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 CC_CAN_LINK 86 bool 87 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT 88 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag)) 89 90# Fixed in GCC 14, 13.3, 12.4 and 11.5 91# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 92config GCC_ASM_GOTO_OUTPUT_BROKEN 93 bool 94 depends on CC_IS_GCC 95 default y if GCC_VERSION < 110500 96 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400 97 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300 98 99config CC_HAS_ASM_GOTO_OUTPUT 100 def_bool y 101 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN 102 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) 103 104config CC_HAS_ASM_GOTO_TIED_OUTPUT 105 depends on CC_HAS_ASM_GOTO_OUTPUT 106 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 107 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) 108 109config TOOLS_SUPPORT_RELR 110 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 111 112config CC_HAS_ASM_INLINE 113 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 114 115config CC_HAS_NO_PROFILE_FN_ATTR 116 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 117 118config CC_HAS_COUNTED_BY 119 # TODO: when gcc 15 is released remove the build test and add 120 # a gcc version check 121 def_bool $(success,echo 'struct flex { int count; int array[] __attribute__((__counted_by__(count))); };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 122 # clang needs to be at least 19.1.3 to avoid __bdos miscalculations 123 # https://github.com/llvm/llvm-project/pull/110497 124 # https://github.com/llvm/llvm-project/pull/112636 125 depends on !(CC_IS_CLANG && CLANG_VERSION < 190103) 126 127config CC_HAS_MULTIDIMENSIONAL_NONSTRING 128 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 129 130config LD_CAN_USE_KEEP_IN_OVERLAY 131 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 132 # https://github.com/llvm/llvm-project/pull/130661 133 def_bool LD_IS_BFD || LLD_VERSION >= 210000 134 135config RUSTC_HAS_COERCE_POINTEE 136 def_bool RUSTC_VERSION >= 108400 137 138config RUSTC_HAS_UNNECESSARY_TRANSMUTES 139 def_bool RUSTC_VERSION >= 108800 140 141config PAHOLE_VERSION 142 int 143 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) 144 145config CONSTRUCTORS 146 bool 147 148config IRQ_WORK 149 def_bool y if SMP 150 151config BUILDTIME_TABLE_SORT 152 bool 153 154config THREAD_INFO_IN_TASK 155 bool 156 help 157 Select this to move thread_info off the stack into task_struct. To 158 make this work, an arch will need to remove all thread_info fields 159 except flags and fix any runtime bugs. 160 161 One subtle change that will be needed is to use try_get_task_stack() 162 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 163 164menu "General setup" 165 166config BROKEN 167 bool 168 169config BROKEN_ON_SMP 170 bool 171 depends on BROKEN || !SMP 172 default y 173 174config INIT_ENV_ARG_LIMIT 175 int 176 default 32 if !UML 177 default 128 if UML 178 help 179 Maximum of each of the number of arguments and environment 180 variables passed to init from the kernel command line. 181 182config COMPILE_TEST 183 bool "Compile also drivers which will not load" 184 depends on HAS_IOMEM 185 help 186 Some drivers can be compiled on a different platform than they are 187 intended to be run on. Despite they cannot be loaded there (or even 188 when they load they cannot be used due to missing HW support), 189 developers still, opposing to distributors, might want to build such 190 drivers to compile-test them. 191 192 If you are a developer and want to build everything available, say Y 193 here. If you are a user/distributor, say N here to exclude useless 194 drivers to be distributed. 195 196config WERROR 197 bool "Compile the kernel with warnings as errors" 198 default COMPILE_TEST 199 help 200 A kernel build should not cause any compiler warnings, and this 201 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 202 to enforce that rule by default. Certain warnings from other tools 203 such as the linker may be upgraded to errors with this option as 204 well. 205 206 However, if you have a new (or very old) compiler or linker with odd 207 and unusual warnings, or you have some architecture with problems, 208 you may need to disable this config option in order to 209 successfully build the kernel. 