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 # Detect basic support 122 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) 123 # Detect clang (< v17) scoped label issues 124 depends on $(success,echo 'void b(void **);void* c(void);int f(void){{asm goto(""::::l0);return 0;l0:return 1;}void *x __attribute__((cleanup(b)))=c();{asm goto(""::::l1);return 2;l1:return 3;}}' | $(CC) -x c - -c -o /dev/null) 125 126config CC_HAS_ASM_GOTO_TIED_OUTPUT 127 depends on CC_HAS_ASM_GOTO_OUTPUT 128 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 129 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) 130 131config TOOLS_SUPPORT_RELR 132 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 133 134config CC_HAS_ASM_INLINE 135 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 136 137config CC_HAS_ASSUME 138 bool 139 # clang needs to be at least 19.1.0 since the meaning of the assume 140 # attribute changed: 141 # https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17 142 default y if CC_IS_CLANG && CLANG_VERSION >= 190100 143 # supported since gcc 13.1.0 144 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654 145 default y if CC_IS_GCC && GCC_VERSION >= 130100 146 147config CC_HAS_NO_PROFILE_FN_ATTR 148 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 149 150config CC_HAS_COUNTED_BY 151 bool 152 # clang needs to be at least 20.1.0 to avoid potential crashes 153 # when building structures that contain __counted_by 154 # https://github.com/ClangBuiltLinux/linux/issues/2114 155 # https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489 156 default y if CC_IS_CLANG && CLANG_VERSION >= 200100 157 # supported since gcc 15.1.0 158 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 159 default y if CC_IS_GCC && GCC_VERSION >= 150100 160 161config CC_HAS_COUNTED_BY_PTR 162 bool 163 # supported since clang 22 164 default y if CC_IS_CLANG && CLANG_VERSION >= 220000 165 # supported since gcc 16.0.0 166 default y if CC_IS_GCC && GCC_VERSION >= 160000 167 168config CC_HAS_BROKEN_COUNTED_BY_REF 169 bool 170 # https://github.com/llvm/llvm-project/issues/182575 171 default y if CC_IS_CLANG && CLANG_VERSION < 220100 172 173config CC_HAS_MULTIDIMENSIONAL_NONSTRING 174 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 175 176config LD_CAN_USE_KEEP_IN_OVERLAY 177 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 178 # https://github.com/llvm/llvm-project/pull/130661 179 def_bool LD_IS_BFD || LLD_VERSION >= 210000 180 181config RUSTC_HAS_COERCE_POINTEE 182 def_bool RUSTC_VERSION >= 108400 183 184config RUSTC_HAS_SPAN_FILE 185 def_bool RUSTC_VERSION >= 108800 186 187config RUSTC_HAS_UNNECESSARY_TRANSMUTES 188 def_bool RUSTC_VERSION >= 108800 189 190config RUSTC_HAS_FILE_WITH_NUL 191 def_bool RUSTC_VERSION >= 108900 192 193config RUSTC_HAS_FILE_AS_C_STR 194 def_bool RUSTC_VERSION >= 109100 195 196config PAHOLE_VERSION 197 int 198 default "$(PAHOLE_VERSION)" 199 200config CONSTRUCTORS 201 bool 202 203config IRQ_WORK 204 def_bool y if SMP 205 206config BUILDTIME_TABLE_SORT 207 bool 208 209config THREAD_INFO_IN_TASK 210 bool 211 help 212 Select this to move thread_info off the stack into task_struct. To 213 make this work, an arch will need to remove all thread_info fields 214 except flags and fix any runtime bugs. 215 216 One subtle change that will be needed is to use try_get_task_stack() 217 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 218 219menu "General setup" 220 221config BROKEN 222 bool 223 help 224 This option allows you to choose whether you want to try to 225 compile (and fix) old drivers that haven't been updated to 226 new infrastructure. 227 228config BROKEN_ON_SMP 229 bool 230 depends on BROKEN || !SMP 231 default y 232 233config INIT_ENV_ARG_LIMIT 234 int 235 default 32 if !UML 236 default 128 if UML 237 help 238 Maximum of each of the number of arguments and environment 239 variables passed to init from the kernel command line. 240 241config COMPILE_TEST 242 bool "Compile also drivers which will not load" 243 depends on HAS_IOMEM 244 help 245 Some drivers can be compiled on a different platform than they are 246 intended to be run on. Despite they cannot be loaded there (or even 247 when they load they cannot be used due to missing HW support), 248 developers still, opposing to distributors, might want to build such 249 drivers to compile-test them. 250 251 If you are a developer and want to build everything available, say Y 252 here. If you are a user/distributor, say N here to exclude useless 253 drivers to be distributed. 254 255config WERROR 256 bool "Compile the kernel with warnings as errors" 257 default COMPILE_TEST 258 help 259 A kernel build should not cause any compiler warnings, and this 260 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 261 to enforce that rule by default. Certain warnings from other tools 262 such as the linker may be upgraded to errors with this option as 263 well. 264 265 However, if you have a new (or very old) compiler or linker with odd 266 and unusual warnings, or you have some architecture with problems, 267 you may need to disable this config option in order to 268 successfully build the kernel. 269 270 If in doubt, say Y. 271 272config UAPI_HEADER_TEST 273 bool "Compile test UAPI headers" 274 depends on HEADERS_INSTALL 275 help 276 Compile test headers exported to user-space to ensure they are 277 self-contained, i.e. compilable as standalone units. 278 279 If you are a developer or tester and want to ensure the exported 280 headers are self-contained, say Y here. Otherwise, choose N. 281 282config LOCALVERSION 283 string "Local version - append to kernel release" 284 help 285 Append an extra string to the end of your kernel version. 286 This will show up when you type uname, for example. 287 The string you set here will be appended after the contents of 288 any files with a filename matching localversion* in your 289 object and source tree, in that order. Your total string can 290 be a maximum of 64 characters. 291 292config LOCALVERSION_AUTO 293 bool "Automatically append version information to the version string" 294 default y 295 depends on !COMPILE_TEST 296 help 297 This will try to automatically determine if the current tree is a 298 release tree by looking for git tags that belong to the current 299 top of tree revision. 300 301 A string of the format -gxxxxxxxx will be added to the localversion 302 if a git-based tree is found. The string generated by this will be 303 appended after any matching localversion* files, and after the value 304 set in CONFIG_LOCALVERSION. 305 306 (The actual string used here is the first 12 characters produced 307 by running the command: 308 309 $ git rev-parse --verify HEAD 310 311 which is done within the script "scripts/setlocalversion".) 312 313config BUILD_SALT 314 string "Build ID Salt" 315 default "" 316 help 317 The build ID is used to link binaries and their debug info. Setting 318 this option will use the value in the calculation of the build id. 319 This is mostly useful for distributions which want to ensure the 320 build is unique between builds. It's safe to leave the default. 321 322config HAVE_KERNEL_GZIP 323 bool 324 325config HAVE_KERNEL_BZIP2 326 bool 327 328config HAVE_KERNEL_LZMA 329 bool 330 331config HAVE_KERNEL_XZ 332 bool 333 334config HAVE_KERNEL_LZO 335 bool 336 337config HAVE_KERNEL_LZ4 338 bool 339 340config HAVE_KERNEL_ZSTD 341 bool 342 343config HAVE_KERNEL_UNCOMPRESSED 344 bool 345 346choice 347 prompt "Kernel compression mode" 348 default KERNEL_GZIP 349 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED 350 help 351 The linux kernel is a kind of self-extracting executable. 352 Several compression algorithms are available, which differ 353 in efficiency, compression and decompression speed. 354 Compression speed is only relevant when building a kernel. 355 Decompression speed is relevant at each boot. 356 357 If you have any problems with bzip2 or lzma compressed 358 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 359 version of this functionality (bzip2 only), for 2.4, was 360 supplied by Christian Ludwig) 361 362 High compression options are mostly useful for users, who 363 are low on disk space (embedded systems), but for whom ram 364 size matters less. 365 366 If in doubt, select 'gzip' 367 368config KERNEL_GZIP 369 bool "Gzip" 370 depends on HAVE_KERNEL_GZIP 371 help 372 The old and tried gzip compression. It provides a good balance 373 between compression ratio and decompression speed. 374 375config KERNEL_BZIP2 376 bool "Bzip2" 377 depends on HAVE_KERNEL_BZIP2 378 help 379 Its compression ratio and speed is intermediate. 380 Decompression speed is slowest among the choices. The kernel 381 size is about 10% smaller with bzip2, in comparison to gzip. 382 Bzip2 uses a large amount of memory. For modern kernels you 383 will need at least 8MB RAM or more for booting. 384 385config KERNEL_LZMA 386 bool "LZMA" 387 depends on HAVE_KERNEL_LZMA 388 help 389 This compression algorithm's ratio is best. Decompression speed 390 is between gzip and bzip2. Compression is slowest. 