. 705 706config TASK_XACCT 707 bool "Enable extended accounting over taskstats" 708 depends on TASKSTATS 709 help 710 Collect extended task accounting data and send the data 711 to userland for processing over the taskstats interface. 712 713 Say N if unsure. 714 715config TASK_IO_ACCOUNTING 716 bool "Enable per-task storage I/O accounting" 717 depends on TASK_XACCT 718 help 719 Collect information on the number of bytes of storage I/O which this 720 task has caused. 721 722 Say N if unsure. 723 724config PSI 725 bool "Pressure stall information tracking" 726 select KERNFS 727 help 728 Collect metrics that indicate how overcommitted the CPU, memory, 729 and IO capacity are in the system. 730 731 If you say Y here, the kernel will create /proc/pressure/ with the 732 pressure statistics files cpu, memory, and io. These will indicate 733 the share of walltime in which some or all tasks in the system are 734 delayed due to contention of the respective resource. 735 736 In kernels with cgroup support, cgroups (cgroup2 only) will 737 have cpu.pressure, memory.pressure, and io.pressure files, 738 which aggregate pressure stalls for the grouped tasks only. 739 740 For more details see Documentation/accounting/psi.rst. 741 742 Say N if unsure. 743 744config PSI_DEFAULT_DISABLED 745 bool "Require boot parameter to enable pressure stall information tracking" 746 default n 747 depends on PSI 748 help 749 If set, pressure stall information tracking will be disabled 750 per default but can be enabled through passing psi=1 on the 751 kernel commandline during boot. 752 753 This feature adds some code to the task wakeup and sleep 754 paths of the scheduler. The overhead is too low to affect 755 common scheduling-intense workloads in practice (such as 756 webservers, memcache), but it does show up in artificial 757 scheduler stress tests, such as hackbench. 758 759 If you are paranoid and not sure what the kernel will be 760 used for, say Y. 761 762 Say N if unsure. 763 764endmenu # "CPU/Task time and stats accounting" 765 766config CPU_ISOLATION 767 bool "CPU isolation" 768 depends on SMP 769 default y 770 help 771 Make sure that CPUs running critical tasks are not disturbed by 772 any source of "noise" such as unbound workqueues, timers, kthreads... 773 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 774 the "isolcpus=" boot parameter. 775 776 Say Y if unsure. 777 778source "kernel/rcu/Kconfig" 779 780config IKCONFIG 781 tristate "Kernel .config support" 782 help 783 This option enables the complete Linux kernel ".config" file 784 contents to be saved in the kernel. It provides documentation 785 of which kernel options are used in a running kernel or in an 786 on-disk kernel. This information can be extracted from the kernel 787 image file with the script scripts/extract-ikconfig and used as 788 input to rebuild the current kernel or to build another kernel. 789 It can also be extracted from a running kernel by reading 790 /proc/config.gz if enabled (below). 791 792config IKCONFIG_PROC 793 bool "Enable access to .config through /proc/config.gz" 794 depends on IKCONFIG && PROC_FS 795 help 796 This option enables access to the kernel configuration file 797 through /proc/config.gz. 798 799config IKHEADERS 800 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 801 depends on SYSFS 802 help 803 This option enables access to the in-kernel headers that are generated during 804 the build process. These can be used to build eBPF tracing programs, 805 or similar programs. If you build the headers as a module, a module called 806 kheaders.ko is built which can be loaded on-demand to get access to headers. 807 808config LOG_BUF_SHIFT 809 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 810 range 12 25 811 default 17 812 depends on PRINTK 813 help 814 Select the minimal kernel log buffer size as a power of 2. 815 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 816 parameter, see below. Any higher size also might be forced 817 by "log_buf_len" boot parameter. 818 819 Examples: 820 17 => 128 KB 821 16 => 64 KB 822 15 => 32 KB 823 14 => 16 KB 824 13 => 8 KB 825 12 => 4 KB 826 827config LOG_CPU_MAX_BUF_SHIFT 828 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 829 depends on SMP 830 range 0 21 831 default 0 if BASE_SMALL 832 default 12 833 depends on PRINTK 834 help 835 This option allows to increase the default ring buffer size 836 according to the number of CPUs. The value defines the contribution 837 of each CPU as a power of 2. The used space is typically only few 838 lines however it might be much more when problems are reported, 839 e.g. backtraces. 840 841 The increased size means that a new buffer has to be allocated and 842 the original static one is unused. It makes sense only on systems 843 with more CPUs. Therefore this value is used only when the sum of 844 contributions is greater than the half of the default kernel ring 845 buffer as defined by LOG_BUF_SHIFT. The default values are set 846 so that more than 16 CPUs are needed to trigger the allocation. 847 848 Also this option is ignored when "log_buf_len" kernel parameter is 849 used as it forces an exact (power of two) size of the ring buffer. 850 851 The number of possible CPUs is used for this computation ignoring 852 hotplugging making the computation optimal for the worst case 853 scenario while allowing a simple algorithm to be used from bootup. 854 855 Examples shift values and their meaning: 856 17 => 128 KB for each CPU 857 16 => 64 KB for each CPU 858 15 => 32 KB for each CPU 859 14 => 16 KB for each CPU 860 13 => 8 KB for each CPU 861 12 => 4 KB for each CPU 862 863config PRINTK_INDEX 864 bool "Printk indexing debugfs interface" 865 depends on PRINTK && DEBUG_FS 866 help 867 Add support for indexing of all printk formats known at compile time 868 at <debugfs>/printk/index/<module>. 869 870 This can be used as part of maintaining daemons which monitor 871 /dev/kmsg, as it permits auditing the printk formats present in a 872 kernel, allowing detection of cases where monitored printks are 873 changed or no longer present. 874 875 There is no additional runtime cost to printk with this enabled. 876 877# 878# Architectures with an unreliable sched_clock() should select this: 879# 880config HAVE_UNSTABLE_SCHED_CLOCK 881 bool 882 883config GENERIC_SCHED_CLOCK 884 bool 885 886menu "Scheduler features" 887 888config UCLAMP_TASK 889 bool "Enable utilization clamping for RT/FAIR tasks" 890 depends on CPU_FREQ_GOV_SCHEDUTIL 891 help 892 This feature enables the scheduler to track the clamped utilization 893 of each CPU based on RUNNABLE tasks scheduled on that CPU. 894 895 With this option, the user can specify the min and max CPU 896 utilization allowed for RUNNABLE tasks. The max utilization defines 897 the maximum frequency a task should use while the min utilization 898 defines the minimum frequency it should use. 899 900 Both min and max utilization clamp values are hints to the scheduler, 901 aiming at improving its frequency selection policy, but they do not 902 enforce or grant any specific bandwidth for tasks. 