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 ARCH_HAS_CC_CAN_LINK 86 bool 87 88config CC_CAN_LINK 89 bool 90 default ARCH_CC_CAN_LINK if ARCH_HAS_CC_CAN_LINK 91 default $(cc_can_link_user,$(m64-flag)) if 64BIT 92 default $(cc_can_link_user,$(m32-flag)) 93 94# Fixed in GCC 14, 13.3, 12.4 and 11.5 95# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 96config GCC_ASM_GOTO_OUTPUT_BROKEN 97 bool 98 depends on CC_IS_GCC 99 default y if GCC_VERSION < 110500 100 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400 101 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300 102 103config CC_HAS_ASM_GOTO_OUTPUT 104 def_bool y 105 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN 106 # Detect basic support 107 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) 108 # Detect clang (< v17) scoped label issues 109 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) 110 111config CC_HAS_ASM_GOTO_TIED_OUTPUT 112 depends on CC_HAS_ASM_GOTO_OUTPUT 113 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 114 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) 115 116config TOOLS_SUPPORT_RELR 117 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 118 119config CC_HAS_ASM_INLINE 120 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 121 122config CC_HAS_ASSUME 123 bool 124 # clang needs to be at least 19.1.0 since the meaning of the assume 125 # attribute changed: 126 # https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17 127 default y if CC_IS_CLANG && CLANG_VERSION >= 190100 128 # supported since gcc 13.1.0 129 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654 130 default y if CC_IS_GCC && GCC_VERSION >= 130100 131 132config CC_HAS_NO_PROFILE_FN_ATTR 133 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 134 135config CC_HAS_COUNTED_BY 136 bool 137 # clang needs to be at least 20.1.0 to avoid potential crashes 138 # when building structures that contain __counted_by 139 # https://github.com/ClangBuiltLinux/linux/issues/2114 140 # https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489 141 default y if CC_IS_CLANG && CLANG_VERSION >= 200100 142 # supported since gcc 15.1.0 143 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 144 default y if CC_IS_GCC && GCC_VERSION >= 150100 145 146config CC_HAS_COUNTED_BY_PTR 147 bool 148 # supported since clang 22 149 default y if CC_IS_CLANG && CLANG_VERSION >= 220000 150 # supported since gcc 16.0.0 151 default y if CC_IS_GCC && GCC_VERSION >= 160000 152 153config CC_HAS_BROKEN_COUNTED_BY_REF 154 bool 155 # https://github.com/llvm/llvm-project/issues/182575 156 default y if CC_IS_CLANG && CLANG_VERSION < 220000 157 158config CC_HAS_MULTIDIMENSIONAL_NONSTRING 159 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 160 161config LD_CAN_USE_KEEP_IN_OVERLAY 162 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 163 # https://github.com/llvm/llvm-project/pull/130661 164 def_bool LD_IS_BFD || LLD_VERSION >= 210000 165 166config RUSTC_HAS_SLICE_AS_FLATTENED 167 def_bool RUSTC_VERSION >= 108000 168 169config RUSTC_HAS_COERCE_POINTEE 170 def_bool RUSTC_VERSION >= 108400 171 172config RUSTC_HAS_SPAN_FILE 173 def_bool RUSTC_VERSION >= 108800 174 175config RUSTC_HAS_UNNECESSARY_TRANSMUTES 176 def_bool RUSTC_VERSION >= 108800 177 178config RUSTC_HAS_FILE_WITH_NUL 179 def_bool RUSTC_VERSION >= 108900 180 181config RUSTC_HAS_FILE_AS_C_STR 182 def_bool RUSTC_VERSION >= 109100 183 184config PAHOLE_VERSION 185 int 186 default "$(PAHOLE_VERSION)" 187 188config CONSTRUCTORS 189 bool 190 191config IRQ_WORK 192 def_bool y if SMP 193 194config BUILDTIME_TABLE_SORT 195 bool 196 197config THREAD_INFO_IN_TASK 198 bool 199 help 200 Select this to move thread_info off the stack into task_struct. To 201 make this work, an arch will need to remove all thread_info fields 202 except flags and fix any runtime bugs. 203 204 One subtle change that will be needed is to use try_get_task_stack() 205 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 206 207menu "General setup" 208 209config BROKEN 210 bool 211 help 212 This option allows you to choose whether you want to try to 213 compile (and fix) old drivers that haven't been updated to 214 new infrastructure. 215 216config BROKEN_ON_SMP 217 bool 218 depends on BROKEN || !SMP 219 default y 220 221config INIT_ENV_ARG_LIMIT 222 int 223 default 32 if !UML 224 default 128 if UML 225 help 226 Maximum of each of the number of arguments and environment 227 variables passed to init from the kernel command line. 228 229config COMPILE_TEST 230 bool "Compile also drivers which will not load" 231 depends on HAS_IOMEM 232 help 233 Some drivers can be compiled on a different platform than they are 234 intended to be run on. Despite they cannot be loaded there (or even 235 when they load they cannot be used due to missing HW support), 236 developers still, opposing to distributors, might want to build such 237 drivers to compile-test them. 238 239 If you are a developer and want to build everything available, say Y 240 here. If you are a user/distributor, say N here to exclude useless 241 drivers to be distributed. 242 243config WERROR 244 bool "Compile the kernel with warnings as errors" 245 default COMPILE_TEST 246 help 247 A kernel build should not cause any compiler warnings, and this 248 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 249 to enforce that rule by default. Certain warnings from other tools 250 such as the linker may be upgraded to errors with this option as 251 well. 252 253 However, if you have a new (or very old) compiler or linker with odd 254 and unusual warnings, or you have some architecture with problems, 255 you may need to disable this config option in order to 256 successfully build the kernel. 257 258 If in doubt, say Y. 259 260config UAPI_HEADER_TEST 261 bool "Compile test UAPI headers" 262 depends on HEADERS_INSTALL 263 help 264 Compile test headers exported to user-space to ensure they are 265 self-contained, i.e. compilable as standalone units. 266 267 If you are a developer or tester and want to ensure the exported 268 headers are self-contained, say Y here. Otherwise, choose N. 269 270config LOCALVERSION 271 string "Local version - append to kernel release" 272 help 273 Append an extra string to the end of your kernel version. 274 This will show up when you type uname, for example. 275 The string you set here will be appended after the contents of 276 any files with a filename matching localversion* in your 277 object and source tree, in that order. Your total string can 278 be a maximum of 64 characters. 279 280config LOCALVERSION_AUTO 281 bool "Automatically append version information to the version string" 282 default y 283 depends on !COMPILE_TEST 284 help 285 This will try to automatically determine if the current tree is a 286 release tree by looking for git tags that belong to the current 287 top of tree revision. 288 289 A string of the format -gxxxxxxxx will be added to the localversion 290 if a git-based tree is found. The string generated by this will be 291 appended after any matching localversion* files, and after the value 292 set in CONFIG_LOCALVERSION. 293 294 (The actual string used here is the first 12 characters produced 295 by running the command: 296 297 $ git rev-parse --verify HEAD 298 299 which is done within the script "scripts/setlocalversion".) 300 301config BUILD_SALT 302 string "Build ID Salt" 303 default "" 304 help 305 The build ID is used to link binaries and their debug info. Setting 306 this option will use the value in the calculation of the build id. 307 This is mostly useful for distributions which want to ensure the 308 build is unique between builds. It's safe to leave the default. 309 310config HAVE_KERNEL_GZIP 311 bool 312 313config HAVE_KERNEL_BZIP2 314 bool 315 316config HAVE_KERNEL_LZMA 317 bool 318 319config HAVE_KERNEL_XZ 320 bool 321 322config HAVE_KERNEL_LZO 323 bool 324 325config HAVE_KERNEL_LZ4 326 bool 327 328config HAVE_KERNEL_ZSTD 329 bool 330 331config HAVE_KERNEL_UNCOMPRESSED 332 bool 333 334choice 335 prompt "Kernel compression mode" 336 default KERNEL_GZIP 337 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 338 help 339 The linux kernel is a kind of self-extracting executable. 340 Several compression algorithms are available, which differ 341 in efficiency, compression and decompression speed. 342 Compression speed is only relevant when building a kernel. 343 Decompression speed is relevant at each boot. 344 345 If you have any problems with bzip2 or lzma compressed 346 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 347 version of this functionality (bzip2 only), for 2.4, was 348 supplied by Christian Ludwig) 349 350 High compression options are mostly useful for users, who 351 are low on disk space (embedded systems), but for whom ram 352 size matters less. 353 354 If in doubt, select 'gzip' 355 356config KERNEL_GZIP 357 bool "Gzip" 358 depends on HAVE_KERNEL_GZIP 359 help 360 The old and tried gzip compression. It provides a good balance 361 between compression ratio and decompression speed. 362 363config KERNEL_BZIP2 364 bool "Bzip2" 365 depends on HAVE_KERNEL_BZIP2 366 help 367 Its compression ratio and speed is intermediate. 368 Decompression speed is slowest among the choices. The kernel 369 size is about 10% smaller with bzip2, in comparison to gzip. 370 Bzip2 uses a large amount of memory. For modern kernels you 371 will need at least 8MB RAM or more for booting. 