1# SPDX-License-Identifier: GPL-2.0-only 2config CC_VERSION_TEXT 3 string 4 default "$(CC_VERSION_TEXT)" 5 help 6 This is used in unclear ways: 7 8 - Re-run Kconfig when the compiler is updated 9 The 'default' property references the environment variable, 10 CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd. 11 When the compiler is updated, Kconfig will be invoked. 12 13 - Ensure full rebuild when the compiler is updated 14 include/linux/compiler-version.h contains this option in the comment 15 line so fixdep adds include/config/CC_VERSION_TEXT into the 16 auto-generated dependency. When the compiler is updated, syncconfig 17 will touch it and then every file will be rebuilt. 18 19config CC_IS_GCC 20 def_bool $(success,test "$(cc-name)" = GCC) 21 22config GCC_VERSION 23 int 24 default $(cc-version) if CC_IS_GCC 25 default 0 26 27config CC_IS_CLANG 28 def_bool $(success,test "$(cc-name)" = Clang) 29 30config CLANG_VERSION 31 int 32 default $(cc-version) if CC_IS_CLANG 33 default 0 34 35config AS_IS_GNU 36 def_bool $(success,test "$(as-name)" = GNU) 37 38config AS_IS_LLVM 39 def_bool $(success,test "$(as-name)" = LLVM) 40 41config AS_VERSION 42 int 43 # Use clang version if this is the integrated assembler 44 default CLANG_VERSION if AS_IS_LLVM 45 default $(as-version) 46 47config LD_IS_BFD 48 def_bool $(success,test "$(ld-name)" = BFD) 49 50config LD_VERSION 51 int 52 default $(ld-version) if LD_IS_BFD 53 default 0 54 55config LD_IS_LLD 56 def_bool $(success,test "$(ld-name)" = LLD) 57 58config LLD_VERSION 59 int 60 default $(ld-version) if LD_IS_LLD 61 default 0 62 63config RUSTC_VERSION 64 int 65 default $(rustc-version) 66 help 67 It does not depend on `RUST` since that one may need to use the version 68 in a `depends on`. 69 70config RUST_IS_AVAILABLE 71 def_bool $(success,$(srctree)/scripts/rust_is_available.sh) 72 help 73 This shows whether a suitable Rust toolchain is available (found). 74 75 Please see Documentation/rust/quick-start.rst for instructions on how 76 to satisfy the build requirements of Rust support. 77 78 In particular, the Makefile target 'rustavailable' is useful to check 79 why the Rust toolchain is not being detected. 80 81config RUSTC_LLVM_VERSION 82 int 83 default $(rustc-llvm-version) 84 85config RUSTC_LLVM_MAJOR_VERSION 86 int 87 default $(shell,expr $(rustc-llvm-version) / 10000) 88 89config RUSTC_CLANG_LLVM_COMPATIBLE 90 bool 91 default y if CC_IS_CLANG && RUSTC_LLVM_MAJOR_VERSION = $(shell,expr $(cc-version) / 10000) 92 help 93 This indicates whether Rust and Clang use LLVM of the same major 94 version. 95 96 Operations involving handling LLVM IR or bitcode (e.g. cross-language 97 LTO) require the same LLVM major version to work properly. For best 98 compatibility it is recommended that the exact same LLVM is used. 99 100config ARCH_HAS_CC_CAN_LINK 101 bool 102 103config CC_CAN_LINK 104 bool 105 default ARCH_CC_CAN_LINK if ARCH_HAS_CC_CAN_LINK 106 default $(cc_can_link_user,$(m64-flag)) if 64BIT 107 default $(cc_can_link_user,$(m32-flag)) 108 109# Fixed in GCC 14, 13.3, 12.4 and 11.5 110# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 111config GCC_ASM_GOTO_OUTPUT_BROKEN 112 bool 113 depends on CC_IS_GCC 114 default y if GCC_VERSION < 110500 115 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400 116 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300 117 118config CC_HAS_ASM_GOTO_OUTPUT 119 def_bool y 120 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN 121 depends on $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null) 122 123config CC_HAS_ASM_GOTO_TIED_OUTPUT 124 depends on CC_HAS_ASM_GOTO_OUTPUT 125 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 126 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null) 127 128config TOOLS_SUPPORT_RELR 129 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 130 131config CC_HAS_ASM_INLINE 132 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 133 134config CC_HAS_ASSUME 135 bool 136 # clang needs to be at least 19.1.0 since the meaning of the assume 137 # attribute changed: 138 # https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17 139 default y if CC_IS_CLANG && CLANG_VERSION >= 190100 140 # supported since gcc 13.1.0 141 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654 142 default y if CC_IS_GCC && GCC_VERSION >= 130100 143 144config CC_HAS_NO_PROFILE_FN_ATTR 145 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 146 147config CC_HAS_COUNTED_BY 148 bool 149 # clang needs to be at least 20.1.0 to avoid potential crashes 150 # when building structures that contain __counted_by 151 # https://github.com/ClangBuiltLinux/linux/issues/2114 152 # https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489 153 default y if CC_IS_CLANG && CLANG_VERSION >= 200100 154 # supported since gcc 15.1.0 155 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 156 default y if CC_IS_GCC && GCC_VERSION >= 150100 157 158config CC_HAS_COUNTED_BY_PTR 159 bool 160 # supported since clang 22 161 default y if CC_IS_CLANG && CLANG_VERSION >= 220100 162 # supported since gcc 16.0.0 163 default y if CC_IS_GCC && GCC_VERSION >= 160000 164 165config CC_HAS_BROKEN_COUNTED_BY_REF 166 bool 167 # https://github.com/llvm/llvm-project/issues/182575 168 default y if CC_IS_CLANG && CLANG_VERSION < 220100 169 170config CC_HAS_ALLOC_TOKEN 171 def_bool $(cc-option,-falloc-token-max=123) 172 173config CC_HAS_MULTIDIMENSIONAL_NONSTRING 174 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 175 176config LD_CAN_USE_KEEP_IN_OVERLAY 177 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 178 # https://github.com/llvm/llvm-project/pull/130661 179 def_bool LD_IS_BFD || LLD_VERSION >= 210000 180 181config RUSTC_HAS_SPAN_FILE 182 def_bool RUSTC_VERSION >= 108800 183 184config RUSTC_HAS_UNNECESSARY_TRANSMUTES 185 def_bool RUSTC_VERSION >= 108800 186 187config RUSTC_HAS_FILE_WITH_NUL 188 def_bool RUSTC_VERSION >= 108900 189 190config RUSTC_HAS_FILE_AS_C_STR 191 def_bool RUSTC_VERSION >= 109100 192 193config PAHOLE_VERSION 194 int 195 default "$(PAHOLE_VERSION)" 196 197config CONSTRUCTORS 198 bool 199 200config IRQ_WORK 201 def_bool y if SMP 202 203config BUILDTIME_TABLE_SORT 204 bool 205 206config THREAD_INFO_IN_TASK 207 bool 208 help 209 Select this to move thread_info off the stack into task_struct. To 210 make this work, an arch will need to remove all thread_info fields 211 except flags and fix any runtime bugs. 212 213 One subtle change that will be needed is to use try_get_task_stack() 214 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 215 216menu "General setup" 217 218config BROKEN 219 bool 220 help 221 This option allows you to choose whether you want to try to 222 compile (and fix) old drivers that haven't been updated to 223 new infrastructure. 224 225config BROKEN_ON_SMP 226 bool 227 depends on BROKEN || !SMP 228 default y 229 230config INIT_ENV_ARG_LIMIT 231 int 232 default 32 if !UML 233 default 128 if UML 234 help 235 Maximum of each of the number of arguments and environment 236 variables passed to init from the kernel command line. 237 238config COMPILE_TEST 239 bool "Compile also drivers which will not load" 240 depends on HAS_IOMEM 241 help 242 Some drivers can be compiled on a different platform than they are 243 intended to be run on. Despite they cannot be loaded there (or even 244 when they load they cannot be used due to missing HW support), 245 developers still, opposing to distributors, might want to build such 246 drivers to compile-test them. 247 248 If you are a developer and want to build everything available, say Y 249 here. If you are a user/distributor, say N here to exclude useless 250 drivers to be distributed. 251 252config WERROR 253 bool "Compile the kernel with warnings as errors" 254 default COMPILE_TEST 255 help 256 A kernel build should not cause any compiler warnings, and this 257 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 258 to enforce that rule by default. Certain warnings from other tools 259 such as the linker may be upgraded to errors with this option as 260 well. 261 262 However, if you have a new (or very old) compiler or linker with odd 263 and unusual warnings, or you have some architecture with problems, 264 you may need to disable this config option in order to 265 successfully build the kernel. 266 267 If in doubt, say Y. 268 269config UAPI_HEADER_TEST 270 bool "Compile test UAPI headers" 271 depends on HEADERS_INSTALL 272 help 273 Compile test headers exported to user-space to ensure they are 274 self-contained, i.e. compilable as standalone units. 275 276 If you are a developer or tester and want to ensure the exported 277 headers are self-contained, say Y here. Otherwise, choose N. 278 279config LOCALVERSION 280 string "Local version - append to kernel release" 281 help 282 Append an extra string to the end of your kernel version. 283 This will show up when you type uname, for example. 284 The string you set here will be appended after the contents of 285 any files with a filename matching localversion* in your 286 object and source tree, in that order. Your total string can 287 be a maximum of 64 characters. 288 289config LOCALVERSION_AUTO 290 bool "Automatically append version information to the version string" 291 default y 292 depends on !COMPILE_TEST 293 help 294 This will try to automatically determine if the current tree is a 295 release tree by looking for git tags that belong to the current 296 top of tree revision. 297 298 A string of the format -gxxxxxxxx will be added to the localversion 299 if a git-based tree is found. The string generated by this will be 300 appended after any matching localversion* files, and after the value 301 set in CONFIG_LOCALVERSION. 302 303 (The actual string used here is the first 12 characters produced 304 by running the command: 305 306 $ git rev-parse --verify HEAD 307 308 which is done within the script "scripts/setlocalversion".) 