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