210 211 If in doubt, say Y. 212 213config UAPI_HEADER_TEST 214 bool "Compile test UAPI headers" 215 depends on HEADERS_INSTALL && CC_CAN_LINK 216 help 217 Compile test headers exported to user-space to ensure they are 218 self-contained, i.e. compilable as standalone units. 219 220 If you are a developer or tester and want to ensure the exported 221 headers are self-contained, say Y here. Otherwise, choose N. 222 223config LOCALVERSION 224 string "Local version - append to kernel release" 225 help 226 Append an extra string to the end of your kernel version. 227 This will show up when you type uname, for example. 228 The string you set here will be appended after the contents of 229 any files with a filename matching localversion* in your 230 object and source tree, in that order. Your total string can 231 be a maximum of 64 characters. 232 233config LOCALVERSION_AUTO 234 bool "Automatically append version information to the version string" 235 default y 236 depends on !COMPILE_TEST 237 help 238 This will try to automatically determine if the current tree is a 239 release tree by looking for git tags that belong to the current 240 top of tree revision. 241 242 A string of the format -gxxxxxxxx will be added to the localversion 243 if a git-based tree is found. The string generated by this will be 244 appended after any matching localversion* files, and after the value 245 set in CONFIG_LOCALVERSION. 246 247 (The actual string used here is the first 12 characters produced 248 by running the command: 249 250 $ git rev-parse --verify HEAD 251 252 which is done within the script "scripts/setlocalversion".) 253 254config BUILD_SALT 255 string "Build ID Salt" 256 default "" 257 help 258 The build ID is used to link binaries and their debug info. Setting 259 this option will use the value in the calculation of the build id. 260 This is mostly useful for distributions which want to ensure the 261 build is unique between builds. It's safe to leave the default. 262 263config HAVE_KERNEL_GZIP 264 bool 265 266config HAVE_KERNEL_BZIP2 267 bool 268 269config HAVE_KERNEL_LZMA 270 bool 271 272config HAVE_KERNEL_XZ 273 bool 274 275config HAVE_KERNEL_LZO 276 bool 277 278config HAVE_KERNEL_LZ4 279 bool 280 281config HAVE_KERNEL_ZSTD 282 bool 283 284config HAVE_KERNEL_UNCOMPRESSED 285 bool 286 287choice 288 prompt "Kernel compression mode" 289 default KERNEL_GZIP 290 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 291 help 292 The linux kernel is a kind of self-extracting executable. 293 Several compression algorithms are available, which differ 294 in efficiency, compression and decompression speed. 295 Compression speed is only relevant when building a kernel. 296 Decompression speed is relevant at each boot. 297 298 If you have any problems with bzip2 or lzma compressed 299 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 300 version of this functionality (bzip2 only), for 2.4, was 301 supplied by Christian Ludwig) 302 303 High compression options are mostly useful for users, who 304 are low on disk space (embedded systems), but for whom ram 305 size matters less. 306 307 If in doubt, select 'gzip' 308 309config KERNEL_GZIP 310 bool "Gzip" 311 depends on HAVE_KERNEL_GZIP 312 help 313 The old and tried gzip compression. It provides a good balance 314 between compression ratio and decompression speed. 315 316config KERNEL_BZIP2 317 bool "Bzip2" 318 depends on HAVE_KERNEL_BZIP2 319 help 320 Its compression ratio and speed is intermediate. 321 Decompression speed is slowest among the choices. The kernel 322 size is about 10% smaller with bzip2, in comparison to gzip. 323 Bzip2 uses a large amount of memory. For modern kernels you 324 will need at least 8MB RAM or more for booting. 325 326config KERNEL_LZMA 327 bool "LZMA" 328 depends on HAVE_KERNEL_LZMA 329 help 330 This compression algorithm's ratio is best. Decompression speed 331 is between gzip and bzip2. Compression is slowest. 