903 904 If in doubt, say N. 905 906config UCLAMP_BUCKETS_COUNT 907 int "Number of supported utilization clamp buckets" 908 range 5 20 909 default 5 910 depends on UCLAMP_TASK 911 help 912 Defines the number of clamp buckets to use. The range of each bucket 913 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 914 number of clamp buckets the finer their granularity and the higher 915 the precision of clamping aggregation and tracking at run-time. 916 917 For example, with the minimum configuration value we will have 5 918 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 919 be refcounted in the [20..39]% bucket and will set the bucket clamp 920 effective value to 25%. 921 If a second 30% boosted task should be co-scheduled on the same CPU, 922 that task will be refcounted in the same bucket of the first task and 923 it will boost the bucket clamp effective value to 30%. 924 The clamp effective value of a bucket is reset to its nominal value 925 (20% in the example above) when there are no more tasks refcounted in 926 that bucket. 927 928 An additional boost/capping margin can be added to some tasks. In the 929 example above the 25% task will be boosted to 30% until it exits the 930 CPU. If that should be considered not acceptable on certain systems, 931 it's always possible to reduce the margin by increasing the number of 932 clamp buckets to trade off used memory for run-time tracking 933 precision. 934 935 If in doubt, use the default value. 936 937config SCHED_PROXY_EXEC 938 bool "Proxy Execution" 939 # Avoid some build failures w/ PREEMPT_RT until it can be fixed 940 depends on !PREEMPT_RT 941 # Need to investigate how to inform sched_ext of split contexts 942 depends on !SCHED_CLASS_EXT 943 # Not particularly useful until we get to multi-rq proxying 944 depends on EXPERT 945 help 946 This option enables proxy execution, a mechanism for mutex-owning 947 tasks to inherit the scheduling context of higher priority waiters. 948 949endmenu 950 951# 952# For architectures that support present-but-inaccessible (PROT_NONE) page 953# table entries detectable via pte_protnone() / pmd_protnone(): 954# 955config ARCH_HAS_PTE_PROTNONE 956 bool 957 958# 959# For architectures that want to enable the support for NUMA-affine scheduler 960# balancing logic: 961# 962config ARCH_SUPPORTS_NUMA_BALANCING 963 bool 964 965# 966# For architectures that prefer to flush all TLBs after a number of pages 967# are unmapped instead of sending one IPI per page to flush. The architecture 968# must provide guarantees on what happens if a clean TLB cache entry is 969# written after the unmap. Details are in mm/rmap.c near the check for 970# should_defer_flush. The architecture should also consider if the full flush 971# and the refill costs are offset by the savings of sending fewer IPIs. 972config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 973 bool 974 975config CC_HAS_INT128 976 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 977 978config CC_IMPLICIT_FALLTHROUGH 979 string 980 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 981 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 982 983config CC_MS_EXTENSIONS 984 string 985 default "-fms-anonymous-structs" if $(cc-option,-fms-anonymous-structs) 986 default "-fms-extensions" 987 988# Currently, disable gcc-10+ array-bounds globally. 989# It's still broken in gcc-13, so no upper bound yet. 990config GCC10_NO_ARRAY_BOUNDS 991 def_bool y 992 993config CC_NO_ARRAY_BOUNDS 994 bool 995 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 996 997# Currently, disable -Wstringop-overflow for GCC globally. 998config GCC_NO_STRINGOP_OVERFLOW 999 def_bool y 1000 1001config CC_NO_STRINGOP_OVERFLOW 1002 bool 1003 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 1004 1005config CC_STRINGOP_OVERFLOW 1006 bool 1007 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 1008 1009# 1010# For architectures that know their GCC __int128 support is sound 1011# 1012config ARCH_SUPPORTS_INT128 1013 bool 1014 1015# For architectures that (ab)use NUMA to represent different memory regions 1016# all cpu-local but of different latencies, such as SuperH. 1017# 1018config ARCH_WANT_NUMA_VARIABLE_LOCALITY 1019 bool 1020 1021config NUMA_BALANCING 1022 bool "Memory placement aware NUMA scheduler" 1023 depends on ARCH_SUPPORTS_NUMA_BALANCING 1024 depends on ARCH_HAS_PTE_PROTNONE 1025 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 1026 depends on SMP && NUMA_MIGRATION && !PREEMPT_RT 1027 help 1028 This option adds support for automatic NUMA aware memory/task placement. 1029 The mechanism is quite primitive and is based on migrating memory when 1030 it has references to the node the task is running on. 1031 1032 This system will be inactive on UMA systems. 1033 1034config SCHED_CACHE 1035 bool "Cache aware load balance" 1036 default y 1037 depends on SMP 1038 help 1039 When enabled, the scheduler will attempt to aggregate tasks from 1040 the same process onto a single Last Level Cache (LLC) domain when 1041 possible. This improves cache locality by keeping tasks that share 1042 resources within the same cache domain, reducing cache misses and 1043 lowering data access latency. 1044 1045config NUMA_BALANCING_DEFAULT_ENABLED 1046 bool "Automatically enable NUMA aware memory/task placement" 1047 default y 1048 depends on NUMA_BALANCING 1049 help 1050 If set, automatic NUMA balancing will be enabled if running on a NUMA 1051 machine. 1052 1053config SLAB_OBJ_EXT 1054 bool 1055 1056menuconfig CGROUPS 1057 bool "Control Group support" 1058 select KERNFS 1059 help 1060 This option adds support for grouping sets of processes together, for 1061 use with process control subsystems such as Cpusets, CFS, memory 1062 controls or device isolation. 1063 See 1064 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1065 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1066 and resource control) 1067 1068 Say N if unsure. 1069 1070if CGROUPS 1071 1072config PAGE_COUNTER 1073 bool 1074 1075config CGROUP_FAVOR_DYNMODS 1076 bool "Favor dynamic modification latency reduction by default" 1077 help 1078 This option enables the "favordynmods" mount option by default 1079 which reduces the latencies of dynamic cgroup modifications such 1080 as task migrations and controller on/offs at the cost of making 1081 hot path operations such as forks and exits more expensive. 1082 1083 Say N if unsure. 1084 1085config MEMCG 1086 bool "Memory controller" 1087 select PAGE_COUNTER 1088 select EVENTFD 1089 select SLAB_OBJ_EXT 1090 select VM_EVENT_COUNTERS 1091 help 1092 Provides control over the memory footprint of tasks in a cgroup. 1093 1094config MEMCG_NMI_UNSAFE 1095 bool 1096 depends on MEMCG 1097 depends on HAVE_NMI 1098 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1099 default y 1100 1101config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1102 bool 1103 depends on MEMCG 1104 depends on HAVE_NMI 1105 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1106 default y 1107 1108config MEMCG_V1 1109 bool "Legacy cgroup v1 memory controller" 1110 depends on MEMCG 1111 default n 1112 help 1113 Legacy cgroup v1 memory controller which has been deprecated by 1114 cgroup v2 implementation. The v1 is there for legacy applications 1115 which haven't migrated to the new cgroup v2 interface yet. If you 1116 do not have any such application then you are completely fine leaving 1117 this option disabled. 