309 310config BUILD_SALT 311 string "Build ID Salt" 312 default "" 313 help 314 The build ID is used to link binaries and their debug info. Setting 315 this option will use the value in the calculation of the build id. 316 This is mostly useful for distributions which want to ensure the 317 build is unique between builds. It's safe to leave the default. 318 319config HAVE_KERNEL_GZIP 320 bool 321 322config HAVE_KERNEL_BZIP2 323 bool 324 325config HAVE_KERNEL_LZMA 326 bool 327 328config HAVE_KERNEL_XZ 329 bool 330 331config HAVE_KERNEL_LZO 332 bool 333 334config HAVE_KERNEL_LZ4 335 bool 336 337config HAVE_KERNEL_ZSTD 338 bool 339 340config HAVE_KERNEL_UNCOMPRESSED 341 bool 342 343choice 344 prompt "Kernel compression mode" 345 default KERNEL_GZIP 346 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 347 help 348 The linux kernel is a kind of self-extracting executable. 349 Several compression algorithms are available, which differ 350 in efficiency, compression and decompression speed. 351 Compression speed is only relevant when building a kernel. 352 Decompression speed is relevant at each boot. 353 354 If you have any problems with bzip2 or lzma compressed 355 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 356 version of this functionality (bzip2 only), for 2.4, was 357 supplied by Christian Ludwig) 358 359 High compression options are mostly useful for users, who 360 are low on disk space (embedded systems), but for whom ram 361 size matters less. 362 363 If in doubt, select 'gzip' 364 365config KERNEL_GZIP 366 bool "Gzip" 367 depends on HAVE_KERNEL_GZIP 368 help 369 The old and tried gzip compression. It provides a good balance 370 between compression ratio and decompression speed. 371 372config KERNEL_BZIP2 373 bool "Bzip2" 374 depends on HAVE_KERNEL_BZIP2 375 help 376 Its compression ratio and speed is intermediate. 377 Decompression speed is slowest among the choices. The kernel 378 size is about 10% smaller with bzip2, in comparison to gzip. 379 Bzip2 uses a large amount of memory. For modern kernels you 380 will need at least 8MB RAM or more for booting. 381 382config KERNEL_LZMA 383 bool "LZMA" 384 depends on HAVE_KERNEL_LZMA 385 help 386 This compression algorithm's ratio is best. Decompression speed 387 is between gzip and bzip2. Compression is slowest. 388 The kernel size is about 33% smaller with LZMA in comparison to gzip. 389 390config KERNEL_XZ 391 bool "XZ" 392 depends on HAVE_KERNEL_XZ 393 help 394 XZ uses the LZMA2 algorithm and instruction set specific 395 BCJ filters which can improve compression ratio of executable 396 code. The size of the kernel is about 30% smaller with XZ in 397 comparison to gzip. On architectures for which there is a BCJ 398 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 399 and SPARC), XZ will create a few percent smaller kernel than 400 plain LZMA. 401 402 The speed is about the same as with LZMA: The decompression 403 speed of XZ is better than that of bzip2 but worse than gzip 404 and LZO. Compression is slow. 405 406config KERNEL_LZO 407 bool "LZO" 408 depends on HAVE_KERNEL_LZO 409 help 410 Its compression ratio is the poorest among the choices. The kernel 411 size is about 10% bigger than gzip; however its speed 412 (both compression and decompression) is the fastest. 413 414config KERNEL_LZ4 415 bool "LZ4" 416 depends on HAVE_KERNEL_LZ4 417 help 418 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 419 A preliminary version of LZ4 de/compression tool is available at 420 <https://code.google.com/p/lz4/>. 421 422 Its compression ratio is worse than LZO. The size of the kernel 423 is about 8% bigger than LZO. But the decompression speed is 424 faster than LZO. 425 426config KERNEL_ZSTD 427 bool "ZSTD" 428 depends on HAVE_KERNEL_ZSTD 429 help 430 ZSTD is a compression algorithm targeting intermediate compression 431 with fast decompression speed. It will compress better than GZIP and 432 decompress around the same speed as LZO, but slower than LZ4. You 433 will need at least 192 KB RAM or more for booting. The zstd command 434 line tool is required for compression. 435 436config KERNEL_UNCOMPRESSED 437 bool "None" 438 depends on HAVE_KERNEL_UNCOMPRESSED 439 help 440 Produce uncompressed kernel image. This option is usually not what 441 you want. It is useful for debugging the kernel in slow simulation 442 environments, where decompressing and moving the kernel is awfully 443 slow. This option allows early boot code to skip the decompressor 444 and jump right at uncompressed kernel image. 445 446endchoice 447 448config DEFAULT_INIT 449 string "Default init path" 450 default "" 451 help 452 This option determines the default init for the system if no init= 453 option is passed on the kernel command line. If the requested path is 454 not present, we will still then move on to attempting further 455 locations (e.g. /sbin/init, etc). If this is empty, we will just use 456 the fallback list when init= is not passed. 457 458config DEFAULT_HOSTNAME 459 string "Default hostname" 460 default "(none)" 461 help 462 This option determines the default system hostname before userspace 463 calls sethostname(2). The kernel traditionally uses "(none)" here, 464 but you may wish to use a different default here to make a minimal 465 system more usable with less configuration. 466 467config SYSVIPC 468 bool "System V IPC" 469 help 470 Inter Process Communication is a suite of library functions and 471 system calls which let processes (running programs) synchronize and 472 exchange information. It is generally considered to be a good thing, 473 and some programs won't run unless you say Y here. In particular, if 474 you want to run the DOS emulator dosemu under Linux (read the 475 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 476 you'll need to say Y here. 477 478 You can find documentation about IPC with "info ipc" and also in 479 section 6.4 of the Linux Programmer's Guide, available from 480 <http://www.tldp.org/guides.html>. 481 482config SYSVIPC_SYSCTL 483 bool 484 depends on SYSVIPC 485 depends on SYSCTL 486 default y 487 488config SYSVIPC_COMPAT 489 def_bool y 490 depends on COMPAT && SYSVIPC 491 492config POSIX_MQUEUE 493 bool "POSIX Message Queues" 494 depends on NET 495 help 496 POSIX variant of message queues is a part of IPC. In POSIX message 497 queues every message has a priority which decides about succession 498 of receiving it by a process. If you want to compile and run 499 programs written e.g. for Solaris with use of its POSIX message 500 queues (functions mq_*) say Y here. 501 502 POSIX message queues are visible as a filesystem called 'mqueue' 503 and can be mounted somewhere if you want to do filesystem 504 operations on message queues. 505 506 If unsure, say Y. 507 508config POSIX_MQUEUE_SYSCTL 509 bool 510 depends on POSIX_MQUEUE 511 depends on SYSCTL 512 default y 513 514config WATCH_QUEUE 515 bool "General notification queue" 516 default n 517 help 518 519 This is a general notification queue for the kernel to pass events to 520 userspace by splicing them into pipes. It can be used in conjunction 521 with watches for key/keyring change notifications and device 522 notifications. 523 524 See Documentation/core-api/watch_queue.rst 525 526config CROSS_MEMORY_ATTACH 527 bool "Enable process_vm_readv/writev syscalls" 528 depends on MMU 529 default y 530 help 531 Enabling this option adds the system calls process_vm_readv and 532 process_vm_writev which allow a process with the correct privileges 533 to directly read from or write to another process' address space. 534 See the man page for more details. 535 536config AUDIT 537 bool "Auditing support" 538 depends on NET 539 help 540 Enable auditing infrastructure that can be used with another 541 kernel subsystem, such as SELinux (which requires this for 542 logging of avc messages output). System call auditing is included 543 on architectures which support it. 544 545config HAVE_ARCH_AUDITSYSCALL 546 bool 547 548config AUDITSYSCALL 549 def_bool y 550 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 551 select FSNOTIFY 552 553source "kernel/irq/Kconfig" 554source "kernel/time/Kconfig" 555source "kernel/bpf/Kconfig" 556source "kernel/Kconfig.preempt" 557 558menu "CPU/Task time and stats accounting" 559 560config VIRT_CPU_ACCOUNTING 561 bool 562 563choice 564 prompt "Cputime accounting" 565 default VIRT_CPU_ACCOUNTING_GEN if NO_HZ_FULL 566 default TICK_CPU_ACCOUNTING 567 568# Kind of a stub config for the pure tick based cputime accounting 569config TICK_CPU_ACCOUNTING 570 bool "Simple tick based cputime accounting" 571 depends on !S390 && !NO_HZ_FULL 572 help 573 This is the basic tick based cputime accounting that maintains 574 statistics about user, system and idle time spent on per jiffies 575 granularity. 576 577 If unsure, say Y. 578 579config VIRT_CPU_ACCOUNTING_NATIVE 580 bool "Deterministic task and CPU time accounting" 581 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 582 select VIRT_CPU_ACCOUNTING 583 help 584 Select this option to enable more accurate task and CPU time 585 accounting. This is done by reading a CPU counter on each 586 kernel entry and exit and on transitions within the kernel 587 between system, softirq and hardirq state, so there is a 588 small performance impact. In the case of s390 or IBM POWER > 5, 589 this also enables accounting of stolen time on logically-partitioned 590 systems. 591 592config VIRT_CPU_ACCOUNTING_GEN 593 bool "Full dynticks CPU time accounting" 594 depends on HAVE_CONTEXT_TRACKING_USER 595 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 596 depends on GENERIC_CLOCKEVENTS 597 select VIRT_CPU_ACCOUNTING 598 select CONTEXT_TRACKING_USER 599 help 600 Select this option to enable task and CPU time accounting on full 601 dynticks systems. This accounting is implemented by watching every 602 kernel-user boundaries using the context tracking subsystem. 