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 972config CC_MS_EXTENSIONS 973 string 974 default "-fms-anonymous-structs" if $(cc-option,-fms-anonymous-structs) 975 default "-fms-extensions" 976 977# Currently, disable gcc-10+ array-bounds globally. 978# It's still broken in gcc-13, so no upper bound yet. 979config GCC10_NO_ARRAY_BOUNDS 980 def_bool y 981 982config CC_NO_ARRAY_BOUNDS 983 bool 984 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 985 986# Currently, disable -Wstringop-overflow for GCC globally. 987config GCC_NO_STRINGOP_OVERFLOW 988 def_bool y 989 990config CC_NO_STRINGOP_OVERFLOW 991 bool 992 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 993 994config CC_STRINGOP_OVERFLOW 995 bool 996 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 997 998# 999# For architectures that know their GCC __int128 support is sound 1000# 1001config ARCH_SUPPORTS_INT128 1002 bool 1003 1004# For architectures that (ab)use NUMA to represent different memory regions 1005# all cpu-local but of different latencies, such as SuperH. 1006# 1007config ARCH_WANT_NUMA_VARIABLE_LOCALITY 1008 bool 1009 1010config NUMA_BALANCING 1011 bool "Memory placement aware NUMA scheduler" 1012 depends on ARCH_SUPPORTS_NUMA_BALANCING 1013 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 1014 depends on SMP && NUMA_MIGRATION && !PREEMPT_RT 1015 help 1016 This option adds support for automatic NUMA aware memory/task placement. 1017 The mechanism is quite primitive and is based on migrating memory when 1018 it has references to the node the task is running on. 1019 1020 This system will be inactive on UMA systems. 1021 1022config NUMA_BALANCING_DEFAULT_ENABLED 1023 bool "Automatically enable NUMA aware memory/task placement" 1024 default y 1025 depends on NUMA_BALANCING 1026 help 1027 If set, automatic NUMA balancing will be enabled if running on a NUMA 1028 machine. 1029 1030config SLAB_OBJ_EXT 1031 bool 1032 1033menuconfig CGROUPS 1034 bool "Control Group support" 1035 select KERNFS 1036 help 1037 This option adds support for grouping sets of processes together, for 1038 use with process control subsystems such as Cpusets, CFS, memory 1039 controls or device isolation. 1040 See 1041 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1042 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1043 and resource control) 1044 1045 Say N if unsure. 1046 1047if CGROUPS 1048 1049config PAGE_COUNTER 1050 bool 1051 1052config CGROUP_FAVOR_DYNMODS 1053 bool "Favor dynamic modification latency reduction by default" 1054 help 1055 This option enables the "favordynmods" mount option by default 1056 which reduces the latencies of dynamic cgroup modifications such 1057 as task migrations and controller on/offs at the cost of making 1058 hot path operations such as forks and exits more expensive. 1059 1060 Say N if unsure. 1061 1062config MEMCG 1063 bool "Memory controller" 1064 select PAGE_COUNTER 1065 select EVENTFD 1066 select SLAB_OBJ_EXT 1067 select VM_EVENT_COUNTERS 1068 help 1069 Provides control over the memory footprint of tasks in a cgroup. 1070 1071config MEMCG_NMI_UNSAFE 1072 bool 1073 depends on MEMCG 1074 depends on HAVE_NMI 1075 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1076 default y 1077 1078config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1079 bool 1080 depends on MEMCG 1081 depends on HAVE_NMI 1082 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1083 default y 1084 1085config MEMCG_V1 1086 bool "Legacy cgroup v1 memory controller" 1087 depends on MEMCG 1088 default n 1089 help 1090 Legacy cgroup v1 memory controller which has been deprecated by 1091 cgroup v2 implementation. The v1 is there for legacy applications 1092 which haven't migrated to the new cgroup v2 interface yet. If you 1093 do not have any such application then you are completely fine leaving 1094 this option disabled. 1095 1096 Please note that feature set of the legacy memory controller is likely 1097 going to shrink due to deprecation process. New deployments with v1 1098 controller are highly discouraged. 1099 1100 Say N if unsure. 1101 1102config BLK_CGROUP 1103 bool "IO controller" 1104 depends on BLOCK 1105 default n 1106 help 1107 Generic block IO controller cgroup interface. This is the common 1108 cgroup interface which should be used by various IO controlling 1109 policies. 1110 1111 Currently, CFQ IO scheduler uses it to recognize task groups and 1112 control disk bandwidth allocation (proportional time slice allocation) 1113 to such task groups. It is also used by bio throttling logic in 1114 block layer to implement upper limit in IO rates on a device. 1115 1116 This option only enables generic Block IO controller infrastructure. 1117 One needs to also enable actual IO controlling logic/policy. For 1118 enabling proportional weight division of disk bandwidth in CFQ, set 1119 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1120 CONFIG_BLK_DEV_THROTTLING=y. 1121 1122 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1123 1124config CGROUP_WRITEBACK 1125 bool 1126 depends on MEMCG && BLK_CGROUP 1127 default y 1128 1129menuconfig CGROUP_SCHED 1130 bool "CPU controller" 1131 default n 1132 help 1133 This feature lets CPU scheduler recognize task groups and control CPU 1134 bandwidth allocation to such task groups. It uses cgroups to group 1135 tasks. 