1118 1119 Please note that feature set of the legacy memory controller is likely 1120 going to shrink due to deprecation process. New deployments with v1 1121 controller are highly discouraged. 1122 1123 Say N if unsure. 1124 1125config BLK_CGROUP 1126 bool "IO controller" 1127 depends on BLOCK 1128 default n 1129 help 1130 Generic block IO controller cgroup interface. This is the common 1131 cgroup interface which should be used by various IO controlling 1132 policies. 1133 1134 Currently, CFQ IO scheduler uses it to recognize task groups and 1135 control disk bandwidth allocation (proportional time slice allocation) 1136 to such task groups. It is also used by bio throttling logic in 1137 block layer to implement upper limit in IO rates on a device. 1138 1139 This option only enables generic Block IO controller infrastructure. 1140 One needs to also enable actual IO controlling logic/policy. For 1141 enabling proportional weight division of disk bandwidth in CFQ, set 1142 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1143 CONFIG_BLK_DEV_THROTTLING=y. 1144 1145 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1146 1147config CGROUP_WRITEBACK 1148 bool 1149 depends on MEMCG && BLK_CGROUP 1150 default y 1151 1152menuconfig CGROUP_SCHED 1153 bool "CPU controller" 1154 default n 1155 help 1156 This feature lets CPU scheduler recognize task groups and control CPU 1157 bandwidth allocation to such task groups. It uses cgroups to group 1158 tasks. 1159 1160if CGROUP_SCHED 1161config GROUP_SCHED_WEIGHT 1162 def_bool n 1163 1164config GROUP_SCHED_BANDWIDTH 1165 def_bool n 1166 1167config FAIR_GROUP_SCHED 1168 bool "Group scheduling for SCHED_OTHER" 1169 depends on CGROUP_SCHED 1170 select GROUP_SCHED_WEIGHT 1171 default CGROUP_SCHED 1172 1173config CFS_BANDWIDTH 1174 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1175 depends on FAIR_GROUP_SCHED 1176 select GROUP_SCHED_BANDWIDTH 1177 default n 1178 help 1179 This option allows users to define CPU bandwidth rates (limits) for 1180 tasks running within the fair group scheduler. Groups with no limit 1181 set are considered to be unconstrained and will run with no 1182 restriction. 1183 See Documentation/scheduler/sched-bwc.rst for more information. 1184 1185config RT_GROUP_SCHED 1186 bool "Group scheduling for SCHED_RR/FIFO" 1187 depends on CGROUP_SCHED 1188 default n 1189 help 1190 This feature lets you explicitly allocate real CPU bandwidth 1191 to task groups. If enabled, it will also make it impossible to 1192 schedule realtime tasks for non-root users until you allocate 1193 realtime bandwidth for them. 1194 See Documentation/scheduler/sched-rt-group.rst for more information. 1195 1196config RT_GROUP_SCHED_DEFAULT_DISABLED 1197 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1198 depends on RT_GROUP_SCHED 1199 default n 1200 help 1201 When set, the RT group scheduling is disabled by default. The option 1202 is in inverted form so that mere RT_GROUP_SCHED enables the group 1203 scheduling. 1204 1205 Say N if unsure. 1206 1207config EXT_GROUP_SCHED 1208 bool 1209 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1210 select GROUP_SCHED_WEIGHT 1211 select GROUP_SCHED_BANDWIDTH 1212 default y 1213 1214endif #CGROUP_SCHED 1215 1216config EXT_SUB_SCHED 1217 def_bool y 1218 depends on SCHED_CLASS_EXT && CGROUPS 1219 1220config SCHED_MM_CID 1221 def_bool y 1222 depends on SMP && RSEQ 1223 1224config UCLAMP_TASK_GROUP 1225 bool "Utilization clamping per group of tasks" 1226 depends on CGROUP_SCHED 1227 depends on UCLAMP_TASK 1228 default n 1229 help 1230 This feature enables the scheduler to track the clamped utilization 1231 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1232 1233 When this option is enabled, the user can specify a min and max 1234 CPU bandwidth which is allowed for each single task in a group. 1235 The max bandwidth allows to clamp the maximum frequency a task 1236 can use, while the min bandwidth allows to define a minimum 1237 frequency a task will always use. 1238 1239 When task group based utilization clamping is enabled, an eventually 1240 specified task-specific clamp value is constrained by the cgroup 1241 specified clamp value. Both minimum and maximum task clamping cannot 1242 be bigger than the corresponding clamping defined at task group level. 1243 1244 If in doubt, say N. 1245 1246config CGROUP_PIDS 1247 bool "PIDs controller" 1248 help 1249 Provides enforcement of process number limits in the scope of a 1250 cgroup. Any attempt to fork more processes than is allowed in the 1251 cgroup will fail. PIDs are fundamentally a global resource because it 1252 is fairly trivial to reach PID exhaustion before you reach even a 1253 conservative kmemcg limit. As a result, it is possible to grind a 1254 system to halt without being limited by other cgroup policies. The 1255 PIDs controller is designed to stop this from happening. 1256 1257 It should be noted that organisational operations (such as attaching 1258 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1259 since the PIDs limit only affects a process's ability to fork, not to 1260 attach to a cgroup. 1261 1262config CGROUP_RDMA 1263 bool "RDMA controller" 1264 help 1265 Provides enforcement of RDMA resources defined by IB stack. 1266 It is fairly easy for consumers to exhaust RDMA resources, which 1267 can result into resource unavailability to other consumers. 1268 RDMA controller is designed to stop this from happening. 1269 Attaching processes with active RDMA resources to the cgroup 1270 hierarchy is allowed even if can cross the hierarchy's limit. 1271 1272config CGROUP_DMEM 1273 bool "Device memory controller (DMEM)" 1274 select PAGE_COUNTER 1275 help 1276 The DMEM controller allows compatible devices to restrict device 1277 memory usage based on the cgroup hierarchy. 1278 1279 As an example, it allows you to restrict VRAM usage for applications 1280 in the DRM subsystem. 1281 1282config CGROUP_FREEZER 1283 bool "Freezer controller" 1284 help 1285 Provides a way to freeze and unfreeze all tasks in a 1286 cgroup. 1287 1288 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1289 controller includes important in-kernel memory consumers per default. 1290 1291 If you're using cgroup2, say N. 1292 1293config CGROUP_HUGETLB 1294 bool "HugeTLB controller" 1295 depends on HUGETLB_PAGE 1296 select PAGE_COUNTER 1297 default n 1298 help 1299 Provides a cgroup controller for HugeTLB pages. 1300 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1301 The limit is enforced during page fault. Since HugeTLB doesn't 1302 support page reclaim, enforcing the limit at page fault time implies 1303 that, the application will get SIGBUS signal if it tries to access 1304 HugeTLB pages beyond its limit. This requires the application to know 1305 beforehand how much HugeTLB pages it would require for its use. The 1306 control group is tracked in the third page lru pointer. This means 1307 that we cannot use the controller with huge page less than 3 pages. 