603 The accounting is thus performed at the expense of some significant 604 overhead. 605 606 For now this is only useful if you are working on the full 607 dynticks subsystem development. 608 609 If unsure, say N. 610 611endchoice 612 613config IRQ_TIME_ACCOUNTING 614 bool "Fine granularity task level IRQ time accounting" 615 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 616 help 617 Select this option to enable fine granularity task irq time 618 accounting. This is done by reading a timestamp on each 619 transitions between softirq and hardirq state, so there can be a 620 small performance impact. 621 622 If in doubt, say N here. 623 624config HAVE_SCHED_AVG_IRQ 625 def_bool y 626 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 627 depends on SMP 628 629config SCHED_HW_PRESSURE 630 bool 631 default y if ARM && ARM_CPU_TOPOLOGY 632 default y if ARM64 633 depends on SMP 634 depends on CPU_FREQ_THERMAL 635 help 636 Select this option to enable HW pressure accounting in the 637 scheduler. HW pressure is the value conveyed to the scheduler 638 that reflects the reduction in CPU compute capacity resulted from 639 HW throttling. HW throttling occurs when the performance of 640 a CPU is capped due to high operating temperatures as an example. 641 642 If selected, the scheduler will be able to balance tasks accordingly, 643 i.e. put less load on throttled CPUs than on non/less throttled ones. 644 645 This requires the architecture to implement 646 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 647 648config BSD_PROCESS_ACCT 649 bool "BSD Process Accounting (DEPRECATED)" 650 depends on MULTIUSER 651 default n 652 help 653 If you say Y here, a user level program will be able to instruct the 654 kernel (via a special system call) to write process accounting 655 information to a file: whenever a process exits, information about 656 that process will be appended to the file by the kernel. The 657 information includes things such as creation time, owning user, 658 command name, memory usage, controlling terminal etc. (the complete 659 list is in the struct acct in <file:include/linux/acct.h>). It is 660 up to the user level program to do useful things with this 661 information. This mechanism is antiquated and has significant 662 scalability issues. You probably want to use eBPF instead. Say 663 N unless you really need this. 664 665config BSD_PROCESS_ACCT_V3 666 bool "BSD Process Accounting version 3 file format" 667 depends on BSD_PROCESS_ACCT 668 default n 669 help 670 If you say Y here, the process accounting information is written 671 in a new file format that also logs the process IDs of each 672 process and its parent. Note that this file format is incompatible 673 with previous v0/v1/v2 file formats, so you will need updated tools 674 for processing it. A preliminary version of these tools is available 675 at <http://www.gnu.org/software/acct/>. 676 677config TASKSTATS 678 bool "Export task/process statistics through netlink" 679 depends on NET 680 depends on MULTIUSER 681 default n 682 help 683 Export selected statistics for tasks/processes through the 684 generic netlink interface. Unlike BSD process accounting, the 685 statistics are available during the lifetime of tasks/processes as 686 responses to commands. Like BSD accounting, they are sent to user 687 space on task exit. 688 689 Say N if unsure. 690 691config TASK_DELAY_ACCT 692 bool "Enable per-task delay accounting" 693 depends on TASKSTATS 694 select SCHED_INFO 695 help 696 Collect information on time spent by a task waiting for system 697 resources like cpu, synchronous block I/O completion and swapping 698 in pages. Such statistics can help in setting a task's priorities 699 relative to other tasks for cpu, io, rss limits etc. 700 701 Say N if unsure. 702 703config TASK_XACCT 704 bool "Enable extended accounting over taskstats" 705 depends on TASKSTATS 706 help 707 Collect extended task accounting data and send the data 708 to userland for processing over the taskstats interface. 709 710 Say N if unsure. 711 712config TASK_IO_ACCOUNTING 713 bool "Enable per-task storage I/O accounting" 714 depends on TASK_XACCT 715 help 716 Collect information on the number of bytes of storage I/O which this 717 task has caused. 718 719 Say N if unsure. 720 721config PSI 722 bool "Pressure stall information tracking" 723 select KERNFS 724 help 725 Collect metrics that indicate how overcommitted the CPU, memory, 726 and IO capacity are in the system. 727 728 If you say Y here, the kernel will create /proc/pressure/ with the 729 pressure statistics files cpu, memory, and io. These will indicate 730 the share of walltime in which some or all tasks in the system are 731 delayed due to contention of the respective resource. 732 733 In kernels with cgroup support, cgroups (cgroup2 only) will 734 have cpu.pressure, memory.pressure, and io.pressure files, 735 which aggregate pressure stalls for the grouped tasks only. 736 737 For more details see Documentation/accounting/psi.rst. 738 739 Say N if unsure. 740 741config PSI_DEFAULT_DISABLED 742 bool "Require boot parameter to enable pressure stall information tracking" 743 default n 744 depends on PSI 745 help 746 If set, pressure stall information tracking will be disabled 747 per default but can be enabled through passing psi=1 on the 748 kernel commandline during boot. 749 750 This feature adds some code to the task wakeup and sleep 751 paths of the scheduler. The overhead is too low to affect 752 common scheduling-intense workloads in practice (such as 753 webservers, memcache), but it does show up in artificial 754 scheduler stress tests, such as hackbench. 755 756 If you are paranoid and not sure what the kernel will be 757 used for, say Y. 758 759 Say N if unsure. 760 761endmenu # "CPU/Task time and stats accounting" 762 763config CPU_ISOLATION 764 bool "CPU isolation" 765 depends on SMP 766 default y 767 help 768 Make sure that CPUs running critical tasks are not disturbed by 769 any source of "noise" such as unbound workqueues, timers, kthreads... 770 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 771 the "isolcpus=" boot parameter. 772 773 Say Y if unsure. 774 775source "kernel/rcu/Kconfig" 776 777config IKCONFIG 778 tristate "Kernel .config support" 779 help 780 This option enables the complete Linux kernel ".config" file 781 contents to be saved in the kernel. It provides documentation 782 of which kernel options are used in a running kernel or in an 783 on-disk kernel. This information can be extracted from the kernel 784 image file with the script scripts/extract-ikconfig and used as 785 input to rebuild the current kernel or to build another kernel. 786 It can also be extracted from a running kernel by reading 787 /proc/config.gz if enabled (below). 788 789config IKCONFIG_PROC 790 bool "Enable access to .config through /proc/config.gz" 791 depends on IKCONFIG && PROC_FS 792 help 793 This option enables access to the kernel configuration file 794 through /proc/config.gz. 795 796config IKHEADERS 797 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 798 depends on SYSFS 799 help 800 This option enables access to the in-kernel headers that are generated during 801 the build process. These can be used to build eBPF tracing programs, 802 or similar programs. If you build the headers as a module, a module called 803 kheaders.ko is built which can be loaded on-demand to get access to headers. 804 805config LOG_BUF_SHIFT 806 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 807 range 12 25 808 default 17 809 depends on PRINTK 810 help 811 Select the minimal kernel log buffer size as a power of 2. 812 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 813 parameter, see below. Any higher size also might be forced 814 by "log_buf_len" boot parameter. 815 816 Examples: 817 17 => 128 KB 818 16 => 64 KB 819 15 => 32 KB 820 14 => 16 KB 821 13 => 8 KB 822 12 => 4 KB 823 824config LOG_CPU_MAX_BUF_SHIFT 825 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 826 depends on SMP 827 range 0 21 828 default 0 if BASE_SMALL 829 default 12 830 depends on PRINTK 831 help 832 This option allows to increase the default ring buffer size 833 according to the number of CPUs. The value defines the contribution 834 of each CPU as a power of 2. The used space is typically only few 835 lines however it might be much more when problems are reported, 836 e.g. backtraces. 837 838 The increased size means that a new buffer has to be allocated and 839 the original static one is unused. It makes sense only on systems 840 with more CPUs. Therefore this value is used only when the sum of 841 contributions is greater than the half of the default kernel ring 842 buffer as defined by LOG_BUF_SHIFT. The default values are set 843 so that more than 16 CPUs are needed to trigger the allocation. 844 845 Also this option is ignored when "log_buf_len" kernel parameter is 846 used as it forces an exact (power of two) size of the ring buffer. 847 848 The number of possible CPUs is used for this computation ignoring 849 hotplugging making the computation optimal for the worst case 850 scenario while allowing a simple algorithm to be used from bootup. 851 852 Examples shift values and their meaning: 853 17 => 128 KB for each CPU 854 16 => 64 KB for each CPU 855 15 => 32 KB for each CPU 856 14 => 16 KB for each CPU 857 13 => 8 KB for each CPU 858 12 => 4 KB for each CPU 859 860config PRINTK_INDEX 861 bool "Printk indexing debugfs interface" 862 depends on PRINTK && DEBUG_FS 863 help 864 Add support for indexing of all printk formats known at compile time 865 at <debugfs>/printk/index/<module>. 866 867 This can be used as part of maintaining daemons which monitor 868 /dev/kmsg, as it permits auditing the printk formats present in a 869 kernel, allowing detection of cases where monitored printks are 870 changed or no longer present. 