372 373config KERNEL_LZMA 374 bool "LZMA" 375 depends on HAVE_KERNEL_LZMA 376 help 377 This compression algorithm's ratio is best. Decompression speed 378 is between gzip and bzip2. Compression is slowest. 379 The kernel size is about 33% smaller with LZMA in comparison to gzip. 380 381config KERNEL_XZ 382 bool "XZ" 383 depends on HAVE_KERNEL_XZ 384 help 385 XZ uses the LZMA2 algorithm and instruction set specific 386 BCJ filters which can improve compression ratio of executable 387 code. The size of the kernel is about 30% smaller with XZ in 388 comparison to gzip. On architectures for which there is a BCJ 389 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 390 and SPARC), XZ will create a few percent smaller kernel than 391 plain LZMA. 392 393 The speed is about the same as with LZMA: The decompression 394 speed of XZ is better than that of bzip2 but worse than gzip 395 and LZO. Compression is slow. 396 397config KERNEL_LZO 398 bool "LZO" 399 depends on HAVE_KERNEL_LZO 400 help 401 Its compression ratio is the poorest among the choices. The kernel 402 size is about 10% bigger than gzip; however its speed 403 (both compression and decompression) is the fastest. 404 405config KERNEL_LZ4 406 bool "LZ4" 407 depends on HAVE_KERNEL_LZ4 408 help 409 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 410 A preliminary version of LZ4 de/compression tool is available at 411 <https://code.google.com/p/lz4/>. 412 413 Its compression ratio is worse than LZO. The size of the kernel 414 is about 8% bigger than LZO. But the decompression speed is 415 faster than LZO. 416 417config KERNEL_ZSTD 418 bool "ZSTD" 419 depends on HAVE_KERNEL_ZSTD 420 help 421 ZSTD is a compression algorithm targeting intermediate compression 422 with fast decompression speed. It will compress better than GZIP and 423 decompress around the same speed as LZO, but slower than LZ4. You 424 will need at least 192 KB RAM or more for booting. The zstd command 425 line tool is required for compression. 426 427config KERNEL_UNCOMPRESSED 428 bool "None" 429 depends on HAVE_KERNEL_UNCOMPRESSED 430 help 431 Produce uncompressed kernel image. This option is usually not what 432 you want. It is useful for debugging the kernel in slow simulation 433 environments, where decompressing and moving the kernel is awfully 434 slow. This option allows early boot code to skip the decompressor 435 and jump right at uncompressed kernel image. 436 437endchoice 438 439config DEFAULT_INIT 440 string "Default init path" 441 default "" 442 help 443 This option determines the default init for the system if no init= 444 option is passed on the kernel command line. If the requested path is 445 not present, we will still then move on to attempting further 446 locations (e.g. /sbin/init, etc). If this is empty, we will just use 447 the fallback list when init= is not passed. 448 449config DEFAULT_HOSTNAME 450 string "Default hostname" 451 default "(none)" 452 help 453 This option determines the default system hostname before userspace 454 calls sethostname(2). The kernel traditionally uses "(none)" here, 455 but you may wish to use a different default here to make a minimal 456 system more usable with less configuration. 457 458config SYSVIPC 459 bool "System V IPC" 460 help 461 Inter Process Communication is a suite of library functions and 462 system calls which let processes (running programs) synchronize and 463 exchange information. It is generally considered to be a good thing, 464 and some programs won't run unless you say Y here. In particular, if 465 you want to run the DOS emulator dosemu under Linux (read the 466 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 467 you'll need to say Y here. 468 469 You can find documentation about IPC with "info ipc" and also in 470 section 6.4 of the Linux Programmer's Guide, available from 471 <http://www.tldp.org/guides.html>. 472 473config SYSVIPC_SYSCTL 474 bool 475 depends on SYSVIPC 476 depends on SYSCTL 477 default y 478 479config SYSVIPC_COMPAT 480 def_bool y 481 depends on COMPAT && SYSVIPC 482 483config POSIX_MQUEUE 484 bool "POSIX Message Queues" 485 depends on NET 486 help 487 POSIX variant of message queues is a part of IPC. In POSIX message 488 queues every message has a priority which decides about succession 489 of receiving it by a process. If you want to compile and run 490 programs written e.g. for Solaris with use of its POSIX message 491 queues (functions mq_*) say Y here. 492 493 POSIX message queues are visible as a filesystem called 'mqueue' 494 and can be mounted somewhere if you want to do filesystem 495 operations on message queues. 496 497 If unsure, say Y. 498 499config POSIX_MQUEUE_SYSCTL 500 bool 501 depends on POSIX_MQUEUE 502 depends on SYSCTL 503 default y 504 505config WATCH_QUEUE 506 bool "General notification queue" 507 default n 508 help 509 510 This is a general notification queue for the kernel to pass events to 511 userspace by splicing them into pipes. It can be used in conjunction 512 with watches for key/keyring change notifications and device 513 notifications. 514 515 See Documentation/core-api/watch_queue.rst 516 517config CROSS_MEMORY_ATTACH 518 bool "Enable process_vm_readv/writev syscalls" 519 depends on MMU 520 default y 521 help 522 Enabling this option adds the system calls process_vm_readv and 523 process_vm_writev which allow a process with the correct privileges 524 to directly read from or write to another process' address space. 525 See the man page for more details. 526 527config AUDIT 528 bool "Auditing support" 529 depends on NET 530 help 531 Enable auditing infrastructure that can be used with another 532 kernel subsystem, such as SELinux (which requires this for 533 logging of avc messages output). System call auditing is included 534 on architectures which support it. 535 536config HAVE_ARCH_AUDITSYSCALL 537 bool 538 539config AUDITSYSCALL 540 def_bool y 541 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 542 select FSNOTIFY 543 544source "kernel/irq/Kconfig" 545source "kernel/time/Kconfig" 546source "kernel/bpf/Kconfig" 547source "kernel/Kconfig.preempt" 548 549menu "CPU/Task time and stats accounting" 550 551config VIRT_CPU_ACCOUNTING 552 bool 553 554choice 555 prompt "Cputime accounting" 556 default TICK_CPU_ACCOUNTING 557 558# Kind of a stub config for the pure tick based cputime accounting 559config TICK_CPU_ACCOUNTING 560 bool "Simple tick based cputime accounting" 561 depends on !S390 && !NO_HZ_FULL 562 help 563 This is the basic tick based cputime accounting that maintains 564 statistics about user, system and idle time spent on per jiffies 565 granularity. 566 567 If unsure, say Y. 568 569config VIRT_CPU_ACCOUNTING_NATIVE 570 bool "Deterministic task and CPU time accounting" 571 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 572 select VIRT_CPU_ACCOUNTING 573 help 574 Select this option to enable more accurate task and CPU time 575 accounting. This is done by reading a CPU counter on each 576 kernel entry and exit and on transitions within the kernel 577 between system, softirq and hardirq state, so there is a 578 small performance impact. In the case of s390 or IBM POWER > 5, 579 this also enables accounting of stolen time on logically-partitioned 580 systems. 581 582config VIRT_CPU_ACCOUNTING_GEN 583 bool "Full dynticks CPU time accounting" 584 depends on HAVE_CONTEXT_TRACKING_USER 585 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 586 depends on GENERIC_CLOCKEVENTS 587 select VIRT_CPU_ACCOUNTING 588 select CONTEXT_TRACKING_USER 589 help 590 Select this option to enable task and CPU time accounting on full 591 dynticks systems. This accounting is implemented by watching every 592 kernel-user boundaries using the context tracking subsystem. 593 The accounting is thus performed at the expense of some significant 594 overhead. 595 596 For now this is only useful if you are working on the full 597 dynticks subsystem development. 598 599 If unsure, say N. 600 601endchoice 602 603config IRQ_TIME_ACCOUNTING 604 bool "Fine granularity task level IRQ time accounting" 605 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 606 help 607 Select this option to enable fine granularity task irq time 608 accounting. This is done by reading a timestamp on each 609 transitions between softirq and hardirq state, so there can be a 610 small performance impact. 611 612 If in doubt, say N here. 613 614config HAVE_SCHED_AVG_IRQ 615 def_bool y 616 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 617 depends on SMP 618 619config SCHED_HW_PRESSURE 620 bool 621 default y if ARM && ARM_CPU_TOPOLOGY 622 default y if ARM64 623 depends on SMP 624 depends on CPU_FREQ_THERMAL 625 help 626 Select this option to enable HW pressure accounting in the 627 scheduler. HW pressure is the value conveyed to the scheduler 628 that reflects the reduction in CPU compute capacity resulted from 629 HW throttling. HW throttling occurs when the performance of 630 a CPU is capped due to high operating temperatures as an example. 