332 The kernel size is about 33% smaller with LZMA in comparison to gzip. 333 334config KERNEL_XZ 335 bool "XZ" 336 depends on HAVE_KERNEL_XZ 337 help 338 XZ uses the LZMA2 algorithm and instruction set specific 339 BCJ filters which can improve compression ratio of executable 340 code. The size of the kernel is about 30% smaller with XZ in 341 comparison to gzip. On architectures for which there is a BCJ 342 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 343 and SPARC), XZ will create a few percent smaller kernel than 344 plain LZMA. 345 346 The speed is about the same as with LZMA: The decompression 347 speed of XZ is better than that of bzip2 but worse than gzip 348 and LZO. Compression is slow. 349 350config KERNEL_LZO 351 bool "LZO" 352 depends on HAVE_KERNEL_LZO 353 help 354 Its compression ratio is the poorest among the choices. The kernel 355 size is about 10% bigger than gzip; however its speed 356 (both compression and decompression) is the fastest. 357 358config KERNEL_LZ4 359 bool "LZ4" 360 depends on HAVE_KERNEL_LZ4 361 help 362 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 363 A preliminary version of LZ4 de/compression tool is available at 364 <https://code.google.com/p/lz4/>. 365 366 Its compression ratio is worse than LZO. The size of the kernel 367 is about 8% bigger than LZO. But the decompression speed is 368 faster than LZO. 369 370config KERNEL_ZSTD 371 bool "ZSTD" 372 depends on HAVE_KERNEL_ZSTD 373 help 374 ZSTD is a compression algorithm targeting intermediate compression 375 with fast decompression speed. It will compress better than GZIP and 376 decompress around the same speed as LZO, but slower than LZ4. You 377 will need at least 192 KB RAM or more for booting. The zstd command 378 line tool is required for compression. 379 380config KERNEL_UNCOMPRESSED 381 bool "None" 382 depends on HAVE_KERNEL_UNCOMPRESSED 383 help 384 Produce uncompressed kernel image. This option is usually not what 385 you want. It is useful for debugging the kernel in slow simulation 386 environments, where decompressing and moving the kernel is awfully 387 slow. This option allows early boot code to skip the decompressor 388 and jump right at uncompressed kernel image. 389 390endchoice 391 392config DEFAULT_INIT 393 string "Default init path" 394 default "" 395 help 396 This option determines the default init for the system if no init= 397 option is passed on the kernel command line. If the requested path is 398 not present, we will still then move on to attempting further 399 locations (e.g. /sbin/init, etc). If this is empty, we will just use 400 the fallback list when init= is not passed. 401 402config DEFAULT_HOSTNAME 403 string "Default hostname" 404 default "(none)" 405 help 406 This option determines the default system hostname before userspace 407 calls sethostname(2). The kernel traditionally uses "(none)" here, 408 but you may wish to use a different default here to make a minimal 409 system more usable with less configuration. 410 411config SYSVIPC 412 bool "System V IPC" 413 help 414 Inter Process Communication is a suite of library functions and 415 system calls which let processes (running programs) synchronize and 416 exchange information. It is generally considered to be a good thing, 417 and some programs won't run unless you say Y here. In particular, if 418 you want to run the DOS emulator dosemu under Linux (read the 419 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 420 you'll need to say Y here. 421 422 You can find documentation about IPC with "info ipc" and also in 423 section 6.4 of the Linux Programmer's Guide, available from 424 <http://www.tldp.org/guides.html>. 425 426config SYSVIPC_SYSCTL 427 bool 428 depends on SYSVIPC 429 depends on SYSCTL 430 default y 431 432config SYSVIPC_COMPAT 433 def_bool y 434 depends on COMPAT && SYSVIPC 435 436config POSIX_MQUEUE 437 bool "POSIX Message Queues" 438 depends on NET 439 help 440 POSIX variant of message queues is a part of IPC. In POSIX message 441 queues every message has a priority which decides about succession 442 of receiving it by a process. If you want to compile and run 443 programs written e.g. for Solaris with use of its POSIX message 444 queues (functions mq_*) say Y here. 445 446 POSIX message queues are visible as a filesystem called 'mqueue' 447 and can be mounted somewhere if you want to do filesystem 448 operations on message queues. 449 450 If unsure, say Y. 451 452config POSIX_MQUEUE_SYSCTL 453 bool 454 depends on POSIX_MQUEUE 455 depends on SYSCTL 456 default y 457 458config WATCH_QUEUE 459 bool "General notification queue" 460 default n 461 help 462 463 This is a general notification queue for the kernel to pass events to 464 userspace by splicing them into pipes. It can be used in conjunction 465 with watches for key/keyring change notifications and device 466 notifications. 