871 872 There is no additional runtime cost to printk with this enabled. 873 874# 875# Architectures with an unreliable sched_clock() should select this: 876# 877config HAVE_UNSTABLE_SCHED_CLOCK 878 bool 879 880config GENERIC_SCHED_CLOCK 881 bool 882 883menu "Scheduler features" 884 885config UCLAMP_TASK 886 bool "Enable utilization clamping for RT/FAIR tasks" 887 depends on CPU_FREQ_GOV_SCHEDUTIL 888 help 889 This feature enables the scheduler to track the clamped utilization 890 of each CPU based on RUNNABLE tasks scheduled on that CPU. 891 892 With this option, the user can specify the min and max CPU 893 utilization allowed for RUNNABLE tasks. The max utilization defines 894 the maximum frequency a task should use while the min utilization 895 defines the minimum frequency it should use. 896 897 Both min and max utilization clamp values are hints to the scheduler, 898 aiming at improving its frequency selection policy, but they do not 899 enforce or grant any specific bandwidth for tasks. 900 901 If in doubt, say N. 902 903config UCLAMP_BUCKETS_COUNT 904 int "Number of supported utilization clamp buckets" 905 range 5 20 906 default 5 907 depends on UCLAMP_TASK 908 help 909 Defines the number of clamp buckets to use. The range of each bucket 910 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 911 number of clamp buckets the finer their granularity and the higher 912 the precision of clamping aggregation and tracking at run-time. 913 914 For example, with the minimum configuration value we will have 5 915 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 916 be refcounted in the [20..39]% bucket and will set the bucket clamp 917 effective value to 25%. 918 If a second 30% boosted task should be co-scheduled on the same CPU, 919 that task will be refcounted in the same bucket of the first task and 920 it will boost the bucket clamp effective value to 30%. 921 The clamp effective value of a bucket is reset to its nominal value 922 (20% in the example above) when there are no more tasks refcounted in 923 that bucket. 924 925 An additional boost/capping margin can be added to some tasks. In the 926 example above the 25% task will be boosted to 30% until it exits the 927 CPU. If that should be considered not acceptable on certain systems, 928 it's always possible to reduce the margin by increasing the number of 929 clamp buckets to trade off used memory for run-time tracking 930 precision. 931 932 If in doubt, use the default value. 933 934config SCHED_PROXY_EXEC 935 bool "Proxy Execution" 936 # Avoid some build failures w/ PREEMPT_RT until it can be fixed 937 depends on !PREEMPT_RT 938 # Need to investigate how to inform sched_ext of split contexts 939 depends on !SCHED_CLASS_EXT 940 # Not particularly useful until we get to multi-rq proxying 941 depends on EXPERT 942 help 943 This option enables proxy execution, a mechanism for mutex-owning 944 tasks to inherit the scheduling context of higher priority waiters. 945 946endmenu 947 948# 949# For architectures that want to enable the support for NUMA-affine scheduler 950# balancing logic: 951# 952config ARCH_SUPPORTS_NUMA_BALANCING 953 bool 954 955# 956# For architectures that prefer to flush all TLBs after a number of pages 957# are unmapped instead of sending one IPI per page to flush. The architecture 958# must provide guarantees on what happens if a clean TLB cache entry is 959# written after the unmap. Details are in mm/rmap.c near the check for 960# should_defer_flush. The architecture should also consider if the full flush 961# and the refill costs are offset by the savings of sending fewer IPIs. 962config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 963 bool 964 965config CC_HAS_INT128 966 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 967 968config CC_IMPLICIT_FALLTHROUGH 969 string 970 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 971 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 972 973config CC_MS_EXTENSIONS 974 string 975 default "-fms-anonymous-structs" if $(cc-option,-fms-anonymous-structs) 976 default "-fms-extensions" 977 978# Currently, disable gcc-10+ array-bounds globally. 979# It's still broken in gcc-13, so no upper bound yet. 980config GCC10_NO_ARRAY_BOUNDS 981 def_bool y 982 983config CC_NO_ARRAY_BOUNDS 984 bool 985 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 986 987# Currently, disable -Wstringop-overflow for GCC globally. 988config GCC_NO_STRINGOP_OVERFLOW 989 def_bool y 990 991config CC_NO_STRINGOP_OVERFLOW 992 bool 993 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 994 995config CC_STRINGOP_OVERFLOW 996 bool 997 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 998 999# 1000# For architectures that know their GCC __int128 support is sound 1001# 1002config ARCH_SUPPORTS_INT128 1003 bool 1004 1005# For architectures that (ab)use NUMA to represent different memory regions 1006# all cpu-local but of different latencies, such as SuperH. 1007# 1008config ARCH_WANT_NUMA_VARIABLE_LOCALITY 1009 bool 1010 1011config NUMA_BALANCING 1012 bool "Memory placement aware NUMA scheduler" 1013 depends on ARCH_SUPPORTS_NUMA_BALANCING 1014 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 1015 depends on SMP && NUMA_MIGRATION && !PREEMPT_RT 1016 help 1017 This option adds support for automatic NUMA aware memory/task placement. 1018 The mechanism is quite primitive and is based on migrating memory when 1019 it has references to the node the task is running on. 1020 1021 This system will be inactive on UMA systems. 1022 1023config SCHED_CACHE 1024 bool "Cache aware load balance" 1025 default y 1026 depends on SMP 1027 help 1028 When enabled, the scheduler will attempt to aggregate tasks from 1029 the same process onto a single Last Level Cache (LLC) domain when 1030 possible. This improves cache locality by keeping tasks that share 1031 resources within the same cache domain, reducing cache misses and 1032 lowering data access latency. 1033 1034config NUMA_BALANCING_DEFAULT_ENABLED 1035 bool "Automatically enable NUMA aware memory/task placement" 1036 default y 1037 depends on NUMA_BALANCING 1038 help 1039 If set, automatic NUMA balancing will be enabled if running on a NUMA 1040 machine. 1041 1042config SLAB_OBJ_EXT 1043 bool 1044 1045menuconfig CGROUPS 1046 bool "Control Group support" 1047 select KERNFS 1048 help 1049 This option adds support for grouping sets of processes together, for 1050 use with process control subsystems such as Cpusets, CFS, memory 1051 controls or device isolation. 1052 See 1053 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1054 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1055 and resource control) 1056 1057 Say N if unsure. 1058 1059if CGROUPS 1060 1061config PAGE_COUNTER 1062 bool 1063 1064config CGROUP_FAVOR_DYNMODS 1065 bool "Favor dynamic modification latency reduction by default" 1066 help 1067 This option enables the "favordynmods" mount option by default 1068 which reduces the latencies of dynamic cgroup modifications such 1069 as task migrations and controller on/offs at the cost of making 1070 hot path operations such as forks and exits more expensive. 1071 1072 Say N if unsure. 1073 1074config MEMCG 1075 bool "Memory controller" 1076 select PAGE_COUNTER 1077 select EVENTFD 1078 select SLAB_OBJ_EXT 1079 select VM_EVENT_COUNTERS 1080 help 1081 Provides control over the memory footprint of tasks in a cgroup. 1082 1083config MEMCG_NMI_UNSAFE 1084 bool 1085 depends on MEMCG 1086 depends on HAVE_NMI 1087 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1088 default y 1089 1090config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1091 bool 1092 depends on MEMCG 1093 depends on HAVE_NMI 1094 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1095 default y 1096 1097config MEMCG_V1 1098 bool "Legacy cgroup v1 memory controller" 1099 depends on MEMCG 1100 default n 1101 help 1102 Legacy cgroup v1 memory controller which has been deprecated by 1103 cgroup v2 implementation. The v1 is there for legacy applications 1104 which haven't migrated to the new cgroup v2 interface yet. If you 1105 do not have any such application then you are completely fine leaving 1106 this option disabled. 1107 1108 Please note that feature set of the legacy memory controller is likely 1109 going to shrink due to deprecation process. New deployments with v1 1110 controller are highly discouraged. 1111 1112 Say N if unsure. 1113 1114config BLK_CGROUP 1115 bool "IO controller" 1116 depends on BLOCK 1117 default n 1118 help 1119 Generic block IO controller cgroup interface. This is the common 1120 cgroup interface which should be used by various IO controlling 1121 policies. 1122 1123 Currently, CFQ IO scheduler uses it to recognize task groups and 1124 control disk bandwidth allocation (proportional time slice allocation) 1125 to such task groups. It is also used by bio throttling logic in 1126 block layer to implement upper limit in IO rates on a device. 1127 1128 This option only enables generic Block IO controller infrastructure. 1129 One needs to also enable actual IO controlling logic/policy. For 1130 enabling proportional weight division of disk bandwidth in CFQ, set 1131 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1132 CONFIG_BLK_DEV_THROTTLING=y. 1133 1134 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1135 1136config CGROUP_WRITEBACK 1137 bool 1138 depends on MEMCG && BLK_CGROUP 1139 default y 1140 1141menuconfig CGROUP_SCHED 1142 bool "CPU controller" 1143 default n 1144 help 1145 This feature lets CPU scheduler recognize task groups and control CPU 1146 bandwidth allocation to such task groups. It uses cgroups to group 1147 tasks. 