1136 1137if CGROUP_SCHED 1138config GROUP_SCHED_WEIGHT 1139 def_bool n 1140 1141config GROUP_SCHED_BANDWIDTH 1142 def_bool n 1143 1144config FAIR_GROUP_SCHED 1145 bool "Group scheduling for SCHED_OTHER" 1146 depends on CGROUP_SCHED 1147 select GROUP_SCHED_WEIGHT 1148 default CGROUP_SCHED 1149 1150config CFS_BANDWIDTH 1151 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1152 depends on FAIR_GROUP_SCHED 1153 select GROUP_SCHED_BANDWIDTH 1154 default n 1155 help 1156 This option allows users to define CPU bandwidth rates (limits) for 1157 tasks running within the fair group scheduler. Groups with no limit 1158 set are considered to be unconstrained and will run with no 1159 restriction. 1160 See Documentation/scheduler/sched-bwc.rst for more information. 1161 1162config RT_GROUP_SCHED 1163 bool "Group scheduling for SCHED_RR/FIFO" 1164 depends on CGROUP_SCHED 1165 default n 1166 help 1167 This feature lets you explicitly allocate real CPU bandwidth 1168 to task groups. If enabled, it will also make it impossible to 1169 schedule realtime tasks for non-root users until you allocate 1170 realtime bandwidth for them. 1171 See Documentation/scheduler/sched-rt-group.rst for more information. 1172 1173config RT_GROUP_SCHED_DEFAULT_DISABLED 1174 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1175 depends on RT_GROUP_SCHED 1176 default n 1177 help 1178 When set, the RT group scheduling is disabled by default. The option 1179 is in inverted form so that mere RT_GROUP_SCHED enables the group 1180 scheduling. 1181 1182 Say N if unsure. 1183 1184config EXT_GROUP_SCHED 1185 bool 1186 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1187 select GROUP_SCHED_WEIGHT 1188 select GROUP_SCHED_BANDWIDTH 1189 default y 1190 1191endif #CGROUP_SCHED 1192 1193config EXT_SUB_SCHED 1194 def_bool y 1195 depends on SCHED_CLASS_EXT && CGROUPS 1196 1197config SCHED_MM_CID 1198 def_bool y 1199 depends on SMP && RSEQ 1200 1201config UCLAMP_TASK_GROUP 1202 bool "Utilization clamping per group of tasks" 1203 depends on CGROUP_SCHED 1204 depends on UCLAMP_TASK 1205 default n 1206 help 1207 This feature enables the scheduler to track the clamped utilization 1208 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1209 1210 When this option is enabled, the user can specify a min and max 1211 CPU bandwidth which is allowed for each single task in a group. 1212 The max bandwidth allows to clamp the maximum frequency a task 1213 can use, while the min bandwidth allows to define a minimum 1214 frequency a task will always use. 1215 1216 When task group based utilization clamping is enabled, an eventually 1217 specified task-specific clamp value is constrained by the cgroup 1218 specified clamp value. Both minimum and maximum task clamping cannot 1219 be bigger than the corresponding clamping defined at task group level. 1220 1221 If in doubt, say N. 1222 1223config CGROUP_PIDS 1224 bool "PIDs controller" 1225 help 1226 Provides enforcement of process number limits in the scope of a 1227 cgroup. Any attempt to fork more processes than is allowed in the 1228 cgroup will fail. PIDs are fundamentally a global resource because it 1229 is fairly trivial to reach PID exhaustion before you reach even a 1230 conservative kmemcg limit. As a result, it is possible to grind a 1231 system to halt without being limited by other cgroup policies. The 1232 PIDs controller is designed to stop this from happening. 1233 1234 It should be noted that organisational operations (such as attaching 1235 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1236 since the PIDs limit only affects a process's ability to fork, not to 1237 attach to a cgroup. 1238 1239config CGROUP_RDMA 1240 bool "RDMA controller" 1241 help 1242 Provides enforcement of RDMA resources defined by IB stack. 1243 It is fairly easy for consumers to exhaust RDMA resources, which 1244 can result into resource unavailability to other consumers. 1245 RDMA controller is designed to stop this from happening. 1246 Attaching processes with active RDMA resources to the cgroup 1247 hierarchy is allowed even if can cross the hierarchy's limit. 1248 1249config CGROUP_DMEM 1250 bool "Device memory controller (DMEM)" 1251 select PAGE_COUNTER 1252 help 1253 The DMEM controller allows compatible devices to restrict device 1254 memory usage based on the cgroup hierarchy. 1255 1256 As an example, it allows you to restrict VRAM usage for applications 1257 in the DRM subsystem. 1258 1259config CGROUP_FREEZER 1260 bool "Freezer controller" 1261 help 1262 Provides a way to freeze and unfreeze all tasks in a 1263 cgroup. 1264 1265 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1266 controller includes important in-kernel memory consumers per default. 1267 1268 If you're using cgroup2, say N. 1269 1270config CGROUP_HUGETLB 1271 bool "HugeTLB controller" 1272 depends on HUGETLB_PAGE 1273 select PAGE_COUNTER 1274 default n 1275 help 1276 Provides a cgroup controller for HugeTLB pages. 1277 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1278 The limit is enforced during page fault. Since HugeTLB doesn't 1279 support page reclaim, enforcing the limit at page fault time implies 1280 that, the application will get SIGBUS signal if it tries to access 1281 HugeTLB pages beyond its limit. This requires the application to know 1282 beforehand how much HugeTLB pages it would require for its use. The 1283 control group is tracked in the third page lru pointer. This means 1284 that we cannot use the controller with huge page less than 3 pages. 1285 1286config CPUSETS 1287 bool "Cpuset controller" 1288 depends on SMP 1289 select UNION_FIND 1290 select CPU_ISOLATION 1291 help 1292 This option will let you create and manage CPUSETs which 1293 allow dynamically partitioning a system into sets of CPUs and 1294 Memory Nodes and assigning tasks to run only within those sets. 1295 This is primarily useful on large SMP or NUMA systems. 