391 The kernel size is about 33% smaller with LZMA in comparison to gzip. 392 393config KERNEL_XZ 394 bool "XZ" 395 depends on HAVE_KERNEL_XZ 396 help 397 XZ uses the LZMA2 algorithm and instruction set specific 398 BCJ filters which can improve compression ratio of executable 399 code. The size of the kernel is about 30% smaller with XZ in 400 comparison to gzip. On architectures for which there is a BCJ 401 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 402 and SPARC), XZ will create a few percent smaller kernel than 403 plain LZMA. 404 405 The speed is about the same as with LZMA: The decompression 406 speed of XZ is better than that of bzip2 but worse than gzip 407 and LZO. Compression is slow. 408 409config KERNEL_LZO 410 bool "LZO" 411 depends on HAVE_KERNEL_LZO 412 help 413 Its compression ratio is the poorest among the choices. The kernel 414 size is about 10% bigger than gzip; however its speed 415 (both compression and decompression) is the fastest. 416 417config KERNEL_LZ4 418 bool "LZ4" 419 depends on HAVE_KERNEL_LZ4 420 help 421 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 422 A preliminary version of LZ4 de/compression tool is available at 423 <https://code.google.com/p/lz4/>. 424 425 Its compression ratio is worse than LZO. The size of the kernel 426 is about 8% bigger than LZO. But the decompression speed is 427 faster than LZO. 428 429config KERNEL_ZSTD 430 bool "ZSTD" 431 depends on HAVE_KERNEL_ZSTD 432 help 433 ZSTD is a compression algorithm targeting intermediate compression 434 with fast decompression speed. It will compress better than GZIP and 435 decompress around the same speed as LZO, but slower than LZ4. You 436 will need at least 192 KB RAM or more for booting. The zstd command 437 line tool is required for compression. 438 439config KERNEL_UNCOMPRESSED 440 bool "None" 441 depends on HAVE_KERNEL_UNCOMPRESSED 442 help 443 Produce uncompressed kernel image. This option is usually not what 444 you want. It is useful for debugging the kernel in slow simulation 445 environments, where decompressing and moving the kernel is awfully 446 slow. This option allows early boot code to skip the decompressor 447 and jump right at uncompressed kernel image. 448 449endchoice 450 451config DEFAULT_INIT 452 string "Default init path" 453 default "" 454 help 455 This option determines the default init for the system if no init= 456 option is passed on the kernel command line. If the requested path is 457 not present, we will still then move on to attempting further 458 locations (e.g. /sbin/init, etc). If this is empty, we will just use 459 the fallback list when init= is not passed. 460 461config DEFAULT_HOSTNAME 462 string "Default hostname" 463 default "(none)" 464 help 465 This option determines the default system hostname before userspace 466 calls sethostname(2). The kernel traditionally uses "(none)" here, 467 but you may wish to use a different default here to make a minimal 468 system more usable with less configuration. 469 470config SYSVIPC 471 bool "System V IPC" 472 help 473 Inter Process Communication is a suite of library functions and 474 system calls which let processes (running programs) synchronize and 475 exchange information. It is generally considered to be a good thing, 476 and some programs won't run unless you say Y here. In particular, if 477 you want to run the DOS emulator dosemu under Linux (read the 478 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 479 you'll need to say Y here. 480 481 You can find documentation about IPC with "info ipc" and also in 482 section 6.4 of the Linux Programmer's Guide, available from 483 <http://www.tldp.org/guides.html>. 484 485config SYSVIPC_SYSCTL 486 bool 487 depends on SYSVIPC 488 depends on SYSCTL 489 default y 490 491config SYSVIPC_COMPAT 492 def_bool y 493 depends on COMPAT && SYSVIPC 494 495config POSIX_MQUEUE 496 bool "POSIX Message Queues" 497 depends on NET 498 help 499 POSIX variant of message queues is a part of IPC. In POSIX message 500 queues every message has a priority which decides about succession 501 of receiving it by a process. If you want to compile and run 502 programs written e.g. for Solaris with use of its POSIX message 503 queues (functions mq_*) say Y here. 504 505 POSIX message queues are visible as a filesystem called 'mqueue' 506 and can be mounted somewhere if you want to do filesystem 507 operations on message queues. 508 509 If unsure, say Y. 510 511config POSIX_MQUEUE_SYSCTL 512 bool 513 depends on POSIX_MQUEUE 514 depends on SYSCTL 515 default y 516 517config WATCH_QUEUE 518 bool "General notification queue" 519 default n 520 help 521 522 This is a general notification queue for the kernel to pass events to 523 userspace by splicing them into pipes. It can be used in conjunction 524 with watches for key/keyring change notifications and device 525 notifications. 526 527 See Documentation/core-api/watch_queue.rst 528 529config CROSS_MEMORY_ATTACH 530 bool "Enable process_vm_readv/writev syscalls" 531 depends on MMU 532 default y 533 help 534 Enabling this option adds the system calls process_vm_readv and 535 process_vm_writev which allow a process with the correct privileges 536 to directly read from or write to another process' address space. 537 See the man page for more details. 538 539config AUDIT 540 bool "Auditing support" 541 depends on NET 542 help 543 Enable auditing infrastructure that can be used with another 544 kernel subsystem, such as SELinux (which requires this for 545 logging of avc messages output). System call auditing is included 546 on architectures which support it. 547 548config HAVE_ARCH_AUDITSYSCALL 549 bool 550 551config AUDITSYSCALL 552 def_bool y 553 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 554 select FSNOTIFY 555 556source "kernel/irq/Kconfig" 557source "kernel/time/Kconfig" 558source "kernel/bpf/Kconfig" 559source "kernel/Kconfig.preempt" 560 561menu "CPU/Task time and stats accounting" 562 563config VIRT_CPU_ACCOUNTING 564 bool 565 566choice 567 prompt "Cputime accounting" 568 default TICK_CPU_ACCOUNTING 569 570# Kind of a stub config for the pure tick based cputime accounting 571config TICK_CPU_ACCOUNTING 572 bool "Simple tick based cputime accounting" 573 depends on !S390 && !NO_HZ_FULL 574 help 575 This is the basic tick based cputime accounting that maintains 576 statistics about user, system and idle time spent on per jiffies 577 granularity. 578 579 If unsure, say Y. 580 581config VIRT_CPU_ACCOUNTING_NATIVE 582 bool "Deterministic task and CPU time accounting" 583 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 584 select VIRT_CPU_ACCOUNTING 585 help 586 Select this option to enable more accurate task and CPU time 587 accounting. This is done by reading a CPU counter on each 588 kernel entry and exit and on transitions within the kernel 589 between system, softirq and hardirq state, so there is a 590 small performance impact. In the case of s390 or IBM POWER > 5, 591 this also enables accounting of stolen time on logically-partitioned 592 systems. 593 594config VIRT_CPU_ACCOUNTING_GEN 595 bool "Full dynticks CPU time accounting" 596 depends on HAVE_CONTEXT_TRACKING_USER 597 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 598 depends on GENERIC_CLOCKEVENTS 599 select VIRT_CPU_ACCOUNTING 600 select CONTEXT_TRACKING_USER 601 help 602 Select this option to enable task and CPU time accounting on full 603 dynticks systems. This accounting is implemented by watching every 604 kernel-user boundaries using the context tracking subsystem. 605 The accounting is thus performed at the expense of some significant 606 overhead. 607 608 For now this is only useful if you are working on the full 609 dynticks subsystem development. 610 611 If unsure, say N. 612 613endchoice 614 615config IRQ_TIME_ACCOUNTING 616 bool "Fine granularity task level IRQ time accounting" 617 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 618 help 619 Select this option to enable fine granularity task irq time 620 accounting. This is done by reading a timestamp on each 621 transitions between softirq and hardirq state, so there can be a 622 small performance impact. 623 624 If in doubt, say N here. 625 626config HAVE_SCHED_AVG_IRQ 627 def_bool y 628 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 629 depends on SMP 630 631config SCHED_HW_PRESSURE 632 bool 633 default y if ARM && ARM_CPU_TOPOLOGY 634 default y if ARM64 635 depends on SMP 636 depends on CPU_FREQ_THERMAL 637 help 638 Select this option to enable HW pressure accounting in the 639 scheduler. HW pressure is the value conveyed to the scheduler 640 that reflects the reduction in CPU compute capacity resulted from 641 HW throttling. HW throttling occurs when the performance of 642 a CPU is capped due to high operating temperatures as an example. 