1148 1149if CGROUP_SCHED 1150config GROUP_SCHED_WEIGHT 1151 def_bool n 1152 1153config GROUP_SCHED_BANDWIDTH 1154 def_bool n 1155 1156config FAIR_GROUP_SCHED 1157 bool "Group scheduling for SCHED_OTHER" 1158 depends on CGROUP_SCHED 1159 select GROUP_SCHED_WEIGHT 1160 default CGROUP_SCHED 1161 1162config CFS_BANDWIDTH 1163 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1164 depends on FAIR_GROUP_SCHED 1165 select GROUP_SCHED_BANDWIDTH 1166 default n 1167 help 1168 This option allows users to define CPU bandwidth rates (limits) for 1169 tasks running within the fair group scheduler. Groups with no limit 1170 set are considered to be unconstrained and will run with no 1171 restriction. 1172 See Documentation/scheduler/sched-bwc.rst for more information. 1173 1174config RT_GROUP_SCHED 1175 bool "Group scheduling for SCHED_RR/FIFO" 1176 depends on CGROUP_SCHED 1177 default n 1178 help 1179 This feature lets you explicitly allocate real CPU bandwidth 1180 to task groups. If enabled, it will also make it impossible to 1181 schedule realtime tasks for non-root users until you allocate 1182 realtime bandwidth for them. 1183 See Documentation/scheduler/sched-rt-group.rst for more information. 1184 1185config RT_GROUP_SCHED_DEFAULT_DISABLED 1186 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1187 depends on RT_GROUP_SCHED 1188 default n 1189 help 1190 When set, the RT group scheduling is disabled by default. The option 1191 is in inverted form so that mere RT_GROUP_SCHED enables the group 1192 scheduling. 1193 1194 Say N if unsure. 1195 1196config EXT_GROUP_SCHED 1197 bool 1198 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1199 select GROUP_SCHED_WEIGHT 1200 select GROUP_SCHED_BANDWIDTH 1201 default y 1202 1203endif #CGROUP_SCHED 1204 1205config EXT_SUB_SCHED 1206 def_bool y 1207 depends on SCHED_CLASS_EXT && CGROUPS 1208 1209config SCHED_MM_CID 1210 def_bool y 1211 depends on SMP && RSEQ 1212 1213config UCLAMP_TASK_GROUP 1214 bool "Utilization clamping per group of tasks" 1215 depends on CGROUP_SCHED 1216 depends on UCLAMP_TASK 1217 default n 1218 help 1219 This feature enables the scheduler to track the clamped utilization 1220 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1221 1222 When this option is enabled, the user can specify a min and max 1223 CPU bandwidth which is allowed for each single task in a group. 1224 The max bandwidth allows to clamp the maximum frequency a task 1225 can use, while the min bandwidth allows to define a minimum 1226 frequency a task will always use. 1227 1228 When task group based utilization clamping is enabled, an eventually 1229 specified task-specific clamp value is constrained by the cgroup 1230 specified clamp value. Both minimum and maximum task clamping cannot 1231 be bigger than the corresponding clamping defined at task group level. 1232 1233 If in doubt, say N. 1234 1235config CGROUP_PIDS 1236 bool "PIDs controller" 1237 help 1238 Provides enforcement of process number limits in the scope of a 1239 cgroup. Any attempt to fork more processes than is allowed in the 1240 cgroup will fail. PIDs are fundamentally a global resource because it 1241 is fairly trivial to reach PID exhaustion before you reach even a 1242 conservative kmemcg limit. As a result, it is possible to grind a 1243 system to halt without being limited by other cgroup policies. The 1244 PIDs controller is designed to stop this from happening. 1245 1246 It should be noted that organisational operations (such as attaching 1247 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1248 since the PIDs limit only affects a process's ability to fork, not to 1249 attach to a cgroup. 1250 1251config CGROUP_RDMA 1252 bool "RDMA controller" 1253 help 1254 Provides enforcement of RDMA resources defined by IB stack. 1255 It is fairly easy for consumers to exhaust RDMA resources, which 1256 can result into resource unavailability to other consumers. 1257 RDMA controller is designed to stop this from happening. 1258 Attaching processes with active RDMA resources to the cgroup 1259 hierarchy is allowed even if can cross the hierarchy's limit. 1260 1261config CGROUP_DMEM 1262 bool "Device memory controller (DMEM)" 1263 select PAGE_COUNTER 1264 help 1265 The DMEM controller allows compatible devices to restrict device 1266 memory usage based on the cgroup hierarchy. 1267 1268 As an example, it allows you to restrict VRAM usage for applications 1269 in the DRM subsystem. 1270 1271config CGROUP_FREEZER 1272 bool "Freezer controller" 1273 help 1274 Provides a way to freeze and unfreeze all tasks in a 1275 cgroup. 1276 1277 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1278 controller includes important in-kernel memory consumers per default. 1279 1280 If you're using cgroup2, say N. 1281 1282config CGROUP_HUGETLB 1283 bool "HugeTLB controller" 1284 depends on HUGETLB_PAGE 1285 select PAGE_COUNTER 1286 default n 1287 help 1288 Provides a cgroup controller for HugeTLB pages. 1289 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1290 The limit is enforced during page fault. Since HugeTLB doesn't 1291 support page reclaim, enforcing the limit at page fault time implies 1292 that, the application will get SIGBUS signal if it tries to access 1293 HugeTLB pages beyond its limit. This requires the application to know 1294 beforehand how much HugeTLB pages it would require for its use. The 1295 control group is tracked in the third page lru pointer. This means 1296 that we cannot use the controller with huge page less than 3 pages. 1297 1298config CPUSETS 1299 bool "Cpuset controller" 1300 depends on SMP 1301 select UNION_FIND 1302 select CPU_ISOLATION 1303 help 1304 This option will let you create and manage CPUSETs which 1305 allow dynamically partitioning a system into sets of CPUs and 1306 Memory Nodes and assigning tasks to run only within those sets. 1307 This is primarily useful on large SMP or NUMA systems. 1308 1309 Say N if unsure. 1310 1311config CPUSETS_V1 1312 bool "Legacy cgroup v1 cpusets controller" 1313 depends on CPUSETS 1314 default n 1315 help 1316 Legacy cgroup v1 cpusets controller which has been deprecated by 1317 cgroup v2 implementation. The v1 is there for legacy applications 1318 which haven't migrated to the new cgroup v2 interface yet. Legacy 1319 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1320 do not have any such application then you are completely fine leaving 1321 this option disabled. 1322 1323 Say N if unsure. 1324 1325config PROC_PID_CPUSET 1326 bool "Include legacy /proc/<pid>/cpuset file" 1327 depends on CPUSETS_V1 1328 default y 1329 1330config CGROUP_DEVICE 1331 bool "Device controller" 1332 help 1333 Provides a cgroup controller implementing whitelists for 1334 devices which a process in the cgroup can mknod or open. 1335 1336config CGROUP_CPUACCT 1337 bool "Simple CPU accounting controller" 1338 help 1339 Provides a simple controller for monitoring the 1340 total CPU consumed by the tasks in a cgroup. 1341 1342config CGROUP_PERF 1343 bool "Perf controller" 1344 depends on PERF_EVENTS 1345 help 1346 This option extends the perf per-cpu mode to restrict monitoring 1347 to threads which belong to the cgroup specified and run on the 1348 designated cpu. Or this can be used to have cgroup ID in samples 1349 so that it can monitor performance events among cgroups. 1350 1351 Say N if unsure. 1352 1353config CGROUP_BPF 1354 bool "Support for eBPF programs attached to cgroups" 1355 depends on BPF_SYSCALL 1356 select SOCK_CGROUP_DATA 1357 help 1358 Allow attaching eBPF programs to a cgroup using the bpf(2) 1359 syscall command BPF_PROG_ATTACH. 1360 1361 In which context these programs are accessed depends on the type 1362 of attachment. For instance, programs that are attached using 1363 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1364 inet sockets. 1365 1366config CGROUP_MISC 1367 bool "Misc resource controller" 1368 default n 1369 help 1370 Provides a controller for miscellaneous resources on a host. 1371 1372 Miscellaneous scalar resources are the resources on the host system 1373 which cannot be abstracted like the other cgroups. This controller 1374 tracks and limits the miscellaneous resources used by a process 1375 attached to a cgroup hierarchy. 1376 1377 For more information, please check misc cgroup section in 1378 /Documentation/admin-guide/cgroup-v2.rst. 1379 1380config CGROUP_DEBUG 1381 bool "Debug controller" 1382 default n 1383 depends on DEBUG_KERNEL 1384 help 1385 This option enables a simple controller that exports 1386 debugging information about the cgroups framework. This 1387 controller is for control cgroup debugging only. Its 1388 interfaces are not stable. 1389 1390 Say N. 1391 1392config SOCK_CGROUP_DATA 1393 bool 1394 default n 1395 1396endif # CGROUPS 1397 1398menuconfig NAMESPACES 1399 bool "Namespaces support" if EXPERT 1400 depends on MULTIUSER 1401 default !EXPERT 1402 help 1403 Provides the way to make tasks work with different objects using 1404 the same id. For example same IPC id may refer to different objects 1405 or same user id or pid may refer to different tasks when used in 1406 different namespaces. 1407 1408if NAMESPACES 1409 1410config UTS_NS 1411 bool "UTS namespace" 1412 default y 1413 help 1414 In this namespace tasks see different info provided with the 1415 uname() system call 1416 1417config TIME_NS 1418 bool "TIME namespace" 1419 default y 1420 help 1421 In this namespace boottime and monotonic clocks can be set. 1422 The time will keep going with the same pace. 1423 1424config TIME_NS_VDSO 1425 def_bool TIME_NS && GENERIC_GETTIMEOFDAY 1426 1427config IPC_NS 1428 bool "IPC namespace" 1429 depends on (SYSVIPC || POSIX_MQUEUE) 1430 default y 1431 help 1432 In this namespace tasks work with IPC ids which correspond to 1433 different IPC objects in different namespaces. 1434 1435config USER_NS 1436 bool "User namespace" 1437 default n 1438 help 1439 This allows containers, i.e. vservers, to use user namespaces 1440 to provide different user info for different servers. 