631 632 If selected, the scheduler will be able to balance tasks accordingly, 633 i.e. put less load on throttled CPUs than on non/less throttled ones. 634 635 This requires the architecture to implement 636 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 637 638config BSD_PROCESS_ACCT 639 bool "BSD Process Accounting (DEPRECATED)" 640 depends on MULTIUSER 641 default n 642 help 643 If you say Y here, a user level program will be able to instruct the 644 kernel (via a special system call) to write process accounting 645 information to a file: whenever a process exits, information about 646 that process will be appended to the file by the kernel. The 647 information includes things such as creation time, owning user, 648 command name, memory usage, controlling terminal etc. (the complete 649 list is in the struct acct in <file:include/linux/acct.h>). It is 650 up to the user level program to do useful things with this 651 information. This mechanism is antiquated and has significant 652 scalability issues. You probably want to use eBPF instead. Say 653 N unless you really need this. 654 655config BSD_PROCESS_ACCT_V3 656 bool "BSD Process Accounting version 3 file format" 657 depends on BSD_PROCESS_ACCT 658 default n 659 help 660 If you say Y here, the process accounting information is written 661 in a new file format that also logs the process IDs of each 662 process and its parent. Note that this file format is incompatible 663 with previous v0/v1/v2 file formats, so you will need updated tools 664 for processing it. A preliminary version of these tools is available 665 at <http://www.gnu.org/software/acct/>. 666 667config TASKSTATS 668 bool "Export task/process statistics through netlink" 669 depends on NET 670 depends on MULTIUSER 671 default n 672 help 673 Export selected statistics for tasks/processes through the 674 generic netlink interface. Unlike BSD process accounting, the 675 statistics are available during the lifetime of tasks/processes as 676 responses to commands. Like BSD accounting, they are sent to user 677 space on task exit. 678 679 Say N if unsure. 680 681config TASK_DELAY_ACCT 682 bool "Enable per-task delay accounting" 683 depends on TASKSTATS 684 select SCHED_INFO 685 help 686 Collect information on time spent by a task waiting for system 687 resources like cpu, synchronous block I/O completion and swapping 688 in pages. Such statistics can help in setting a task's priorities 689 relative to other tasks for cpu, io, rss limits etc. 690 691 Say N if unsure. 692 693config TASK_XACCT 694 bool "Enable extended accounting over taskstats" 695 depends on TASKSTATS 696 help 697 Collect extended task accounting data and send the data 698 to userland for processing over the taskstats interface. 699 700 Say N if unsure. 701 702config TASK_IO_ACCOUNTING 703 bool "Enable per-task storage I/O accounting" 704 depends on TASK_XACCT 705 help 706 Collect information on the number of bytes of storage I/O which this 707 task has caused. 708 709 Say N if unsure. 710 711config PSI 712 bool "Pressure stall information tracking" 713 select KERNFS 714 help 715 Collect metrics that indicate how overcommitted the CPU, memory, 716 and IO capacity are in the system. 717 718 If you say Y here, the kernel will create /proc/pressure/ with the 719 pressure statistics files cpu, memory, and io. These will indicate 720 the share of walltime in which some or all tasks in the system are 721 delayed due to contention of the respective resource. 722 723 In kernels with cgroup support, cgroups (cgroup2 only) will 724 have cpu.pressure, memory.pressure, and io.pressure files, 725 which aggregate pressure stalls for the grouped tasks only. 726 727 For more details see Documentation/accounting/psi.rst. 728 729 Say N if unsure. 730 731config PSI_DEFAULT_DISABLED 732 bool "Require boot parameter to enable pressure stall information tracking" 733 default n 734 depends on PSI 735 help 736 If set, pressure stall information tracking will be disabled 737 per default but can be enabled through passing psi=1 on the 738 kernel commandline during boot. 739 740 This feature adds some code to the task wakeup and sleep 741 paths of the scheduler. The overhead is too low to affect 742 common scheduling-intense workloads in practice (such as 743 webservers, memcache), but it does show up in artificial 744 scheduler stress tests, such as hackbench. 745 746 If you are paranoid and not sure what the kernel will be 747 used for, say Y. 748 749 Say N if unsure. 750 751endmenu # "CPU/Task time and stats accounting" 752 753config CPU_ISOLATION 754 bool "CPU isolation" 755 depends on SMP 756 default y 757 help 758 Make sure that CPUs running critical tasks are not disturbed by 759 any source of "noise" such as unbound workqueues, timers, kthreads... 760 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 761 the "isolcpus=" boot parameter. 762 763 Say Y if unsure. 764 765source "kernel/rcu/Kconfig" 766 767config IKCONFIG 768 tristate "Kernel .config support" 769 help 770 This option enables the complete Linux kernel ".config" file 771 contents to be saved in the kernel. It provides documentation 772 of which kernel options are used in a running kernel or in an 773 on-disk kernel. This information can be extracted from the kernel 774 image file with the script scripts/extract-ikconfig and used as 775 input to rebuild the current kernel or to build another kernel. 776 It can also be extracted from a running kernel by reading 777 /proc/config.gz if enabled (below). 778 779config IKCONFIG_PROC 780 bool "Enable access to .config through /proc/config.gz" 781 depends on IKCONFIG && PROC_FS 782 help 783 This option enables access to the kernel configuration file 784 through /proc/config.gz. 785 786config IKHEADERS 787 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 788 depends on SYSFS 789 help 790 This option enables access to the in-kernel headers that are generated during 791 the build process. These can be used to build eBPF tracing programs, 792 or similar programs. If you build the headers as a module, a module called 793 kheaders.ko is built which can be loaded on-demand to get access to headers. 794 795config LOG_BUF_SHIFT 796 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 797 range 12 25 798 default 17 799 depends on PRINTK 800 help 801 Select the minimal kernel log buffer size as a power of 2. 802 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 803 parameter, see below. Any higher size also might be forced 804 by "log_buf_len" boot parameter. 805 806 Examples: 807 17 => 128 KB 808 16 => 64 KB 809 15 => 32 KB 810 14 => 16 KB 811 13 => 8 KB 812 12 => 4 KB 813 814config LOG_CPU_MAX_BUF_SHIFT 815 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 816 depends on SMP 817 range 0 21 818 default 0 if BASE_SMALL 819 default 12 820 depends on PRINTK 821 help 822 This option allows to increase the default ring buffer size 823 according to the number of CPUs. The value defines the contribution 824 of each CPU as a power of 2. The used space is typically only few 825 lines however it might be much more when problems are reported, 826 e.g. backtraces. 827 828 The increased size means that a new buffer has to be allocated and 829 the original static one is unused. It makes sense only on systems 830 with more CPUs. Therefore this value is used only when the sum of 831 contributions is greater than the half of the default kernel ring 832 buffer as defined by LOG_BUF_SHIFT. The default values are set 833 so that more than 16 CPUs are needed to trigger the allocation. 834 835 Also this option is ignored when "log_buf_len" kernel parameter is 836 used as it forces an exact (power of two) size of the ring buffer. 837 838 The number of possible CPUs is used for this computation ignoring 839 hotplugging making the computation optimal for the worst case 840 scenario while allowing a simple algorithm to be used from bootup. 841 842 Examples shift values and their meaning: 843 17 => 128 KB for each CPU 844 16 => 64 KB for each CPU 845 15 => 32 KB for each CPU 846 14 => 16 KB for each CPU 847 13 => 8 KB for each CPU 848 12 => 4 KB for each CPU 849 850config PRINTK_INDEX 851 bool "Printk indexing debugfs interface" 852 depends on PRINTK && DEBUG_FS 853 help 854 Add support for indexing of all printk formats known at compile time 855 at <debugfs>/printk/index/<module>. 856 857 This can be used as part of maintaining daemons which monitor 858 /dev/kmsg, as it permits auditing the printk formats present in a 859 kernel, allowing detection of cases where monitored printks are 860 changed or no longer present. 861 862 There is no additional runtime cost to printk with this enabled. 863 864# 865# Architectures with an unreliable sched_clock() should select this: 866# 867config HAVE_UNSTABLE_SCHED_CLOCK 868 bool 869 870config GENERIC_SCHED_CLOCK 871 bool 872 873menu "Scheduler features" 874 875config UCLAMP_TASK 876 bool "Enable utilization clamping for RT/FAIR tasks" 877 depends on CPU_FREQ_GOV_SCHEDUTIL 878 help 879 This feature enables the scheduler to track the clamped utilization 880 of each CPU based on RUNNABLE tasks scheduled on that CPU. 881 882 With this option, the user can specify the min and max CPU 883 utilization allowed for RUNNABLE tasks. The max utilization defines 884 the maximum frequency a task should use while the min utilization 885 defines the minimum frequency it should use. 886 887 Both min and max utilization clamp values are hints to the scheduler, 888 aiming at improving its frequency selection policy, but they do not 889 enforce or grant any specific bandwidth for tasks. 890 891 If in doubt, say N. 892 893config UCLAMP_BUCKETS_COUNT 894 int "Number of supported utilization clamp buckets" 895 range 5 20 896 default 5 897 depends on UCLAMP_TASK 898 help 899 Defines the number of clamp buckets to use. The range of each bucket 900 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 901 number of clamp buckets the finer their granularity and the higher 902 the precision of clamping aggregation and tracking at run-time. 903 904 For example, with the minimum configuration value we will have 5 905 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 906 be refcounted in the [20..39]% bucket and will set the bucket clamp 907 effective value to 25%. 