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 >= 220100 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) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 175 176config LD_CAN_USE_KEEP_IN_OVERLAY 177 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 178 # https://github.com/llvm/llvm-project/pull/130661 179 def_bool LD_IS_BFD || LLD_VERSION >= 210000 180 181config RUSTC_HAS_SPAN_FILE 182 def_bool RUSTC_VERSION >= 108800 183 184config RUSTC_HAS_UNNECESSARY_TRANSMUTES 185 def_bool RUSTC_VERSION >= 108800 186 187config RUSTC_HAS_FILE_WITH_NUL 188 def_bool RUSTC_VERSION >= 108900 189 190config RUSTC_HAS_FILE_AS_C_STR 191 def_bool RUSTC_VERSION >= 109100 192 193config PAHOLE_VERSION 194 int 195 default "$(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 TICK_CPU_ACCOUNTING 566 567# Kind of a stub config for the pure tick based cputime accounting 568config TICK_CPU_ACCOUNTING 569 bool "Simple tick based cputime accounting" 570 depends on !S390 && !NO_HZ_FULL 571 help 572 This is the basic tick based cputime accounting that maintains 573 statistics about user, system and idle time spent on per jiffies 574 granularity. 575 576 If unsure, say Y. 577 578config VIRT_CPU_ACCOUNTING_NATIVE 579 bool "Deterministic task and CPU time accounting" 580 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 581 select VIRT_CPU_ACCOUNTING 582 help 583 Select this option to enable more accurate task and CPU time 584 accounting. This is done by reading a CPU counter on each 585 kernel entry and exit and on transitions within the kernel 586 between system, softirq and hardirq state, so there is a 587 small performance impact. In the case of s390 or IBM POWER > 5, 588 this also enables accounting of stolen time on logically-partitioned 589 systems. 590 591config VIRT_CPU_ACCOUNTING_GEN 592 bool "Full dynticks CPU time accounting" 593 depends on HAVE_CONTEXT_TRACKING_USER 594 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 595 depends on GENERIC_CLOCKEVENTS 596 select VIRT_CPU_ACCOUNTING 597 select CONTEXT_TRACKING_USER 598 help 599 Select this option to enable task and CPU time accounting on full 600 dynticks systems. This accounting is implemented by watching every 601 kernel-user boundaries using the context tracking subsystem. 602 The accounting is thus performed at the expense of some significant 603 overhead. 604 605 For now this is only useful if you are working on the full 606 dynticks subsystem development. 607 608 If unsure, say N. 609 610endchoice 611 612config IRQ_TIME_ACCOUNTING 613 bool "Fine granularity task level IRQ time accounting" 614 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 615 help 616 Select this option to enable fine granularity task irq time 617 accounting. This is done by reading a timestamp on each 618 transitions between softirq and hardirq state, so there can be a 619 small performance impact. 620 621 If in doubt, say N here. 622 623config HAVE_SCHED_AVG_IRQ 624 def_bool y 625 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 626 depends on SMP 627 628config SCHED_HW_PRESSURE 629 bool 630 default y if ARM && ARM_CPU_TOPOLOGY 631 default y if ARM64 632 depends on SMP 633 depends on CPU_FREQ_THERMAL 634 help 635 Select this option to enable HW pressure accounting in the 636 scheduler. HW pressure is the value conveyed to the scheduler 637 that reflects the reduction in CPU compute capacity resulted from 638 HW throttling. HW throttling occurs when the performance of 639 a CPU is capped due to high operating temperatures as an example. 640 641 If selected, the scheduler will be able to balance tasks accordingly, 642 i.e. put less load on throttled CPUs than on non/less throttled ones. 643 644 This requires the architecture to implement 645 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 646 647config BSD_PROCESS_ACCT 648 bool "BSD Process Accounting (DEPRECATED)" 649 depends on MULTIUSER 650 default n 651 help 652 If you say Y here, a user level program will be able to instruct the 653 kernel (via a special system call) to write process accounting 654 information to a file: whenever a process exits, information about 655 that process will be appended to the file by the kernel. The 656 information includes things such as creation time, owning user, 657 command name, memory usage, controlling terminal etc. (the complete 658 list is in the struct acct in <file:include/linux/acct.h>). It is 659 up to the user level program to do useful things with this 660 information. This mechanism is antiquated and has significant 661 scalability issues. You probably want to use eBPF instead. Say 662 N unless you really need this. 663 664config BSD_PROCESS_ACCT_V3 665 bool "BSD Process Accounting version 3 file format" 666 depends on BSD_PROCESS_ACCT 667 default n 668 help 669 If you say Y here, the process accounting information is written 670 in a new file format that also logs the process IDs of each 671 process and its parent. Note that this file format is incompatible 672 with previous v0/v1/v2 file formats, so you will need updated tools 673 for processing it. A preliminary version of these tools is available 674 at <http://www.gnu.org/software/acct/>. 675 676config TASKSTATS 677 bool "Export task/process statistics through netlink" 678 depends on NET 679 depends on MULTIUSER 680 default n 681 help 682 Export selected statistics for tasks/processes through the 683 generic netlink interface. Unlike BSD process accounting, the 684 statistics are available during the lifetime of tasks/processes as 685 responses to commands. Like BSD accounting, they are sent to user 686 space on task exit. 687 688 Say N if unsure. 689 690config TASK_DELAY_ACCT 691 bool "Enable per-task delay accounting" 692 depends on TASKSTATS 693 select SCHED_INFO 694 help 695 Collect information on time spent by a task waiting for system 696 resources like cpu, synchronous block I/O completion and swapping 697 in pages. Such statistics can help in setting a task's priorities 698 relative to other tasks for cpu, io, rss limits etc. 699 700 Say N if unsure. 701 702config TASK_XACCT 703 bool "Enable extended accounting over taskstats" 704 depends on TASKSTATS 705 help 706 Collect extended task accounting data and send the data 707 to userland for processing over the taskstats interface. 708 709 Say N if unsure. 710 711config TASK_IO_ACCOUNTING 712 bool "Enable per-task storage I/O accounting" 713 depends on TASK_XACCT 714 help 715 Collect information on the number of bytes of storage I/O which this 716 task has caused. 717 718 Say N if unsure. 719 720config PSI 721 bool "Pressure stall information tracking" 722 select KERNFS 723 help 724 Collect metrics that indicate how overcommitted the CPU, memory, 725 and IO capacity are in the system. 726 727 If you say Y here, the kernel will create /proc/pressure/ with the 728 pressure statistics files cpu, memory, and io. These will indicate 729 the share of walltime in which some or all tasks in the system are 730 delayed due to contention of the respective resource. 731 732 In kernels with cgroup support, cgroups (cgroup2 only) will 733 have cpu.pressure, memory.pressure, and io.pressure files, 734 which aggregate pressure stalls for the grouped tasks only. 735 736 For more details see Documentation/accounting/psi.rst. 737 738 Say N if unsure. 