1308 1309config CPUSETS 1310 bool "Cpuset controller" 1311 depends on SMP 1312 select UNION_FIND 1313 select CPU_ISOLATION 1314 help 1315 This option will let you create and manage CPUSETs which 1316 allow dynamically partitioning a system into sets of CPUs and 1317 Memory Nodes and assigning tasks to run only within those sets. 1318 This is primarily useful on large SMP or NUMA systems. 1319 1320 Say N if unsure. 1321 1322config CPUSETS_V1 1323 bool "Legacy cgroup v1 cpusets controller" 1324 depends on CPUSETS 1325 default n 1326 help 1327 Legacy cgroup v1 cpusets controller which has been deprecated by 1328 cgroup v2 implementation. The v1 is there for legacy applications 1329 which haven't migrated to the new cgroup v2 interface yet. Legacy 1330 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1331 do not have any such application then you are completely fine leaving 1332 this option disabled. 1333 1334 Say N if unsure. 1335 1336config PROC_PID_CPUSET 1337 bool "Include legacy /proc/<pid>/cpuset file" 1338 depends on CPUSETS_V1 1339 default y 1340 1341config CGROUP_DEVICE 1342 bool "Device controller" 1343 help 1344 Provides a cgroup controller implementing whitelists for 1345 devices which a process in the cgroup can mknod or open. 1346 1347config CGROUP_CPUACCT 1348 bool "Simple CPU accounting controller" 1349 help 1350 Provides a simple controller for monitoring the 1351 total CPU consumed by the tasks in a cgroup. 1352 1353config CGROUP_PERF 1354 bool "Perf controller" 1355 depends on PERF_EVENTS 1356 help 1357 This option extends the perf per-cpu mode to restrict monitoring 1358 to threads which belong to the cgroup specified and run on the 1359 designated cpu. Or this can be used to have cgroup ID in samples 1360 so that it can monitor performance events among cgroups. 1361 1362 Say N if unsure. 1363 1364config CGROUP_BPF 1365 bool "Support for eBPF programs attached to cgroups" 1366 depends on BPF_SYSCALL 1367 select SOCK_CGROUP_DATA 1368 help 1369 Allow attaching eBPF programs to a cgroup using the bpf(2) 1370 syscall command BPF_PROG_ATTACH. 1371 1372 In which context these programs are accessed depends on the type 1373 of attachment. For instance, programs that are attached using 1374 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1375 inet sockets. 1376 1377config CGROUP_MISC 1378 bool "Misc resource controller" 1379 default n 1380 help 1381 Provides a controller for miscellaneous resources on a host. 1382 1383 Miscellaneous scalar resources are the resources on the host system 1384 which cannot be abstracted like the other cgroups. This controller 1385 tracks and limits the miscellaneous resources used by a process 1386 attached to a cgroup hierarchy. 1387 1388 For more information, please check misc cgroup section in 1389 /Documentation/admin-guide/cgroup-v2.rst. 1390 1391config CGROUP_DEBUG 1392 bool "Debug controller" 1393 default n 1394 depends on DEBUG_KERNEL 1395 help 1396 This option enables a simple controller that exports 1397 debugging information about the cgroups framework. This 1398 controller is for control cgroup debugging only. Its 1399 interfaces are not stable. 1400 1401 Say N. 1402 1403config SOCK_CGROUP_DATA 1404 bool 1405 default n 1406 1407endif # CGROUPS 1408 1409menuconfig NAMESPACES 1410 bool "Namespaces support" if EXPERT 1411 depends on MULTIUSER 1412 default !EXPERT 1413 help 1414 Provides the way to make tasks work with different objects using 1415 the same id. For example same IPC id may refer to different objects 1416 or same user id or pid may refer to different tasks when used in 1417 different namespaces. 1418 1419if NAMESPACES 1420 1421config UTS_NS 1422 bool "UTS namespace" 1423 default y 1424 help 1425 In this namespace tasks see different info provided with the 1426 uname() system call 1427 1428config TIME_NS 1429 bool "TIME namespace" 1430 default y 1431 help 1432 In this namespace boottime and monotonic clocks can be set. 1433 The time will keep going with the same pace. 1434 1435config TIME_NS_VDSO 1436 def_bool TIME_NS && GENERIC_GETTIMEOFDAY 1437 1438config IPC_NS 1439 bool "IPC namespace" 1440 depends on (SYSVIPC || POSIX_MQUEUE) 1441 default y 1442 help 1443 In this namespace tasks work with IPC ids which correspond to 1444 different IPC objects in different namespaces. 1445 1446config USER_NS 1447 bool "User namespace" 1448 default n 1449 help 1450 This allows containers, i.e. vservers, to use user namespaces 1451 to provide different user info for different servers. 1452 1453 When user namespaces are enabled in the kernel it is 1454 recommended that the MEMCG option also be enabled and that 1455 user-space use the memory control groups to limit the amount 1456 of memory a memory unprivileged users can use. 1457 1458 If unsure, say N. 1459 1460config PID_NS 1461 bool "PID Namespaces" 1462 default y 1463 help 1464 Support process id namespaces. This allows having multiple 1465 processes with the same pid as long as they are in different 1466 pid namespaces. This is a building block of containers. 1467 1468config NET_NS 1469 bool "Network namespace" 1470 depends on NET 1471 default y 1472 help 1473 Allow user space to create what appear to be multiple instances 1474 of the network stack. 1475 1476endif # NAMESPACES 1477 1478config CHECKPOINT_RESTORE 1479 bool "Checkpoint/restore support" 1480 depends on PROC_FS 1481 select PROC_CHILDREN 1482 select KCMP 1483 default n 1484 help 1485 Enables additional kernel features in a sake of checkpoint/restore. 1486 In particular it adds auxiliary prctl codes to setup process text, 1487 data and heap segment sizes, and a few additional /proc filesystem 1488 entries. 1489 1490 If unsure, say N here. 1491 1492config SCHED_AUTOGROUP 1493 bool "Automatic process group scheduling" 1494 select CGROUPS 1495 select CGROUP_SCHED 1496 select FAIR_GROUP_SCHED 1497 help 1498 This option optimizes the scheduler for common desktop workloads by 1499 automatically creating and populating task groups. This separation 1500 of workloads isolates aggressive CPU burners (like build jobs) from 1501 desktop applications. Task group autogeneration is currently based 1502 upon task session. 1503 1504config RELAY 1505 bool "Kernel->user space relay support (formerly relayfs)" 1506 select IRQ_WORK 1507 help 1508 This option enables support for relay interface support in 1509 certain file systems (such as debugfs). 1510 It is designed to provide an efficient mechanism for tools and 1511 facilities to relay large amounts of data from kernel space to 1512 user space. 1513 1514 If unsure, say N. 1515 1516config BLK_DEV_INITRD 1517 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1518 help 1519 The initial RAM filesystem is a ramfs which is loaded by the 1520 boot loader (loadlin or lilo) and that is mounted as root 1521 before the normal boot procedure. It is typically used to 1522 load modules needed to mount the "real" root file system, 1523 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1524 1525 If RAM disk support (BLK_DEV_RAM) is also included, this 1526 also enables initial RAM disk (initrd) support and adds 1527 15 Kbytes (more on some other architectures) to the kernel size. 1528 1529 If unsure say Y. 1530 1531if BLK_DEV_INITRD 1532 1533source "usr/Kconfig" 1534 1535endif 1536 1537config BOOT_CONFIG 1538 bool "Boot config support" 1539 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1540 help 1541 Extra boot config allows system admin to pass a config file as 1542 complemental extension of kernel cmdline when booting. 