908 If a second 30% boosted task should be co-scheduled on the same CPU, 909 that task will be refcounted in the same bucket of the first task and 910 it will boost the bucket clamp effective value to 30%. 911 The clamp effective value of a bucket is reset to its nominal value 912 (20% in the example above) when there are no more tasks refcounted in 913 that bucket. 914 915 An additional boost/capping margin can be added to some tasks. In the 916 example above the 25% task will be boosted to 30% until it exits the 917 CPU. If that should be considered not acceptable on certain systems, 918 it's always possible to reduce the margin by increasing the number of 919 clamp buckets to trade off used memory for run-time tracking 920 precision. 921 922 If in doubt, use the default value. 923 924config SCHED_PROXY_EXEC 925 bool "Proxy Execution" 926 # Avoid some build failures w/ PREEMPT_RT until it can be fixed 927 depends on !PREEMPT_RT 928 # Need to investigate how to inform sched_ext of split contexts 929 depends on !SCHED_CLASS_EXT 930 # Not particularly useful until we get to multi-rq proxying 931 depends on EXPERT 932 help 933 This option enables proxy execution, a mechanism for mutex-owning 934 tasks to inherit the scheduling context of higher priority waiters. 935 936endmenu 937 938# 939# For architectures that want to enable the support for NUMA-affine scheduler 940# balancing logic: 941# 942config ARCH_SUPPORTS_NUMA_BALANCING 943 bool 944 945# 946# For architectures that prefer to flush all TLBs after a number of pages 947# are unmapped instead of sending one IPI per page to flush. The architecture 948# must provide guarantees on what happens if a clean TLB cache entry is 949# written after the unmap. Details are in mm/rmap.c near the check for 950# should_defer_flush. The architecture should also consider if the full flush 951# and the refill costs are offset by the savings of sending fewer IPIs. 952config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 953 bool 954 955config CC_HAS_INT128 956 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 957 958config CC_IMPLICIT_FALLTHROUGH 959 string 960 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 961 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 962 963config CC_MS_EXTENSIONS 964 string 965 default "-fms-anonymous-structs" if $(cc-option,-fms-anonymous-structs) 966 default "-fms-extensions" 967 968# Currently, disable gcc-10+ array-bounds globally. 969# It's still broken in gcc-13, so no upper bound yet. 970config GCC10_NO_ARRAY_BOUNDS 971 def_bool y 972 973config CC_NO_ARRAY_BOUNDS 974 bool 975 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 976 977# Currently, disable -Wstringop-overflow for GCC globally. 978config GCC_NO_STRINGOP_OVERFLOW 979 def_bool y 980 981config CC_NO_STRINGOP_OVERFLOW 982 bool 983 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 984 985config CC_STRINGOP_OVERFLOW 986 bool 987 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 988 989# 990# For architectures that know their GCC __int128 support is sound 991# 992config ARCH_SUPPORTS_INT128 993 bool 994 995# For architectures that (ab)use NUMA to represent different memory regions 996# all cpu-local but of different latencies, such as SuperH. 997# 998config ARCH_WANT_NUMA_VARIABLE_LOCALITY 999 bool 1000 1001config NUMA_BALANCING 1002 bool "Memory placement aware NUMA scheduler" 1003 depends on ARCH_SUPPORTS_NUMA_BALANCING 1004 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 1005 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 1006 help 1007 This option adds support for automatic NUMA aware memory/task placement. 1008 The mechanism is quite primitive and is based on migrating memory when 1009 it has references to the node the task is running on. 1010 1011 This system will be inactive on UMA systems. 1012 1013config NUMA_BALANCING_DEFAULT_ENABLED 1014 bool "Automatically enable NUMA aware memory/task placement" 1015 default y 1016 depends on NUMA_BALANCING 1017 help 1018 If set, automatic NUMA balancing will be enabled if running on a NUMA 1019 machine. 1020 1021config SLAB_OBJ_EXT 1022 bool 1023 1024menuconfig CGROUPS 1025 bool "Control Group support" 1026 select KERNFS 1027 help 1028 This option adds support for grouping sets of processes together, for 1029 use with process control subsystems such as Cpusets, CFS, memory 1030 controls or device isolation. 1031 See 1032 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1033 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1034 and resource control) 1035 1036 Say N if unsure. 1037 1038if CGROUPS 1039 1040config PAGE_COUNTER 1041 bool 1042 1043config CGROUP_FAVOR_DYNMODS 1044 bool "Favor dynamic modification latency reduction by default" 1045 help 1046 This option enables the "favordynmods" mount option by default 1047 which reduces the latencies of dynamic cgroup modifications such 1048 as task migrations and controller on/offs at the cost of making 1049 hot path operations such as forks and exits more expensive. 1050 1051 Say N if unsure. 1052 1053config MEMCG 1054 bool "Memory controller" 1055 select PAGE_COUNTER 1056 select EVENTFD 1057 select SLAB_OBJ_EXT 1058 select VM_EVENT_COUNTERS 1059 help 1060 Provides control over the memory footprint of tasks in a cgroup. 1061 1062config MEMCG_NMI_UNSAFE 1063 bool 1064 depends on MEMCG 1065 depends on HAVE_NMI 1066 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1067 default y 1068 1069config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1070 bool 1071 depends on MEMCG 1072 depends on HAVE_NMI 1073 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1074 default y 1075 1076config MEMCG_V1 1077 bool "Legacy cgroup v1 memory controller" 1078 depends on MEMCG 1079 default n 1080 help 1081 Legacy cgroup v1 memory controller which has been deprecated by 1082 cgroup v2 implementation. The v1 is there for legacy applications 1083 which haven't migrated to the new cgroup v2 interface yet. If you 1084 do not have any such application then you are completely fine leaving 1085 this option disabled. 1086 1087 Please note that feature set of the legacy memory controller is likely 1088 going to shrink due to deprecation process. New deployments with v1 1089 controller are highly discouraged. 1090 1091 Say N if unsure. 1092 1093config BLK_CGROUP 1094 bool "IO controller" 1095 depends on BLOCK 1096 default n 1097 help 1098 Generic block IO controller cgroup interface. This is the common 1099 cgroup interface which should be used by various IO controlling 1100 policies. 1101 1102 Currently, CFQ IO scheduler uses it to recognize task groups and 1103 control disk bandwidth allocation (proportional time slice allocation) 1104 to such task groups. It is also used by bio throttling logic in 1105 block layer to implement upper limit in IO rates on a device. 1106 1107 This option only enables generic Block IO controller infrastructure. 1108 One needs to also enable actual IO controlling logic/policy. For 1109 enabling proportional weight division of disk bandwidth in CFQ, set 1110 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1111 CONFIG_BLK_DEV_THROTTLING=y. 1112 1113 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1114 1115config CGROUP_WRITEBACK 1116 bool 1117 depends on MEMCG && BLK_CGROUP 1118 default y 1119 1120menuconfig CGROUP_SCHED 1121 bool "CPU controller" 1122 default n 1123 help 1124 This feature lets CPU scheduler recognize task groups and control CPU 1125 bandwidth allocation to such task groups. It uses cgroups to group 1126 tasks. 1127 1128if CGROUP_SCHED 1129config GROUP_SCHED_WEIGHT 1130 def_bool n 1131 1132config GROUP_SCHED_BANDWIDTH 1133 def_bool n 1134 1135config FAIR_GROUP_SCHED 1136 bool "Group scheduling for SCHED_OTHER" 1137 depends on CGROUP_SCHED 1138 select GROUP_SCHED_WEIGHT 1139 default CGROUP_SCHED 1140 1141config CFS_BANDWIDTH 1142 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1143 depends on FAIR_GROUP_SCHED 1144 select GROUP_SCHED_BANDWIDTH 1145 default n 1146 help 1147 This option allows users to define CPU bandwidth rates (limits) for 1148 tasks running within the fair group scheduler. Groups with no limit 1149 set are considered to be unconstrained and will run with no 1150 restriction. 1151 See Documentation/scheduler/sched-bwc.rst for more information. 1152 1153config RT_GROUP_SCHED 1154 bool "Group scheduling for SCHED_RR/FIFO" 1155 depends on CGROUP_SCHED 1156 default n 1157 help 1158 This feature lets you explicitly allocate real CPU bandwidth 1159 to task groups. If enabled, it will also make it impossible to 1160 schedule realtime tasks for non-root users until you allocate 1161 realtime bandwidth for them. 1162 See Documentation/scheduler/sched-rt-group.rst for more information. 1163 1164config RT_GROUP_SCHED_DEFAULT_DISABLED 1165 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1166 depends on RT_GROUP_SCHED 1167 default n 1168 help 1169 When set, the RT group scheduling is disabled by default. The option 1170 is in inverted form so that mere RT_GROUP_SCHED enables the group 1171 scheduling. 1172 1173 Say N if unsure. 