643 644 If selected, the scheduler will be able to balance tasks accordingly, 645 i.e. put less load on throttled CPUs than on non/less throttled ones. 646 647 This requires the architecture to implement 648 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 649 650config BSD_PROCESS_ACCT 651 bool "BSD Process Accounting (DEPRECATED)" 652 depends on MULTIUSER 653 default n 654 help 655 If you say Y here, a user level program will be able to instruct the 656 kernel (via a special system call) to write process accounting 657 information to a file: whenever a process exits, information about 658 that process will be appended to the file by the kernel. The 659 information includes things such as creation time, owning user, 660 command name, memory usage, controlling terminal etc. (the complete 661 list is in the struct acct in <file:include/linux/acct.h>). It is 662 up to the user level program to do useful things with this 663 information. This mechanism is antiquated and has significant 664 scalability issues. You probably want to use eBPF instead. Say 665 N unless you really need this. 666 667config BSD_PROCESS_ACCT_V3 668 bool "BSD Process Accounting version 3 file format" 669 depends on BSD_PROCESS_ACCT 670 default n 671 help 672 If you say Y here, the process accounting information is written 673 in a new file format that also logs the process IDs of each 674 process and its parent. Note that this file format is incompatible 675 with previous v0/v1/v2 file formats, so you will need updated tools 676 for processing it. A preliminary version of these tools is available 677 at <http://www.gnu.org/software/acct/>. 678 679config TASKSTATS 680 bool "Export task/process statistics through netlink" 681 depends on NET 682 depends on MULTIUSER 683 default n 684 help 685 Export selected statistics for tasks/processes through the 686 generic netlink interface. Unlike BSD process accounting, the 687 statistics are available during the lifetime of tasks/processes as 688 responses to commands. Like BSD accounting, they are sent to user 689 space on task exit. 690 691 Say N if unsure. 692 693config TASK_DELAY_ACCT 694 bool "Enable per-task delay accounting" 695 depends on TASKSTATS 696 select SCHED_INFO 697 help 698 Collect information on time spent by a task waiting for system 699 resources like cpu, synchronous block I/O completion and swapping 700 in pages. Such statistics can help in setting a task's priorities 701 relative to other tasks for cpu, io, rss limits etc. 702 703 Say N if unsure. 704 705config TASK_XACCT 706 bool "Enable extended accounting over taskstats" 707 depends on TASKSTATS 708 help 709 Collect extended task accounting data and send the data 710 to userland for processing over the taskstats interface. 711 712 Say N if unsure. 713 714config TASK_IO_ACCOUNTING 715 bool "Enable per-task storage I/O accounting" 716 depends on TASK_XACCT 717 help 718 Collect information on the number of bytes of storage I/O which this 719 task has caused. 720 721 Say N if unsure. 722 723config PSI 724 bool "Pressure stall information tracking" 725 select KERNFS 726 help 727 Collect metrics that indicate how overcommitted the CPU, memory, 728 and IO capacity are in the system. 729 730 If you say Y here, the kernel will create /proc/pressure/ with the 731 pressure statistics files cpu, memory, and io. These will indicate 732 the share of walltime in which some or all tasks in the system are 733 delayed due to contention of the respective resource. 734 735 In kernels with cgroup support, cgroups (cgroup2 only) will 736 have cpu.pressure, memory.pressure, and io.pressure files, 737 which aggregate pressure stalls for the grouped tasks only. 738 739 For more details see Documentation/accounting/psi.rst. 740 741 Say N if unsure. 742 743config PSI_DEFAULT_DISABLED 744 bool "Require boot parameter to enable pressure stall information tracking" 745 default n 746 depends on PSI 747 help 748 If set, pressure stall information tracking will be disabled 749 per default but can be enabled through passing psi=1 on the 750 kernel commandline during boot. 751 752 This feature adds some code to the task wakeup and sleep 753 paths of the scheduler. The overhead is too low to affect 754 common scheduling-intense workloads in practice (such as 755 webservers, memcache), but it does show up in artificial 756 scheduler stress tests, such as hackbench. 757 758 If you are paranoid and not sure what the kernel will be 759 used for, say Y. 760 761 Say N if unsure. 762 763endmenu # "CPU/Task time and stats accounting" 764 765config CPU_ISOLATION 766 bool "CPU isolation" 767 depends on SMP 768 default y 769 help 770 Make sure that CPUs running critical tasks are not disturbed by 771 any source of "noise" such as unbound workqueues, timers, kthreads... 772 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 773 the "isolcpus=" boot parameter. 774 775 Say Y if unsure. 776 777source "kernel/rcu/Kconfig" 778 779config IKCONFIG 780 tristate "Kernel .config support" 781 help 782 This option enables the complete Linux kernel ".config" file 783 contents to be saved in the kernel. It provides documentation 784 of which kernel options are used in a running kernel or in an 785 on-disk kernel. This information can be extracted from the kernel 786 image file with the script scripts/extract-ikconfig and used as 787 input to rebuild the current kernel or to build another kernel. 788 It can also be extracted from a running kernel by reading 789 /proc/config.gz if enabled (below). 790 791config IKCONFIG_PROC 792 bool "Enable access to .config through /proc/config.gz" 793 depends on IKCONFIG && PROC_FS 794 help 795 This option enables access to the kernel configuration file 796 through /proc/config.gz. 797 798config IKHEADERS 799 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 800 depends on SYSFS 801 help 802 This option enables access to the in-kernel headers that are generated during 803 the build process. These can be used to build eBPF tracing programs, 804 or similar programs. If you build the headers as a module, a module called 805 kheaders.ko is built which can be loaded on-demand to get access to headers. 806 807config LOG_BUF_SHIFT 808 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 809 range 12 25 810 default 17 811 depends on PRINTK 812 help 813 Select the minimal kernel log buffer size as a power of 2. 814 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 815 parameter, see below. Any higher size also might be forced 816 by "log_buf_len" boot parameter. 817 818 Examples: 819 17 => 128 KB 820 16 => 64 KB 821 15 => 32 KB 822 14 => 16 KB 823 13 => 8 KB 824 12 => 4 KB 825 826config LOG_CPU_MAX_BUF_SHIFT 827 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 828 depends on SMP 829 range 0 21 830 default 0 if BASE_SMALL 831 default 12 832 depends on PRINTK 833 help 834 This option allows to increase the default ring buffer size 835 according to the number of CPUs. The value defines the contribution 836 of each CPU as a power of 2. The used space is typically only few 837 lines however it might be much more when problems are reported, 838 e.g. backtraces. 839 840 The increased size means that a new buffer has to be allocated and 841 the original static one is unused. It makes sense only on systems 842 with more CPUs. Therefore this value is used only when the sum of 843 contributions is greater than the half of the default kernel ring 844 buffer as defined by LOG_BUF_SHIFT. The default values are set 845 so that more than 16 CPUs are needed to trigger the allocation. 846 847 Also this option is ignored when "log_buf_len" kernel parameter is 848 used as it forces an exact (power of two) size of the ring buffer. 849 850 The number of possible CPUs is used for this computation ignoring 851 hotplugging making the computation optimal for the worst case 852 scenario while allowing a simple algorithm to be used from bootup. 853 854 Examples shift values and their meaning: 855 17 => 128 KB for each CPU 856 16 => 64 KB for each CPU 857 15 => 32 KB for each CPU 858 14 => 16 KB for each CPU 859 13 => 8 KB for each CPU 860 12 => 4 KB for each CPU 861 862config PRINTK_INDEX 863 bool "Printk indexing debugfs interface" 864 depends on PRINTK && DEBUG_FS 865 help 866 Add support for indexing of all printk formats known at compile time 867 at <debugfs>/printk/index/<module>. 868 869 This can be used as part of maintaining daemons which monitor 870 /dev/kmsg, as it permits auditing the printk formats present in a 871 kernel, allowing detection of cases where monitored printks are 872 changed or no longer present. 873 874 There is no additional runtime cost to printk with this enabled. 875 876# 877# Architectures with an unreliable sched_clock() should select this: 878# 879config HAVE_UNSTABLE_SCHED_CLOCK 880 bool 881 882config GENERIC_SCHED_CLOCK 883 bool 884 885menu "Scheduler features" 886 887config UCLAMP_TASK 888 bool "Enable utilization clamping for RT/FAIR tasks" 889 depends on CPU_FREQ_GOV_SCHEDUTIL 890 help 891 This feature enables the scheduler to track the clamped utilization 892 of each CPU based on RUNNABLE tasks scheduled on that CPU. 893 894 With this option, the user can specify the min and max CPU 895 utilization allowed for RUNNABLE tasks. The max utilization defines 896 the maximum frequency a task should use while the min utilization 897 defines the minimum frequency it should use. 898 899 Both min and max utilization clamp values are hints to the scheduler, 900 aiming at improving its frequency selection policy, but they do not 901 enforce or grant any specific bandwidth for tasks. 