467 468 See Documentation/core-api/watch_queue.rst 469 470config CROSS_MEMORY_ATTACH 471 bool "Enable process_vm_readv/writev syscalls" 472 depends on MMU 473 default y 474 help 475 Enabling this option adds the system calls process_vm_readv and 476 process_vm_writev which allow a process with the correct privileges 477 to directly read from or write to another process' address space. 478 See the man page for more details. 479 480config AUDIT 481 bool "Auditing support" 482 depends on NET 483 help 484 Enable auditing infrastructure that can be used with another 485 kernel subsystem, such as SELinux (which requires this for 486 logging of avc messages output). System call auditing is included 487 on architectures which support it. 488 489config HAVE_ARCH_AUDITSYSCALL 490 bool 491 492config AUDITSYSCALL 493 def_bool y 494 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 495 select FSNOTIFY 496 497source "kernel/irq/Kconfig" 498source "kernel/time/Kconfig" 499source "kernel/bpf/Kconfig" 500source "kernel/Kconfig.preempt" 501 502menu "CPU/Task time and stats accounting" 503 504config VIRT_CPU_ACCOUNTING 505 bool 506 507choice 508 prompt "Cputime accounting" 509 default TICK_CPU_ACCOUNTING 510 511# Kind of a stub config for the pure tick based cputime accounting 512config TICK_CPU_ACCOUNTING 513 bool "Simple tick based cputime accounting" 514 depends on !S390 && !NO_HZ_FULL 515 help 516 This is the basic tick based cputime accounting that maintains 517 statistics about user, system and idle time spent on per jiffies 518 granularity. 519 520 If unsure, say Y. 521 522config VIRT_CPU_ACCOUNTING_NATIVE 523 bool "Deterministic task and CPU time accounting" 524 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 525 select VIRT_CPU_ACCOUNTING 526 help 527 Select this option to enable more accurate task and CPU time 528 accounting. This is done by reading a CPU counter on each 529 kernel entry and exit and on transitions within the kernel 530 between system, softirq and hardirq state, so there is a 531 small performance impact. In the case of s390 or IBM POWER > 5, 532 this also enables accounting of stolen time on logically-partitioned 533 systems. 534 535config VIRT_CPU_ACCOUNTING_GEN 536 bool "Full dynticks CPU time accounting" 537 depends on HAVE_CONTEXT_TRACKING_USER 538 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 539 depends on GENERIC_CLOCKEVENTS 540 select VIRT_CPU_ACCOUNTING 541 select CONTEXT_TRACKING_USER 542 help 543 Select this option to enable task and CPU time accounting on full 544 dynticks systems. This accounting is implemented by watching every 545 kernel-user boundaries using the context tracking subsystem. 546 The accounting is thus performed at the expense of some significant 547 overhead. 548 549 For now this is only useful if you are working on the full 550 dynticks subsystem development. 551 552 If unsure, say N. 553 554endchoice 555 556config IRQ_TIME_ACCOUNTING 557 bool "Fine granularity task level IRQ time accounting" 558 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 559 help 560 Select this option to enable fine granularity task irq time 561 accounting. This is done by reading a timestamp on each 562 transitions between softirq and hardirq state, so there can be a 563 small performance impact. 564 565 If in doubt, say N here. 566 567config HAVE_SCHED_AVG_IRQ 568 def_bool y 569 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 570 depends on SMP 571 572config SCHED_HW_PRESSURE 573 bool 574 default y if ARM && ARM_CPU_TOPOLOGY 575 default y if ARM64 576 depends on SMP 577 depends on CPU_FREQ_THERMAL 578 help 579 Select this option to enable HW pressure accounting in the 580 scheduler. HW pressure is the value conveyed to the scheduler 581 that reflects the reduction in CPU compute capacity resulted from 582 HW throttling. HW throttling occurs when the performance of 583 a CPU is capped due to high operating temperatures as an example. 