1174 1175config EXT_GROUP_SCHED 1176 bool 1177 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1178 select GROUP_SCHED_WEIGHT 1179 select GROUP_SCHED_BANDWIDTH 1180 default y 1181 1182endif #CGROUP_SCHED 1183 1184config SCHED_MM_CID 1185 def_bool y 1186 depends on SMP && RSEQ 1187 1188config UCLAMP_TASK_GROUP 1189 bool "Utilization clamping per group of tasks" 1190 depends on CGROUP_SCHED 1191 depends on UCLAMP_TASK 1192 default n 1193 help 1194 This feature enables the scheduler to track the clamped utilization 1195 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1196 1197 When this option is enabled, the user can specify a min and max 1198 CPU bandwidth which is allowed for each single task in a group. 1199 The max bandwidth allows to clamp the maximum frequency a task 1200 can use, while the min bandwidth allows to define a minimum 1201 frequency a task will always use. 1202 1203 When task group based utilization clamping is enabled, an eventually 1204 specified task-specific clamp value is constrained by the cgroup 1205 specified clamp value. Both minimum and maximum task clamping cannot 1206 be bigger than the corresponding clamping defined at task group level. 1207 1208 If in doubt, say N. 1209 1210config CGROUP_PIDS 1211 bool "PIDs controller" 1212 help 1213 Provides enforcement of process number limits in the scope of a 1214 cgroup. Any attempt to fork more processes than is allowed in the 1215 cgroup will fail. PIDs are fundamentally a global resource because it 1216 is fairly trivial to reach PID exhaustion before you reach even a 1217 conservative kmemcg limit. As a result, it is possible to grind a 1218 system to halt without being limited by other cgroup policies. The 1219 PIDs controller is designed to stop this from happening. 1220 1221 It should be noted that organisational operations (such as attaching 1222 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1223 since the PIDs limit only affects a process's ability to fork, not to 1224 attach to a cgroup. 1225 1226config CGROUP_RDMA 1227 bool "RDMA controller" 1228 help 1229 Provides enforcement of RDMA resources defined by IB stack. 1230 It is fairly easy for consumers to exhaust RDMA resources, which 1231 can result into resource unavailability to other consumers. 1232 RDMA controller is designed to stop this from happening. 1233 Attaching processes with active RDMA resources to the cgroup 1234 hierarchy is allowed even if can cross the hierarchy's limit. 1235 1236config CGROUP_DMEM 1237 bool "Device memory controller (DMEM)" 1238 select PAGE_COUNTER 1239 help 1240 The DMEM controller allows compatible devices to restrict device 1241 memory usage based on the cgroup hierarchy. 1242 1243 As an example, it allows you to restrict VRAM usage for applications 1244 in the DRM subsystem. 1245 1246config CGROUP_FREEZER 1247 bool "Freezer controller" 1248 help 1249 Provides a way to freeze and unfreeze all tasks in a 1250 cgroup. 1251 1252 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1253 controller includes important in-kernel memory consumers per default. 1254 1255 If you're using cgroup2, say N. 1256 1257config CGROUP_HUGETLB 1258 bool "HugeTLB controller" 1259 depends on HUGETLB_PAGE 1260 select PAGE_COUNTER 1261 default n 1262 help 1263 Provides a cgroup controller for HugeTLB pages. 1264 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1265 The limit is enforced during page fault. Since HugeTLB doesn't 1266 support page reclaim, enforcing the limit at page fault time implies 1267 that, the application will get SIGBUS signal if it tries to access 1268 HugeTLB pages beyond its limit. This requires the application to know 1269 beforehand how much HugeTLB pages it would require for its use. The 1270 control group is tracked in the third page lru pointer. This means 1271 that we cannot use the controller with huge page less than 3 pages. 1272 1273config CPUSETS 1274 bool "Cpuset controller" 1275 depends on SMP 1276 select UNION_FIND 1277 select CPU_ISOLATION 1278 help 1279 This option will let you create and manage CPUSETs which 1280 allow dynamically partitioning a system into sets of CPUs and 1281 Memory Nodes and assigning tasks to run only within those sets. 1282 This is primarily useful on large SMP or NUMA systems. 1283 1284 Say N if unsure. 1285 1286config CPUSETS_V1 1287 bool "Legacy cgroup v1 cpusets controller" 1288 depends on CPUSETS 1289 default n 1290 help 1291 Legacy cgroup v1 cpusets controller which has been deprecated by 1292 cgroup v2 implementation. The v1 is there for legacy applications 1293 which haven't migrated to the new cgroup v2 interface yet. Legacy 1294 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1295 do not have any such application then you are completely fine leaving 1296 this option disabled. 1297 1298 Say N if unsure. 1299 1300config PROC_PID_CPUSET 1301 bool "Include legacy /proc/<pid>/cpuset file" 1302 depends on CPUSETS_V1 1303 default y 1304 1305config CGROUP_DEVICE 1306 bool "Device controller" 1307 help 1308 Provides a cgroup controller implementing whitelists for 1309 devices which a process in the cgroup can mknod or open. 1310 1311config CGROUP_CPUACCT 1312 bool "Simple CPU accounting controller" 1313 help 1314 Provides a simple controller for monitoring the 1315 total CPU consumed by the tasks in a cgroup. 1316 1317config CGROUP_PERF 1318 bool "Perf controller" 1319 depends on PERF_EVENTS 1320 help 1321 This option extends the perf per-cpu mode to restrict monitoring 1322 to threads which belong to the cgroup specified and run on the 1323 designated cpu. Or this can be used to have cgroup ID in samples 1324 so that it can monitor performance events among cgroups. 1325 1326 Say N if unsure. 1327 1328config CGROUP_BPF 1329 bool "Support for eBPF programs attached to cgroups" 1330 depends on BPF_SYSCALL 1331 select SOCK_CGROUP_DATA 1332 help 1333 Allow attaching eBPF programs to a cgroup using the bpf(2) 1334 syscall command BPF_PROG_ATTACH. 1335 1336 In which context these programs are accessed depends on the type 1337 of attachment. For instance, programs that are attached using 1338 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1339 inet sockets. 1340 1341config CGROUP_MISC 1342 bool "Misc resource controller" 1343 default n 1344 help 1345 Provides a controller for miscellaneous resources on a host. 1346 1347 Miscellaneous scalar resources are the resources on the host system 1348 which cannot be abstracted like the other cgroups. This controller 1349 tracks and limits the miscellaneous resources used by a process 1350 attached to a cgroup hierarchy. 1351 1352 For more information, please check misc cgroup section in 1353 /Documentation/admin-guide/cgroup-v2.rst. 1354 1355config CGROUP_DEBUG 1356 bool "Debug controller" 1357 default n 1358 depends on DEBUG_KERNEL 1359 help 1360 This option enables a simple controller that exports 1361 debugging information about the cgroups framework. This 1362 controller is for control cgroup debugging only. Its 1363 interfaces are not stable. 1364 1365 Say N. 1366 1367config SOCK_CGROUP_DATA 1368 bool 1369 default n 1370 1371endif # CGROUPS 1372 1373menuconfig NAMESPACES 1374 bool "Namespaces support" if EXPERT 1375 depends on MULTIUSER 1376 default !EXPERT 1377 help 1378 Provides the way to make tasks work with different objects using 1379 the same id. For example same IPC id may refer to different objects 1380 or same user id or pid may refer to different tasks when used in 1381 different namespaces. 1382 1383if NAMESPACES 1384 1385config UTS_NS 1386 bool "UTS namespace" 1387 default y 1388 help 1389 In this namespace tasks see different info provided with the 1390 uname() system call 1391 1392config TIME_NS 1393 bool "TIME namespace" 1394 depends on GENERIC_GETTIMEOFDAY 1395 default y 1396 help 1397 In this namespace boottime and monotonic clocks can be set. 1398 The time will keep going with the same pace. 1399 1400config IPC_NS 1401 bool "IPC namespace" 1402 depends on (SYSVIPC || POSIX_MQUEUE) 1403 default y 1404 help 1405 In this namespace tasks work with IPC ids which correspond to 1406 different IPC objects in different namespaces. 1407 1408config USER_NS 1409 bool "User namespace" 1410 default n 1411 help 1412 This allows containers, i.e. vservers, to use user namespaces 1413 to provide different user info for different servers. 1414 1415 When user namespaces are enabled in the kernel it is 1416 recommended that the MEMCG option also be enabled and that 1417 user-space use the memory control groups to limit the amount 1418 of memory a memory unprivileged users can use. 1419 1420 If unsure, say N. 1421 1422config PID_NS 1423 bool "PID Namespaces" 1424 default y 1425 help 1426 Support process id namespaces. This allows having multiple 1427 processes with the same pid as long as they are in different 1428 pid namespaces. This is a building block of containers. 1429 1430config NET_NS 1431 bool "Network namespace" 1432 depends on NET 1433 default y 1434 help 1435 Allow user space to create what appear to be multiple instances 1436 of the network stack. 1437 1438endif # NAMESPACES 1439 1440config CHECKPOINT_RESTORE 1441 bool "Checkpoint/restore support" 1442 depends on PROC_FS 1443 select PROC_CHILDREN 1444 select KCMP 1445 default n 1446 help 1447 Enables additional kernel features in a sake of checkpoint/restore. 1448 In particular it adds auxiliary prctl codes to setup process text, 1449 data and heap segment sizes, and a few additional /proc filesystem 1450 entries. 