902 903 If in doubt, say N. 904 905config UCLAMP_BUCKETS_COUNT 906 int "Number of supported utilization clamp buckets" 907 range 5 20 908 default 5 909 depends on UCLAMP_TASK 910 help 911 Defines the number of clamp buckets to use. The range of each bucket 912 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 913 number of clamp buckets the finer their granularity and the higher 914 the precision of clamping aggregation and tracking at run-time. 915 916 For example, with the minimum configuration value we will have 5 917 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 918 be refcounted in the [20..39]% bucket and will set the bucket clamp 919 effective value to 25%. 920 If a second 30% boosted task should be co-scheduled on the same CPU, 921 that task will be refcounted in the same bucket of the first task and 922 it will boost the bucket clamp effective value to 30%. 923 The clamp effective value of a bucket is reset to its nominal value 924 (20% in the example above) when there are no more tasks refcounted in 925 that bucket. 926 927 An additional boost/capping margin can be added to some tasks. In the 928 example above the 25% task will be boosted to 30% until it exits the 929 CPU. If that should be considered not acceptable on certain systems, 930 it's always possible to reduce the margin by increasing the number of 931 clamp buckets to trade off used memory for run-time tracking 932 precision. 933 934 If in doubt, use the default value. 935 936config SCHED_PROXY_EXEC 937 bool "Proxy Execution" 938 # Avoid some build failures w/ PREEMPT_RT until it can be fixed 939 depends on !PREEMPT_RT 940 # Need to investigate how to inform sched_ext of split contexts 941 depends on !SCHED_CLASS_EXT 942 # Not particularly useful until we get to multi-rq proxying 943 depends on EXPERT 944 help 945 This option enables proxy execution, a mechanism for mutex-owning 946 tasks to inherit the scheduling context of higher priority waiters. 947 948endmenu 949 950# 951# For architectures that want to enable the support for NUMA-affine scheduler 952# balancing logic: 953# 954config ARCH_SUPPORTS_NUMA_BALANCING 955 bool 956 957# 958# For architectures that prefer to flush all TLBs after a number of pages 959# are unmapped instead of sending one IPI per page to flush. The architecture 960# must provide guarantees on what happens if a clean TLB cache entry is 961# written after the unmap. Details are in mm/rmap.c near the check for 962# should_defer_flush. The architecture should also consider if the full flush 963# and the refill costs are offset by the savings of sending fewer IPIs. 964config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 965 bool 966 967config CC_HAS_INT128 968 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 969 970config CC_IMPLICIT_FALLTHROUGH 971 string 972 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 973 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 974 975# Currently, disable gcc-10+ array-bounds globally. 976# It's still broken in gcc-13, so no upper bound yet. 977config GCC10_NO_ARRAY_BOUNDS 978 def_bool y 979 980config CC_NO_ARRAY_BOUNDS 981 bool 982 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 983 984# Currently, disable -Wstringop-overflow for GCC globally. 985config GCC_NO_STRINGOP_OVERFLOW 986 def_bool y 987 988config CC_NO_STRINGOP_OVERFLOW 989 bool 990 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 991 992config CC_STRINGOP_OVERFLOW 993 bool 994 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 995 996# 997# For architectures that know their GCC __int128 support is sound 998# 999config ARCH_SUPPORTS_INT128 1000 bool 1001 1002# For architectures that (ab)use NUMA to represent different memory regions 1003# all cpu-local but of different latencies, such as SuperH. 1004# 1005config ARCH_WANT_NUMA_VARIABLE_LOCALITY 1006 bool 1007 1008config NUMA_BALANCING 1009 bool "Memory placement aware NUMA scheduler" 1010 depends on ARCH_SUPPORTS_NUMA_BALANCING 1011 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 1012 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 1013 help 1014 This option adds support for automatic NUMA aware memory/task placement. 1015 The mechanism is quite primitive and is based on migrating memory when 1016 it has references to the node the task is running on. 1017 1018 This system will be inactive on UMA systems. 1019 1020config NUMA_BALANCING_DEFAULT_ENABLED 1021 bool "Automatically enable NUMA aware memory/task placement" 1022 default y 1023 depends on NUMA_BALANCING 1024 help 1025 If set, automatic NUMA balancing will be enabled if running on a NUMA 1026 machine. 1027 1028config SLAB_OBJ_EXT 1029 bool 1030 1031menuconfig CGROUPS 1032 bool "Control Group support" 1033 select KERNFS 1034 help 1035 This option adds support for grouping sets of processes together, for 1036 use with process control subsystems such as Cpusets, CFS, memory 1037 controls or device isolation. 1038 See 1039 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1040 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1041 and resource control) 1042 1043 Say N if unsure. 1044 1045if CGROUPS 1046 1047config PAGE_COUNTER 1048 bool 1049 1050config CGROUP_FAVOR_DYNMODS 1051 bool "Favor dynamic modification latency reduction by default" 1052 help 1053 This option enables the "favordynmods" mount option by default 1054 which reduces the latencies of dynamic cgroup modifications such 1055 as task migrations and controller on/offs at the cost of making 1056 hot path operations such as forks and exits more expensive. 1057 1058 Say N if unsure. 1059 1060config MEMCG 1061 bool "Memory controller" 1062 select PAGE_COUNTER 1063 select EVENTFD 1064 select SLAB_OBJ_EXT 1065 select VM_EVENT_COUNTERS 1066 help 1067 Provides control over the memory footprint of tasks in a cgroup. 1068 1069config MEMCG_NMI_UNSAFE 1070 bool 1071 depends on MEMCG 1072 depends on HAVE_NMI 1073 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1074 default y 1075 1076config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1077 bool 1078 depends on MEMCG 1079 depends on HAVE_NMI 1080 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1081 default y 1082 1083config MEMCG_V1 1084 bool "Legacy cgroup v1 memory controller" 1085 depends on MEMCG 1086 default n 1087 help 1088 Legacy cgroup v1 memory controller which has been deprecated by 1089 cgroup v2 implementation. The v1 is there for legacy applications 1090 which haven't migrated to the new cgroup v2 interface yet. If you 1091 do not have any such application then you are completely fine leaving 1092 this option disabled. 1093 1094 Please note that feature set of the legacy memory controller is likely 1095 going to shrink due to deprecation process. New deployments with v1 1096 controller are highly discouraged. 1097 1098 Say N if unsure. 1099 1100config BLK_CGROUP 1101 bool "IO controller" 1102 depends on BLOCK 1103 default n 1104 help 1105 Generic block IO controller cgroup interface. This is the common 1106 cgroup interface which should be used by various IO controlling 1107 policies. 1108 1109 Currently, CFQ IO scheduler uses it to recognize task groups and 1110 control disk bandwidth allocation (proportional time slice allocation) 1111 to such task groups. It is also used by bio throttling logic in 1112 block layer to implement upper limit in IO rates on a device. 1113 1114 This option only enables generic Block IO controller infrastructure. 1115 One needs to also enable actual IO controlling logic/policy. For 1116 enabling proportional weight division of disk bandwidth in CFQ, set 1117 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1118 CONFIG_BLK_DEV_THROTTLING=y. 1119 1120 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1121 1122config CGROUP_WRITEBACK 1123 bool 1124 depends on MEMCG && BLK_CGROUP 1125 default y 1126 1127menuconfig CGROUP_SCHED 1128 bool "CPU controller" 1129 default n 1130 help 1131 This feature lets CPU scheduler recognize task groups and control CPU 1132 bandwidth allocation to such task groups. It uses cgroups to group 1133 tasks. 1134 1135if CGROUP_SCHED 1136config GROUP_SCHED_WEIGHT 1137 def_bool n 1138 1139config GROUP_SCHED_BANDWIDTH 1140 def_bool n 1141 1142config FAIR_GROUP_SCHED 1143 bool "Group scheduling for SCHED_OTHER" 1144 depends on CGROUP_SCHED 1145 select GROUP_SCHED_WEIGHT 1146 default CGROUP_SCHED 1147 1148config CFS_BANDWIDTH 1149 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1150 depends on FAIR_GROUP_SCHED 1151 select GROUP_SCHED_BANDWIDTH 1152 default n 1153 help 1154 This option allows users to define CPU bandwidth rates (limits) for 1155 tasks running within the fair group scheduler. Groups with no limit 1156 set are considered to be unconstrained and will run with no 1157 restriction. 1158 See Documentation/scheduler/sched-bwc.rst for more information. 1159 1160config RT_GROUP_SCHED 1161 bool "Group scheduling for SCHED_RR/FIFO" 1162 depends on CGROUP_SCHED 1163 default n 1164 help 1165 This feature lets you explicitly allocate real CPU bandwidth 1166 to task groups. If enabled, it will also make it impossible to 1167 schedule realtime tasks for non-root users until you allocate 1168 realtime bandwidth for them. 1169 See Documentation/scheduler/sched-rt-group.rst for more information. 