739 740config PSI_DEFAULT_DISABLED 741 bool "Require boot parameter to enable pressure stall information tracking" 742 default n 743 depends on PSI 744 help 745 If set, pressure stall information tracking will be disabled 746 per default but can be enabled through passing psi=1 on the 747 kernel commandline during boot. 748 749 This feature adds some code to the task wakeup and sleep 750 paths of the scheduler. The overhead is too low to affect 751 common scheduling-intense workloads in practice (such as 752 webservers, memcache), but it does show up in artificial 753 scheduler stress tests, such as hackbench. 754 755 If you are paranoid and not sure what the kernel will be 756 used for, say Y. 757 758 Say N if unsure. 759 760endmenu # "CPU/Task time and stats accounting" 761 762config CPU_ISOLATION 763 bool "CPU isolation" 764 depends on SMP 765 default y 766 help 767 Make sure that CPUs running critical tasks are not disturbed by 768 any source of "noise" such as unbound workqueues, timers, kthreads... 769 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 770 the "isolcpus=" boot parameter. 771 772 Say Y if unsure. 773 774source "kernel/rcu/Kconfig" 775 776config IKCONFIG 777 tristate "Kernel .config support" 778 help 779 This option enables the complete Linux kernel ".config" file 780 contents to be saved in the kernel. It provides documentation 781 of which kernel options are used in a running kernel or in an 782 on-disk kernel. This information can be extracted from the kernel 783 image file with the script scripts/extract-ikconfig and used as 784 input to rebuild the current kernel or to build another kernel. 785 It can also be extracted from a running kernel by reading 786 /proc/config.gz if enabled (below). 787 788config IKCONFIG_PROC 789 bool "Enable access to .config through /proc/config.gz" 790 depends on IKCONFIG && PROC_FS 791 help 792 This option enables access to the kernel configuration file 793 through /proc/config.gz. 794 795config IKHEADERS 796 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 797 depends on SYSFS 798 help 799 This option enables access to the in-kernel headers that are generated during 800 the build process. These can be used to build eBPF tracing programs, 801 or similar programs. If you build the headers as a module, a module called 802 kheaders.ko is built which can be loaded on-demand to get access to headers. 803 804config LOG_BUF_SHIFT 805 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 806 range 12 25 807 default 17 808 depends on PRINTK 809 help 810 Select the minimal kernel log buffer size as a power of 2. 811 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 812 parameter, see below. Any higher size also might be forced 813 by "log_buf_len" boot parameter. 814 815 Examples: 816 17 => 128 KB 817 16 => 64 KB 818 15 => 32 KB 819 14 => 16 KB 820 13 => 8 KB 821 12 => 4 KB 822 823config LOG_CPU_MAX_BUF_SHIFT 824 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 825 depends on SMP 826 range 0 21 827 default 0 if BASE_SMALL 828 default 12 829 depends on PRINTK 830 help 831 This option allows to increase the default ring buffer size 832 according to the number of CPUs. The value defines the contribution 833 of each CPU as a power of 2. The used space is typically only few 834 lines however it might be much more when problems are reported, 835 e.g. backtraces. 836 837 The increased size means that a new buffer has to be allocated and 838 the original static one is unused. It makes sense only on systems 839 with more CPUs. Therefore this value is used only when the sum of 840 contributions is greater than the half of the default kernel ring 841 buffer as defined by LOG_BUF_SHIFT. The default values are set 842 so that more than 16 CPUs are needed to trigger the allocation. 843 844 Also this option is ignored when "log_buf_len" kernel parameter is 845 used as it forces an exact (power of two) size of the ring buffer. 846 847 The number of possible CPUs is used for this computation ignoring 848 hotplugging making the computation optimal for the worst case 849 scenario while allowing a simple algorithm to be used from bootup. 850 851 Examples shift values and their meaning: 852 17 => 128 KB for each CPU 853 16 => 64 KB for each CPU 854 15 => 32 KB for each CPU 855 14 => 16 KB for each CPU 856 13 => 8 KB for each CPU 857 12 => 4 KB for each CPU 858 859config PRINTK_INDEX 860 bool "Printk indexing debugfs interface" 861 depends on PRINTK && DEBUG_FS 862 help 863 Add support for indexing of all printk formats known at compile time 864 at <debugfs>/printk/index/<module>. 865 866 This can be used as part of maintaining daemons which monitor 867 /dev/kmsg, as it permits auditing the printk formats present in a 868 kernel, allowing detection of cases where monitored printks are 869 changed or no longer present. 870 871 There is no additional runtime cost to printk with this enabled. 872 873# 874# Architectures with an unreliable sched_clock() should select this: 875# 876config HAVE_UNSTABLE_SCHED_CLOCK 877 bool 878 879config GENERIC_SCHED_CLOCK 880 bool 881 882menu "Scheduler features" 883 884config UCLAMP_TASK 885 bool "Enable utilization clamping for RT/FAIR tasks" 886 depends on CPU_FREQ_GOV_SCHEDUTIL 887 help 888 This feature enables the scheduler to track the clamped utilization 889 of each CPU based on RUNNABLE tasks scheduled on that CPU. 890 891 With this option, the user can specify the min and max CPU 892 utilization allowed for RUNNABLE tasks. The max utilization defines 893 the maximum frequency a task should use while the min utilization 894 defines the minimum frequency it should use. 895 896 Both min and max utilization clamp values are hints to the scheduler, 897 aiming at improving its frequency selection policy, but they do not 898 enforce or grant any specific bandwidth for tasks. 899 900 If in doubt, say N. 901 902config UCLAMP_BUCKETS_COUNT 903 int "Number of supported utilization clamp buckets" 904 range 5 20 905 default 5 906 depends on UCLAMP_TASK 907 help 908 Defines the number of clamp buckets to use. The range of each bucket 909 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 910 number of clamp buckets the finer their granularity and the higher 911 the precision of clamping aggregation and tracking at run-time. 912 913 For example, with the minimum configuration value we will have 5 914 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 915 be refcounted in the [20..39]% bucket and will set the bucket clamp 916 effective value to 25%. 917 If a second 30% boosted task should be co-scheduled on the same CPU, 918 that task will be refcounted in the same bucket of the first task and 919 it will boost the bucket clamp effective value to 30%. 920 The clamp effective value of a bucket is reset to its nominal value 921 (20% in the example above) when there are no more tasks refcounted in 922 that bucket. 923 924 An additional boost/capping margin can be added to some tasks. In the 925 example above the 25% task will be boosted to 30% until it exits the 926 CPU. If that should be considered not acceptable on certain systems, 927 it's always possible to reduce the margin by increasing the number of 928 clamp buckets to trade off used memory for run-time tracking 929 precision. 930 931 If in doubt, use the default value. 932 933config SCHED_PROXY_EXEC 934 bool "Proxy Execution" 935 # Avoid some build failures w/ PREEMPT_RT until it can be fixed 936 depends on !PREEMPT_RT 937 # Need to investigate how to inform sched_ext of split contexts 938 depends on !SCHED_CLASS_EXT 939 # Not particularly useful until we get to multi-rq proxying 940 depends on EXPERT 941 help 942 This option enables proxy execution, a mechanism for mutex-owning 943 tasks to inherit the scheduling context of higher priority waiters. 