1296 1297 Say N if unsure. 1298 1299config CPUSETS_V1 1300 bool "Legacy cgroup v1 cpusets controller" 1301 depends on CPUSETS 1302 default n 1303 help 1304 Legacy cgroup v1 cpusets controller which has been deprecated by 1305 cgroup v2 implementation. The v1 is there for legacy applications 1306 which haven't migrated to the new cgroup v2 interface yet. Legacy 1307 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1308 do not have any such application then you are completely fine leaving 1309 this option disabled. 1310 1311 Say N if unsure. 1312 1313config PROC_PID_CPUSET 1314 bool "Include legacy /proc/<pid>/cpuset file" 1315 depends on CPUSETS_V1 1316 default y 1317 1318config CGROUP_DEVICE 1319 bool "Device controller" 1320 help 1321 Provides a cgroup controller implementing whitelists for 1322 devices which a process in the cgroup can mknod or open. 1323 1324config CGROUP_CPUACCT 1325 bool "Simple CPU accounting controller" 1326 help 1327 Provides a simple controller for monitoring the 1328 total CPU consumed by the tasks in a cgroup. 1329 1330config CGROUP_PERF 1331 bool "Perf controller" 1332 depends on PERF_EVENTS 1333 help 1334 This option extends the perf per-cpu mode to restrict monitoring 1335 to threads which belong to the cgroup specified and run on the 1336 designated cpu. Or this can be used to have cgroup ID in samples 1337 so that it can monitor performance events among cgroups. 1338 1339 Say N if unsure. 1340 1341config CGROUP_BPF 1342 bool "Support for eBPF programs attached to cgroups" 1343 depends on BPF_SYSCALL 1344 select SOCK_CGROUP_DATA 1345 help 1346 Allow attaching eBPF programs to a cgroup using the bpf(2) 1347 syscall command BPF_PROG_ATTACH. 1348 1349 In which context these programs are accessed depends on the type 1350 of attachment. For instance, programs that are attached using 1351 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1352 inet sockets. 1353 1354config CGROUP_MISC 1355 bool "Misc resource controller" 1356 default n 1357 help 1358 Provides a controller for miscellaneous resources on a host. 1359 1360 Miscellaneous scalar resources are the resources on the host system 1361 which cannot be abstracted like the other cgroups. This controller 1362 tracks and limits the miscellaneous resources used by a process 1363 attached to a cgroup hierarchy. 1364 1365 For more information, please check misc cgroup section in 1366 /Documentation/admin-guide/cgroup-v2.rst. 1367 1368config CGROUP_DEBUG 1369 bool "Debug controller" 1370 default n 1371 depends on DEBUG_KERNEL 1372 help 1373 This option enables a simple controller that exports 1374 debugging information about the cgroups framework. This 1375 controller is for control cgroup debugging only. Its 1376 interfaces are not stable. 1377 1378 Say N. 1379 1380config SOCK_CGROUP_DATA 1381 bool 1382 default n 1383 1384endif # CGROUPS 1385 1386menuconfig NAMESPACES 1387 bool "Namespaces support" if EXPERT 1388 depends on MULTIUSER 1389 default !EXPERT 1390 help 1391 Provides the way to make tasks work with different objects using 1392 the same id. For example same IPC id may refer to different objects 1393 or same user id or pid may refer to different tasks when used in 1394 different namespaces. 1395 1396if NAMESPACES 1397 1398config UTS_NS 1399 bool "UTS namespace" 1400 default y 1401 help 1402 In this namespace tasks see different info provided with the 1403 uname() system call 1404 1405config TIME_NS 1406 bool "TIME namespace" 1407 default y 1408 help 1409 In this namespace boottime and monotonic clocks can be set. 1410 The time will keep going with the same pace. 1411 1412config TIME_NS_VDSO 1413 def_bool TIME_NS && GENERIC_GETTIMEOFDAY 1414 1415config IPC_NS 1416 bool "IPC namespace" 1417 depends on (SYSVIPC || POSIX_MQUEUE) 1418 default y 1419 help 1420 In this namespace tasks work with IPC ids which correspond to 1421 different IPC objects in different namespaces. 1422 1423config USER_NS 1424 bool "User namespace" 1425 default n 1426 help 1427 This allows containers, i.e. vservers, to use user namespaces 1428 to provide different user info for different servers. 1429 1430 When user namespaces are enabled in the kernel it is 1431 recommended that the MEMCG option also be enabled and that 1432 user-space use the memory control groups to limit the amount 1433 of memory a memory unprivileged users can use. 1434 1435 If unsure, say N. 1436 1437config PID_NS 1438 bool "PID Namespaces" 1439 default y 1440 help 1441 Support process id namespaces. This allows having multiple 1442 processes with the same pid as long as they are in different 1443 pid namespaces. This is a building block of containers. 1444 1445config NET_NS 1446 bool "Network namespace" 1447 depends on NET 1448 default y 1449 help 1450 Allow user space to create what appear to be multiple instances 1451 of the network stack. 1452 1453endif # NAMESPACES 1454 1455config CHECKPOINT_RESTORE 1456 bool "Checkpoint/restore support" 1457 depends on PROC_FS 1458 select PROC_CHILDREN 1459 select KCMP 1460 default n 1461 help 1462 Enables additional kernel features in a sake of checkpoint/restore. 1463 In particular it adds auxiliary prctl codes to setup process text, 1464 data and heap segment sizes, and a few additional /proc filesystem 1465 entries. 1466 1467 If unsure, say N here. 1468 1469config SCHED_AUTOGROUP 1470 bool "Automatic process group scheduling" 1471 select CGROUPS 1472 select CGROUP_SCHED 1473 select FAIR_GROUP_SCHED 1474 help 1475 This option optimizes the scheduler for common desktop workloads by 1476 automatically creating and populating task groups. This separation 1477 of workloads isolates aggressive CPU burners (like build jobs) from 1478 desktop applications. Task group autogeneration is currently based 1479 upon task session. 