1543 The boot config file must be attached at the end of initramfs 1544 with checksum, size and magic word. 1545 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1546 1547 If unsure, say Y. 1548 1549config BOOT_CONFIG_FORCE 1550 bool "Force unconditional bootconfig processing" 1551 depends on BOOT_CONFIG 1552 default y if BOOT_CONFIG_EMBED 1553 help 1554 With this Kconfig option set, BOOT_CONFIG processing is carried 1555 out even when the "bootconfig" kernel-boot parameter is omitted. 1556 In fact, with this Kconfig option set, there is no way to 1557 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1558 parameters. 1559 1560 If unsure, say N. 1561 1562config BOOT_CONFIG_EMBED 1563 bool "Embed bootconfig file in the kernel" 1564 depends on BOOT_CONFIG 1565 help 1566 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1567 kernel. Usually, the bootconfig file is loaded with the initrd 1568 image. But if the system doesn't support initrd, this option will 1569 help you by embedding a bootconfig file while building the kernel. 1570 1571 If unsure, say N. 1572 1573config BOOT_CONFIG_EMBED_FILE 1574 string "Embedded bootconfig file path" 1575 depends on BOOT_CONFIG_EMBED 1576 help 1577 Specify a bootconfig file which will be embedded to the kernel. 1578 This bootconfig will be used if there is no initrd or no other 1579 bootconfig in the initrd. 1580 1581config ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG 1582 bool 1583 help 1584 Silent symbol; no C code reads it directly. Architectures 1585 select it once their setup_arch() calls 1586 xbc_prepend_embedded_cmdline() before parse_early_param(). 1587 Its only role is to gate the user-visible 1588 CMDLINE_FROM_BOOTCONFIG option per-arch, the same 1589 ARCH_SUPPORTS_* idiom used by ARCH_SUPPORTS_CFI, etc. 1590 1591config CMDLINE_FROM_BOOTCONFIG 1592 bool "Render embedded bootconfig as kernel cmdline at build time" 1593 depends on BOOT_CONFIG_EMBED_FILE != "" 1594 depends on ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG 1595 depends on CMDLINE = "" 1596 default n 1597 help 1598 Render the "kernel" subtree of the embedded bootconfig file into a 1599 flat cmdline string at kernel build time and prepend it to 1600 boot_command_line during early architecture setup. This makes 1601 early_param() handlers (e.g. mem=, earlycon=, loglevel=) see the 1602 values supplied via the embedded bootconfig. 1603 1604 The runtime bootconfig parser is unaffected, so tree-structured 1605 consumers such as ftrace boot-time tracing keep working. 1606 1607 Note: when an initrd also carries a bootconfig, its "kernel" 1608 subtree is still parsed at runtime, but the embedded "kernel" 1609 keys remain in boot_command_line for parse_early_param() and 1610 end up later than the initrd keys in saved_command_line, so 1611 parse_args() last-wins favors the embedded values. If you need 1612 initrd to override embedded kernel.* keys, leave this option 1613 off. 1614 1615 If unsure, say N. 1616 1617config CMDLINE_LOG_WRAP_IDEAL_LEN 1618 int "Length to try to wrap the cmdline when logged at boot" 1619 default 1021 1620 range 0 1021 1621 help 1622 At boot time, the kernel command line is logged to the console. 1623 The log message will start with the prefix "Kernel command line: ". 1624 The log message will attempt to be wrapped (split into multiple log 1625 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters. 1626 If wrapping happens, each log message will start with the prefix and 1627 all but the last message will end with " \". Messages may exceed the 1628 ideal length if a place to wrap isn't found before the specified 1629 number of characters. 1630 1631 A value of 0 disables wrapping, though be warned that the maximum 1632 length of a log message (1021 characters) may cause the cmdline to 1633 be truncated. 1634 1635config INITRAMFS_PRESERVE_MTIME 1636 bool "Preserve cpio archive mtimes in initramfs" 1637 depends on BLK_DEV_INITRD 1638 default y 1639 help 1640 Each entry in an initramfs cpio archive carries an mtime value. When 1641 enabled, extracted cpio items take this mtime, with directory mtime 1642 setting deferred until after creation of any child entries. 1643 1644 If unsure, say Y. 1645 1646config INITRAMFS_TEST 1647 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1648 depends on BLK_DEV_INITRD && KUNIT=y 1649 default KUNIT_ALL_TESTS 1650 help 1651 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1652 1653choice 1654 prompt "Compiler optimization level" 1655 default CC_OPTIMIZE_FOR_PERFORMANCE 1656 1657config CC_OPTIMIZE_FOR_PERFORMANCE 1658 bool "Optimize for performance (-O2)" 1659 help 1660 This is the default optimization level for the kernel, building 1661 with the "-O2" compiler flag for best performance and most 1662 helpful compile-time warnings. 1663 1664config CC_OPTIMIZE_FOR_SIZE 1665 bool "Optimize for size (-Os)" 1666 help 1667 Choosing this option will pass "-Os" to your compiler resulting 1668 in a smaller kernel. 1669 1670endchoice 1671 1672config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1673 bool 1674 help 1675 This requires that the arch annotates or otherwise protects 1676 its external entry points from being discarded. Linker scripts 1677 must also merge .text.*, .data.*, and .bss.* correctly into 1678 output sections. Care must be taken not to pull in unrelated 1679 sections (e.g., '.text.init'). Typically '.' in section names 1680 is used to distinguish them from label names / C identifiers. 1681 1682config LD_DEAD_CODE_DATA_ELIMINATION 1683 bool "Dead code and data elimination (EXPERIMENTAL)" 1684 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1685 depends on EXPERT 1686 depends on $(cc-option,-ffunction-sections -fdata-sections) 1687 depends on $(ld-option,--gc-sections) 1688 help 1689 Enable this if you want to do dead code and data elimination with 1690 the linker by compiling with -ffunction-sections -fdata-sections, 1691 and linking with --gc-sections. 1692 1693 This can reduce on disk and in-memory size of the kernel 1694 code and static data, particularly for small configs and 1695 on small systems. This has the possibility of introducing 1696 silently broken kernel if the required annotations are not 1697 present. This option is not well tested yet, so use at your 1698 own risk. 1699 1700config LD_ORPHAN_WARN 1701 def_bool y 1702 depends on ARCH_WANT_LD_ORPHAN_WARN 1703 depends on $(ld-option,--orphan-handling=warn) 1704 depends on $(ld-option,--orphan-handling=error) 1705 1706config LD_ORPHAN_WARN_LEVEL 1707 string 1708 depends on LD_ORPHAN_WARN 1709 default "error" if WERROR 1710 default "warn" 1711 1712config HAVE_UID16 1713 bool 1714 1715config SYSCTL_EXCEPTION_TRACE 1716 bool 1717 help 1718 Enable support for /proc/sys/debug/exception-trace. 