944 945endmenu 946 947# 948# For architectures that want to enable the support for NUMA-affine scheduler 949# balancing logic: 950# 951config ARCH_SUPPORTS_NUMA_BALANCING 952 bool 953 954# 955# For architectures that prefer to flush all TLBs after a number of pages 956# are unmapped instead of sending one IPI per page to flush. The architecture 957# must provide guarantees on what happens if a clean TLB cache entry is 958# written after the unmap. Details are in mm/rmap.c near the check for 959# should_defer_flush. The architecture should also consider if the full flush 960# and the refill costs are offset by the savings of sending fewer IPIs. 961config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 962 bool 963 964config CC_HAS_INT128 965 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 966 967config CC_IMPLICIT_FALLTHROUGH 968 string 969 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 970 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 971 972# Currently, disable gcc-10+ array-bounds globally. 973# It's still broken in gcc-13, so no upper bound yet. 974config GCC10_NO_ARRAY_BOUNDS 975 def_bool y 976 977config CC_NO_ARRAY_BOUNDS 978 bool 979 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 980 981# Currently, disable -Wstringop-overflow for GCC globally. 982config GCC_NO_STRINGOP_OVERFLOW 983 def_bool y 984 985config CC_NO_STRINGOP_OVERFLOW 986 bool 987 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 988 989config CC_STRINGOP_OVERFLOW 990 bool 991 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 992 993# 994# For architectures that know their GCC __int128 support is sound 995# 996config ARCH_SUPPORTS_INT128 997 bool 998 999# For architectures that (ab)use NUMA to represent different memory regions 1000# all cpu-local but of different latencies, such as SuperH. 1001# 1002config ARCH_WANT_NUMA_VARIABLE_LOCALITY 1003 bool 1004 1005config NUMA_BALANCING 1006 bool "Memory placement aware NUMA scheduler" 1007 depends on ARCH_SUPPORTS_NUMA_BALANCING 1008 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 1009 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 1010 help 1011 This option adds support for automatic NUMA aware memory/task placement. 1012 The mechanism is quite primitive and is based on migrating memory when 1013 it has references to the node the task is running on. 1014 1015 This system will be inactive on UMA systems. 1016 1017config NUMA_BALANCING_DEFAULT_ENABLED 1018 bool "Automatically enable NUMA aware memory/task placement" 1019 default y 1020 depends on NUMA_BALANCING 1021 help 1022 If set, automatic NUMA balancing will be enabled if running on a NUMA 1023 machine. 1024 1025config SLAB_OBJ_EXT 1026 bool 1027 1028menuconfig CGROUPS 1029 bool "Control Group support" 1030 select KERNFS 1031 help 1032 This option adds support for grouping sets of processes together, for 1033 use with process control subsystems such as Cpusets, CFS, memory 1034 controls or device isolation. 1035 See 1036 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1037 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1038 and resource control) 1039 1040 Say N if unsure. 1041 1042if CGROUPS 1043 1044config PAGE_COUNTER 1045 bool 1046 1047config CGROUP_FAVOR_DYNMODS 1048 bool "Favor dynamic modification latency reduction by default" 1049 help 1050 This option enables the "favordynmods" mount option by default 1051 which reduces the latencies of dynamic cgroup modifications such 1052 as task migrations and controller on/offs at the cost of making 1053 hot path operations such as forks and exits more expensive. 1054 1055 Say N if unsure. 1056 1057config MEMCG 1058 bool "Memory controller" 1059 select PAGE_COUNTER 1060 select EVENTFD 1061 select SLAB_OBJ_EXT 1062 select VM_EVENT_COUNTERS 1063 help 1064 Provides control over the memory footprint of tasks in a cgroup. 1065 1066config MEMCG_NMI_UNSAFE 1067 bool 1068 depends on MEMCG 1069 depends on HAVE_NMI 1070 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1071 default y 1072 1073config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1074 bool 1075 depends on MEMCG 1076 depends on HAVE_NMI 1077 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1078 default y 1079 1080config MEMCG_V1 1081 bool "Legacy cgroup v1 memory controller" 1082 depends on MEMCG 1083 default n 1084 help 1085 Legacy cgroup v1 memory controller which has been deprecated by 1086 cgroup v2 implementation. The v1 is there for legacy applications 1087 which haven't migrated to the new cgroup v2 interface yet. If you 1088 do not have any such application then you are completely fine leaving 1089 this option disabled. 1090 1091 Please note that feature set of the legacy memory controller is likely 1092 going to shrink due to deprecation process. New deployments with v1 1093 controller are highly discouraged. 1094 1095 Say N if unsure. 1096 1097config BLK_CGROUP 1098 bool "IO controller" 1099 depends on BLOCK 1100 default n 1101 help 1102 Generic block IO controller cgroup interface. This is the common 1103 cgroup interface which should be used by various IO controlling 1104 policies. 1105 1106 Currently, CFQ IO scheduler uses it to recognize task groups and 1107 control disk bandwidth allocation (proportional time slice allocation) 1108 to such task groups. It is also used by bio throttling logic in 1109 block layer to implement upper limit in IO rates on a device. 1110 1111 This option only enables generic Block IO controller infrastructure. 1112 One needs to also enable actual IO controlling logic/policy. For 1113 enabling proportional weight division of disk bandwidth in CFQ, set 1114 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1115 CONFIG_BLK_DEV_THROTTLING=y. 1116 1117 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1118 1119config CGROUP_WRITEBACK 1120 bool 1121 depends on MEMCG && BLK_CGROUP 1122 default y 1123 1124menuconfig CGROUP_SCHED 1125 bool "CPU controller" 1126 default n 1127 help 1128 This feature lets CPU scheduler recognize task groups and control CPU 1129 bandwidth allocation to such task groups. It uses cgroups to group 1130 tasks. 1131 1132if CGROUP_SCHED 1133config GROUP_SCHED_WEIGHT 1134 def_bool n 1135 1136config GROUP_SCHED_BANDWIDTH 1137 def_bool n 1138 1139config FAIR_GROUP_SCHED 1140 bool "Group scheduling for SCHED_OTHER" 1141 depends on CGROUP_SCHED 1142 select GROUP_SCHED_WEIGHT 1143 default CGROUP_SCHED 1144 1145config CFS_BANDWIDTH 1146 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1147 depends on FAIR_GROUP_SCHED 1148 select GROUP_SCHED_BANDWIDTH 1149 default n 1150 help 1151 This option allows users to define CPU bandwidth rates (limits) for 1152 tasks running within the fair group scheduler. Groups with no limit 1153 set are considered to be unconstrained and will run with no 1154 restriction. 1155 See Documentation/scheduler/sched-bwc.rst for more information. 1156 1157config RT_GROUP_SCHED 1158 bool "Group scheduling for SCHED_RR/FIFO" 1159 depends on CGROUP_SCHED 1160 default n 1161 help 1162 This feature lets you explicitly allocate real CPU bandwidth 1163 to task groups. If enabled, it will also make it impossible to 1164 schedule realtime tasks for non-root users until you allocate 1165 realtime bandwidth for them. 1166 See Documentation/scheduler/sched-rt-group.rst for more information. 1167 1168config RT_GROUP_SCHED_DEFAULT_DISABLED 1169 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1170 depends on RT_GROUP_SCHED 1171 default n 1172 help 1173 When set, the RT group scheduling is disabled by default. The option 1174 is in inverted form so that mere RT_GROUP_SCHED enables the group 1175 scheduling. 