1480 1481config RELAY 1482 bool "Kernel->user space relay support (formerly relayfs)" 1483 select IRQ_WORK 1484 help 1485 This option enables support for relay interface support in 1486 certain file systems (such as debugfs). 1487 It is designed to provide an efficient mechanism for tools and 1488 facilities to relay large amounts of data from kernel space to 1489 user space. 1490 1491 If unsure, say N. 1492 1493config BLK_DEV_INITRD 1494 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1495 help 1496 The initial RAM filesystem is a ramfs which is loaded by the 1497 boot loader (loadlin or lilo) and that is mounted as root 1498 before the normal boot procedure. It is typically used to 1499 load modules needed to mount the "real" root file system, 1500 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1501 1502 If RAM disk support (BLK_DEV_RAM) is also included, this 1503 also enables initial RAM disk (initrd) support and adds 1504 15 Kbytes (more on some other architectures) to the kernel size. 1505 1506 If unsure say Y. 1507 1508if BLK_DEV_INITRD 1509 1510source "usr/Kconfig" 1511 1512endif 1513 1514config BOOT_CONFIG 1515 bool "Boot config support" 1516 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1517 help 1518 Extra boot config allows system admin to pass a config file as 1519 complemental extension of kernel cmdline when booting. 1520 The boot config file must be attached at the end of initramfs 1521 with checksum, size and magic word. 1522 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1523 1524 If unsure, say Y. 1525 1526config BOOT_CONFIG_FORCE 1527 bool "Force unconditional bootconfig processing" 1528 depends on BOOT_CONFIG 1529 default y if BOOT_CONFIG_EMBED 1530 help 1531 With this Kconfig option set, BOOT_CONFIG processing is carried 1532 out even when the "bootconfig" kernel-boot parameter is omitted. 1533 In fact, with this Kconfig option set, there is no way to 1534 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1535 parameters. 1536 1537 If unsure, say N. 1538 1539config BOOT_CONFIG_EMBED 1540 bool "Embed bootconfig file in the kernel" 1541 depends on BOOT_CONFIG 1542 help 1543 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1544 kernel. Usually, the bootconfig file is loaded with the initrd 1545 image. But if the system doesn't support initrd, this option will 1546 help you by embedding a bootconfig file while building the kernel. 1547 1548 If unsure, say N. 1549 1550config BOOT_CONFIG_EMBED_FILE 1551 string "Embedded bootconfig file path" 1552 depends on BOOT_CONFIG_EMBED 1553 help 1554 Specify a bootconfig file which will be embedded to the kernel. 1555 This bootconfig will be used if there is no initrd or no other 1556 bootconfig in the initrd. 1557 1558config CMDLINE_LOG_WRAP_IDEAL_LEN 1559 int "Length to try to wrap the cmdline when logged at boot" 1560 default 1021 1561 range 0 1021 1562 help 1563 At boot time, the kernel command line is logged to the console. 1564 The log message will start with the prefix "Kernel command line: ". 1565 The log message will attempt to be wrapped (split into multiple log 1566 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters. 1567 If wrapping happens, each log message will start with the prefix and 1568 all but the last message will end with " \". Messages may exceed the 1569 ideal length if a place to wrap isn't found before the specified 1570 number of characters. 1571 1572 A value of 0 disables wrapping, though be warned that the maximum 1573 length of a log message (1021 characters) may cause the cmdline to 1574 be truncated. 1575 1576config INITRAMFS_PRESERVE_MTIME 1577 bool "Preserve cpio archive mtimes in initramfs" 1578 depends on BLK_DEV_INITRD 1579 default y 1580 help 1581 Each entry in an initramfs cpio archive carries an mtime value. When 1582 enabled, extracted cpio items take this mtime, with directory mtime 1583 setting deferred until after creation of any child entries. 1584 1585 If unsure, say Y. 1586 1587config INITRAMFS_TEST 1588 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1589 depends on BLK_DEV_INITRD && KUNIT=y 1590 default KUNIT_ALL_TESTS 1591 help 1592 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1593 1594choice 1595 prompt "Compiler optimization level" 1596 default CC_OPTIMIZE_FOR_PERFORMANCE 1597 1598config CC_OPTIMIZE_FOR_PERFORMANCE 1599 bool "Optimize for performance (-O2)" 1600 help 1601 This is the default optimization level for the kernel, building 1602 with the "-O2" compiler flag for best performance and most 1603 helpful compile-time warnings. 1604 1605config CC_OPTIMIZE_FOR_SIZE 1606 bool "Optimize for size (-Os)" 1607 help 1608 Choosing this option will pass "-Os" to your compiler resulting 1609 in a smaller kernel. 1610 1611endchoice 1612 1613config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1614 bool 1615 help 1616 This requires that the arch annotates or otherwise protects 1617 its external entry points from being discarded. Linker scripts 1618 must also merge .text.*, .data.*, and .bss.* correctly into 1619 output sections. Care must be taken not to pull in unrelated 1620 sections (e.g., '.text.init'). Typically '.' in section names 1621 is used to distinguish them from label names / C identifiers. 