1451 1452 If unsure, say N here. 1453 1454config SCHED_AUTOGROUP 1455 bool "Automatic process group scheduling" 1456 select CGROUPS 1457 select CGROUP_SCHED 1458 select FAIR_GROUP_SCHED 1459 help 1460 This option optimizes the scheduler for common desktop workloads by 1461 automatically creating and populating task groups. This separation 1462 of workloads isolates aggressive CPU burners (like build jobs) from 1463 desktop applications. Task group autogeneration is currently based 1464 upon task session. 1465 1466config RELAY 1467 bool "Kernel->user space relay support (formerly relayfs)" 1468 select IRQ_WORK 1469 help 1470 This option enables support for relay interface support in 1471 certain file systems (such as debugfs). 1472 It is designed to provide an efficient mechanism for tools and 1473 facilities to relay large amounts of data from kernel space to 1474 user space. 1475 1476 If unsure, say N. 1477 1478config BLK_DEV_INITRD 1479 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1480 help 1481 The initial RAM filesystem is a ramfs which is loaded by the 1482 boot loader (loadlin or lilo) and that is mounted as root 1483 before the normal boot procedure. It is typically used to 1484 load modules needed to mount the "real" root file system, 1485 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1486 1487 If RAM disk support (BLK_DEV_RAM) is also included, this 1488 also enables initial RAM disk (initrd) support and adds 1489 15 Kbytes (more on some other architectures) to the kernel size. 1490 1491 If unsure say Y. 1492 1493if BLK_DEV_INITRD 1494 1495source "usr/Kconfig" 1496 1497endif 1498 1499config BOOT_CONFIG 1500 bool "Boot config support" 1501 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1502 help 1503 Extra boot config allows system admin to pass a config file as 1504 complemental extension of kernel cmdline when booting. 1505 The boot config file must be attached at the end of initramfs 1506 with checksum, size and magic word. 1507 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1508 1509 If unsure, say Y. 1510 1511config BOOT_CONFIG_FORCE 1512 bool "Force unconditional bootconfig processing" 1513 depends on BOOT_CONFIG 1514 default y if BOOT_CONFIG_EMBED 1515 help 1516 With this Kconfig option set, BOOT_CONFIG processing is carried 1517 out even when the "bootconfig" kernel-boot parameter is omitted. 1518 In fact, with this Kconfig option set, there is no way to 1519 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1520 parameters. 1521 1522 If unsure, say N. 1523 1524config BOOT_CONFIG_EMBED 1525 bool "Embed bootconfig file in the kernel" 1526 depends on BOOT_CONFIG 1527 help 1528 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1529 kernel. Usually, the bootconfig file is loaded with the initrd 1530 image. But if the system doesn't support initrd, this option will 1531 help you by embedding a bootconfig file while building the kernel. 1532 1533 If unsure, say N. 1534 1535config BOOT_CONFIG_EMBED_FILE 1536 string "Embedded bootconfig file path" 1537 depends on BOOT_CONFIG_EMBED 1538 help 1539 Specify a bootconfig file which will be embedded to the kernel. 1540 This bootconfig will be used if there is no initrd or no other 1541 bootconfig in the initrd. 1542 1543config CMDLINE_LOG_WRAP_IDEAL_LEN 1544 int "Length to try to wrap the cmdline when logged at boot" 1545 default 1021 1546 range 0 1021 1547 help 1548 At boot time, the kernel command line is logged to the console. 1549 The log message will start with the prefix "Kernel command line: ". 1550 The log message will attempt to be wrapped (split into multiple log 1551 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters. 1552 If wrapping happens, each log message will start with the prefix and 1553 all but the last message will end with " \". Messages may exceed the 1554 ideal length if a place to wrap isn't found before the specified 1555 number of characters. 1556 1557 A value of 0 disables wrapping, though be warned that the maximum 1558 length of a log message (1021 characters) may cause the cmdline to 1559 be truncated. 1560 1561config INITRAMFS_PRESERVE_MTIME 1562 bool "Preserve cpio archive mtimes in initramfs" 1563 depends on BLK_DEV_INITRD 1564 default y 1565 help 1566 Each entry in an initramfs cpio archive carries an mtime value. When 1567 enabled, extracted cpio items take this mtime, with directory mtime 1568 setting deferred until after creation of any child entries. 1569 1570 If unsure, say Y. 1571 1572config INITRAMFS_TEST 1573 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1574 depends on BLK_DEV_INITRD && KUNIT=y 1575 default KUNIT_ALL_TESTS 1576 help 1577 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1578 1579choice 1580 prompt "Compiler optimization level" 1581 default CC_OPTIMIZE_FOR_PERFORMANCE 1582 1583config CC_OPTIMIZE_FOR_PERFORMANCE 1584 bool "Optimize for performance (-O2)" 1585 help 1586 This is the default optimization level for the kernel, building 1587 with the "-O2" compiler flag for best performance and most 1588 helpful compile-time warnings. 1589 1590config CC_OPTIMIZE_FOR_SIZE 1591 bool "Optimize for size (-Os)" 1592 help 1593 Choosing this option will pass "-Os" to your compiler resulting 1594 in a smaller kernel. 1595 1596endchoice 1597 1598config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1599 bool 1600 help 1601 This requires that the arch annotates or otherwise protects 1602 its external entry points from being discarded. Linker scripts 1603 must also merge .text.*, .data.*, and .bss.* correctly into 1604 output sections. Care must be taken not to pull in unrelated 1605 sections (e.g., '.text.init'). Typically '.' in section names 1606 is used to distinguish them from label names / C identifiers. 1607 1608config LD_DEAD_CODE_DATA_ELIMINATION 1609 bool "Dead code and data elimination (EXPERIMENTAL)" 1610 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1611 depends on EXPERT 1612 depends on $(cc-option,-ffunction-sections -fdata-sections) 1613 depends on $(ld-option,--gc-sections) 1614 help 1615 Enable this if you want to do dead code and data elimination with 1616 the linker by compiling with -ffunction-sections -fdata-sections, 1617 and linking with --gc-sections. 1618 1619 This can reduce on disk and in-memory size of the kernel 1620 code and static data, particularly for small configs and 1621 on small systems. This has the possibility of introducing 1622 silently broken kernel if the required annotations are not 1623 present. This option is not well tested yet, so use at your 1624 own risk. 1625 1626config LD_ORPHAN_WARN 1627 def_bool y 1628 depends on ARCH_WANT_LD_ORPHAN_WARN 1629 depends on $(ld-option,--orphan-handling=warn) 1630 depends on $(ld-option,--orphan-handling=error) 1631 1632config LD_ORPHAN_WARN_LEVEL 1633 string 1634 depends on LD_ORPHAN_WARN 1635 default "error" if WERROR 1636 default "warn" 1637 1638config SYSCTL 1639 bool 1640 1641config HAVE_UID16 1642 bool 1643 1644config SYSCTL_EXCEPTION_TRACE 1645 bool 1646 help 1647 Enable support for /proc/sys/debug/exception-trace. 1648 1649config SYSCTL_ARCH_UNALIGN_NO_WARN 1650 bool 1651 help 1652 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1653 Allows arch to define/use @no_unaligned_warning to possibly warn 1654 about unaligned access emulation going on under the hood. 1655 1656config SYSCTL_ARCH_UNALIGN_ALLOW 1657 bool 1658 help 1659 Enable support for /proc/sys/kernel/unaligned-trap 1660 Allows arches to define/use @unaligned_enabled to runtime toggle 1661 the unaligned access emulation. 1662 see arch/parisc/kernel/unaligned.c for reference 1663 1664config SYSFS_SYSCALL 1665 bool "Sysfs syscall support" 1666 default n 1667 help 1668 sys_sysfs is an obsolete system call no longer supported in libc. 1669 Note that disabling this option is more secure but might break 1670 compatibility with some systems. 1671 1672 If unsure say N here. 1673 1674config HAVE_PCSPKR_PLATFORM 1675 bool 1676 1677menuconfig EXPERT 1678 bool "Configure standard kernel features (expert users)" 1679 # Unhide debug options, to make the on-by-default options visible 1680 select DEBUG_KERNEL 1681 help 1682 This option allows certain base kernel options and settings 1683 to be disabled or tweaked. This is for specialized 1684 environments which can tolerate a "non-standard" kernel. 1685 Only use this if you really know what you are doing. 1686 1687config UID16 1688 bool "Enable 16-bit UID system calls" if EXPERT 1689 depends on HAVE_UID16 && MULTIUSER 1690 default y 1691 help 1692 This enables the legacy 16-bit UID syscall wrappers. 1693 1694config MULTIUSER 1695 bool "Multiple users, groups and capabilities support" if EXPERT 1696 default y 1697 help 1698 This option enables support for non-root users, groups and 1699 capabilities. 1700 1701 If you say N here, all processes will run with UID 0, GID 0, and all 1702 possible capabilities. Saying N here also compiles out support for 1703 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1704 setgid, and capset. 1705 1706 If unsure, say Y here. 1707 1708config SGETMASK_SYSCALL 1709 bool "sgetmask/ssetmask syscalls support" if EXPERT 1710 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1711 help 1712 sys_sgetmask and sys_ssetmask are obsolete system calls 1713 no longer supported in libc but still enabled by default in some 1714 architectures. 1715 1716 If unsure, leave the default option here. 1717 1718config FHANDLE 1719 bool "open by fhandle syscalls" if EXPERT 1720 select EXPORTFS 1721 default y 1722 help 1723 If you say Y here, a user level program will be able to map 1724 file names to handle and then later use the handle for 1725 different file system operations. This is useful in implementing 1726 userspace file servers, which now track files using handles instead 1727 of names. The handle would remain the same even if file names 1728 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1729 syscalls. 