1176 1177 Say N if unsure. 1178 1179config EXT_GROUP_SCHED 1180 bool 1181 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1182 select GROUP_SCHED_WEIGHT 1183 select GROUP_SCHED_BANDWIDTH 1184 default y 1185 1186endif #CGROUP_SCHED 1187 1188config SCHED_MM_CID 1189 def_bool y 1190 depends on SMP && RSEQ 1191 1192config UCLAMP_TASK_GROUP 1193 bool "Utilization clamping per group of tasks" 1194 depends on CGROUP_SCHED 1195 depends on UCLAMP_TASK 1196 default n 1197 help 1198 This feature enables the scheduler to track the clamped utilization 1199 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1200 1201 When this option is enabled, the user can specify a min and max 1202 CPU bandwidth which is allowed for each single task in a group. 1203 The max bandwidth allows to clamp the maximum frequency a task 1204 can use, while the min bandwidth allows to define a minimum 1205 frequency a task will always use. 1206 1207 When task group based utilization clamping is enabled, an eventually 1208 specified task-specific clamp value is constrained by the cgroup 1209 specified clamp value. Both minimum and maximum task clamping cannot 1210 be bigger than the corresponding clamping defined at task group level. 1211 1212 If in doubt, say N. 1213 1214config CGROUP_PIDS 1215 bool "PIDs controller" 1216 help 1217 Provides enforcement of process number limits in the scope of a 1218 cgroup. Any attempt to fork more processes than is allowed in the 1219 cgroup will fail. PIDs are fundamentally a global resource because it 1220 is fairly trivial to reach PID exhaustion before you reach even a 1221 conservative kmemcg limit. As a result, it is possible to grind a 1222 system to halt without being limited by other cgroup policies. The 1223 PIDs controller is designed to stop this from happening. 1224 1225 It should be noted that organisational operations (such as attaching 1226 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1227 since the PIDs limit only affects a process's ability to fork, not to 1228 attach to a cgroup. 1229 1230config CGROUP_RDMA 1231 bool "RDMA controller" 1232 help 1233 Provides enforcement of RDMA resources defined by IB stack. 1234 It is fairly easy for consumers to exhaust RDMA resources, which 1235 can result into resource unavailability to other consumers. 1236 RDMA controller is designed to stop this from happening. 1237 Attaching processes with active RDMA resources to the cgroup 1238 hierarchy is allowed even if can cross the hierarchy's limit. 1239 1240config CGROUP_DMEM 1241 bool "Device memory controller (DMEM)" 1242 select PAGE_COUNTER 1243 help 1244 The DMEM controller allows compatible devices to restrict device 1245 memory usage based on the cgroup hierarchy. 1246 1247 As an example, it allows you to restrict VRAM usage for applications 1248 in the DRM subsystem. 1249 1250config CGROUP_FREEZER 1251 bool "Freezer controller" 1252 help 1253 Provides a way to freeze and unfreeze all tasks in a 1254 cgroup. 1255 1256 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1257 controller includes important in-kernel memory consumers per default. 1258 1259 If you're using cgroup2, say N. 1260 1261config CGROUP_HUGETLB 1262 bool "HugeTLB controller" 1263 depends on HUGETLB_PAGE 1264 select PAGE_COUNTER 1265 default n 1266 help 1267 Provides a cgroup controller for HugeTLB pages. 1268 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1269 The limit is enforced during page fault. Since HugeTLB doesn't 1270 support page reclaim, enforcing the limit at page fault time implies 1271 that, the application will get SIGBUS signal if it tries to access 1272 HugeTLB pages beyond its limit. This requires the application to know 1273 beforehand how much HugeTLB pages it would require for its use. The 1274 control group is tracked in the third page lru pointer. This means 1275 that we cannot use the controller with huge page less than 3 pages. 1276 1277config CPUSETS 1278 bool "Cpuset controller" 1279 depends on SMP 1280 select UNION_FIND 1281 select CPU_ISOLATION 1282 help 1283 This option will let you create and manage CPUSETs which 1284 allow dynamically partitioning a system into sets of CPUs and 1285 Memory Nodes and assigning tasks to run only within those sets. 1286 This is primarily useful on large SMP or NUMA systems. 1287 1288 Say N if unsure. 1289 1290config CPUSETS_V1 1291 bool "Legacy cgroup v1 cpusets controller" 1292 depends on CPUSETS 1293 default n 1294 help 1295 Legacy cgroup v1 cpusets controller which has been deprecated by 1296 cgroup v2 implementation. The v1 is there for legacy applications 1297 which haven't migrated to the new cgroup v2 interface yet. Legacy 1298 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1299 do not have any such application then you are completely fine leaving 1300 this option disabled. 1301 1302 Say N if unsure. 1303 1304config PROC_PID_CPUSET 1305 bool "Include legacy /proc/<pid>/cpuset file" 1306 depends on CPUSETS_V1 1307 default y 1308 1309config CGROUP_DEVICE 1310 bool "Device controller" 1311 help 1312 Provides a cgroup controller implementing whitelists for 1313 devices which a process in the cgroup can mknod or open. 1314 1315config CGROUP_CPUACCT 1316 bool "Simple CPU accounting controller" 1317 help 1318 Provides a simple controller for monitoring the 1319 total CPU consumed by the tasks in a cgroup. 1320 1321config CGROUP_PERF 1322 bool "Perf controller" 1323 depends on PERF_EVENTS 1324 help 1325 This option extends the perf per-cpu mode to restrict monitoring 1326 to threads which belong to the cgroup specified and run on the 1327 designated cpu. Or this can be used to have cgroup ID in samples 1328 so that it can monitor performance events among cgroups. 1329 1330 Say N if unsure. 1331 1332config CGROUP_BPF 1333 bool "Support for eBPF programs attached to cgroups" 1334 depends on BPF_SYSCALL 1335 select SOCK_CGROUP_DATA 1336 help 1337 Allow attaching eBPF programs to a cgroup using the bpf(2) 1338 syscall command BPF_PROG_ATTACH. 1339 1340 In which context these programs are accessed depends on the type 1341 of attachment. For instance, programs that are attached using 1342 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1343 inet sockets. 1344 1345config CGROUP_MISC 1346 bool "Misc resource controller" 1347 default n 1348 help 1349 Provides a controller for miscellaneous resources on a host. 1350 1351 Miscellaneous scalar resources are the resources on the host system 1352 which cannot be abstracted like the other cgroups. This controller 1353 tracks and limits the miscellaneous resources used by a process 1354 attached to a cgroup hierarchy. 1355 1356 For more information, please check misc cgroup section in 1357 /Documentation/admin-guide/cgroup-v2.rst. 1358 1359config CGROUP_DEBUG 1360 bool "Debug controller" 1361 default n 1362 depends on DEBUG_KERNEL 1363 help 1364 This option enables a simple controller that exports 1365 debugging information about the cgroups framework. This 1366 controller is for control cgroup debugging only. Its 1367 interfaces are not stable. 1368 1369 Say N. 1370 1371config SOCK_CGROUP_DATA 1372 bool 1373 default n 1374 1375endif # CGROUPS 1376 1377menuconfig NAMESPACES 1378 bool "Namespaces support" if EXPERT 1379 depends on MULTIUSER 1380 default !EXPERT 1381 help 1382 Provides the way to make tasks work with different objects using 1383 the same id. For example same IPC id may refer to different objects 1384 or same user id or pid may refer to different tasks when used in 1385 different namespaces. 