1622 1623config LD_DEAD_CODE_DATA_ELIMINATION 1624 bool "Dead code and data elimination (EXPERIMENTAL)" 1625 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1626 depends on EXPERT 1627 depends on $(cc-option,-ffunction-sections -fdata-sections) 1628 depends on $(ld-option,--gc-sections) 1629 help 1630 Enable this if you want to do dead code and data elimination with 1631 the linker by compiling with -ffunction-sections -fdata-sections, 1632 and linking with --gc-sections. 1633 1634 This can reduce on disk and in-memory size of the kernel 1635 code and static data, particularly for small configs and 1636 on small systems. This has the possibility of introducing 1637 silently broken kernel if the required annotations are not 1638 present. This option is not well tested yet, so use at your 1639 own risk. 1640 1641config LD_ORPHAN_WARN 1642 def_bool y 1643 depends on ARCH_WANT_LD_ORPHAN_WARN 1644 depends on $(ld-option,--orphan-handling=warn) 1645 depends on $(ld-option,--orphan-handling=error) 1646 1647config LD_ORPHAN_WARN_LEVEL 1648 string 1649 depends on LD_ORPHAN_WARN 1650 default "error" if WERROR 1651 default "warn" 1652 1653config SYSCTL 1654 bool 1655 1656config HAVE_UID16 1657 bool 1658 1659config SYSCTL_EXCEPTION_TRACE 1660 bool 1661 help 1662 Enable support for /proc/sys/debug/exception-trace. 1663 1664config SYSCTL_ARCH_UNALIGN_NO_WARN 1665 bool 1666 help 1667 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1668 Allows arch to define/use @no_unaligned_warning to possibly warn 1669 about unaligned access emulation going on under the hood. 1670 1671config SYSCTL_ARCH_UNALIGN_ALLOW 1672 bool 1673 help 1674 Enable support for /proc/sys/kernel/unaligned-trap 1675 Allows arches to define/use @unaligned_enabled to runtime toggle 1676 the unaligned access emulation. 1677 see arch/parisc/kernel/unaligned.c for reference 1678 1679config SYSFS_SYSCALL 1680 bool "Sysfs syscall support" 1681 default n 1682 help 1683 sys_sysfs is an obsolete system call no longer supported in libc. 1684 Note that disabling this option is more secure but might break 1685 compatibility with some systems. 1686 1687 If unsure say N here. 1688 1689config HAVE_PCSPKR_PLATFORM 1690 bool 1691 1692menuconfig EXPERT 1693 bool "Configure standard kernel features (expert users)" 1694 # Unhide debug options, to make the on-by-default options visible 1695 select DEBUG_KERNEL 1696 help 1697 This option allows certain base kernel options and settings 1698 to be disabled or tweaked. This is for specialized 1699 environments which can tolerate a "non-standard" kernel. 1700 Only use this if you really know what you are doing. 1701 1702config UID16 1703 bool "Enable 16-bit UID system calls" if EXPERT 1704 depends on HAVE_UID16 && MULTIUSER 1705 default y 1706 help 1707 This enables the legacy 16-bit UID syscall wrappers. 1708 1709config MULTIUSER 1710 bool "Multiple users, groups and capabilities support" if EXPERT 1711 default y 1712 help 1713 This option enables support for non-root users, groups and 1714 capabilities. 1715 1716 If you say N here, all processes will run with UID 0, GID 0, and all 1717 possible capabilities. Saying N here also compiles out support for 1718 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1719 setgid, and capset. 1720 1721 If unsure, say Y here. 1722 1723config SGETMASK_SYSCALL 1724 bool "sgetmask/ssetmask syscalls support" if EXPERT 1725 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1726 help 1727 sys_sgetmask and sys_ssetmask are obsolete system calls 1728 no longer supported in libc but still enabled by default in some 1729 architectures. 1730 1731 If unsure, leave the default option here. 1732 1733config FHANDLE 1734 bool "open by fhandle syscalls" if EXPERT 1735 select EXPORTFS 1736 default y 1737 help 1738 If you say Y here, a user level program will be able to map 1739 file names to handle and then later use the handle for 1740 different file system operations. This is useful in implementing 1741 userspace file servers, which now track files using handles instead 1742 of names. The handle would remain the same even if file names 1743 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1744 syscalls. 1745 1746config POSIX_TIMERS 1747 bool "Posix Clocks & timers" if EXPERT 1748 default y 1749 help 1750 This includes native support for POSIX timers to the kernel. 1751 Some embedded systems have no use for them and therefore they 1752 can be configured out to reduce the size of the kernel image. 1753 1754 When this option is disabled, the following syscalls won't be 1755 available: timer_create, timer_gettime: timer_getoverrun, 1756 timer_settime, timer_delete, clock_adjtime, getitimer, 1757 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1758 clock_getres and clock_nanosleep syscalls will be limited to 1759 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1760 1761 If unsure say y. 1762 1763config PRINTK 1764 default y 1765 bool "Enable support for printk" if EXPERT 1766 select IRQ_WORK 1767 help 1768 This option enables normal printk support. Removing it 1769 eliminates most of the message strings from the kernel image 1770 and makes the kernel more or less silent. As this makes it 1771 very difficult to diagnose system problems, saying N here is 1772 strongly discouraged. 1773 1774config PRINTK_RINGBUFFER_KUNIT_TEST 1775 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1776 depends on PRINTK && KUNIT 1777 default KUNIT_ALL_TESTS 1778 help 1779 This builds the printk ringbuffer KUnit test suite. 1780 1781 For more information on KUnit and unit tests in general, please refer 1782 to the KUnit documentation. 