1719 1720config SYSCTL_ARCH_UNALIGN_NO_WARN 1721 bool 1722 help 1723 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1724 Allows arch to define/use @no_unaligned_warning to possibly warn 1725 about unaligned access emulation going on under the hood. 1726 1727config SYSCTL_ARCH_UNALIGN_ALLOW 1728 bool 1729 help 1730 Enable support for /proc/sys/kernel/unaligned-trap 1731 Allows arches to define/use @unaligned_enabled to runtime toggle 1732 the unaligned access emulation. 1733 see arch/parisc/kernel/unaligned.c for reference 1734 1735config SYSFS_SYSCALL 1736 bool "Sysfs syscall support" 1737 default n 1738 help 1739 sys_sysfs is an obsolete system call no longer supported in libc. 1740 Note that disabling this option is more secure but might break 1741 compatibility with some systems. 1742 1743 If unsure say N here. 1744 1745config HAVE_PCSPKR_PLATFORM 1746 bool 1747 1748menuconfig EXPERT 1749 bool "Configure standard kernel features (expert users)" 1750 # Unhide debug options, to make the on-by-default options visible 1751 select DEBUG_KERNEL 1752 help 1753 This option allows certain base kernel options and settings 1754 to be disabled or tweaked. This is for specialized 1755 environments which can tolerate a "non-standard" kernel. 1756 Only use this if you really know what you are doing. 1757 1758config UID16 1759 bool "Enable 16-bit UID system calls" if EXPERT 1760 depends on HAVE_UID16 && MULTIUSER 1761 default y 1762 help 1763 This enables the legacy 16-bit UID syscall wrappers. 1764 1765config MULTIUSER 1766 bool "Multiple users, groups and capabilities support" if EXPERT 1767 default y 1768 help 1769 This option enables support for non-root users, groups and 1770 capabilities. 1771 1772 If you say N here, all processes will run with UID 0, GID 0, and all 1773 possible capabilities. Saying N here also compiles out support for 1774 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1775 setgid, and capset. 1776 1777 If unsure, say Y here. 1778 1779config SGETMASK_SYSCALL 1780 bool "sgetmask/ssetmask syscalls support" if EXPERT 1781 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1782 help 1783 sys_sgetmask and sys_ssetmask are obsolete system calls 1784 no longer supported in libc but still enabled by default in some 1785 architectures. 1786 1787 If unsure, leave the default option here. 1788 1789config FHANDLE 1790 bool "open by fhandle syscalls" if EXPERT 1791 select EXPORTFS 1792 default y 1793 help 1794 If you say Y here, a user level program will be able to map 1795 file names to handle and then later use the handle for 1796 different file system operations. This is useful in implementing 1797 userspace file servers, which now track files using handles instead 1798 of names. The handle would remain the same even if file names 1799 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1800 syscalls. 1801 1802config POSIX_TIMERS 1803 bool "Posix Clocks & timers" if EXPERT 1804 default y 1805 help 1806 This includes native support for POSIX timers to the kernel. 1807 Some embedded systems have no use for them and therefore they 1808 can be configured out to reduce the size of the kernel image. 1809 1810 When this option is disabled, the following syscalls won't be 1811 available: timer_create, timer_gettime: timer_getoverrun, 1812 timer_settime, timer_delete, clock_adjtime, getitimer, 1813 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1814 clock_getres and clock_nanosleep syscalls will be limited to 1815 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1816 1817 If unsure say y. 1818 1819config PRINTK 1820 default y 1821 bool "Enable support for printk" if EXPERT 1822 select IRQ_WORK 1823 help 1824 This option enables normal printk support. Removing it 1825 eliminates most of the message strings from the kernel image 1826 and makes the kernel more or less silent. As this makes it 1827 very difficult to diagnose system problems, saying N here is 1828 strongly discouraged. 1829 1830config PRINTK_RINGBUFFER_KUNIT_TEST 1831 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1832 depends on PRINTK && KUNIT 1833 default KUNIT_ALL_TESTS 1834 help 1835 This builds the printk ringbuffer KUnit test suite. 1836 1837 For more information on KUnit and unit tests in general, please refer 1838 to the KUnit documentation. 1839 1840 If unsure, say N. 1841 1842config BUG 1843 bool "BUG() support" if EXPERT 1844 default y 1845 help 1846 Disabling this option eliminates support for BUG and WARN, reducing 1847 the size of your kernel image and potentially quietly ignoring 1848 numerous fatal conditions. You should only consider disabling this 1849 option for embedded systems with no facilities for reporting errors. 1850 Just say Y. 1851 1852config ELF_CORE 1853 depends on COREDUMP 1854 default y 1855 bool "Enable ELF core dumps" if EXPERT 1856 help 1857 Enable support for generating core dumps. Disabling saves about 4k. 1858 1859 1860config PCSPKR_PLATFORM 1861 bool "Enable PC-Speaker support" if EXPERT 1862 depends on HAVE_PCSPKR_PLATFORM 1863 select I8253_LOCK 1864 default y 1865 help 1866 This option allows to disable the internal PC-Speaker 1867 support, saving some memory. 1868 1869config BASE_SMALL 1870 bool "Enable smaller-sized data structures for core" if EXPERT 1871 help 1872 Enabling this option reduces the size of miscellaneous core 1873 kernel data structures. This saves memory on small machines, 1874 but may reduce performance. 1875 1876config FUTEX 1877 bool "Enable futex support" if EXPERT 1878 depends on !(SPARC32 && SMP) 1879 default y 1880 imply RT_MUTEXES 1881 help 1882 Disabling this option will cause the kernel to be built without 1883 support for "fast userspace mutexes". The resulting kernel may not 1884 run glibc-based applications correctly. 1885 1886config FUTEX_PI 1887 bool 1888 depends on FUTEX && RT_MUTEXES 1889 default y 1890 1891config FUTEX_PRIVATE_HASH 1892 bool 1893 depends on FUTEX && !BASE_SMALL && MMU 1894 default y 1895 1896config FUTEX_MPOL 1897 bool 1898 depends on FUTEX && NUMA 1899 default y 1900 1901config HAVE_FUTEX_ROBUST_UNLOCK 1902 bool 1903 1904config FUTEX_ROBUST_UNLOCK 1905 def_bool FUTEX && GENERIC_IRQ_ENTRY && RSEQ && HAVE_FUTEX_ROBUST_UNLOCK 1906 1907config EPOLL 1908 bool "Enable eventpoll support" if EXPERT 1909 default y 1910 help 1911 Disabling this option will cause the kernel to be built without 1912 support for epoll family of system calls. 1913 1914config SIGNALFD 1915 bool "Enable signalfd() system call" if EXPERT 1916 default y 1917 help 1918 Enable the signalfd() system call that allows to receive signals 1919 on a file descriptor. 1920 1921 If unsure, say Y. 1922 1923config TIMERFD 1924 bool "Enable timerfd() system call" if EXPERT 1925 default y 1926 help 1927 Enable the timerfd() system call that allows to receive timer 1928 events on a file descriptor. 1929 1930 If unsure, say Y. 1931 1932config EVENTFD 1933 bool "Enable eventfd() system call" if EXPERT 1934 default y 1935 help 1936 Enable the eventfd() system call that allows to receive both 1937 kernel notification (ie. KAIO) or userspace notifications. 