1386 1387if NAMESPACES 1388 1389config UTS_NS 1390 bool "UTS namespace" 1391 default y 1392 help 1393 In this namespace tasks see different info provided with the 1394 uname() system call 1395 1396config TIME_NS 1397 bool "TIME namespace" 1398 depends on GENERIC_GETTIMEOFDAY 1399 default y 1400 help 1401 In this namespace boottime and monotonic clocks can be set. 1402 The time will keep going with the same pace. 1403 1404config IPC_NS 1405 bool "IPC namespace" 1406 depends on (SYSVIPC || POSIX_MQUEUE) 1407 default y 1408 help 1409 In this namespace tasks work with IPC ids which correspond to 1410 different IPC objects in different namespaces. 1411 1412config USER_NS 1413 bool "User namespace" 1414 default n 1415 help 1416 This allows containers, i.e. vservers, to use user namespaces 1417 to provide different user info for different servers. 1418 1419 When user namespaces are enabled in the kernel it is 1420 recommended that the MEMCG option also be enabled and that 1421 user-space use the memory control groups to limit the amount 1422 of memory a memory unprivileged users can use. 1423 1424 If unsure, say N. 1425 1426config PID_NS 1427 bool "PID Namespaces" 1428 default y 1429 help 1430 Support process id namespaces. This allows having multiple 1431 processes with the same pid as long as they are in different 1432 pid namespaces. This is a building block of containers. 1433 1434config NET_NS 1435 bool "Network namespace" 1436 depends on NET 1437 default y 1438 help 1439 Allow user space to create what appear to be multiple instances 1440 of the network stack. 1441 1442endif # NAMESPACES 1443 1444config CHECKPOINT_RESTORE 1445 bool "Checkpoint/restore support" 1446 depends on PROC_FS 1447 select PROC_CHILDREN 1448 select KCMP 1449 default n 1450 help 1451 Enables additional kernel features in a sake of checkpoint/restore. 1452 In particular it adds auxiliary prctl codes to setup process text, 1453 data and heap segment sizes, and a few additional /proc filesystem 1454 entries. 1455 1456 If unsure, say N here. 1457 1458config SCHED_AUTOGROUP 1459 bool "Automatic process group scheduling" 1460 select CGROUPS 1461 select CGROUP_SCHED 1462 select FAIR_GROUP_SCHED 1463 help 1464 This option optimizes the scheduler for common desktop workloads by 1465 automatically creating and populating task groups. This separation 1466 of workloads isolates aggressive CPU burners (like build jobs) from 1467 desktop applications. Task group autogeneration is currently based 1468 upon task session. 1469 1470config RELAY 1471 bool "Kernel->user space relay support (formerly relayfs)" 1472 select IRQ_WORK 1473 help 1474 This option enables support for relay interface support in 1475 certain file systems (such as debugfs). 1476 It is designed to provide an efficient mechanism for tools and 1477 facilities to relay large amounts of data from kernel space to 1478 user space. 1479 1480 If unsure, say N. 1481 1482config BLK_DEV_INITRD 1483 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1484 help 1485 The initial RAM filesystem is a ramfs which is loaded by the 1486 boot loader (loadlin or lilo) and that is mounted as root 1487 before the normal boot procedure. It is typically used to 1488 load modules needed to mount the "real" root file system, 1489 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1490 1491 If RAM disk support (BLK_DEV_RAM) is also included, this 1492 also enables initial RAM disk (initrd) support and adds 1493 15 Kbytes (more on some other architectures) to the kernel size. 1494 1495 If unsure say Y. 1496 1497if BLK_DEV_INITRD 1498 1499source "usr/Kconfig" 1500 1501endif 1502 1503config BOOT_CONFIG 1504 bool "Boot config support" 1505 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1506 help 1507 Extra boot config allows system admin to pass a config file as 1508 complemental extension of kernel cmdline when booting. 1509 The boot config file must be attached at the end of initramfs 1510 with checksum, size and magic word. 1511 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1512 1513 If unsure, say Y. 1514 1515config BOOT_CONFIG_FORCE 1516 bool "Force unconditional bootconfig processing" 1517 depends on BOOT_CONFIG 1518 default y if BOOT_CONFIG_EMBED 1519 help 1520 With this Kconfig option set, BOOT_CONFIG processing is carried 1521 out even when the "bootconfig" kernel-boot parameter is omitted. 1522 In fact, with this Kconfig option set, there is no way to 1523 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1524 parameters. 1525 1526 If unsure, say N. 1527 1528config BOOT_CONFIG_EMBED 1529 bool "Embed bootconfig file in the kernel" 1530 depends on BOOT_CONFIG 1531 help 1532 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1533 kernel. Usually, the bootconfig file is loaded with the initrd 1534 image. But if the system doesn't support initrd, this option will 1535 help you by embedding a bootconfig file while building the kernel. 1536 1537 If unsure, say N. 1538 1539config BOOT_CONFIG_EMBED_FILE 1540 string "Embedded bootconfig file path" 1541 depends on BOOT_CONFIG_EMBED 1542 help 1543 Specify a bootconfig file which will be embedded to the kernel. 1544 This bootconfig will be used if there is no initrd or no other 1545 bootconfig in the initrd. 1546 1547config CMDLINE_LOG_WRAP_IDEAL_LEN 1548 int "Length to try to wrap the cmdline when logged at boot" 1549 default 1021 1550 range 0 1021 1551 help 1552 At boot time, the kernel command line is logged to the console. 1553 The log message will start with the prefix "Kernel command line: ". 1554 The log message will attempt to be wrapped (split into multiple log 1555 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters. 1556 If wrapping happens, each log message will start with the prefix and 1557 all but the last message will end with " \". Messages may exceed the 1558 ideal length if a place to wrap isn't found before the specified 1559 number of characters. 1560 1561 A value of 0 disables wrapping, though be warned that the maximum 1562 length of a log message (1021 characters) may cause the cmdline to 1563 be truncated. 1564 1565config INITRAMFS_PRESERVE_MTIME 1566 bool "Preserve cpio archive mtimes in initramfs" 1567 depends on BLK_DEV_INITRD 1568 default y 1569 help 1570 Each entry in an initramfs cpio archive carries an mtime value. When 1571 enabled, extracted cpio items take this mtime, with directory mtime 1572 setting deferred until after creation of any child entries. 1573 1574 If unsure, say Y. 1575 1576config INITRAMFS_TEST 1577 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1578 depends on BLK_DEV_INITRD && KUNIT=y 1579 default KUNIT_ALL_TESTS 1580 help 1581 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1582 1583choice 1584 prompt "Compiler optimization level" 1585 default CC_OPTIMIZE_FOR_PERFORMANCE 1586 1587config CC_OPTIMIZE_FOR_PERFORMANCE 1588 bool "Optimize for performance (-O2)" 1589 help 1590 This is the default optimization level for the kernel, building 1591 with the "-O2" compiler flag for best performance and most 1592 helpful compile-time warnings. 1593 1594config CC_OPTIMIZE_FOR_SIZE 1595 bool "Optimize for size (-Os)" 1596 help 1597 Choosing this option will pass "-Os" to your compiler resulting 1598 in a smaller kernel. 1599 1600endchoice 1601 1602config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1603 bool 1604 help 1605 This requires that the arch annotates or otherwise protects 1606 its external entry points from being discarded. Linker scripts 1607 must also merge .text.*, .data.*, and .bss.