1441 1442 When user namespaces are enabled in the kernel it is 1443 recommended that the MEMCG option also be enabled and that 1444 user-space use the memory control groups to limit the amount 1445 of memory a memory unprivileged users can use. 1446 1447 If unsure, say N. 1448 1449config PID_NS 1450 bool "PID Namespaces" 1451 default y 1452 help 1453 Support process id namespaces. This allows having multiple 1454 processes with the same pid as long as they are in different 1455 pid namespaces. This is a building block of containers. 1456 1457config NET_NS 1458 bool "Network namespace" 1459 depends on NET 1460 default y 1461 help 1462 Allow user space to create what appear to be multiple instances 1463 of the network stack. 1464 1465endif # NAMESPACES 1466 1467config CHECKPOINT_RESTORE 1468 bool "Checkpoint/restore support" 1469 depends on PROC_FS 1470 select PROC_CHILDREN 1471 select KCMP 1472 default n 1473 help 1474 Enables additional kernel features in a sake of checkpoint/restore. 1475 In particular it adds auxiliary prctl codes to setup process text, 1476 data and heap segment sizes, and a few additional /proc filesystem 1477 entries. 1478 1479 If unsure, say N here. 1480 1481config SCHED_AUTOGROUP 1482 bool "Automatic process group scheduling" 1483 select CGROUPS 1484 select CGROUP_SCHED 1485 select FAIR_GROUP_SCHED 1486 help 1487 This option optimizes the scheduler for common desktop workloads by 1488 automatically creating and populating task groups. This separation 1489 of workloads isolates aggressive CPU burners (like build jobs) from 1490 desktop applications. Task group autogeneration is currently based 1491 upon task session. 1492 1493config RELAY 1494 bool "Kernel->user space relay support (formerly relayfs)" 1495 select IRQ_WORK 1496 help 1497 This option enables support for relay interface support in 1498 certain file systems (such as debugfs). 1499 It is designed to provide an efficient mechanism for tools and 1500 facilities to relay large amounts of data from kernel space to 1501 user space. 1502 1503 If unsure, say N. 1504 1505config BLK_DEV_INITRD 1506 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1507 help 1508 The initial RAM filesystem is a ramfs which is loaded by the 1509 boot loader (loadlin or lilo) and that is mounted as root 1510 before the normal boot procedure. It is typically used to 1511 load modules needed to mount the "real" root file system, 1512 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1513 1514 If RAM disk support (BLK_DEV_RAM) is also included, this 1515 also enables initial RAM disk (initrd) support and adds 1516 15 Kbytes (more on some other architectures) to the kernel size. 1517 1518 If unsure say Y. 1519 1520if BLK_DEV_INITRD 1521 1522source "usr/Kconfig" 1523 1524endif 1525 1526config BOOT_CONFIG 1527 bool "Boot config support" 1528 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1529 help 1530 Extra boot config allows system admin to pass a config file as 1531 complemental extension of kernel cmdline when booting. 1532 The boot config file must be attached at the end of initramfs 1533 with checksum, size and magic word. 1534 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1535 1536 If unsure, say Y. 1537 1538config BOOT_CONFIG_FORCE 1539 bool "Force unconditional bootconfig processing" 1540 depends on BOOT_CONFIG 1541 default y if BOOT_CONFIG_EMBED 1542 help 1543 With this Kconfig option set, BOOT_CONFIG processing is carried 1544 out even when the "bootconfig" kernel-boot parameter is omitted. 1545 In fact, with this Kconfig option set, there is no way to 1546 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1547 parameters. 1548 1549 If unsure, say N. 1550 1551config BOOT_CONFIG_EMBED 1552 bool "Embed bootconfig file in the kernel" 1553 depends on BOOT_CONFIG 1554 help 1555 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1556 kernel. Usually, the bootconfig file is loaded with the initrd 1557 image. But if the system doesn't support initrd, this option will 1558 help you by embedding a bootconfig file while building the kernel. 1559 1560 If unsure, say N. 1561 1562config BOOT_CONFIG_EMBED_FILE 1563 string "Embedded bootconfig file path" 1564 depends on BOOT_CONFIG_EMBED 1565 help 1566 Specify a bootconfig file which will be embedded to the kernel. 1567 This bootconfig will be used if there is no initrd or no other 1568 bootconfig in the initrd. 1569 1570config CMDLINE_LOG_WRAP_IDEAL_LEN 1571 int "Length to try to wrap the cmdline when logged at boot" 1572 default 1021 1573 range 0 1021 1574 help 1575 At boot time, the kernel command line is logged to the console. 1576 The log message will start with the prefix "Kernel command line: ". 1577 The log message will attempt to be wrapped (split into multiple log 1578 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters. 1579 If wrapping happens, each log message will start with the prefix and 1580 all but the last message will end with " \". Messages may exceed the 1581 ideal length if a place to wrap isn't found before the specified 1582 number of characters. 1583 1584 A value of 0 disables wrapping, though be warned that the maximum 1585 length of a log message (1021 characters) may cause the cmdline to 1586 be truncated. 1587 1588config INITRAMFS_PRESERVE_MTIME 1589 bool "Preserve cpio archive mtimes in initramfs" 1590 depends on BLK_DEV_INITRD 1591 default y 1592 help 1593 Each entry in an initramfs cpio archive carries an mtime value. When 1594 enabled, extracted cpio items take this mtime, with directory mtime 1595 setting deferred until after creation of any child entries. 1596 1597 If unsure, say Y. 1598 1599config INITRAMFS_TEST 1600 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1601 depends on BLK_DEV_INITRD && KUNIT=y 1602 default KUNIT_ALL_TESTS 1603 help 1604 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1605 1606choice 1607 prompt "Compiler optimization level" 1608 default CC_OPTIMIZE_FOR_PERFORMANCE 1609 1610config CC_OPTIMIZE_FOR_PERFORMANCE 1611 bool "Optimize for performance (-O2)" 1612 help 1613 This is the default optimization level for the kernel, building 1614 with the "-O2" compiler flag for best performance and most 1615 helpful compile-time warnings. 1616 1617config CC_OPTIMIZE_FOR_SIZE 1618 bool "Optimize for size (-Os)" 1619 help 1620 Choosing this option will pass "-Os" to your compiler resulting 1621 in a smaller kernel. 1622 1623endchoice 1624 1625config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1626 bool 1627 help 1628 This requires that the arch annotates or otherwise protects 1629 its external entry points from being discarded. Linker scripts 1630 must also merge .text.*, .data.*, and .bss.* correctly into 1631 output sections. Care must be taken not to pull in unrelated 1632 sections (e.g., '.text.init'). Typically '.' in section names 1633 is used to distinguish them from label names / C identifiers. 1634 1635config LD_DEAD_CODE_DATA_ELIMINATION 1636 bool "Dead code and data elimination (EXPERIMENTAL)" 1637 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1638 depends on EXPERT 1639 depends on $(cc-option,-ffunction-sections -fdata-sections) 1640 depends on $(ld-option,--gc-sections) 1641 help 1642 Enable this if you want to do dead code and data elimination with 1643 the linker by compiling with -ffunction-sections -fdata-sections, 1644 and linking with --gc-sections. 1645 1646 This can reduce on disk and in-memory size of the kernel 1647 code and static data, particularly for small configs and 1648 on small systems. This has the possibility of introducing 1649 silently broken kernel if the required annotations are not 1650 present. This option is not well tested yet, so use at your 1651 own risk. 1652 1653config LD_ORPHAN_WARN 1654 def_bool y 1655 depends on ARCH_WANT_LD_ORPHAN_WARN 1656 depends on $(ld-option,--orphan-handling=warn) 1657 depends on $(ld-option,--orphan-handling=error) 1658 1659config LD_ORPHAN_WARN_LEVEL 1660 string 1661 depends on LD_ORPHAN_WARN 1662 default "error" if WERROR 1663 default "warn" 1664 1665config SYSCTL 1666 bool 1667 1668config HAVE_UID16 1669 bool 1670 1671config SYSCTL_EXCEPTION_TRACE 1672 bool 1673 help 1674 Enable support for /proc/sys/debug/exception-trace. 1675 1676config SYSCTL_ARCH_UNALIGN_NO_WARN 1677 bool 1678 help 1679 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1680 Allows arch to define/use @no_unaligned_warning to possibly warn 1681 about unaligned access emulation going on under the hood. 1682 1683config SYSCTL_ARCH_UNALIGN_ALLOW 1684 bool 1685 help 1686 Enable support for /proc/sys/kernel/unaligned-trap 1687 Allows arches to define/use @unaligned_enabled to runtime toggle 1688 the unaligned access emulation. 1689 see arch/parisc/kernel/unaligned.c for reference 1690 1691config SYSFS_SYSCALL 1692 bool "Sysfs syscall support" 1693 default n 1694 help 1695 sys_sysfs is an obsolete system call no longer supported in libc. 1696 Note that disabling this option is more secure but might break 1697 compatibility with some systems. 1698 1699 If unsure say N here. 1700 1701config HAVE_PCSPKR_PLATFORM 1702 bool 1703 1704menuconfig EXPERT 1705 bool "Configure standard kernel features (expert users)" 1706 # Unhide debug options, to make the on-by-default options visible 1707 select DEBUG_KERNEL 1708 help 1709 This option allows certain base kernel options and settings 1710 to be disabled or tweaked. This is for specialized 1711 environments which can tolerate a "non-standard" kernel. 1712 Only use this if you really know what you are doing. 1713 1714config UID16 1715 bool "Enable 16-bit UID system calls" if EXPERT 1716 depends on HAVE_UID16 && MULTIUSER 1717 default y 1718 help 1719 This enables the legacy 16-bit UID syscall wrappers. 1720 1721config MULTIUSER 1722 bool "Multiple users, groups and capabilities support" if EXPERT 1723 default y 1724 help 1725 This option enables support for non-root users, groups and 1726 capabilities. 