1938 1939 If unsure, say Y. 1940 1941config SHMEM 1942 bool "Use full shmem filesystem" if EXPERT 1943 default y 1944 depends on MMU 1945 help 1946 The shmem is an internal filesystem used to manage shared memory. 1947 It is backed by swap and manages resource limits. It is also exported 1948 to userspace as tmpfs if TMPFS is enabled. Disabling this 1949 option replaces shmem and tmpfs with the much simpler ramfs code, 1950 which may be appropriate on small systems without swap. 1951 1952config AIO 1953 bool "Enable AIO support" if EXPERT 1954 default y 1955 help 1956 This option enables POSIX asynchronous I/O which may by used 1957 by some high performance threaded applications. Disabling 1958 this option saves about 7k. 1959 1960config IO_URING 1961 bool "Enable IO uring support" if EXPERT 1962 select IO_WQ 1963 default y 1964 help 1965 This option enables support for the io_uring interface, enabling 1966 applications to submit and complete IO through submission and 1967 completion rings that are shared between the kernel and application. 1968 1969config GCOV_PROFILE_URING 1970 bool "Enable GCOV profiling on the io_uring subsystem" 1971 depends on IO_URING && GCOV_KERNEL 1972 help 1973 Enable GCOV profiling on the io_uring subsystem, to facilitate 1974 code coverage testing. 1975 1976 If unsure, say N. 1977 1978 Note that this will have a negative impact on the performance of 1979 the io_uring subsystem, hence this should only be enabled for 1980 specific test purposes. 1981 1982config IO_URING_MOCK_FILE 1983 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1984 default n 1985 depends on IO_URING 1986 help 1987 Enable mock files for io_uring subsystem testing. The ABI might 1988 still change, so it's still experimental and should only be enabled 1989 for specific test purposes. 1990 1991 If unsure, say N. 1992 1993config ADVISE_SYSCALLS 1994 bool "Enable madvise/fadvise syscalls" if EXPERT 1995 default y 1996 help 1997 This option enables the madvise and fadvise syscalls, used by 1998 applications to advise the kernel about their future memory or file 1999 usage, improving performance. If building an embedded system where no 2000 applications use these syscalls, you can disable this option to save 2001 space. 2002 2003config MEMBARRIER 2004 bool "Enable membarrier() system call" if EXPERT 2005 default y 2006 help 2007 Enable the membarrier() system call that allows issuing memory 2008 barriers across all running threads, which can be used to distribute 2009 the cost of user-space memory barriers asymmetrically by transforming 2010 pairs of memory barriers into pairs consisting of membarrier() and a 2011 compiler barrier. 2012 2013 If unsure, say Y. 2014 2015config KCMP 2016 bool "Enable kcmp() system call" if EXPERT 2017 help 2018 Enable the kernel resource comparison system call. It provides 2019 user-space with the ability to compare two processes to see if they 2020 share a common resource, such as a file descriptor or even virtual 2021 memory space. 2022 2023 If unsure, say N. 2024 2025config RSEQ 2026 bool "Enable rseq() system call" if EXPERT 2027 default y 2028 depends on HAVE_RSEQ 2029 select MEMBARRIER 2030 help 2031 Enable the restartable sequences system call. It provides a 2032 user-space cache for the current CPU number value, which 2033 speeds up getting the current CPU number from user-space, 2034 as well as an ABI to speed up user-space operations on 2035 per-CPU data. 2036 2037 If unsure, say Y. 2038 2039config RSEQ_SLICE_EXTENSION 2040 bool "Enable rseq-based time slice extension mechanism" 2041 depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS 2042 help 2043 Allows userspace to request a limited time slice extension when 2044 returning from an interrupt to user space via the RSEQ shared 2045 data ABI. If granted, that allows to complete a critical section, 2046 so that other threads are not stuck on a conflicted resource, 2047 while the task is scheduled out. 2048 2049 If unsure, say N. 2050 2051config RSEQ_STATS 2052 default n 2053 bool "Enable lightweight statistics of restartable sequences" if EXPERT 2054 depends on RSEQ && DEBUG_FS 2055 help 2056 Enable lightweight counters which expose information about the 2057 frequency of RSEQ operations via debugfs. Mostly interesting for 2058 kernel debugging or performance analysis. While lightweight it's 2059 still adding code into the user/kernel mode transitions. 2060 2061 If unsure, say N. 2062 2063config RSEQ_DEBUG_DEFAULT_ENABLE 2064 default n 2065 bool "Enable restartable sequences debug mode by default" if EXPERT 2066 depends on RSEQ 2067 help 2068 This enables the static branch for debug mode of restartable 2069 sequences. 2070 2071 This also can be controlled on the kernel command line via the 2072 command line parameter "rseq_debug=0/1" and through debugfs. 2073 2074 If unsure, say N. 2075 2076config DEBUG_RSEQ 2077 default n 2078 bool "Enable debugging of rseq() system call" if EXPERT 2079 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY 2080 select RSEQ_DEBUG_DEFAULT_ENABLE 2081 help 2082 Enable extra debugging checks for the rseq system call. 2083 2084 If unsure, say N. 2085 2086config CACHESTAT_SYSCALL 2087 bool "Enable cachestat() system call" if EXPERT 2088 default y 2089 help 2090 Enable the cachestat system call, which queries the page cache 2091 statistics of a file (number of cached pages, dirty pages, 2092 pages marked for writeback, (recently) evicted pages). 2093 2094 If unsure say Y here. 2095 2096config KALLSYMS 2097 bool "Load all symbols for debugging/ksymoops" if EXPERT 2098 default y 2099 help 2100 Say Y here to let the kernel print out symbolic crash information and 2101 symbolic stack backtraces. This increases the size of the kernel 2102 somewhat, as all symbols have to be loaded into the kernel image. 2103 2104config KALLSYMS_SELFTEST 2105 bool "Test the basic functions and performance of kallsyms" 2106 depends on KALLSYMS 2107 default n 2108 help 2109 Test the basic functions and performance of some interfaces, such as 2110 kallsyms_lookup_name. It also calculates the compression rate of the 2111 kallsyms compression algorithm for the current symbol set. 2112 2113 Start self-test automatically after system startup. Suggest executing 2114 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 2115 displayed in the last line, indicating that the test is complete. 2116 2117config KALLSYMS_ALL 2118 bool "Include all symbols in kallsyms" 2119 depends on DEBUG_KERNEL && KALLSYMS 2120 help 2121 Normally kallsyms only contains the symbols of functions for nicer 2122 OOPS messages and backtraces (i.e., symbols from the text and inittext 2123 sections). This is sufficient for most cases. And only if you want to 2124 enable kernel live patching, or other less common use cases (e.g., 2125 when a debugger is used) all symbols are required (i.e., names of 2126 variables from the data sections, etc). 2127 2128 This option makes sure that all symbols are loaded into the kernel 2129 image (i.e., symbols from all sections) in cost of increased kernel 2130 size (depending on the kernel configuration, it may be 300KiB or 2131 something like this). 2132 2133 Say N unless you really need all symbols, or kernel live patching. 