* correctly into 1608 output sections. Care must be taken not to pull in unrelated 1609 sections (e.g., '.text.init'). Typically '.' in section names 1610 is used to distinguish them from label names / C identifiers. 1611 1612config LD_DEAD_CODE_DATA_ELIMINATION 1613 bool "Dead code and data elimination (EXPERIMENTAL)" 1614 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1615 depends on EXPERT 1616 depends on $(cc-option,-ffunction-sections -fdata-sections) 1617 depends on $(ld-option,--gc-sections) 1618 help 1619 Enable this if you want to do dead code and data elimination with 1620 the linker by compiling with -ffunction-sections -fdata-sections, 1621 and linking with --gc-sections. 1622 1623 This can reduce on disk and in-memory size of the kernel 1624 code and static data, particularly for small configs and 1625 on small systems. This has the possibility of introducing 1626 silently broken kernel if the required annotations are not 1627 present. This option is not well tested yet, so use at your 1628 own risk. 1629 1630config LD_ORPHAN_WARN 1631 def_bool y 1632 depends on ARCH_WANT_LD_ORPHAN_WARN 1633 depends on $(ld-option,--orphan-handling=warn) 1634 depends on $(ld-option,--orphan-handling=error) 1635 1636config LD_ORPHAN_WARN_LEVEL 1637 string 1638 depends on LD_ORPHAN_WARN 1639 default "error" if WERROR 1640 default "warn" 1641 1642config SYSCTL 1643 bool 1644 1645config HAVE_UID16 1646 bool 1647 1648config SYSCTL_EXCEPTION_TRACE 1649 bool 1650 help 1651 Enable support for /proc/sys/debug/exception-trace. 1652 1653config SYSCTL_ARCH_UNALIGN_NO_WARN 1654 bool 1655 help 1656 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1657 Allows arch to define/use @no_unaligned_warning to possibly warn 1658 about unaligned access emulation going on under the hood. 1659 1660config SYSCTL_ARCH_UNALIGN_ALLOW 1661 bool 1662 help 1663 Enable support for /proc/sys/kernel/unaligned-trap 1664 Allows arches to define/use @unaligned_enabled to runtime toggle 1665 the unaligned access emulation. 1666 see arch/parisc/kernel/unaligned.c for reference 1667 1668config SYSFS_SYSCALL 1669 bool "Sysfs syscall support" 1670 default n 1671 help 1672 sys_sysfs is an obsolete system call no longer supported in libc. 1673 Note that disabling this option is more secure but might break 1674 compatibility with some systems. 1675 1676 If unsure say N here. 1677 1678config HAVE_PCSPKR_PLATFORM 1679 bool 1680 1681menuconfig EXPERT 1682 bool "Configure standard kernel features (expert users)" 1683 # Unhide debug options, to make the on-by-default options visible 1684 select DEBUG_KERNEL 1685 help 1686 This option allows certain base kernel options and settings 1687 to be disabled or tweaked. This is for specialized 1688 environments which can tolerate a "non-standard" kernel. 1689 Only use this if you really know what you are doing. 1690 1691config UID16 1692 bool "Enable 16-bit UID system calls" if EXPERT 1693 depends on HAVE_UID16 && MULTIUSER 1694 default y 1695 help 1696 This enables the legacy 16-bit UID syscall wrappers. 1697 1698config MULTIUSER 1699 bool "Multiple users, groups and capabilities support" if EXPERT 1700 default y 1701 help 1702 This option enables support for non-root users, groups and 1703 capabilities. 1704 1705 If you say N here, all processes will run with UID 0, GID 0, and all 1706 possible capabilities. Saying N here also compiles out support for 1707 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1708 setgid, and capset. 1709 1710 If unsure, say Y here. 1711 1712config SGETMASK_SYSCALL 1713 bool "sgetmask/ssetmask syscalls support" if EXPERT 1714 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1715 help 1716 sys_sgetmask and sys_ssetmask are obsolete system calls 1717 no longer supported in libc but still enabled by default in some 1718 architectures. 1719 1720 If unsure, leave the default option here. 1721 1722config FHANDLE 1723 bool "open by fhandle syscalls" if EXPERT 1724 select EXPORTFS 1725 default y 1726 help 1727 If you say Y here, a user level program will be able to map 1728 file names to handle and then later use the handle for 1729 different file system operations. This is useful in implementing 1730 userspace file servers, which now track files using handles instead 1731 of names. The handle would remain the same even if file names 1732 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1733 syscalls. 1734 1735config POSIX_TIMERS 1736 bool "Posix Clocks & timers" if EXPERT 1737 default y 1738 help 1739 This includes native support for POSIX timers to the kernel. 1740 Some embedded systems have no use for them and therefore they 1741 can be configured out to reduce the size of the kernel image. 1742 1743 When this option is disabled, the following syscalls won't be 1744 available: timer_create, timer_gettime: timer_getoverrun, 1745 timer_settime, timer_delete, clock_adjtime, getitimer, 1746 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1747 clock_getres and clock_nanosleep syscalls will be limited to 1748 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1749 1750 If unsure say y. 1751 1752config PRINTK 1753 default y 1754 bool "Enable support for printk" if EXPERT 1755 select IRQ_WORK 1756 help 1757 This option enables normal printk support. Removing it 1758 eliminates most of the message strings from the kernel image 1759 and makes the kernel more or less silent. As this makes it 1760 very difficult to diagnose system problems, saying N here is 1761 strongly discouraged. 1762 1763config PRINTK_RINGBUFFER_KUNIT_TEST 1764 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1765 depends on PRINTK && KUNIT 1766 default KUNIT_ALL_TESTS 1767 help 1768 This builds the printk ringbuffer KUnit test suite. 1769 1770 For more information on KUnit and unit tests in general, please refer 1771 to the KUnit documentation. 1772 1773 If unsure, say N. 1774 1775config BUG 1776 bool "BUG() support" if EXPERT 1777 default y 1778 help 1779 Disabling this option eliminates support for BUG and WARN, reducing 1780 the size of your kernel image and potentially quietly ignoring 1781 numerous fatal conditions. You should only consider disabling this 1782 option for embedded systems with no facilities for reporting errors. 1783 Just say Y. 1784 1785config ELF_CORE 1786 depends on COREDUMP 1787 default y 1788 bool "Enable ELF core dumps" if EXPERT 1789 help 1790 Enable support for generating core dumps. Disabling saves about 4k. 1791 1792 1793config PCSPKR_PLATFORM 1794 bool "Enable PC-Speaker support" if EXPERT 1795 depends on HAVE_PCSPKR_PLATFORM 1796 select I8253_LOCK 1797 default y 1798 help 1799 This option allows to disable the internal PC-Speaker 1800 support, saving some memory. 1801 1802config BASE_SMALL 1803 bool "Enable smaller-sized data structures for core" if EXPERT 1804 help 1805 Enabling this option reduces the size of miscellaneous core 1806 kernel data structures. This saves memory on small machines, 1807 but may reduce performance. 1808 1809config FUTEX 1810 bool "Enable futex support" if EXPERT 1811 depends on !(SPARC32 && SMP) 1812 default y 1813 imply RT_MUTEXES 1814 help 1815 Disabling this option will cause the kernel to be built without 1816 support for "fast userspace mutexes". The resulting kernel may not 1817 run glibc-based applications correctly. 1818 1819config FUTEX_PI 1820 bool 1821 depends on FUTEX && RT_MUTEXES 1822 default y 1823 1824config FUTEX_PRIVATE_HASH 1825 bool 1826 depends on FUTEX && !BASE_SMALL && MMU 1827 default y 1828 1829config FUTEX_MPOL 1830 bool 1831 depends on FUTEX && NUMA 1832 default y 1833 1834config EPOLL 1835 bool "Enable eventpoll support" if EXPERT 1836 default y 1837 help 1838 Disabling this option will cause the kernel to be built without 1839 support for epoll family of system calls. 