584 585 If selected, the scheduler will be able to balance tasks accordingly, 586 i.e. put less load on throttled CPUs than on non/less throttled ones. 587 588 This requires the architecture to implement 589 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 590 591config BSD_PROCESS_ACCT 592 bool "BSD Process Accounting" 593 depends on MULTIUSER 594 help 595 If you say Y here, a user level program will be able to instruct the 596 kernel (via a special system call) to write process accounting 597 information to a file: whenever a process exits, information about 598 that process will be appended to the file by the kernel. The 599 information includes things such as creation time, owning user, 600 command name, memory usage, controlling terminal etc. (the complete 601 list is in the struct acct in <file:include/linux/acct.h>). It is 602 up to the user level program to do useful things with this 603 information. This is generally a good idea, so say Y. 604 605config BSD_PROCESS_ACCT_V3 606 bool "BSD Process Accounting version 3 file format" 607 depends on BSD_PROCESS_ACCT 608 default n 609 help 610 If you say Y here, the process accounting information is written 611 in a new file format that also logs the process IDs of each 612 process and its parent. Note that this file format is incompatible 613 with previous v0/v1/v2 file formats, so you will need updated tools 614 for processing it. A preliminary version of these tools is available 615 at <http://www.gnu.org/software/acct/>. 616 617config TASKSTATS 618 bool "Export task/process statistics through netlink" 619 depends on NET 620 depends on MULTIUSER 621 default n 622 help 623 Export selected statistics for tasks/processes through the 624 generic netlink interface. Unlike BSD process accounting, the 625 statistics are available during the lifetime of tasks/processes as 626 responses to commands. Like BSD accounting, they are sent to user 627 space on task exit. 628 629 Say N if unsure. 630 631config TASK_DELAY_ACCT 632 bool "Enable per-task delay accounting" 633 depends on TASKSTATS 634 select SCHED_INFO 635 help 636 Collect information on time spent by a task waiting for system 637 resources like cpu, synchronous block I/O completion and swapping 638 in pages. Such statistics can help in setting a task's priorities 639 relative to other tasks for cpu, io, rss limits etc. 640 641 Say N if unsure. 642 643config TASK_XACCT 644 bool "Enable extended accounting over taskstats" 645 depends on TASKSTATS 646 help 647 Collect extended task accounting data and send the data 648 to userland for processing over the taskstats interface. 649 650 Say N if unsure. 651 652config TASK_IO_ACCOUNTING 653 bool "Enable per-task storage I/O accounting" 654 depends on TASK_XACCT 655 help 656 Collect information on the number of bytes of storage I/O which this 657 task has caused. 658 659 Say N if unsure. 660 661config PSI 662 bool "Pressure stall information tracking" 663 select KERNFS 664 help 665 Collect metrics that indicate how overcommitted the CPU, memory, 666 and IO capacity are in the system. 667 668 If you say Y here, the kernel will create /proc/pressure/ with the 669 pressure statistics files cpu, memory, and io. These will indicate 670 the share of walltime in which some or all tasks in the system are 671 delayed due to contention of the respective resource. 672 673 In kernels with cgroup support, cgroups (cgroup2 only) will 674 have cpu.pressure, memory.pressure, and io.pressure files, 675 which aggregate pressure stalls for the grouped tasks only. 676 677 For more details see Documentation/accounting/psi.rst. 678 679 Say N if unsure. 680 681config PSI_DEFAULT_DISABLED 682 bool "Require boot parameter to enable pressure stall information tracking" 683 default n 684 depends on PSI 685 help 686 If set, pressure stall information tracking will be disabled 687 per default but can be enabled through passing psi=1 on the 688 kernel commandline during boot. 689 690 This feature adds some code to the task wakeup and sleep 691 paths of the scheduler. The overhead is too low to affect 692 common scheduling-intense workloads in practice (such as 693 webservers, memcache), but it does show up in artificial 694 scheduler stress tests, such as hackbench. 695 696 If you are paranoid and not sure what the kernel will be 697 used for, say Y. 698 699 Say N if unsure. 700 701endmenu # "CPU/Task time and stats accounting" 702 703config CPU_ISOLATION 704 bool "CPU isolation" 705 depends on SMP 706 default y 707 help 708 Make sure that CPUs running critical tasks are not disturbed by 709 any source of "noise" such as unbound workqueues, timers, kthreads... 