1730 1731config POSIX_TIMERS 1732 bool "Posix Clocks & timers" if EXPERT 1733 default y 1734 help 1735 This includes native support for POSIX timers to the kernel. 1736 Some embedded systems have no use for them and therefore they 1737 can be configured out to reduce the size of the kernel image. 1738 1739 When this option is disabled, the following syscalls won't be 1740 available: timer_create, timer_gettime: timer_getoverrun, 1741 timer_settime, timer_delete, clock_adjtime, getitimer, 1742 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1743 clock_getres and clock_nanosleep syscalls will be limited to 1744 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1745 1746 If unsure say y. 1747 1748config PRINTK 1749 default y 1750 bool "Enable support for printk" if EXPERT 1751 select IRQ_WORK 1752 help 1753 This option enables normal printk support. Removing it 1754 eliminates most of the message strings from the kernel image 1755 and makes the kernel more or less silent. As this makes it 1756 very difficult to diagnose system problems, saying N here is 1757 strongly discouraged. 1758 1759config PRINTK_RINGBUFFER_KUNIT_TEST 1760 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1761 depends on PRINTK && KUNIT 1762 default KUNIT_ALL_TESTS 1763 help 1764 This builds the printk ringbuffer KUnit test suite. 1765 1766 For more information on KUnit and unit tests in general, please refer 1767 to the KUnit documentation. 1768 1769 If unsure, say N. 1770 1771config BUG 1772 bool "BUG() support" if EXPERT 1773 default y 1774 help 1775 Disabling this option eliminates support for BUG and WARN, reducing 1776 the size of your kernel image and potentially quietly ignoring 1777 numerous fatal conditions. You should only consider disabling this 1778 option for embedded systems with no facilities for reporting errors. 1779 Just say Y. 1780 1781config ELF_CORE 1782 depends on COREDUMP 1783 default y 1784 bool "Enable ELF core dumps" if EXPERT 1785 help 1786 Enable support for generating core dumps. Disabling saves about 4k. 1787 1788 1789config PCSPKR_PLATFORM 1790 bool "Enable PC-Speaker support" if EXPERT 1791 depends on HAVE_PCSPKR_PLATFORM 1792 select I8253_LOCK 1793 default y 1794 help 1795 This option allows to disable the internal PC-Speaker 1796 support, saving some memory. 1797 1798config BASE_SMALL 1799 bool "Enable smaller-sized data structures for core" if EXPERT 1800 help 1801 Enabling this option reduces the size of miscellaneous core 1802 kernel data structures. This saves memory on small machines, 1803 but may reduce performance. 1804 1805config FUTEX 1806 bool "Enable futex support" if EXPERT 1807 depends on !(SPARC32 && SMP) 1808 default y 1809 imply RT_MUTEXES 1810 help 1811 Disabling this option will cause the kernel to be built without 1812 support for "fast userspace mutexes". The resulting kernel may not 1813 run glibc-based applications correctly. 1814 1815config FUTEX_PI 1816 bool 1817 depends on FUTEX && RT_MUTEXES 1818 default y 1819 1820config FUTEX_PRIVATE_HASH 1821 bool 1822 depends on FUTEX && !BASE_SMALL && MMU 1823 default y 1824 1825config FUTEX_MPOL 1826 bool 1827 depends on FUTEX && NUMA 1828 default y 1829 1830config EPOLL 1831 bool "Enable eventpoll support" if EXPERT 1832 default y 1833 help 1834 Disabling this option will cause the kernel to be built without 1835 support for epoll family of system calls. 1836 1837config SIGNALFD 1838 bool "Enable signalfd() system call" if EXPERT 1839 default y 1840 help 1841 Enable the signalfd() system call that allows to receive signals 1842 on a file descriptor. 1843 1844 If unsure, say Y. 1845 1846config TIMERFD 1847 bool "Enable timerfd() system call" if EXPERT 1848 default y 1849 help 1850 Enable the timerfd() system call that allows to receive timer 1851 events on a file descriptor. 1852 1853 If unsure, say Y. 1854 1855config EVENTFD 1856 bool "Enable eventfd() system call" if EXPERT 1857 default y 1858 help 1859 Enable the eventfd() system call that allows to receive both 1860 kernel notification (ie. KAIO) or userspace notifications. 1861 1862 If unsure, say Y. 1863 1864config SHMEM 1865 bool "Use full shmem filesystem" if EXPERT 1866 default y 1867 depends on MMU 1868 help 1869 The shmem is an internal filesystem used to manage shared memory. 1870 It is backed by swap and manages resource limits. It is also exported 1871 to userspace as tmpfs if TMPFS is enabled. Disabling this 1872 option replaces shmem and tmpfs with the much simpler ramfs code, 1873 which may be appropriate on small systems without swap. 1874 1875config AIO 1876 bool "Enable AIO support" if EXPERT 1877 default y 1878 help 1879 This option enables POSIX asynchronous I/O which may by used 1880 by some high performance threaded applications. Disabling 1881 this option saves about 7k. 1882 1883config IO_URING 1884 bool "Enable IO uring support" if EXPERT 1885 select IO_WQ 1886 default y 1887 help 1888 This option enables support for the io_uring interface, enabling 1889 applications to submit and complete IO through submission and 1890 completion rings that are shared between the kernel and application. 1891 1892config GCOV_PROFILE_URING 1893 bool "Enable GCOV profiling on the io_uring subsystem" 1894 depends on IO_URING && GCOV_KERNEL 1895 help 1896 Enable GCOV profiling on the io_uring subsystem, to facilitate 1897 code coverage testing. 1898 1899 If unsure, say N. 1900 1901 Note that this will have a negative impact on the performance of 1902 the io_uring subsystem, hence this should only be enabled for 1903 specific test purposes. 1904 1905config IO_URING_MOCK_FILE 1906 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1907 default n 1908 depends on IO_URING 1909 help 1910 Enable mock files for io_uring subststem testing. The ABI might 1911 still change, so it's still experimental and should only be enabled 1912 for specific test purposes. 1913 1914 If unsure, say N. 1915 1916config ADVISE_SYSCALLS 1917 bool "Enable madvise/fadvise syscalls" if EXPERT 1918 default y 1919 help 1920 This option enables the madvise and fadvise syscalls, used by 1921 applications to advise the kernel about their future memory or file 1922 usage, improving performance. If building an embedded system where no 1923 applications use these syscalls, you can disable this option to save 1924 space. 1925 1926config MEMBARRIER 1927 bool "Enable membarrier() system call" if EXPERT 1928 default y 1929 help 1930 Enable the membarrier() system call that allows issuing memory 1931 barriers across all running threads, which can be used to distribute 1932 the cost of user-space memory barriers asymmetrically by transforming 1933 pairs of memory barriers into pairs consisting of membarrier() and a 1934 compiler barrier. 1935 1936 If unsure, say Y. 1937 1938config KCMP 1939 bool "Enable kcmp() system call" if EXPERT 1940 help 1941 Enable the kernel resource comparison system call. It provides 1942 user-space with the ability to compare two processes to see if they 1943 share a common resource, such as a file descriptor or even virtual 1944 memory space. 1945 1946 If unsure, say N. 1947 1948config RSEQ 1949 bool "Enable rseq() system call" if EXPERT 1950 default y 1951 depends on HAVE_RSEQ 1952 select MEMBARRIER 1953 help 1954 Enable the restartable sequences system call. It provides a 1955 user-space cache for the current CPU number value, which 1956 speeds up getting the current CPU number from user-space, 1957 as well as an ABI to speed up user-space operations on 1958 per-CPU data. 1959 1960 If unsure, say Y. 1961 1962config RSEQ_SLICE_EXTENSION 1963 bool "Enable rseq-based time slice extension mechanism" 1964 depends on RSEQ && HIGH_RES_TIMERS && GENERIC_ENTRY && HAVE_GENERIC_TIF_BITS 1965 help 1966 Allows userspace to request a limited time slice extension when 1967 returning from an interrupt to user space via the RSEQ shared 1968 data ABI. If granted, that allows to complete a critical section, 1969 so that other threads are not stuck on a conflicted resource, 1970 while the task is scheduled out. 1971 1972 If unsure, say N. 1973 1974config RSEQ_STATS 1975 default n 1976 bool "Enable lightweight statistics of restartable sequences" if EXPERT 1977 depends on RSEQ && DEBUG_FS 1978 help 1979 Enable lightweight counters which expose information about the 1980 frequency of RSEQ operations via debugfs. Mostly interesting for 1981 kernel debugging or performance analysis. While lightweight it's 1982 still adding code into the user/kernel mode transitions. 1983 1984 If unsure, say N. 1985 1986config RSEQ_DEBUG_DEFAULT_ENABLE 1987 default n 1988 bool "Enable restartable sequences debug mode by default" if EXPERT 1989 depends on RSEQ 1990 help 1991 This enables the static branch for debug mode of restartable 1992 sequences. 1993 1994 This also can be controlled on the kernel command line via the 1995 command line parameter "rseq_debug=0/1" and through debugfs. 1996 1997 If unsure, say N. 1998 1999config DEBUG_RSEQ 2000 default n 2001 bool "Enable debugging of rseq() system call" if EXPERT 2002 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY 2003 select RSEQ_DEBUG_DEFAULT_ENABLE 2004 help 2005 Enable extra debugging checks for the rseq system call. 2006 2007 If unsure, say N. 2008 2009config CACHESTAT_SYSCALL 2010 bool "Enable cachestat() system call" if EXPERT 2011 default y 2012 help 2013 Enable the cachestat system call, which queries the page cache 2014 statistics of a file (number of cached pages, dirty pages, 2015 pages marked for writeback, (recently) evicted pages). 