1170 1171config RT_GROUP_SCHED_DEFAULT_DISABLED 1172 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1173 depends on RT_GROUP_SCHED 1174 default n 1175 help 1176 When set, the RT group scheduling is disabled by default. The option 1177 is in inverted form so that mere RT_GROUP_SCHED enables the group 1178 scheduling. 1179 1180 Say N if unsure. 1181 1182config EXT_GROUP_SCHED 1183 bool 1184 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1185 select GROUP_SCHED_WEIGHT 1186 select GROUP_SCHED_BANDWIDTH 1187 default y 1188 1189endif #CGROUP_SCHED 1190 1191config SCHED_MM_CID 1192 def_bool y 1193 depends on SMP && RSEQ 1194 1195config UCLAMP_TASK_GROUP 1196 bool "Utilization clamping per group of tasks" 1197 depends on CGROUP_SCHED 1198 depends on UCLAMP_TASK 1199 default n 1200 help 1201 This feature enables the scheduler to track the clamped utilization 1202 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1203 1204 When this option is enabled, the user can specify a min and max 1205 CPU bandwidth which is allowed for each single task in a group. 1206 The max bandwidth allows to clamp the maximum frequency a task 1207 can use, while the min bandwidth allows to define a minimum 1208 frequency a task will always use. 1209 1210 When task group based utilization clamping is enabled, an eventually 1211 specified task-specific clamp value is constrained by the cgroup 1212 specified clamp value. Both minimum and maximum task clamping cannot 1213 be bigger than the corresponding clamping defined at task group level. 1214 1215 If in doubt, say N. 1216 1217config CGROUP_PIDS 1218 bool "PIDs controller" 1219 help 1220 Provides enforcement of process number limits in the scope of a 1221 cgroup. Any attempt to fork more processes than is allowed in the 1222 cgroup will fail. PIDs are fundamentally a global resource because it 1223 is fairly trivial to reach PID exhaustion before you reach even a 1224 conservative kmemcg limit. As a result, it is possible to grind a 1225 system to halt without being limited by other cgroup policies. The 1226 PIDs controller is designed to stop this from happening. 1227 1228 It should be noted that organisational operations (such as attaching 1229 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1230 since the PIDs limit only affects a process's ability to fork, not to 1231 attach to a cgroup. 1232 1233config CGROUP_RDMA 1234 bool "RDMA controller" 1235 help 1236 Provides enforcement of RDMA resources defined by IB stack. 1237 It is fairly easy for consumers to exhaust RDMA resources, which 1238 can result into resource unavailability to other consumers. 1239 RDMA controller is designed to stop this from happening. 1240 Attaching processes with active RDMA resources to the cgroup 1241 hierarchy is allowed even if can cross the hierarchy's limit. 1242 1243config CGROUP_DMEM 1244 bool "Device memory controller (DMEM)" 1245 select PAGE_COUNTER 1246 help 1247 The DMEM controller allows compatible devices to restrict device 1248 memory usage based on the cgroup hierarchy. 1249 1250 As an example, it allows you to restrict VRAM usage for applications 1251 in the DRM subsystem. 1252 1253config CGROUP_FREEZER 1254 bool "Freezer controller" 1255 help 1256 Provides a way to freeze and unfreeze all tasks in a 1257 cgroup. 1258 1259 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1260 controller includes important in-kernel memory consumers per default. 1261 1262 If you're using cgroup2, say N. 1263 1264config CGROUP_HUGETLB 1265 bool "HugeTLB controller" 1266 depends on HUGETLB_PAGE 1267 select PAGE_COUNTER 1268 default n 1269 help 1270 Provides a cgroup controller for HugeTLB pages. 1271 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1272 The limit is enforced during page fault. Since HugeTLB doesn't 1273 support page reclaim, enforcing the limit at page fault time implies 1274 that, the application will get SIGBUS signal if it tries to access 1275 HugeTLB pages beyond its limit. This requires the application to know 1276 beforehand how much HugeTLB pages it would require for its use. The 1277 control group is tracked in the third page lru pointer. This means 1278 that we cannot use the controller with huge page less than 3 pages. 1279 1280config CPUSETS 1281 bool "Cpuset controller" 1282 depends on SMP 1283 select UNION_FIND 1284 select CPU_ISOLATION 1285 help 1286 This option will let you create and manage CPUSETs which 1287 allow dynamically partitioning a system into sets of CPUs and 1288 Memory Nodes and assigning tasks to run only within those sets. 1289 This is primarily useful on large SMP or NUMA systems. 1290 1291 Say N if unsure. 1292 1293config CPUSETS_V1 1294 bool "Legacy cgroup v1 cpusets controller" 1295 depends on CPUSETS 1296 default n 1297 help 1298 Legacy cgroup v1 cpusets controller which has been deprecated by 1299 cgroup v2 implementation. The v1 is there for legacy applications 1300 which haven't migrated to the new cgroup v2 interface yet. Legacy 1301 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1302 do not have any such application then you are completely fine leaving 1303 this option disabled. 1304 1305 Say N if unsure. 1306 1307config PROC_PID_CPUSET 1308 bool "Include legacy /proc/<pid>/cpuset file" 1309 depends on CPUSETS_V1 1310 default y 1311 1312config CGROUP_DEVICE 1313 bool "Device controller" 1314 help 1315 Provides a cgroup controller implementing whitelists for 1316 devices which a process in the cgroup can mknod or open. 1317 1318config CGROUP_CPUACCT 1319 bool "Simple CPU accounting controller" 1320 help 1321 Provides a simple controller for monitoring the 1322 total CPU consumed by the tasks in a cgroup. 1323 1324config CGROUP_PERF 1325 bool "Perf controller" 1326 depends on PERF_EVENTS 1327 help 1328 This option extends the perf per-cpu mode to restrict monitoring 1329 to threads which belong to the cgroup specified and run on the 1330 designated cpu. Or this can be used to have cgroup ID in samples 1331 so that it can monitor performance events among cgroups. 1332 1333 Say N if unsure. 1334 1335config CGROUP_BPF 1336 bool "Support for eBPF programs attached to cgroups" 1337 depends on BPF_SYSCALL 1338 select SOCK_CGROUP_DATA 1339 help 1340 Allow attaching eBPF programs to a cgroup using the bpf(2) 1341 syscall command BPF_PROG_ATTACH. 1342 1343 In which context these programs are accessed depends on the type 1344 of attachment. For instance, programs that are attached using 1345 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1346 inet sockets. 1347 1348config CGROUP_MISC 1349 bool "Misc resource controller" 1350 default n 1351 help 1352 Provides a controller for miscellaneous resources on a host. 1353 1354 Miscellaneous scalar resources are the resources on the host system 1355 which cannot be abstracted like the other cgroups. This controller 1356 tracks and limits the miscellaneous resources used by a process 1357 attached to a cgroup hierarchy. 1358 1359 For more information, please check misc cgroup section in 1360 /Documentation/admin-guide/cgroup-v2.rst. 1361 1362config CGROUP_DEBUG 1363 bool "Debug controller" 1364 default n 1365 depends on DEBUG_KERNEL 1366 help 1367 This option enables a simple controller that exports 1368 debugging information about the cgroups framework. This 1369 controller is for control cgroup debugging only. Its 1370 interfaces are not stable. 1371 1372 Say N. 1373 1374config SOCK_CGROUP_DATA 1375 bool 1376 default n 1377 1378endif # CGROUPS 1379 1380menuconfig NAMESPACES 1381 bool "Namespaces support" if EXPERT 1382 depends on MULTIUSER 1383 default !EXPERT 1384 help 1385 Provides the way to make tasks work with different objects using 1386 the same id. For example same IPC id may refer to different objects 1387 or same user id or pid may refer to different tasks when used in 1388 different namespaces. 1389 1390if NAMESPACES 1391 1392config UTS_NS 1393 bool "UTS namespace" 1394 default y 1395 help 1396 In this namespace tasks see different info provided with the 1397 uname() system call 1398 1399config TIME_NS 1400 bool "TIME namespace" 1401 depends on GENERIC_GETTIMEOFDAY 1402 default y 1403 help 1404 In this namespace boottime and monotonic clocks can be set. 1405 The time will keep going with the same pace. 1406 1407config IPC_NS 1408 bool "IPC namespace" 1409 depends on (SYSVIPC || POSIX_MQUEUE) 1410 default y 1411 help 1412 In this namespace tasks work with IPC ids which correspond to 1413 different IPC objects in different namespaces. 1414 1415config USER_NS 1416 bool "User namespace" 1417 default n 1418 help 1419 This allows containers, i.e. vservers, to use user namespaces 1420 to provide different user info for different servers. 