710 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 711 the "isolcpus=" boot parameter. 712 713 Say Y if unsure. 714 715source "kernel/rcu/Kconfig" 716 717config IKCONFIG 718 tristate "Kernel .config support" 719 help 720 This option enables the complete Linux kernel ".config" file 721 contents to be saved in the kernel. It provides documentation 722 of which kernel options are used in a running kernel or in an 723 on-disk kernel. This information can be extracted from the kernel 724 image file with the script scripts/extract-ikconfig and used as 725 input to rebuild the current kernel or to build another kernel. 726 It can also be extracted from a running kernel by reading 727 /proc/config.gz if enabled (below). 728 729config IKCONFIG_PROC 730 bool "Enable access to .config through /proc/config.gz" 731 depends on IKCONFIG && PROC_FS 732 help 733 This option enables access to the kernel configuration file 734 through /proc/config.gz. 735 736config IKHEADERS 737 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 738 depends on SYSFS 739 help 740 This option enables access to the in-kernel headers that are generated during 741 the build process. These can be used to build eBPF tracing programs, 742 or similar programs. If you build the headers as a module, a module called 743 kheaders.ko is built which can be loaded on-demand to get access to headers. 744 745config LOG_BUF_SHIFT 746 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 747 range 12 25 748 default 17 749 depends on PRINTK 750 help 751 Select the minimal kernel log buffer size as a power of 2. 752 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 753 parameter, see below. Any higher size also might be forced 754 by "log_buf_len" boot parameter. 755 756 Examples: 757 17 => 128 KB 758 16 => 64 KB 759 15 => 32 KB 760 14 => 16 KB 761 13 => 8 KB 762 12 => 4 KB 763 764config LOG_CPU_MAX_BUF_SHIFT 765 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 766 depends on SMP 767 range 0 21 768 default 0 if BASE_SMALL 769 default 12 770 depends on PRINTK 771 help 772 This option allows to increase the default ring buffer size 773 according to the number of CPUs. The value defines the contribution 774 of each CPU as a power of 2. The used space is typically only few 775 lines however it might be much more when problems are reported, 776 e.g. backtraces. 777 778 The increased size means that a new buffer has to be allocated and 779 the original static one is unused. It makes sense only on systems 780 with more CPUs. Therefore this value is used only when the sum of 781 contributions is greater than the half of the default kernel ring 782 buffer as defined by LOG_BUF_SHIFT. The default values are set 783 so that more than 16 CPUs are needed to trigger the allocation. 784 785 Also this option is ignored when "log_buf_len" kernel parameter is 786 used as it forces an exact (power of two) size of the ring buffer. 787 788 The number of possible CPUs is used for this computation ignoring 789 hotplugging making the computation optimal for the worst case 790 scenario while allowing a simple algorithm to be used from bootup. 791 792 Examples shift values and their meaning: 793 17 => 128 KB for each CPU 794 16 => 64 KB for each CPU 795 15 => 32 KB for each CPU 796 14 => 16 KB for each CPU 797 13 => 8 KB for each CPU 798 12 => 4 KB for each CPU 799 800config PRINTK_INDEX 801 bool "Printk indexing debugfs interface" 802 depends on PRINTK && DEBUG_FS 803 help 804 Add support for indexing of all printk formats known at compile time 805 at <debugfs>/printk/index/<module>. 806 807 This can be used as part of maintaining daemons which monitor 808 /dev/kmsg, as it permits auditing the printk formats present in a 809 kernel, allowing detection of cases where monitored printks are 810 changed or no longer present. 811 812 There is no additional runtime cost to printk with this enabled. 813 814# 815# Architectures with an unreliable sched_clock() should select this: 816# 817config HAVE_UNSTABLE_SCHED_CLOCK 818 bool 819 820config GENERIC_SCHED_CLOCK 821 bool 822 823menu "Scheduler features" 824 825config UCLAMP_TASK 826 bool "Enable utilization clamping for RT/FAIR tasks" 827 depends on CPU_FREQ_GOV_SCHEDUTIL 828 help 829 This feature enables the scheduler to track the clamped utilization 830 of each CPU based on RUNNABLE tasks scheduled on that CPU. 831 832 With this option, the user can specify the min and max CPU 833 utilization allowed for RUNNABLE tasks. The max utilization defines 834 the maximum frequency a task should use while the min utilization 835 defines the minimum frequency it should use. 836 837 Both min and max utilization clamp values are hints to the scheduler, 838 aiming at improving its frequency selection policy, but they do not 839 enforce or grant any specific bandwidth for tasks. 