1783 1784 If unsure, say N. 1785 1786config BUG 1787 bool "BUG() support" if EXPERT 1788 default y 1789 help 1790 Disabling this option eliminates support for BUG and WARN, reducing 1791 the size of your kernel image and potentially quietly ignoring 1792 numerous fatal conditions. You should only consider disabling this 1793 option for embedded systems with no facilities for reporting errors. 1794 Just say Y. 1795 1796config ELF_CORE 1797 depends on COREDUMP 1798 default y 1799 bool "Enable ELF core dumps" if EXPERT 1800 help 1801 Enable support for generating core dumps. Disabling saves about 4k. 1802 1803 1804config PCSPKR_PLATFORM 1805 bool "Enable PC-Speaker support" if EXPERT 1806 depends on HAVE_PCSPKR_PLATFORM 1807 select I8253_LOCK 1808 default y 1809 help 1810 This option allows to disable the internal PC-Speaker 1811 support, saving some memory. 1812 1813config BASE_SMALL 1814 bool "Enable smaller-sized data structures for core" if EXPERT 1815 help 1816 Enabling this option reduces the size of miscellaneous core 1817 kernel data structures. This saves memory on small machines, 1818 but may reduce performance. 1819 1820config FUTEX 1821 bool "Enable futex support" if EXPERT 1822 depends on !(SPARC32 && SMP) 1823 default y 1824 imply RT_MUTEXES 1825 help 1826 Disabling this option will cause the kernel to be built without 1827 support for "fast userspace mutexes". The resulting kernel may not 1828 run glibc-based applications correctly. 1829 1830config FUTEX_PI 1831 bool 1832 depends on FUTEX && RT_MUTEXES 1833 default y 1834 1835config FUTEX_PRIVATE_HASH 1836 bool 1837 depends on FUTEX && !BASE_SMALL && MMU 1838 default y 1839 1840config FUTEX_MPOL 1841 bool 1842 depends on FUTEX && NUMA 1843 default y 1844 1845config EPOLL 1846 bool "Enable eventpoll support" if EXPERT 1847 default y 1848 help 1849 Disabling this option will cause the kernel to be built without 1850 support for epoll family of system calls. 1851 1852config SIGNALFD 1853 bool "Enable signalfd() system call" if EXPERT 1854 default y 1855 help 1856 Enable the signalfd() system call that allows to receive signals 1857 on a file descriptor. 1858 1859 If unsure, say Y. 1860 1861config TIMERFD 1862 bool "Enable timerfd() system call" if EXPERT 1863 default y 1864 help 1865 Enable the timerfd() system call that allows to receive timer 1866 events on a file descriptor. 1867 1868 If unsure, say Y. 1869 1870config EVENTFD 1871 bool "Enable eventfd() system call" if EXPERT 1872 default y 1873 help 1874 Enable the eventfd() system call that allows to receive both 1875 kernel notification (ie. KAIO) or userspace notifications. 1876 1877 If unsure, say Y. 1878 1879config SHMEM 1880 bool "Use full shmem filesystem" if EXPERT 1881 default y 1882 depends on MMU 1883 help 1884 The shmem is an internal filesystem used to manage shared memory. 1885 It is backed by swap and manages resource limits. It is also exported 1886 to userspace as tmpfs if TMPFS is enabled. Disabling this 1887 option replaces shmem and tmpfs with the much simpler ramfs code, 1888 which may be appropriate on small systems without swap. 1889 1890config AIO 1891 bool "Enable AIO support" if EXPERT 1892 default y 1893 help 1894 This option enables POSIX asynchronous I/O which may by used 1895 by some high performance threaded applications. Disabling 1896 this option saves about 7k. 1897 1898config IO_URING 1899 bool "Enable IO uring support" if EXPERT 1900 select IO_WQ 1901 default y 1902 help 1903 This option enables support for the io_uring interface, enabling 1904 applications to submit and complete IO through submission and 1905 completion rings that are shared between the kernel and application. 1906 1907config GCOV_PROFILE_URING 1908 bool "Enable GCOV profiling on the io_uring subsystem" 1909 depends on IO_URING && GCOV_KERNEL 1910 help 1911 Enable GCOV profiling on the io_uring subsystem, to facilitate 1912 code coverage testing. 1913 1914 If unsure, say N. 1915 1916 Note that this will have a negative impact on the performance of 1917 the io_uring subsystem, hence this should only be enabled for 1918 specific test purposes. 1919 1920config IO_URING_MOCK_FILE 1921 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1922 default n 1923 depends on IO_URING 1924 help 1925 Enable mock files for io_uring subsystem testing. The ABI might 1926 still change, so it's still experimental and should only be enabled 1927 for specific test purposes. 1928 1929 If unsure, say N. 1930 1931config ADVISE_SYSCALLS 1932 bool "Enable madvise/fadvise syscalls" if EXPERT 1933 default y 1934 help 1935 This option enables the madvise and fadvise syscalls, used by 1936 applications to advise the kernel about their future memory or file 1937 usage, improving performance. If building an embedded system where no 1938 applications use these syscalls, you can disable this option to save 1939 space. 1940 1941config MEMBARRIER 1942 bool "Enable membarrier() system call" if EXPERT 1943 default y 1944 help 1945 Enable the membarrier() system call that allows issuing memory 1946 barriers across all running threads, which can be used to distribute 1947 the cost of user-space memory barriers asymmetrically by transforming 1948 pairs of memory barriers into pairs consisting of membarrier() and a 1949 compiler barrier. 1950 1951 If unsure, say Y. 1952 1953config KCMP 1954 bool "Enable kcmp() system call" if EXPERT 1955 help 1956 Enable the kernel resource comparison system call. It provides 1957 user-space with the ability to compare two processes to see if they 1958 share a common resource, such as a file descriptor or even virtual 1959 memory space. 