1421 1422 When user namespaces are enabled in the kernel it is 1423 recommended that the MEMCG option also be enabled and that 1424 user-space use the memory control groups to limit the amount 1425 of memory a memory unprivileged users can use. 1426 1427 If unsure, say N. 1428 1429config PID_NS 1430 bool "PID Namespaces" 1431 default y 1432 help 1433 Support process id namespaces. This allows having multiple 1434 processes with the same pid as long as they are in different 1435 pid namespaces. This is a building block of containers. 1436 1437config NET_NS 1438 bool "Network namespace" 1439 depends on NET 1440 default y 1441 help 1442 Allow user space to create what appear to be multiple instances 1443 of the network stack. 1444 1445endif # NAMESPACES 1446 1447config CHECKPOINT_RESTORE 1448 bool "Checkpoint/restore support" 1449 depends on PROC_FS 1450 select PROC_CHILDREN 1451 select KCMP 1452 default n 1453 help 1454 Enables additional kernel features in a sake of checkpoint/restore. 1455 In particular it adds auxiliary prctl codes to setup process text, 1456 data and heap segment sizes, and a few additional /proc filesystem 1457 entries. 1458 1459 If unsure, say N here. 1460 1461config SCHED_AUTOGROUP 1462 bool "Automatic process group scheduling" 1463 select CGROUPS 1464 select CGROUP_SCHED 1465 select FAIR_GROUP_SCHED 1466 help 1467 This option optimizes the scheduler for common desktop workloads by 1468 automatically creating and populating task groups. This separation 1469 of workloads isolates aggressive CPU burners (like build jobs) from 1470 desktop applications. Task group autogeneration is currently based 1471 upon task session. 1472 1473config RELAY 1474 bool "Kernel->user space relay support (formerly relayfs)" 1475 select IRQ_WORK 1476 help 1477 This option enables support for relay interface support in 1478 certain file systems (such as debugfs). 1479 It is designed to provide an efficient mechanism for tools and 1480 facilities to relay large amounts of data from kernel space to 1481 user space. 1482 1483 If unsure, say N. 1484 1485config BLK_DEV_INITRD 1486 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1487 help 1488 The initial RAM filesystem is a ramfs which is loaded by the 1489 boot loader (loadlin or lilo) and that is mounted as root 1490 before the normal boot procedure. It is typically used to 1491 load modules needed to mount the "real" root file system, 1492 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1493 1494 If RAM disk support (BLK_DEV_RAM) is also included, this 1495 also enables initial RAM disk (initrd) support and adds 1496 15 Kbytes (more on some other architectures) to the kernel size. 1497 1498 If unsure say Y. 1499 1500if BLK_DEV_INITRD 1501 1502source "usr/Kconfig" 1503 1504endif 1505 1506config BOOT_CONFIG 1507 bool "Boot config support" 1508 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1509 help 1510 Extra boot config allows system admin to pass a config file as 1511 complemental extension of kernel cmdline when booting. 1512 The boot config file must be attached at the end of initramfs 1513 with checksum, size and magic word. 1514 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1515 1516 If unsure, say Y. 1517 1518config BOOT_CONFIG_FORCE 1519 bool "Force unconditional bootconfig processing" 1520 depends on BOOT_CONFIG 1521 default y if BOOT_CONFIG_EMBED 1522 help 1523 With this Kconfig option set, BOOT_CONFIG processing is carried 1524 out even when the "bootconfig" kernel-boot parameter is omitted. 1525 In fact, with this Kconfig option set, there is no way to 1526 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1527 parameters. 1528 1529 If unsure, say N. 1530 1531config BOOT_CONFIG_EMBED 1532 bool "Embed bootconfig file in the kernel" 1533 depends on BOOT_CONFIG 1534 help 1535 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1536 kernel. Usually, the bootconfig file is loaded with the initrd 1537 image. But if the system doesn't support initrd, this option will 1538 help you by embedding a bootconfig file while building the kernel. 1539 1540 If unsure, say N. 1541 1542config BOOT_CONFIG_EMBED_FILE 1543 string "Embedded bootconfig file path" 1544 depends on BOOT_CONFIG_EMBED 1545 help 1546 Specify a bootconfig file which will be embedded to the kernel. 1547 This bootconfig will be used if there is no initrd or no other 1548 bootconfig in the initrd. 1549 1550config CMDLINE_LOG_WRAP_IDEAL_LEN 1551 int "Length to try to wrap the cmdline when logged at boot" 1552 default 1021 1553 range 0 1021 1554 help 1555 At boot time, the kernel command line is logged to the console. 1556 The log message will start with the prefix "Kernel command line: ". 1557 The log message will attempt to be wrapped (split into multiple log 1558 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters. 1559 If wrapping happens, each log message will start with the prefix and 1560 all but the last message will end with " \". Messages may exceed the 1561 ideal length if a place to wrap isn't found before the specified 1562 number of characters. 1563 1564 A value of 0 disables wrapping, though be warned that the maximum 1565 length of a log message (1021 characters) may cause the cmdline to 1566 be truncated. 1567 1568config INITRAMFS_PRESERVE_MTIME 1569 bool "Preserve cpio archive mtimes in initramfs" 1570 depends on BLK_DEV_INITRD 1571 default y 1572 help 1573 Each entry in an initramfs cpio archive carries an mtime value. When 1574 enabled, extracted cpio items take this mtime, with directory mtime 1575 setting deferred until after creation of any child entries. 1576 1577 If unsure, say Y. 1578 1579config INITRAMFS_TEST 1580 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1581 depends on BLK_DEV_INITRD && KUNIT=y 1582 default KUNIT_ALL_TESTS 1583 help 1584 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1585 1586choice 1587 prompt "Compiler optimization level" 1588 default CC_OPTIMIZE_FOR_PERFORMANCE 1589 1590config CC_OPTIMIZE_FOR_PERFORMANCE 1591 bool "Optimize for performance (-O2)" 1592 help 1593 This is the default optimization level for the kernel, building 1594 with the "-O2" compiler flag for best performance and most 1595 helpful compile-time warnings. 1596 1597config CC_OPTIMIZE_FOR_SIZE 1598 bool "Optimize for size (-Os)" 1599 help 1600 Choosing this option will pass "-Os" to your compiler resulting 1601 in a smaller kernel. 1602 1603endchoice 1604 1605config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1606 bool 1607 help 1608 This requires that the arch annotates or otherwise protects 1609 its external entry points from being discarded. Linker scripts 1610 must also merge .text.*, .data.*, and .bss.* correctly into 1611 output sections. Care must be taken not to pull in unrelated 1612 sections (e.g., '.text.init'). Typically '.' in section names 1613 is used to distinguish them from label names / C identifiers. 1614 1615config LD_DEAD_CODE_DATA_ELIMINATION 1616 bool "Dead code and data elimination (EXPERIMENTAL)" 1617 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1618 depends on EXPERT 1619 depends on $(cc-option,-ffunction-sections -fdata-sections) 1620 depends on $(ld-option,--gc-sections) 1621 help 1622 Enable this if you want to do dead code and data elimination with 1623 the linker by compiling with -ffunction-sections -fdata-sections, 1624 and linking with --gc-sections. 1625 1626 This can reduce on disk and in-memory size of the kernel 1627 code and static data, particularly for small configs and 1628 on small systems. This has the possibility of introducing 1629 silently broken kernel if the required annotations are not 1630 present. This option is not well tested yet, so use at your 1631 own risk. 1632 1633config LD_ORPHAN_WARN 1634 def_bool y 1635 depends on ARCH_WANT_LD_ORPHAN_WARN 1636 depends on $(ld-option,--orphan-handling=warn) 1637 depends on $(ld-option,--orphan-handling=error) 1638 1639config LD_ORPHAN_WARN_LEVEL 1640 string 1641 depends on LD_ORPHAN_WARN 1642 default "error" if WERROR 1643 default "warn" 1644 1645config SYSCTL 1646 bool 1647 1648config HAVE_UID16 1649 bool 1650 1651config SYSCTL_EXCEPTION_TRACE 1652 bool 1653 help 1654 Enable support for /proc/sys/debug/exception-trace. 1655 1656config SYSCTL_ARCH_UNALIGN_NO_WARN 1657 bool 1658 help 1659 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1660 Allows arch to define/use @no_unaligned_warning to possibly warn 1661 about unaligned access emulation going on under the hood. 1662 1663config SYSCTL_ARCH_UNALIGN_ALLOW 1664 bool 1665 help 1666 Enable support for /proc/sys/kernel/unaligned-trap 1667 Allows arches to define/use @unaligned_enabled to runtime toggle 1668 the unaligned access emulation. 1669 see arch/parisc/kernel/unaligned.c for reference 1670 1671config SYSFS_SYSCALL 1672 bool "Sysfs syscall support" 1673 default n 1674 help 1675 sys_sysfs is an obsolete system call no longer supported in libc. 1676 Note that disabling this option is more secure but might break 1677 compatibility with some systems. 1678 1679 If unsure say N here. 1680 1681config HAVE_PCSPKR_PLATFORM 1682 bool 1683 1684menuconfig EXPERT 1685 bool "Configure standard kernel features (expert users)" 1686 # Unhide debug options, to make the on-by-default options visible 1687 select DEBUG_KERNEL 1688 help 1689 This option allows certain base kernel options and settings 1690 to be disabled or tweaked. This is for specialized 1691 environments which can tolerate a "non-standard" kernel. 