2134 2135# end of the "standard kernel features (expert users)" menu 2136 2137config ARCH_HAS_MEMBARRIER_CALLBACKS 2138 bool 2139 2140config ARCH_HAS_MEMBARRIER_SYNC_CORE 2141 bool 2142 2143config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 2144 bool 2145 help 2146 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 2147 2148 A 64-bit kernel is required for the memory sealing feature. 2149 No specific hardware features from the CPU are needed. 2150 2151 To enable this feature, the architecture needs to update their 2152 special mappings calls to include the sealing flag and confirm 2153 that it doesn't unmap/remap system mappings during the life 2154 time of the process. The existence of this flag for an architecture 2155 implies that it does not require the remapping of the system 2156 mappings during process lifetime, so sealing these mappings is safe 2157 from a kernel perspective. 2158 2159 After the architecture enables this, a distribution can set 2160 CONFIG_MSEAL_SYSTEM_MAPPINGS to manage access to the feature. 2161 2162 For complete descriptions of memory sealing, please see 2163 Documentation/userspace-api/mseal.rst 2164 2165config HAVE_PERF_EVENTS 2166 bool 2167 help 2168 See tools/perf/design.txt for details. 2169 2170config GUEST_PERF_EVENTS 2171 bool 2172 depends on HAVE_PERF_EVENTS 2173 2174config PERF_GUEST_MEDIATED_PMU 2175 bool 2176 depends on GUEST_PERF_EVENTS 2177 2178config PERF_USE_VMALLOC 2179 bool 2180 help 2181 See tools/perf/design.txt for details 2182 2183menu "Kernel Performance Events And Counters" 2184 2185config PERF_EVENTS 2186 bool "Kernel performance events and counters" 2187 default y if PROFILING 2188 depends on HAVE_PERF_EVENTS 2189 select IRQ_WORK 2190 help 2191 Enable kernel support for various performance events provided 2192 by software and hardware. 2193 2194 Software events are supported either built-in or via the 2195 use of generic tracepoints. 2196 2197 Most modern CPUs support performance events via performance 2198 counter registers. These registers count the number of certain 2199 types of hw events: such as instructions executed, cachemisses 2200 suffered, or branches mis-predicted - without slowing down the 2201 kernel or applications. These registers can also trigger interrupts 2202 when a threshold number of events have passed - and can thus be 2203 used to profile the code that runs on that CPU. 2204 2205 The Linux Performance Event subsystem provides an abstraction of 2206 these software and hardware event capabilities, available via a 2207 system call and used by the "perf" utility in tools/perf/. It 2208 provides per task and per CPU counters, and it provides event 2209 capabilities on top of those. 2210 2211 Say Y if unsure. 2212 2213config DEBUG_PERF_USE_VMALLOC 2214 default n 2215 bool "Debug: use vmalloc to back perf mmap() buffers" 2216 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2217 select PERF_USE_VMALLOC 2218 help 2219 Use vmalloc memory to back perf mmap() buffers. 2220 2221 Mostly useful for debugging the vmalloc code on platforms 2222 that don't require it. 2223 2224 Say N if unsure. 2225 2226endmenu 2227 2228config SYSTEM_DATA_VERIFICATION 2229 def_bool n 2230 select SYSTEM_TRUSTED_KEYRING 2231 select KEYS 2232 select CRYPTO 2233 select CRYPTO_RSA 2234 select ASYMMETRIC_KEY_TYPE 2235 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2236 select ASN1 2237 select OID_REGISTRY 2238 select X509_CERTIFICATE_PARSER 2239 select PKCS7_MESSAGE_PARSER 2240 help 2241 Provide PKCS#7 message verification using the contents of the system 2242 trusted keyring to provide public keys. This then can be used for 2243 module verification, kexec image verification and firmware blob 2244 verification. 2245 2246config PROFILING 2247 bool "Profiling support" 2248 help 2249 Say Y here to enable the extended profiling support mechanisms used 2250 by profilers. 2251 2252config RUST 2253 bool "Rust support" 2254 depends on HAVE_RUST 2255 depends on RUST_IS_AVAILABLE 2256 select EXTENDED_MODVERSIONS if MODVERSIONS 2257 depends on !MODVERSIONS || GENDWARFKSYMS 2258 depends on !GCC_PLUGIN_RANDSTRUCT 2259 depends on !RANDSTRUCT 2260 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2261 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2262 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2263 depends on !KASAN || CC_IS_CLANG 2264 depends on !KASAN_SW_TAGS || RUSTC_VERSION >= 109600 2265 help 2266 Enables Rust support in the kernel. 2267 2268 This allows other Rust-related options, like drivers written in Rust, 2269 to be selected. 2270 2271 It is also required to be able to load external kernel modules 2272 written in Rust. 2273 2274 See Documentation/rust/ for more information. 2275 2276 If unsure, say N. 2277 2278source "rust/kernel/Kconfig.test" 2279 2280config RUSTC_VERSION_TEXT 2281 string 2282 depends on RUST 2283 default "$(RUSTC_VERSION_TEXT)" 2284 help 2285 See `CC_VERSION_TEXT`. 2286 2287config BINDGEN_VERSION_TEXT 2288 string 2289 depends on RUST 2290 default "$(shell,$(BINDGEN) --version 2>/dev/null)" 2291 2292# 2293# Place an empty function call at each tracepoint site. Can be 2294# dynamically changed for a probe function. 2295# 2296config TRACEPOINTS 2297 bool 2298 select TASKS_TRACE_RCU 2299 2300source "kernel/Kconfig.kexec" 2301 2302source "kernel/liveupdate/Kconfig" 2303 2304endmenu # General setup 2305 2306source "arch/Kconfig" 2307 2308config RT_MUTEXES 2309 bool 2310 default y if PREEMPT_RT 2311 2312config MODULE_SIG_FORMAT 2313 def_bool n 2314 select SYSTEM_DATA_VERIFICATION 2315 2316source "kernel/module/Kconfig" 2317 2318config INIT_ALL_POSSIBLE 2319 bool 2320 help 2321 Back when each arch used to define their own cpu_online_mask and 2322 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2323 with all 1s, and others with all 0s. When they were centralised, 2324 it was better to provide this option than to break all the archs 2325 and have several arch maintainers pursuing me down dark alleys. 2326 2327source "block/Kconfig" 2328 2329config PREEMPT_NOTIFIERS 2330 bool 2331 2332config PADATA 2333 depends on SMP 2334 bool 2335 2336config ASN1 2337 tristate 2338 help 2339 Build a simple ASN.1 grammar compiler that produces a bytecode output 2340 that can be interpreted by the ASN.1 stream decoder and used to 2341 inform it as to what tags are to be expected in a stream and what 2342 functions to call on what tags. 2343 2344source "kernel/Kconfig.locks" 2345 2346config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2347 bool 2348 2349config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2350 bool 2351 2352config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2353 bool 2354 2355# It may be useful for an architecture to override the definitions of the 2356# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2357# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2358# different calling convention for syscalls. They can also override the 2359# macros for not-implemented syscalls in kernel/sys_ni.c and 2360# kernel/time/posix-stubs.c. All these overrides need to be available in 2361# <asm/syscall_wrapper.h>. 2362config ARCH_HAS_SYSCALL_WRAPPER 2363 def_bool n 2364