1840 1841config SIGNALFD 1842 bool "Enable signalfd() system call" if EXPERT 1843 default y 1844 help 1845 Enable the signalfd() system call that allows to receive signals 1846 on a file descriptor. 1847 1848 If unsure, say Y. 1849 1850config TIMERFD 1851 bool "Enable timerfd() system call" if EXPERT 1852 default y 1853 help 1854 Enable the timerfd() system call that allows to receive timer 1855 events on a file descriptor. 1856 1857 If unsure, say Y. 1858 1859config EVENTFD 1860 bool "Enable eventfd() system call" if EXPERT 1861 default y 1862 help 1863 Enable the eventfd() system call that allows to receive both 1864 kernel notification (ie. KAIO) or userspace notifications. 1865 1866 If unsure, say Y. 1867 1868config SHMEM 1869 bool "Use full shmem filesystem" if EXPERT 1870 default y 1871 depends on MMU 1872 help 1873 The shmem is an internal filesystem used to manage shared memory. 1874 It is backed by swap and manages resource limits. It is also exported 1875 to userspace as tmpfs if TMPFS is enabled. Disabling this 1876 option replaces shmem and tmpfs with the much simpler ramfs code, 1877 which may be appropriate on small systems without swap. 1878 1879config AIO 1880 bool "Enable AIO support" if EXPERT 1881 default y 1882 help 1883 This option enables POSIX asynchronous I/O which may by used 1884 by some high performance threaded applications. Disabling 1885 this option saves about 7k. 1886 1887config IO_URING 1888 bool "Enable IO uring support" if EXPERT 1889 select IO_WQ 1890 default y 1891 help 1892 This option enables support for the io_uring interface, enabling 1893 applications to submit and complete IO through submission and 1894 completion rings that are shared between the kernel and application. 1895 1896config GCOV_PROFILE_URING 1897 bool "Enable GCOV profiling on the io_uring subsystem" 1898 depends on IO_URING && GCOV_KERNEL 1899 help 1900 Enable GCOV profiling on the io_uring subsystem, to facilitate 1901 code coverage testing. 1902 1903 If unsure, say N. 1904 1905 Note that this will have a negative impact on the performance of 1906 the io_uring subsystem, hence this should only be enabled for 1907 specific test purposes. 1908 1909config IO_URING_MOCK_FILE 1910 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1911 default n 1912 depends on IO_URING 1913 help 1914 Enable mock files for io_uring subsystem testing. The ABI might 1915 still change, so it's still experimental and should only be enabled 1916 for specific test purposes. 1917 1918 If unsure, say N. 1919 1920config ADVISE_SYSCALLS 1921 bool "Enable madvise/fadvise syscalls" if EXPERT 1922 default y 1923 help 1924 This option enables the madvise and fadvise syscalls, used by 1925 applications to advise the kernel about their future memory or file 1926 usage, improving performance. If building an embedded system where no 1927 applications use these syscalls, you can disable this option to save 1928 space. 1929 1930config MEMBARRIER 1931 bool "Enable membarrier() system call" if EXPERT 1932 default y 1933 help 1934 Enable the membarrier() system call that allows issuing memory 1935 barriers across all running threads, which can be used to distribute 1936 the cost of user-space memory barriers asymmetrically by transforming 1937 pairs of memory barriers into pairs consisting of membarrier() and a 1938 compiler barrier. 1939 1940 If unsure, say Y. 1941 1942config KCMP 1943 bool "Enable kcmp() system call" if EXPERT 1944 help 1945 Enable the kernel resource comparison system call. It provides 1946 user-space with the ability to compare two processes to see if they 1947 share a common resource, such as a file descriptor or even virtual 1948 memory space. 1949 1950 If unsure, say N. 1951 1952config RSEQ 1953 bool "Enable rseq() system call" if EXPERT 1954 default y 1955 depends on HAVE_RSEQ 1956 select MEMBARRIER 1957 help 1958 Enable the restartable sequences system call. It provides a 1959 user-space cache for the current CPU number value, which 1960 speeds up getting the current CPU number from user-space, 1961 as well as an ABI to speed up user-space operations on 1962 per-CPU data. 1963 1964 If unsure, say Y. 1965 1966config RSEQ_SLICE_EXTENSION 1967 bool "Enable rseq-based time slice extension mechanism" 1968 depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS 1969 help 1970 Allows userspace to request a limited time slice extension when 1971 returning from an interrupt to user space via the RSEQ shared 1972 data ABI. If granted, that allows to complete a critical section, 1973 so that other threads are not stuck on a conflicted resource, 1974 while the task is scheduled out. 1975 1976 If unsure, say N. 1977 1978config RSEQ_STATS 1979 default n 1980 bool "Enable lightweight statistics of restartable sequences" if EXPERT 1981 depends on RSEQ && DEBUG_FS 1982 help 1983 Enable lightweight counters which expose information about the 1984 frequency of RSEQ operations via debugfs. Mostly interesting for 1985 kernel debugging or performance analysis. While lightweight it's 1986 still adding code into the user/kernel mode transitions. 1987 1988 If unsure, say N. 1989 1990config RSEQ_DEBUG_DEFAULT_ENABLE 1991 default n 1992 bool "Enable restartable sequences debug mode by default" if EXPERT 1993 depends on RSEQ 1994 help 1995 This enables the static branch for debug mode of restartable 1996 sequences. 1997 1998 This also can be controlled on the kernel command line via the 1999 command line parameter "rseq_debug=0/1" and through debugfs. 2000 2001 If unsure, say N. 2002 2003config DEBUG_RSEQ 2004 default n 2005 bool "Enable debugging of rseq() system call" if EXPERT 2006 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY 2007 select RSEQ_DEBUG_DEFAULT_ENABLE 2008 help 2009 Enable extra debugging checks for the rseq system call. 2010 2011 If unsure, say N. 2012 2013config CACHESTAT_SYSCALL 2014 bool "Enable cachestat() system call" if EXPERT 2015 default y 2016 help 2017 Enable the cachestat system call, which queries the page cache 2018 statistics of a file (number of cached pages, dirty pages, 2019 pages marked for writeback, (recently) evicted pages). 2020 2021 If unsure say Y here. 2022 2023config KALLSYMS 2024 bool "Load all symbols for debugging/ksymoops" if EXPERT 2025 default y 2026 help 2027 Say Y here to let the kernel print out symbolic crash information and 2028 symbolic stack backtraces. This increases the size of the kernel 2029 somewhat, as all symbols have to be loaded into the kernel image. 2030 2031config KALLSYMS_SELFTEST 2032 bool "Test the basic functions and performance of kallsyms" 2033 depends on KALLSYMS 2034 default n 2035 help 2036 Test the basic functions and performance of some interfaces, such as 2037 kallsyms_lookup_name. It also calculates the compression rate of the 2038 kallsyms compression algorithm for the current symbol set. 2039 2040 Start self-test automatically after system startup. Suggest executing 2041 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 2042 displayed in the last line, indicating that the test is complete. 2043 2044config KALLSYMS_ALL 2045 bool "Include all symbols in kallsyms" 2046 depends on DEBUG_KERNEL && KALLSYMS 2047 help 2048 Normally kallsyms only contains the symbols of functions for nicer 2049 OOPS messages and backtraces (i.e., symbols from the text and inittext 2050 sections). This is sufficient for most cases. And only if you want to 2051 enable kernel live patching, or other less common use cases (e.g., 2052 when a debugger is used) all symbols are required (i.e., names of 2053 variables from the data sections, etc). 