1727 1728 If you say N here, all processes will run with UID 0, GID 0, and all 1729 possible capabilities. Saying N here also compiles out support for 1730 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1731 setgid, and capset. 1732 1733 If unsure, say Y here. 1734 1735config SGETMASK_SYSCALL 1736 bool "sgetmask/ssetmask syscalls support" if EXPERT 1737 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1738 help 1739 sys_sgetmask and sys_ssetmask are obsolete system calls 1740 no longer supported in libc but still enabled by default in some 1741 architectures. 1742 1743 If unsure, leave the default option here. 1744 1745config FHANDLE 1746 bool "open by fhandle syscalls" if EXPERT 1747 select EXPORTFS 1748 default y 1749 help 1750 If you say Y here, a user level program will be able to map 1751 file names to handle and then later use the handle for 1752 different file system operations. This is useful in implementing 1753 userspace file servers, which now track files using handles instead 1754 of names. The handle would remain the same even if file names 1755 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1756 syscalls. 1757 1758config POSIX_TIMERS 1759 bool "Posix Clocks & timers" if EXPERT 1760 default y 1761 help 1762 This includes native support for POSIX timers to the kernel. 1763 Some embedded systems have no use for them and therefore they 1764 can be configured out to reduce the size of the kernel image. 1765 1766 When this option is disabled, the following syscalls won't be 1767 available: timer_create, timer_gettime: timer_getoverrun, 1768 timer_settime, timer_delete, clock_adjtime, getitimer, 1769 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1770 clock_getres and clock_nanosleep syscalls will be limited to 1771 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1772 1773 If unsure say y. 1774 1775config PRINTK 1776 default y 1777 bool "Enable support for printk" if EXPERT 1778 select IRQ_WORK 1779 help 1780 This option enables normal printk support. Removing it 1781 eliminates most of the message strings from the kernel image 1782 and makes the kernel more or less silent. As this makes it 1783 very difficult to diagnose system problems, saying N here is 1784 strongly discouraged. 1785 1786config PRINTK_RINGBUFFER_KUNIT_TEST 1787 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1788 depends on PRINTK && KUNIT 1789 default KUNIT_ALL_TESTS 1790 help 1791 This builds the printk ringbuffer KUnit test suite. 1792 1793 For more information on KUnit and unit tests in general, please refer 1794 to the KUnit documentation. 1795 1796 If unsure, say N. 1797 1798config BUG 1799 bool "BUG() support" if EXPERT 1800 default y 1801 help 1802 Disabling this option eliminates support for BUG and WARN, reducing 1803 the size of your kernel image and potentially quietly ignoring 1804 numerous fatal conditions. You should only consider disabling this 1805 option for embedded systems with no facilities for reporting errors. 1806 Just say Y. 1807 1808config ELF_CORE 1809 depends on COREDUMP 1810 default y 1811 bool "Enable ELF core dumps" if EXPERT 1812 help 1813 Enable support for generating core dumps. Disabling saves about 4k. 1814 1815 1816config PCSPKR_PLATFORM 1817 bool "Enable PC-Speaker support" if EXPERT 1818 depends on HAVE_PCSPKR_PLATFORM 1819 select I8253_LOCK 1820 default y 1821 help 1822 This option allows to disable the internal PC-Speaker 1823 support, saving some memory. 1824 1825config BASE_SMALL 1826 bool "Enable smaller-sized data structures for core" if EXPERT 1827 help 1828 Enabling this option reduces the size of miscellaneous core 1829 kernel data structures. This saves memory on small machines, 1830 but may reduce performance. 1831 1832config FUTEX 1833 bool "Enable futex support" if EXPERT 1834 depends on !(SPARC32 && SMP) 1835 default y 1836 imply RT_MUTEXES 1837 help 1838 Disabling this option will cause the kernel to be built without 1839 support for "fast userspace mutexes". The resulting kernel may not 1840 run glibc-based applications correctly. 1841 1842config FUTEX_PI 1843 bool 1844 depends on FUTEX && RT_MUTEXES 1845 default y 1846 1847config FUTEX_PRIVATE_HASH 1848 bool 1849 depends on FUTEX && !BASE_SMALL && MMU 1850 default y 1851 1852config FUTEX_MPOL 1853 bool 1854 depends on FUTEX && NUMA 1855 default y 1856 1857config HAVE_FUTEX_ROBUST_UNLOCK 1858 bool 1859 1860config FUTEX_ROBUST_UNLOCK 1861 def_bool FUTEX && HAVE_GENERIC_VDSO && GENERIC_IRQ_ENTRY && RSEQ && HAVE_FUTEX_ROBUST_UNLOCK 1862 1863config EPOLL 1864 bool "Enable eventpoll support" if EXPERT 1865 default y 1866 help 1867 Disabling this option will cause the kernel to be built without 1868 support for epoll family of system calls. 1869 1870config SIGNALFD 1871 bool "Enable signalfd() system call" if EXPERT 1872 default y 1873 help 1874 Enable the signalfd() system call that allows to receive signals 1875 on a file descriptor. 1876 1877 If unsure, say Y. 1878 1879config TIMERFD 1880 bool "Enable timerfd() system call" if EXPERT 1881 default y 1882 help 1883 Enable the timerfd() system call that allows to receive timer 1884 events on a file descriptor. 1885 1886 If unsure, say Y. 1887 1888config EVENTFD 1889 bool "Enable eventfd() system call" if EXPERT 1890 default y 1891 help 1892 Enable the eventfd() system call that allows to receive both 1893 kernel notification (ie. KAIO) or userspace notifications. 1894 1895 If unsure, say Y. 1896 1897config SHMEM 1898 bool "Use full shmem filesystem" if EXPERT 1899 default y 1900 depends on MMU 1901 help 1902 The shmem is an internal filesystem used to manage shared memory. 1903 It is backed by swap and manages resource limits. It is also exported 1904 to userspace as tmpfs if TMPFS is enabled. Disabling this 1905 option replaces shmem and tmpfs with the much simpler ramfs code, 1906 which may be appropriate on small systems without swap. 1907 1908config AIO 1909 bool "Enable AIO support" if EXPERT 1910 default y 1911 help 1912 This option enables POSIX asynchronous I/O which may by used 1913 by some high performance threaded applications. Disabling 1914 this option saves about 7k. 1915 1916config IO_URING 1917 bool "Enable IO uring support" if EXPERT 1918 select IO_WQ 1919 default y 1920 help 1921 This option enables support for the io_uring interface, enabling 1922 applications to submit and complete IO through submission and 1923 completion rings that are shared between the kernel and application. 1924 1925config GCOV_PROFILE_URING 1926 bool "Enable GCOV profiling on the io_uring subsystem" 1927 depends on IO_URING && GCOV_KERNEL 1928 help 1929 Enable GCOV profiling on the io_uring subsystem, to facilitate 1930 code coverage testing. 1931 1932 If unsure, say N. 1933 1934 Note that this will have a negative impact on the performance of 1935 the io_uring subsystem, hence this should only be enabled for 1936 specific test purposes. 1937 1938config IO_URING_MOCK_FILE 1939 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1940 default n 1941 depends on IO_URING 1942 help 1943 Enable mock files for io_uring subsystem testing. The ABI might 1944 still change, so it's still experimental and should only be enabled 1945 for specific test purposes. 1946 1947 If unsure, say N. 1948 1949config ADVISE_SYSCALLS 1950 bool "Enable madvise/fadvise syscalls" if EXPERT 1951 default y 1952 help 1953 This option enables the madvise and fadvise syscalls, used by 1954 applications to advise the kernel about their future memory or file 1955 usage, improving performance. If building an embedded system where no 1956 applications use these syscalls, you can disable this option to save 1957 space. 1958 1959config MEMBARRIER 1960 bool "Enable membarrier() system call" if EXPERT 1961 default y 1962 help 1963 Enable the membarrier() system call that allows issuing memory 1964 barriers across all running threads, which can be used to distribute 1965 the cost of user-space memory barriers asymmetrically by transforming 1966 pairs of memory barriers into pairs consisting of membarrier() and a 1967 compiler barrier. 1968 1969 If unsure, say Y. 1970 1971config KCMP 1972 bool "Enable kcmp() system call" if EXPERT 1973 help 1974 Enable the kernel resource comparison system call. It provides 1975 user-space with the ability to compare two processes to see if they 1976 share a common resource, such as a file descriptor or even virtual 1977 memory space. 1978 1979 If unsure, say N. 1980 1981config RSEQ 1982 bool "Enable rseq() system call" if EXPERT 1983 default y 1984 depends on HAVE_RSEQ 1985 select MEMBARRIER 1986 help 1987 Enable the restartable sequences system call. It provides a 1988 user-space cache for the current CPU number value, which 1989 speeds up getting the current CPU number from user-space, 1990 as well as an ABI to speed up user-space operations on 1991 per-CPU data. 1992 1993 If unsure, say Y. 1994 1995config RSEQ_SLICE_EXTENSION 1996 bool "Enable rseq-based time slice extension mechanism" 1997 depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS 1998 help 1999 Allows userspace to request a limited time slice extension when 2000 returning from an interrupt to user space via the RSEQ shared 2001 data ABI. If granted, that allows to complete a critical section, 2002 so that other threads are not stuck on a conflicted resource, 2003 while the task is scheduled out. 2004 2005 If unsure, say N. 2006 2007config RSEQ_STATS 2008 default n 2009 bool "Enable lightweight statistics of restartable sequences" if EXPERT 2010 depends on RSEQ && DEBUG_FS 2011 help 2012 Enable lightweight counters which expose information about the 2013 frequency of RSEQ operations via debugfs. Mostly interesting for 2014 kernel debugging or performance analysis. While lightweight it's 2015 still adding code into the user/kernel mode transitions. 