2016 2017 If unsure say Y here. 2018 2019config KALLSYMS 2020 bool "Load all symbols for debugging/ksymoops" if EXPERT 2021 default y 2022 help 2023 Say Y here to let the kernel print out symbolic crash information and 2024 symbolic stack backtraces. This increases the size of the kernel 2025 somewhat, as all symbols have to be loaded into the kernel image. 2026 2027config KALLSYMS_SELFTEST 2028 bool "Test the basic functions and performance of kallsyms" 2029 depends on KALLSYMS 2030 default n 2031 help 2032 Test the basic functions and performance of some interfaces, such as 2033 kallsyms_lookup_name. It also calculates the compression rate of the 2034 kallsyms compression algorithm for the current symbol set. 2035 2036 Start self-test automatically after system startup. Suggest executing 2037 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 2038 displayed in the last line, indicating that the test is complete. 2039 2040config KALLSYMS_ALL 2041 bool "Include all symbols in kallsyms" 2042 depends on DEBUG_KERNEL && KALLSYMS 2043 help 2044 Normally kallsyms only contains the symbols of functions for nicer 2045 OOPS messages and backtraces (i.e., symbols from the text and inittext 2046 sections). This is sufficient for most cases. And only if you want to 2047 enable kernel live patching, or other less common use cases (e.g., 2048 when a debugger is used) all symbols are required (i.e., names of 2049 variables from the data sections, etc). 2050 2051 This option makes sure that all symbols are loaded into the kernel 2052 image (i.e., symbols from all sections) in cost of increased kernel 2053 size (depending on the kernel configuration, it may be 300KiB or 2054 something like this). 2055 2056 Say N unless you really need all symbols, or kernel live patching. 2057 2058# end of the "standard kernel features (expert users)" menu 2059 2060config ARCH_HAS_MEMBARRIER_CALLBACKS 2061 bool 2062 2063config ARCH_HAS_MEMBARRIER_SYNC_CORE 2064 bool 2065 2066config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 2067 bool 2068 help 2069 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 2070 2071 A 64-bit kernel is required for the memory sealing feature. 2072 No specific hardware features from the CPU are needed. 2073 2074 To enable this feature, the architecture needs to update their 2075 special mappings calls to include the sealing flag and confirm 2076 that it doesn't unmap/remap system mappings during the life 2077 time of the process. The existence of this flag for an architecture 2078 implies that it does not require the remapping of the system 2079 mappings during process lifetime, so sealing these mappings is safe 2080 from a kernel perspective. 2081 2082 After the architecture enables this, a distribution can set 2083 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 2084 2085 For complete descriptions of memory sealing, please see 2086 Documentation/userspace-api/mseal.rst 2087 2088config HAVE_PERF_EVENTS 2089 bool 2090 help 2091 See tools/perf/design.txt for details. 2092 2093config GUEST_PERF_EVENTS 2094 bool 2095 depends on HAVE_PERF_EVENTS 2096 2097config PERF_GUEST_MEDIATED_PMU 2098 bool 2099 depends on GUEST_PERF_EVENTS 2100 2101config PERF_USE_VMALLOC 2102 bool 2103 help 2104 See tools/perf/design.txt for details 2105 2106menu "Kernel Performance Events And Counters" 2107 2108config PERF_EVENTS 2109 bool "Kernel performance events and counters" 2110 default y if PROFILING 2111 depends on HAVE_PERF_EVENTS 2112 select IRQ_WORK 2113 help 2114 Enable kernel support for various performance events provided 2115 by software and hardware. 2116 2117 Software events are supported either built-in or via the 2118 use of generic tracepoints. 2119 2120 Most modern CPUs support performance events via performance 2121 counter registers. These registers count the number of certain 2122 types of hw events: such as instructions executed, cachemisses 2123 suffered, or branches mis-predicted - without slowing down the 2124 kernel or applications. These registers can also trigger interrupts 2125 when a threshold number of events have passed - and can thus be 2126 used to profile the code that runs on that CPU. 2127 2128 The Linux Performance Event subsystem provides an abstraction of 2129 these software and hardware event capabilities, available via a 2130 system call and used by the "perf" utility in tools/perf/. It 2131 provides per task and per CPU counters, and it provides event 2132 capabilities on top of those. 2133 2134 Say Y if unsure. 2135 2136config DEBUG_PERF_USE_VMALLOC 2137 default n 2138 bool "Debug: use vmalloc to back perf mmap() buffers" 2139 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2140 select PERF_USE_VMALLOC 2141 help 2142 Use vmalloc memory to back perf mmap() buffers. 2143 2144 Mostly useful for debugging the vmalloc code on platforms 2145 that don't require it. 2146 2147 Say N if unsure. 2148 2149endmenu 2150 2151config SYSTEM_DATA_VERIFICATION 2152 def_bool n 2153 select SYSTEM_TRUSTED_KEYRING 2154 select KEYS 2155 select CRYPTO 2156 select CRYPTO_RSA 2157 select ASYMMETRIC_KEY_TYPE 2158 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2159 select ASN1 2160 select OID_REGISTRY 2161 select X509_CERTIFICATE_PARSER 2162 select PKCS7_MESSAGE_PARSER 2163 help 2164 Provide PKCS#7 message verification using the contents of the system 2165 trusted keyring to provide public keys. This then can be used for 2166 module verification, kexec image verification and firmware blob 2167 verification. 2168 2169config PROFILING 2170 bool "Profiling support" 2171 help 2172 Say Y here to enable the extended profiling support mechanisms used 2173 by profilers. 2174 2175config RUST 2176 bool "Rust support" 2177 depends on HAVE_RUST 2178 depends on RUST_IS_AVAILABLE 2179 select EXTENDED_MODVERSIONS if MODVERSIONS 2180 depends on !MODVERSIONS || GENDWARFKSYMS 2181 depends on !GCC_PLUGIN_RANDSTRUCT 2182 depends on !RANDSTRUCT 2183 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2184 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2185 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2186 depends on !CALL_PADDING || RUSTC_VERSION >= 108100 2187 depends on !KASAN_SW_TAGS 2188 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300 2189 help 2190 Enables Rust support in the kernel. 2191 2192 This allows other Rust-related options, like drivers written in Rust, 2193 to be selected. 2194 2195 It is also required to be able to load external kernel modules 2196 written in Rust. 2197 2198 See Documentation/rust/ for more information. 2199 2200 If unsure, say N. 2201 2202config RUSTC_VERSION_TEXT 2203 string 2204 depends on RUST 2205 default "$(RUSTC_VERSION_TEXT)" 2206 help 2207 See `CC_VERSION_TEXT`. 2208 2209config BINDGEN_VERSION_TEXT 2210 string 2211 depends on RUST 2212 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0 2213 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0 2214 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed 2215 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1 2216 # both fixed the issue). 2217 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)" 2218 2219# 2220# Place an empty function call at each tracepoint site. Can be 2221# dynamically changed for a probe function. 2222# 2223config TRACEPOINTS 2224 bool 2225 select TASKS_TRACE_RCU 2226 2227source "kernel/Kconfig.kexec" 2228 2229source "kernel/liveupdate/Kconfig" 2230 2231endmenu # General setup 2232 2233source "arch/Kconfig" 2234 2235config RT_MUTEXES 2236 bool 2237 default y if PREEMPT_RT 2238 2239config MODULE_SIG_FORMAT 2240 def_bool n 2241 select SYSTEM_DATA_VERIFICATION 2242 2243source "kernel/module/Kconfig" 2244 2245config INIT_ALL_POSSIBLE 2246 bool 2247 help 2248 Back when each arch used to define their own cpu_online_mask and 2249 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2250 with all 1s, and others with all 0s. When they were centralised, 2251 it was better to provide this option than to break all the archs 2252 and have several arch maintainers pursuing me down dark alleys. 2253 2254source "block/Kconfig" 2255 2256config PREEMPT_NOTIFIERS 2257 bool 2258 2259config PADATA 2260 depends on SMP 2261 bool 2262 2263config ASN1 2264 tristate 2265 help 2266 Build a simple ASN.1 grammar compiler that produces a bytecode output 2267 that can be interpreted by the ASN.1 stream decoder and used to 2268 inform it as to what tags are to be expected in a stream and what 2269 functions to call on what tags. 2270 2271source "kernel/Kconfig.locks" 2272 2273config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2274 bool 2275 2276config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2277 bool 2278 2279config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2280 bool 2281 2282# It may be useful for an architecture to override the definitions of the 2283# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2284# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2285# different calling convention for syscalls. They can also override the 2286# macros for not-implemented syscalls in kernel/sys_ni.c and 2287# kernel/time/posix-stubs.c. All these overrides need to be available in 2288# <asm/syscall_wrapper.h>. 2289config ARCH_HAS_SYSCALL_WRAPPER 2290 def_bool n 2291