2054 2055 This option makes sure that all symbols are loaded into the kernel 2056 image (i.e., symbols from all sections) in cost of increased kernel 2057 size (depending on the kernel configuration, it may be 300KiB or 2058 something like this). 2059 2060 Say N unless you really need all symbols, or kernel live patching. 2061 2062# end of the "standard kernel features (expert users)" menu 2063 2064config ARCH_HAS_MEMBARRIER_CALLBACKS 2065 bool 2066 2067config ARCH_HAS_MEMBARRIER_SYNC_CORE 2068 bool 2069 2070config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 2071 bool 2072 help 2073 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 2074 2075 A 64-bit kernel is required for the memory sealing feature. 2076 No specific hardware features from the CPU are needed. 2077 2078 To enable this feature, the architecture needs to update their 2079 special mappings calls to include the sealing flag and confirm 2080 that it doesn't unmap/remap system mappings during the life 2081 time of the process. The existence of this flag for an architecture 2082 implies that it does not require the remapping of the system 2083 mappings during process lifetime, so sealing these mappings is safe 2084 from a kernel perspective. 2085 2086 After the architecture enables this, a distribution can set 2087 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 2088 2089 For complete descriptions of memory sealing, please see 2090 Documentation/userspace-api/mseal.rst 2091 2092config HAVE_PERF_EVENTS 2093 bool 2094 help 2095 See tools/perf/design.txt for details. 2096 2097config GUEST_PERF_EVENTS 2098 bool 2099 depends on HAVE_PERF_EVENTS 2100 2101config PERF_GUEST_MEDIATED_PMU 2102 bool 2103 depends on GUEST_PERF_EVENTS 2104 2105config PERF_USE_VMALLOC 2106 bool 2107 help 2108 See tools/perf/design.txt for details 2109 2110menu "Kernel Performance Events And Counters" 2111 2112config PERF_EVENTS 2113 bool "Kernel performance events and counters" 2114 default y if PROFILING 2115 depends on HAVE_PERF_EVENTS 2116 select IRQ_WORK 2117 help 2118 Enable kernel support for various performance events provided 2119 by software and hardware. 2120 2121 Software events are supported either built-in or via the 2122 use of generic tracepoints. 2123 2124 Most modern CPUs support performance events via performance 2125 counter registers. These registers count the number of certain 2126 types of hw events: such as instructions executed, cachemisses 2127 suffered, or branches mis-predicted - without slowing down the 2128 kernel or applications. These registers can also trigger interrupts 2129 when a threshold number of events have passed - and can thus be 2130 used to profile the code that runs on that CPU. 2131 2132 The Linux Performance Event subsystem provides an abstraction of 2133 these software and hardware event capabilities, available via a 2134 system call and used by the "perf" utility in tools/perf/. It 2135 provides per task and per CPU counters, and it provides event 2136 capabilities on top of those. 2137 2138 Say Y if unsure. 2139 2140config DEBUG_PERF_USE_VMALLOC 2141 default n 2142 bool "Debug: use vmalloc to back perf mmap() buffers" 2143 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2144 select PERF_USE_VMALLOC 2145 help 2146 Use vmalloc memory to back perf mmap() buffers. 2147 2148 Mostly useful for debugging the vmalloc code on platforms 2149 that don't require it. 2150 2151 Say N if unsure. 2152 2153endmenu 2154 2155config SYSTEM_DATA_VERIFICATION 2156 def_bool n 2157 select SYSTEM_TRUSTED_KEYRING 2158 select KEYS 2159 select CRYPTO 2160 select CRYPTO_RSA 2161 select ASYMMETRIC_KEY_TYPE 2162 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2163 select ASN1 2164 select OID_REGISTRY 2165 select X509_CERTIFICATE_PARSER 2166 select PKCS7_MESSAGE_PARSER 2167 help 2168 Provide PKCS#7 message verification using the contents of the system 2169 trusted keyring to provide public keys. This then can be used for 2170 module verification, kexec image verification and firmware blob 2171 verification. 2172 2173config PROFILING 2174 bool "Profiling support" 2175 help 2176 Say Y here to enable the extended profiling support mechanisms used 2177 by profilers. 2178 2179config RUST 2180 bool "Rust support" 2181 depends on HAVE_RUST 2182 depends on RUST_IS_AVAILABLE 2183 select EXTENDED_MODVERSIONS if MODVERSIONS 2184 depends on !MODVERSIONS || GENDWARFKSYMS 2185 depends on !GCC_PLUGIN_RANDSTRUCT 2186 depends on !RANDSTRUCT 2187 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2188 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2189 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2190 depends on !KASAN_SW_TAGS 2191 help 2192 Enables Rust support in the kernel. 2193 2194 This allows other Rust-related options, like drivers written in Rust, 2195 to be selected. 2196 2197 It is also required to be able to load external kernel modules 2198 written in Rust. 2199 2200 See Documentation/rust/ for more information. 2201 2202 If unsure, say N. 2203 2204config RUSTC_VERSION_TEXT 2205 string 2206 depends on RUST 2207 default "$(RUSTC_VERSION_TEXT)" 2208 help 2209 See `CC_VERSION_TEXT`. 2210 2211config BINDGEN_VERSION_TEXT 2212 string 2213 depends on RUST 2214 default "$(shell,$(BINDGEN) --version 2>/dev/null)" 2215 2216# 2217# Place an empty function call at each tracepoint site. Can be 2218# dynamically changed for a probe function. 2219# 2220config TRACEPOINTS 2221 bool 2222 select TASKS_TRACE_RCU 2223 2224source "kernel/Kconfig.kexec" 2225 2226source "kernel/liveupdate/Kconfig" 2227 2228endmenu # General setup 2229 2230source "arch/Kconfig" 2231 2232config RT_MUTEXES 2233 bool 2234 default y if PREEMPT_RT 2235 2236config MODULE_SIG_FORMAT 2237 def_bool n 2238 select SYSTEM_DATA_VERIFICATION 2239 2240source "kernel/module/Kconfig" 2241 2242config INIT_ALL_POSSIBLE 2243 bool 2244 help 2245 Back when each arch used to define their own cpu_online_mask and 2246 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2247 with all 1s, and others with all 0s. When they were centralised, 2248 it was better to provide this option than to break all the archs 2249 and have several arch maintainers pursuing me down dark alleys. 2250 2251source "block/Kconfig" 2252 2253config PREEMPT_NOTIFIERS 2254 bool 2255 2256config PADATA 2257 depends on SMP 2258 bool 2259 2260config ASN1 2261 tristate 2262 help 2263 Build a simple ASN.1 grammar compiler that produces a bytecode output 2264 that can be interpreted by the ASN.1 stream decoder and used to 2265 inform it as to what tags are to be expected in a stream and what 2266 functions to call on what tags. 2267 2268source "kernel/Kconfig.locks" 2269 2270config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2271 bool 2272 2273config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2274 bool 2275 2276config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2277 bool 2278 2279# It may be useful for an architecture to override the definitions of the 2280# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2281# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2282# different calling convention for syscalls. They can also override the 2283# macros for not-implemented syscalls in kernel/sys_ni.c and 2284# kernel/time/posix-stubs.c. All these overrides need to be available in 2285# <asm/syscall_wrapper.h>. 2286config ARCH_HAS_SYSCALL_WRAPPER 2287 def_bool n 2288