1692 Only use this if you really know what you are doing. 1693 1694config UID16 1695 bool "Enable 16-bit UID system calls" if EXPERT 1696 depends on HAVE_UID16 && MULTIUSER 1697 default y 1698 help 1699 This enables the legacy 16-bit UID syscall wrappers. 1700 1701config MULTIUSER 1702 bool "Multiple users, groups and capabilities support" if EXPERT 1703 default y 1704 help 1705 This option enables support for non-root users, groups and 1706 capabilities. 1707 1708 If you say N here, all processes will run with UID 0, GID 0, and all 1709 possible capabilities. Saying N here also compiles out support for 1710 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1711 setgid, and capset. 1712 1713 If unsure, say Y here. 1714 1715config SGETMASK_SYSCALL 1716 bool "sgetmask/ssetmask syscalls support" if EXPERT 1717 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1718 help 1719 sys_sgetmask and sys_ssetmask are obsolete system calls 1720 no longer supported in libc but still enabled by default in some 1721 architectures. 1722 1723 If unsure, leave the default option here. 1724 1725config FHANDLE 1726 bool "open by fhandle syscalls" if EXPERT 1727 select EXPORTFS 1728 default y 1729 help 1730 If you say Y here, a user level program will be able to map 1731 file names to handle and then later use the handle for 1732 different file system operations. This is useful in implementing 1733 userspace file servers, which now track files using handles instead 1734 of names. The handle would remain the same even if file names 1735 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1736 syscalls. 1737 1738config POSIX_TIMERS 1739 bool "Posix Clocks & timers" if EXPERT 1740 default y 1741 help 1742 This includes native support for POSIX timers to the kernel. 1743 Some embedded systems have no use for them and therefore they 1744 can be configured out to reduce the size of the kernel image. 1745 1746 When this option is disabled, the following syscalls won't be 1747 available: timer_create, timer_gettime: timer_getoverrun, 1748 timer_settime, timer_delete, clock_adjtime, getitimer, 1749 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1750 clock_getres and clock_nanosleep syscalls will be limited to 1751 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1752 1753 If unsure say y. 1754 1755config PRINTK 1756 default y 1757 bool "Enable support for printk" if EXPERT 1758 select IRQ_WORK 1759 help 1760 This option enables normal printk support. Removing it 1761 eliminates most of the message strings from the kernel image 1762 and makes the kernel more or less silent. As this makes it 1763 very difficult to diagnose system problems, saying N here is 1764 strongly discouraged. 1765 1766config PRINTK_RINGBUFFER_KUNIT_TEST 1767 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1768 depends on PRINTK && KUNIT 1769 default KUNIT_ALL_TESTS 1770 help 1771 This builds the printk ringbuffer KUnit test suite. 1772 1773 For more information on KUnit and unit tests in general, please refer 1774 to the KUnit documentation. 1775 1776 If unsure, say N. 1777 1778config BUG 1779 bool "BUG() support" if EXPERT 1780 default y 1781 help 1782 Disabling this option eliminates support for BUG and WARN, reducing 1783 the size of your kernel image and potentially quietly ignoring 1784 numerous fatal conditions. You should only consider disabling this 1785 option for embedded systems with no facilities for reporting errors. 1786 Just say Y. 1787 1788config ELF_CORE 1789 depends on COREDUMP 1790 default y 1791 bool "Enable ELF core dumps" if EXPERT 1792 help 1793 Enable support for generating core dumps. Disabling saves about 4k. 1794 1795 1796config PCSPKR_PLATFORM 1797 bool "Enable PC-Speaker support" if EXPERT 1798 depends on HAVE_PCSPKR_PLATFORM 1799 select I8253_LOCK 1800 default y 1801 help 1802 This option allows to disable the internal PC-Speaker 1803 support, saving some memory. 1804 1805config BASE_SMALL 1806 bool "Enable smaller-sized data structures for core" if EXPERT 1807 help 1808 Enabling this option reduces the size of miscellaneous core 1809 kernel data structures. This saves memory on small machines, 1810 but may reduce performance. 1811 1812config FUTEX 1813 bool "Enable futex support" if EXPERT 1814 depends on !(SPARC32 && SMP) 1815 default y 1816 imply RT_MUTEXES 1817 help 1818 Disabling this option will cause the kernel to be built without 1819 support for "fast userspace mutexes". The resulting kernel may not 1820 run glibc-based applications correctly. 1821 1822config FUTEX_PI 1823 bool 1824 depends on FUTEX && RT_MUTEXES 1825 default y 1826 1827config FUTEX_PRIVATE_HASH 1828 bool 1829 depends on FUTEX && !BASE_SMALL && MMU 1830 default y 1831 1832config FUTEX_MPOL 1833 bool 1834 depends on FUTEX && NUMA 1835 default y 1836 1837config EPOLL 1838 bool "Enable eventpoll support" if EXPERT 1839 default y 1840 help 1841 Disabling this option will cause the kernel to be built without 1842 support for epoll family of system calls. 1843 1844config SIGNALFD 1845 bool "Enable signalfd() system call" if EXPERT 1846 default y 1847 help 1848 Enable the signalfd() system call that allows to receive signals 1849 on a file descriptor. 1850 1851 If unsure, say Y. 1852 1853config TIMERFD 1854 bool "Enable timerfd() system call" if EXPERT 1855 default y 1856 help 1857 Enable the timerfd() system call that allows to receive timer 1858 events on a file descriptor. 1859 1860 If unsure, say Y. 1861 1862config EVENTFD 1863 bool "Enable eventfd() system call" if EXPERT 1864 default y 1865 help 1866 Enable the eventfd() system call that allows to receive both 1867 kernel notification (ie. KAIO) or userspace notifications. 1868 1869 If unsure, say Y. 1870 1871config SHMEM 1872 bool "Use full shmem filesystem" if EXPERT 1873 default y 1874 depends on MMU 1875 help 1876 The shmem is an internal filesystem used to manage shared memory. 1877 It is backed by swap and manages resource limits. It is also exported 1878 to userspace as tmpfs if TMPFS is enabled. Disabling this 1879 option replaces shmem and tmpfs with the much simpler ramfs code, 1880 which may be appropriate on small systems without swap. 1881 1882config AIO 1883 bool "Enable AIO support" if EXPERT 1884 default y 1885 help 1886 This option enables POSIX asynchronous I/O which may by used 1887 by some high performance threaded applications. Disabling 1888 this option saves about 7k. 1889 1890config IO_URING 1891 bool "Enable IO uring support" if EXPERT 1892 select IO_WQ 1893 default y 1894 help 1895 This option enables support for the io_uring interface, enabling 1896 applications to submit and complete IO through submission and 1897 completion rings that are shared between the kernel and application. 1898 1899config GCOV_PROFILE_URING 1900 bool "Enable GCOV profiling on the io_uring subsystem" 1901 depends on IO_URING && GCOV_KERNEL 1902 help 1903 Enable GCOV profiling on the io_uring subsystem, to facilitate 1904 code coverage testing. 1905 1906 If unsure, say N. 1907 1908 Note that this will have a negative impact on the performance of 1909 the io_uring subsystem, hence this should only be enabled for 1910 specific test purposes. 1911 1912config IO_URING_MOCK_FILE 1913 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1914 default n 1915 depends on IO_URING 1916 help 1917 Enable mock files for io_uring subsystem testing. The ABI might 1918 still change, so it's still experimental and should only be enabled 1919 for specific test purposes. 1920 1921 If unsure, say N. 1922 1923config ADVISE_SYSCALLS 1924 bool "Enable madvise/fadvise syscalls" if EXPERT 1925 default y 1926 help 1927 This option enables the madvise and fadvise syscalls, used by 1928 applications to advise the kernel about their future memory or file 1929 usage, improving performance. If building an embedded system where no 1930 applications use these syscalls, you can disable this option to save 1931 space. 1932 1933config MEMBARRIER 1934 bool "Enable membarrier() system call" if EXPERT 1935 default y 1936 help 1937 Enable the membarrier() system call that allows issuing memory 1938 barriers across all running threads, which can be used to distribute 1939 the cost of user-space memory barriers asymmetrically by transforming 1940 pairs of memory barriers into pairs consisting of membarrier() and a 1941 compiler barrier. 1942 1943 If unsure, say Y. 1944 1945config KCMP 1946 bool "Enable kcmp() system call" if EXPERT 1947 help 1948 Enable the kernel resource comparison system call. It provides 1949 user-space with the ability to compare two processes to see if they 1950 share a common resource, such as a file descriptor or even virtual 1951 memory space. 