1960 1961 If unsure, say N. 1962 1963config RSEQ 1964 bool "Enable rseq() system call" if EXPERT 1965 default y 1966 depends on HAVE_RSEQ 1967 select MEMBARRIER 1968 help 1969 Enable the restartable sequences system call. It provides a 1970 user-space cache for the current CPU number value, which 1971 speeds up getting the current CPU number from user-space, 1972 as well as an ABI to speed up user-space operations on 1973 per-CPU data. 1974 1975 If unsure, say Y. 1976 1977config RSEQ_SLICE_EXTENSION 1978 bool "Enable rseq-based time slice extension mechanism" 1979 depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS 1980 help 1981 Allows userspace to request a limited time slice extension when 1982 returning from an interrupt to user space via the RSEQ shared 1983 data ABI. If granted, that allows to complete a critical section, 1984 so that other threads are not stuck on a conflicted resource, 1985 while the task is scheduled out. 1986 1987 If unsure, say N. 1988 1989config RSEQ_STATS 1990 default n 1991 bool "Enable lightweight statistics of restartable sequences" if EXPERT 1992 depends on RSEQ && DEBUG_FS 1993 help 1994 Enable lightweight counters which expose information about the 1995 frequency of RSEQ operations via debugfs. Mostly interesting for 1996 kernel debugging or performance analysis. While lightweight it's 1997 still adding code into the user/kernel mode transitions. 1998 1999 If unsure, say N. 2000 2001config RSEQ_DEBUG_DEFAULT_ENABLE 2002 default n 2003 bool "Enable restartable sequences debug mode by default" if EXPERT 2004 depends on RSEQ 2005 help 2006 This enables the static branch for debug mode of restartable 2007 sequences. 2008 2009 This also can be controlled on the kernel command line via the 2010 command line parameter "rseq_debug=0/1" and through debugfs. 2011 2012 If unsure, say N. 2013 2014config DEBUG_RSEQ 2015 default n 2016 bool "Enable debugging of rseq() system call" if EXPERT 2017 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY 2018 select RSEQ_DEBUG_DEFAULT_ENABLE 2019 help 2020 Enable extra debugging checks for the rseq system call. 2021 2022 If unsure, say N. 2023 2024config CACHESTAT_SYSCALL 2025 bool "Enable cachestat() system call" if EXPERT 2026 default y 2027 help 2028 Enable the cachestat system call, which queries the page cache 2029 statistics of a file (number of cached pages, dirty pages, 2030 pages marked for writeback, (recently) evicted pages). 2031 2032 If unsure say Y here. 2033 2034config KALLSYMS 2035 bool "Load all symbols for debugging/ksymoops" if EXPERT 2036 default y 2037 help 2038 Say Y here to let the kernel print out symbolic crash information and 2039 symbolic stack backtraces. This increases the size of the kernel 2040 somewhat, as all symbols have to be loaded into the kernel image. 2041 2042config KALLSYMS_SELFTEST 2043 bool "Test the basic functions and performance of kallsyms" 2044 depends on KALLSYMS 2045 default n 2046 help 2047 Test the basic functions and performance of some interfaces, such as 2048 kallsyms_lookup_name. It also calculates the compression rate of the 2049 kallsyms compression algorithm for the current symbol set. 2050 2051 Start self-test automatically after system startup. Suggest executing 2052 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 2053 displayed in the last line, indicating that the test is complete. 2054 2055config KALLSYMS_ALL 2056 bool "Include all symbols in kallsyms" 2057 depends on DEBUG_KERNEL && KALLSYMS 2058 help 2059 Normally kallsyms only contains the symbols of functions for nicer 2060 OOPS messages and backtraces (i.e., symbols from the text and inittext 2061 sections). This is sufficient for most cases. And only if you want to 2062 enable kernel live patching, or other less common use cases (e.g., 2063 when a debugger is used) all symbols are required (i.e., names of 2064 variables from the data sections, etc). 2065 2066 This option makes sure that all symbols are loaded into the kernel 2067 image (i.e., symbols from all sections) in cost of increased kernel 2068 size (depending on the kernel configuration, it may be 300KiB or 2069 something like this). 2070 2071 Say N unless you really need all symbols, or kernel live patching. 2072 2073# end of the "standard kernel features (expert users)" menu 2074 2075config ARCH_HAS_MEMBARRIER_CALLBACKS 2076 bool 2077 2078config ARCH_HAS_MEMBARRIER_SYNC_CORE 2079 bool 2080 2081config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 2082 bool 2083 help 2084 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 2085 2086 A 64-bit kernel is required for the memory sealing feature. 2087 No specific hardware features from the CPU are needed. 2088 2089 To enable this feature, the architecture needs to update their 2090 special mappings calls to include the sealing flag and confirm 2091 that it doesn't unmap/remap system mappings during the life 2092 time of the process. The existence of this flag for an architecture 2093 implies that it does not require the remapping of the system 2094 mappings during process lifetime, so sealing these mappings is safe 2095 from a kernel perspective. 2096 2097 After the architecture enables this, a distribution can set 2098 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 2099 2100 For complete descriptions of memory sealing, please see 2101 Documentation/userspace-api/mseal.rst 2102 2103config HAVE_PERF_EVENTS 2104 bool 2105 help 2106 See tools/perf/design.txt for details. 