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