1952 1953 If unsure, say N. 1954 1955config RSEQ 1956 bool "Enable rseq() system call" if EXPERT 1957 default y 1958 depends on HAVE_RSEQ 1959 select MEMBARRIER 1960 help 1961 Enable the restartable sequences system call. It provides a 1962 user-space cache for the current CPU number value, which 1963 speeds up getting the current CPU number from user-space, 1964 as well as an ABI to speed up user-space operations on 1965 per-CPU data. 1966 1967 If unsure, say Y. 1968 1969config RSEQ_SLICE_EXTENSION 1970 bool "Enable rseq-based time slice extension mechanism" 1971 depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS 1972 help 1973 Allows userspace to request a limited time slice extension when 1974 returning from an interrupt to user space via the RSEQ shared 1975 data ABI. If granted, that allows to complete a critical section, 1976 so that other threads are not stuck on a conflicted resource, 1977 while the task is scheduled out. 1978 1979 If unsure, say N. 1980 1981config RSEQ_STATS 1982 default n 1983 bool "Enable lightweight statistics of restartable sequences" if EXPERT 1984 depends on RSEQ && DEBUG_FS 1985 help 1986 Enable lightweight counters which expose information about the 1987 frequency of RSEQ operations via debugfs. Mostly interesting for 1988 kernel debugging or performance analysis. While lightweight it's 1989 still adding code into the user/kernel mode transitions. 1990 1991 If unsure, say N. 1992 1993config RSEQ_DEBUG_DEFAULT_ENABLE 1994 default n 1995 bool "Enable restartable sequences debug mode by default" if EXPERT 1996 depends on RSEQ 1997 help 1998 This enables the static branch for debug mode of restartable 1999 sequences. 2000 2001 This also can be controlled on the kernel command line via the 2002 command line parameter "rseq_debug=0/1" and through debugfs. 2003 2004 If unsure, say N. 2005 2006config DEBUG_RSEQ 2007 default n 2008 bool "Enable debugging of rseq() system call" if EXPERT 2009 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY 2010 select RSEQ_DEBUG_DEFAULT_ENABLE 2011 help 2012 Enable extra debugging checks for the rseq system call. 2013 2014 If unsure, say N. 2015 2016config CACHESTAT_SYSCALL 2017 bool "Enable cachestat() system call" if EXPERT 2018 default y 2019 help 2020 Enable the cachestat system call, which queries the page cache 2021 statistics of a file (number of cached pages, dirty pages, 2022 pages marked for writeback, (recently) evicted pages). 2023 2024 If unsure say Y here. 2025 2026config KALLSYMS 2027 bool "Load all symbols for debugging/ksymoops" if EXPERT 2028 default y 2029 help 2030 Say Y here to let the kernel print out symbolic crash information and 2031 symbolic stack backtraces. This increases the size of the kernel 2032 somewhat, as all symbols have to be loaded into the kernel image. 2033 2034config KALLSYMS_SELFTEST 2035 bool "Test the basic functions and performance of kallsyms" 2036 depends on KALLSYMS 2037 default n 2038 help 2039 Test the basic functions and performance of some interfaces, such as 2040 kallsyms_lookup_name. It also calculates the compression rate of the 2041 kallsyms compression algorithm for the current symbol set. 2042 2043 Start self-test automatically after system startup. Suggest executing 2044 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 2045 displayed in the last line, indicating that the test is complete. 2046 2047config KALLSYMS_ALL 2048 bool "Include all symbols in kallsyms" 2049 depends on DEBUG_KERNEL && KALLSYMS 2050 help 2051 Normally kallsyms only contains the symbols of functions for nicer 2052 OOPS messages and backtraces (i.e., symbols from the text and inittext 2053 sections). This is sufficient for most cases. And only if you want to 2054 enable kernel live patching, or other less common use cases (e.g., 2055 when a debugger is used) all symbols are required (i.e., names of 2056 variables from the data sections, etc). 2057 2058 This option makes sure that all symbols are loaded into the kernel 2059 image (i.e., symbols from all sections) in cost of increased kernel 2060 size (depending on the kernel configuration, it may be 300KiB or 2061 something like this). 2062 2063 Say N unless you really need all symbols, or kernel live patching. 2064 2065# end of the "standard kernel features (expert users)" menu 2066 2067config ARCH_HAS_MEMBARRIER_CALLBACKS 2068 bool 2069 2070config ARCH_HAS_MEMBARRIER_SYNC_CORE 2071 bool 2072 2073config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 2074 bool 2075 help 2076 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 2077 2078 A 64-bit kernel is required for the memory sealing feature. 2079 No specific hardware features from the CPU are needed. 2080 2081 To enable this feature, the architecture needs to update their 2082 special mappings calls to include the sealing flag and confirm 2083 that it doesn't unmap/remap system mappings during the life 2084 time of the process. The existence of this flag for an architecture 2085 implies that it does not require the remapping of the system 2086 mappings during process lifetime, so sealing these mappings is safe 2087 from a kernel perspective. 2088 2089 After the architecture enables this, a distribution can set 2090 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 2091 2092 For complete descriptions of memory sealing, please see 2093 Documentation/userspace-api/mseal.rst 2094 2095config HAVE_PERF_EVENTS 2096 bool 2097 help 2098 See tools/perf/design.txt for details. 2099 2100config GUEST_PERF_EVENTS 2101 bool 2102 depends on HAVE_PERF_EVENTS 2103 2104config PERF_GUEST_MEDIATED_PMU 2105 bool 2106 depends on GUEST_PERF_EVENTS 2107 2108config PERF_USE_VMALLOC 2109 bool 2110 help 2111 See tools/perf/design.txt for details 2112 2113menu "Kernel Performance Events And Counters" 2114 2115config PERF_EVENTS 2116 bool "Kernel performance events and counters" 2117 default y if PROFILING 2118 depends on HAVE_PERF_EVENTS 2119 select IRQ_WORK 2120 help 2121 Enable kernel support for various performance events provided 2122 by software and hardware. 2123 2124 Software events are supported either built-in or via the 2125 use of generic tracepoints. 2126 2127 Most modern CPUs support performance events via performance 2128 counter registers. These registers count the number of certain 2129 types of hw events: such as instructions executed, cachemisses 2130 suffered, or branches mis-predicted - without slowing down the 2131 kernel or applications. These registers can also trigger interrupts 2132 when a threshold number of events have passed - and can thus be 2133 used to profile the code that runs on that CPU. 2134 2135 The Linux Performance Event subsystem provides an abstraction of 2136 these software and hardware event capabilities, available via a 2137 system call and used by the "perf" utility in tools/perf/. It 2138 provides per task and per CPU counters, and it provides event 2139 capabilities on top of those. 2140 2141 Say Y if unsure. 2142 2143config DEBUG_PERF_USE_VMALLOC 2144 default n 2145 bool "Debug: use vmalloc to back perf mmap() buffers" 2146 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2147 select PERF_USE_VMALLOC 2148 help 2149 Use vmalloc memory to back perf mmap() buffers. 2150 2151 Mostly useful for debugging the vmalloc code on platforms 2152 that don't require it. 2153 2154 Say N if unsure. 2155 2156endmenu 2157 2158config SYSTEM_DATA_VERIFICATION 2159 def_bool n 2160 select SYSTEM_TRUSTED_KEYRING 2161 select KEYS 2162 select CRYPTO 2163 select CRYPTO_RSA 2164 select ASYMMETRIC_KEY_TYPE 2165 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2166 select ASN1 2167 select OID_REGISTRY 2168 select X509_CERTIFICATE_PARSER 2169 select PKCS7_MESSAGE_PARSER 2170 help 2171 Provide PKCS#7 message verification using the contents of the system 2172 trusted keyring to provide public keys. This then can be used for 2173 module verification, kexec image verification and firmware blob 2174 verification. 2175 2176config PROFILING 2177 bool "Profiling support" 2178 help 2179 Say Y here to enable the extended profiling support mechanisms used 2180 by profilers. 2181 2182config RUST 2183 bool "Rust support" 2184 depends on HAVE_RUST 2185 depends on RUST_IS_AVAILABLE 2186 select EXTENDED_MODVERSIONS if MODVERSIONS 2187 depends on !MODVERSIONS || GENDWARFKSYMS 2188 depends on !GCC_PLUGIN_RANDSTRUCT 2189 depends on !RANDSTRUCT 2190 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2191 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2192 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2193 depends on !KASAN_SW_TAGS 2194 help 2195 Enables Rust support in the kernel. 2196 2197 This allows other Rust-related options, like drivers written in Rust, 2198 to be selected. 2199 2200 It is also required to be able to load external kernel modules 2201 written in Rust. 2202 2203 See Documentation/rust/ for more information. 2204 2205 If unsure, say N. 2206 2207config RUSTC_VERSION_TEXT 2208 string 2209 depends on RUST 2210 default "$(RUSTC_VERSION_TEXT)" 2211 help 2212 See `CC_VERSION_TEXT`. 2213 2214config BINDGEN_VERSION_TEXT 2215 string 2216 depends on RUST 2217 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0 2218 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0 2219 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed 2220 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1 2221 # both fixed the issue). 2222 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 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