2016 2017 If unsure, say N. 2018 2019config RSEQ_DEBUG_DEFAULT_ENABLE 2020 default n 2021 bool "Enable restartable sequences debug mode by default" if EXPERT 2022 depends on RSEQ 2023 help 2024 This enables the static branch for debug mode of restartable 2025 sequences. 2026 2027 This also can be controlled on the kernel command line via the 2028 command line parameter "rseq_debug=0/1" and through debugfs. 2029 2030 If unsure, say N. 2031 2032config DEBUG_RSEQ 2033 default n 2034 bool "Enable debugging of rseq() system call" if EXPERT 2035 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY 2036 select RSEQ_DEBUG_DEFAULT_ENABLE 2037 help 2038 Enable extra debugging checks for the rseq system call. 2039 2040 If unsure, say N. 2041 2042config CACHESTAT_SYSCALL 2043 bool "Enable cachestat() system call" if EXPERT 2044 default y 2045 help 2046 Enable the cachestat system call, which queries the page cache 2047 statistics of a file (number of cached pages, dirty pages, 2048 pages marked for writeback, (recently) evicted pages). 2049 2050 If unsure say Y here. 2051 2052config KALLSYMS 2053 bool "Load all symbols for debugging/ksymoops" if EXPERT 2054 default y 2055 help 2056 Say Y here to let the kernel print out symbolic crash information and 2057 symbolic stack backtraces. This increases the size of the kernel 2058 somewhat, as all symbols have to be loaded into the kernel image. 2059 2060config KALLSYMS_SELFTEST 2061 bool "Test the basic functions and performance of kallsyms" 2062 depends on KALLSYMS 2063 default n 2064 help 2065 Test the basic functions and performance of some interfaces, such as 2066 kallsyms_lookup_name. It also calculates the compression rate of the 2067 kallsyms compression algorithm for the current symbol set. 2068 2069 Start self-test automatically after system startup. Suggest executing 2070 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 2071 displayed in the last line, indicating that the test is complete. 2072 2073config KALLSYMS_ALL 2074 bool "Include all symbols in kallsyms" 2075 depends on DEBUG_KERNEL && KALLSYMS 2076 help 2077 Normally kallsyms only contains the symbols of functions for nicer 2078 OOPS messages and backtraces (i.e., symbols from the text and inittext 2079 sections). This is sufficient for most cases. And only if you want to 2080 enable kernel live patching, or other less common use cases (e.g., 2081 when a debugger is used) all symbols are required (i.e., names of 2082 variables from the data sections, etc). 2083 2084 This option makes sure that all symbols are loaded into the kernel 2085 image (i.e., symbols from all sections) in cost of increased kernel 2086 size (depending on the kernel configuration, it may be 300KiB or 2087 something like this). 2088 2089 Say N unless you really need all symbols, or kernel live patching. 2090 2091# end of the "standard kernel features (expert users)" menu 2092 2093config ARCH_HAS_MEMBARRIER_CALLBACKS 2094 bool 2095 2096config ARCH_HAS_MEMBARRIER_SYNC_CORE 2097 bool 2098 2099config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 2100 bool 2101 help 2102 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 2103 2104 A 64-bit kernel is required for the memory sealing feature. 2105 No specific hardware features from the CPU are needed. 2106 2107 To enable this feature, the architecture needs to update their 2108 special mappings calls to include the sealing flag and confirm 2109 that it doesn't unmap/remap system mappings during the life 2110 time of the process. The existence of this flag for an architecture 2111 implies that it does not require the remapping of the system 2112 mappings during process lifetime, so sealing these mappings is safe 2113 from a kernel perspective. 2114 2115 After the architecture enables this, a distribution can set 2116 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 2117 2118 For complete descriptions of memory sealing, please see 2119 Documentation/userspace-api/mseal.rst 2120 2121config HAVE_PERF_EVENTS 2122 bool 2123 help 2124 See tools/perf/design.txt for details. 2125 2126config GUEST_PERF_EVENTS 2127 bool 2128 depends on HAVE_PERF_EVENTS 2129 2130config PERF_GUEST_MEDIATED_PMU 2131 bool 2132 depends on GUEST_PERF_EVENTS 2133 2134config PERF_USE_VMALLOC 2135 bool 2136 help 2137 See tools/perf/design.txt for details 2138 2139menu "Kernel Performance Events And Counters" 2140 2141config PERF_EVENTS 2142 bool "Kernel performance events and counters" 2143 default y if PROFILING 2144 depends on HAVE_PERF_EVENTS 2145 select IRQ_WORK 2146 help 2147 Enable kernel support for various performance events provided 2148 by software and hardware. 2149 2150 Software events are supported either built-in or via the 2151 use of generic tracepoints. 2152 2153 Most modern CPUs support performance events via performance 2154 counter registers. These registers count the number of certain 2155 types of hw events: such as instructions executed, cachemisses 2156 suffered, or branches mis-predicted - without slowing down the 2157 kernel or applications. These registers can also trigger interrupts 2158 when a threshold number of events have passed - and can thus be 2159 used to profile the code that runs on that CPU. 2160 2161 The Linux Performance Event subsystem provides an abstraction of 2162 these software and hardware event capabilities, available via a 2163 system call and used by the "perf" utility in tools/perf/. It 2164 provides per task and per CPU counters, and it provides event 2165 capabilities on top of those. 2166 2167 Say Y if unsure. 2168 2169config DEBUG_PERF_USE_VMALLOC 2170 default n 2171 bool "Debug: use vmalloc to back perf mmap() buffers" 2172 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2173 select PERF_USE_VMALLOC 2174 help 2175 Use vmalloc memory to back perf mmap() buffers. 2176 2177 Mostly useful for debugging the vmalloc code on platforms 2178 that don't require it. 2179 2180 Say N if unsure. 2181 2182endmenu 2183 2184config SYSTEM_DATA_VERIFICATION 2185 def_bool n 2186 select SYSTEM_TRUSTED_KEYRING 2187 select KEYS 2188 select CRYPTO 2189 select CRYPTO_RSA 2190 select ASYMMETRIC_KEY_TYPE 2191 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2192 select ASN1 2193 select OID_REGISTRY 2194 select X509_CERTIFICATE_PARSER 2195 select PKCS7_MESSAGE_PARSER 2196 help 2197 Provide PKCS#7 message verification using the contents of the system 2198 trusted keyring to provide public keys. This then can be used for 2199 module verification, kexec image verification and firmware blob 2200 verification. 2201 2202config PROFILING 2203 bool "Profiling support" 2204 help 2205 Say Y here to enable the extended profiling support mechanisms used 2206 by profilers. 2207 2208config RUST 2209 bool "Rust support" 2210 depends on HAVE_RUST 2211 depends on RUST_IS_AVAILABLE 2212 select EXTENDED_MODVERSIONS if MODVERSIONS 2213 depends on !MODVERSIONS || GENDWARFKSYMS 2214 depends on !GCC_PLUGIN_RANDSTRUCT 2215 depends on !RANDSTRUCT 2216 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2217 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2218 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2219 depends on !KASAN || CC_IS_CLANG 2220 depends on !KASAN_SW_TAGS || RUSTC_VERSION >= 109600 2221 help 2222 Enables Rust support in the kernel. 2223 2224 This allows other Rust-related options, like drivers written in Rust, 2225 to be selected. 2226 2227 It is also required to be able to load external kernel modules 2228 written in Rust. 2229 2230 See Documentation/rust/ for more information. 2231 2232 If unsure, say N. 2233 2234source "rust/kernel/Kconfig.test" 2235 2236config RUSTC_VERSION_TEXT 2237 string 2238 depends on RUST 2239 default "$(RUSTC_VERSION_TEXT)" 2240 help 2241 See `CC_VERSION_TEXT`. 2242 2243config BINDGEN_VERSION_TEXT 2244 string 2245 depends on RUST 2246 default "$(shell,$(BINDGEN) --version 2>/dev/null)" 2247 2248# 2249# Place an empty function call at each tracepoint site. Can be 2250# dynamically changed for a probe function. 2251# 2252config TRACEPOINTS 2253 bool 2254 select TASKS_TRACE_RCU 2255 2256source "kernel/Kconfig.kexec" 2257 2258source "kernel/liveupdate/Kconfig" 2259 2260endmenu # General setup 2261 2262source "arch/Kconfig" 2263 2264config RT_MUTEXES 2265 bool 2266 default y if PREEMPT_RT 2267 2268config MODULE_SIG_FORMAT 2269 def_bool n 2270 select SYSTEM_DATA_VERIFICATION 2271 2272source "kernel/module/Kconfig" 2273 2274config INIT_ALL_POSSIBLE 2275 bool 2276 help 2277 Back when each arch used to define their own cpu_online_mask and 2278 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2279 with all 1s, and others with all 0s. When they were centralised, 2280 it was better to provide this option than to break all the archs 2281 and have several arch maintainers pursuing me down dark alleys. 2282 2283source "block/Kconfig" 2284 2285config PREEMPT_NOTIFIERS 2286 bool 2287 2288config PADATA 2289 depends on SMP 2290 bool 2291 2292config ASN1 2293 tristate 2294 help 2295 Build a simple ASN.1 grammar compiler that produces a bytecode output 2296 that can be interpreted by the ASN.1 stream decoder and used to 2297 inform it as to what tags are to be expected in a stream and what 2298 functions to call on what tags. 2299 2300source "kernel/Kconfig.locks" 2301 2302config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2303 bool 2304 2305config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2306 bool 2307 2308config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2309 bool 2310 2311# It may be useful for an architecture to override the definitions of the 2312# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2313# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2314# different calling convention for syscalls. They can also override the 2315# macros for not-implemented syscalls in kernel/sys_ni.c and 2316# kernel/time/posix-stubs.c. All these overrides need to be available in 2317# <asm/syscall_wrapper.h>. 2318config ARCH_HAS_SYSCALL_WRAPPER 2319 def_bool n 2320