2107 2108config GUEST_PERF_EVENTS 2109 bool 2110 depends on HAVE_PERF_EVENTS 2111 2112config PERF_GUEST_MEDIATED_PMU 2113 bool 2114 depends on GUEST_PERF_EVENTS 2115 2116config PERF_USE_VMALLOC 2117 bool 2118 help 2119 See tools/perf/design.txt for details 2120 2121menu "Kernel Performance Events And Counters" 2122 2123config PERF_EVENTS 2124 bool "Kernel performance events and counters" 2125 default y if PROFILING 2126 depends on HAVE_PERF_EVENTS 2127 select IRQ_WORK 2128 help 2129 Enable kernel support for various performance events provided 2130 by software and hardware. 2131 2132 Software events are supported either built-in or via the 2133 use of generic tracepoints. 2134 2135 Most modern CPUs support performance events via performance 2136 counter registers. These registers count the number of certain 2137 types of hw events: such as instructions executed, cachemisses 2138 suffered, or branches mis-predicted - without slowing down the 2139 kernel or applications. These registers can also trigger interrupts 2140 when a threshold number of events have passed - and can thus be 2141 used to profile the code that runs on that CPU. 2142 2143 The Linux Performance Event subsystem provides an abstraction of 2144 these software and hardware event capabilities, available via a 2145 system call and used by the "perf" utility in tools/perf/. It 2146 provides per task and per CPU counters, and it provides event 2147 capabilities on top of those. 2148 2149 Say Y if unsure. 2150 2151config DEBUG_PERF_USE_VMALLOC 2152 default n 2153 bool "Debug: use vmalloc to back perf mmap() buffers" 2154 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2155 select PERF_USE_VMALLOC 2156 help 2157 Use vmalloc memory to back perf mmap() buffers. 2158 2159 Mostly useful for debugging the vmalloc code on platforms 2160 that don't require it. 2161 2162 Say N if unsure. 2163 2164endmenu 2165 2166config SYSTEM_DATA_VERIFICATION 2167 def_bool n 2168 select SYSTEM_TRUSTED_KEYRING 2169 select KEYS 2170 select CRYPTO 2171 select CRYPTO_RSA 2172 select ASYMMETRIC_KEY_TYPE 2173 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2174 select ASN1 2175 select OID_REGISTRY 2176 select X509_CERTIFICATE_PARSER 2177 select PKCS7_MESSAGE_PARSER 2178 help 2179 Provide PKCS#7 message verification using the contents of the system 2180 trusted keyring to provide public keys. This then can be used for 2181 module verification, kexec image verification and firmware blob 2182 verification. 2183 2184config PROFILING 2185 bool "Profiling support" 2186 help 2187 Say Y here to enable the extended profiling support mechanisms used 2188 by profilers. 2189 2190config RUST 2191 bool "Rust support" 2192 depends on HAVE_RUST 2193 depends on RUST_IS_AVAILABLE 2194 select EXTENDED_MODVERSIONS if MODVERSIONS 2195 depends on !MODVERSIONS || GENDWARFKSYMS 2196 depends on !GCC_PLUGIN_RANDSTRUCT 2197 depends on !RANDSTRUCT 2198 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2199 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2200 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2201 depends on !KASAN_SW_TAGS 2202 help 2203 Enables Rust support in the kernel. 2204 2205 This allows other Rust-related options, like drivers written in Rust, 2206 to be selected. 2207 2208 It is also required to be able to load external kernel modules 2209 written in Rust. 2210 2211 See Documentation/rust/ for more information. 2212 2213 If unsure, say N. 2214 2215config RUSTC_VERSION_TEXT 2216 string 2217 depends on RUST 2218 default "$(RUSTC_VERSION_TEXT)" 2219 help 2220 See `CC_VERSION_TEXT`. 2221 2222config BINDGEN_VERSION_TEXT 2223 string 2224 depends on RUST 2225 default "$(shell,$(BINDGEN) --version 2>/dev/null)" 2226 2227# 2228# Place an empty function call at each tracepoint site. Can be 2229# dynamically changed for a probe function. 2230# 2231config TRACEPOINTS 2232 bool 2233 select TASKS_TRACE_RCU 2234 2235source "kernel/Kconfig.kexec" 2236 2237source "kernel/liveupdate/Kconfig" 2238 2239endmenu # General setup 2240 2241source "arch/Kconfig" 2242 2243config RT_MUTEXES 2244 bool 2245 default y if PREEMPT_RT 2246 2247config MODULE_SIG_FORMAT 2248 def_bool n 2249 select SYSTEM_DATA_VERIFICATION 2250 2251source "kernel/module/Kconfig" 2252 2253config INIT_ALL_POSSIBLE 2254 bool 2255 help 2256 Back when each arch used to define their own cpu_online_mask and 2257 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2258 with all 1s, and others with all 0s. When they were centralised, 2259 it was better to provide this option than to break all the archs 2260 and have several arch maintainers pursuing me down dark alleys. 2261 2262source "block/Kconfig" 2263 2264config PREEMPT_NOTIFIERS 2265 bool 2266 2267config PADATA 2268 depends on SMP 2269 bool 2270 2271config ASN1 2272 tristate 2273 help 2274 Build a simple ASN.1 grammar compiler that produces a bytecode output 2275 that can be interpreted by the ASN.1 stream decoder and used to 2276 inform it as to what tags are to be expected in a stream and what 2277 functions to call on what tags. 2278 2279source "kernel/Kconfig.locks" 2280 2281config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2282 bool 2283 2284config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2285 bool 2286 2287config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2288 bool 2289 2290# It may be useful for an architecture to override the definitions of the 2291# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2292# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2293# different calling convention for syscalls. They can also override the 2294# macros for not-implemented syscalls in kernel/sys_ni.c and 2295# kernel/time/posix-stubs.c. All these overrides need to be available in 2296# <asm/syscall_wrapper.h>. 2297config ARCH_HAS_SYSCALL_WRAPPER 2298 def_bool n 2299