840 841 If in doubt, say N. 842 843config UCLAMP_BUCKETS_COUNT 844 int "Number of supported utilization clamp buckets" 845 range 5 20 846 default 5 847 depends on UCLAMP_TASK 848 help 849 Defines the number of clamp buckets to use. The range of each bucket 850 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 851 number of clamp buckets the finer their granularity and the higher 852 the precision of clamping aggregation and tracking at run-time. 853 854 For example, with the minimum configuration value we will have 5 855 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 856 be refcounted in the [20..39]% bucket and will set the bucket clamp 857 effective value to 25%. 858 If a second 30% boosted task should be co-scheduled on the same CPU, 859 that task will be refcounted in the same bucket of the first task and 860 it will boost the bucket clamp effective value to 30%. 861 The clamp effective value of a bucket is reset to its nominal value 862 (20% in the example above) when there are no more tasks refcounted in 863 that bucket. 864 865 An additional boost/capping margin can be added to some tasks. In the 866 example above the 25% task will be boosted to 30% until it exits the 867 CPU. If that should be considered not acceptable on certain systems, 868 it's always possible to reduce the margin by increasing the number of 869 clamp buckets to trade off used memory for run-time tracking 870 precision. 871 872 If in doubt, use the default value. 873 874endmenu 875 876# 877# For architectures that want to enable the support for NUMA-affine scheduler 878# balancing logic: 879# 880config ARCH_SUPPORTS_NUMA_BALANCING 881 bool 882 883# 884# For architectures that prefer to flush all TLBs after a number of pages 885# are unmapped instead of sending one IPI per page to flush. The architecture 886# must provide guarantees on what happens if a clean TLB cache entry is 887# written after the unmap. Details are in mm/rmap.c near the check for 888# should_defer_flush. The architecture should also consider if the full flush 889# and the refill costs are offset by the savings of sending fewer IPIs. 890config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 891 bool 892 893config CC_HAS_INT128 894 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 895 896config CC_IMPLICIT_FALLTHROUGH 897 string 898 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 899 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 900 901# Currently, disable gcc-10+ array-bounds globally. 902# It's still broken in gcc-13, so no upper bound yet. 903config GCC10_NO_ARRAY_BOUNDS 904 def_bool y 905 906config CC_NO_ARRAY_BOUNDS 907 bool 908 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 909 910# Currently, disable -Wstringop-overflow for GCC globally. 911config GCC_NO_STRINGOP_OVERFLOW 912 def_bool y 913 914config CC_NO_STRINGOP_OVERFLOW 915 bool 916 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 917 918config CC_STRINGOP_OVERFLOW 919 bool 920 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 921 922# 923# For architectures that know their GCC __int128 support is sound 924# 925config ARCH_SUPPORTS_INT128 926 bool 927 928# For architectures that (ab)use NUMA to represent different memory regions 929# all cpu-local but of different latencies, such as SuperH. 930# 931config ARCH_WANT_NUMA_VARIABLE_LOCALITY 932 bool 933 934config NUMA_BALANCING 935 bool "Memory placement aware NUMA scheduler" 936 depends on ARCH_SUPPORTS_NUMA_BALANCING 937 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 938 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 939 help 940 This option adds support for automatic NUMA aware memory/task placement. 941 The mechanism is quite primitive and is based on migrating memory when 942 it has references to the node the task is running on. 943 944 This system will be inactive on UMA systems. 945 946config NUMA_BALANCING_DEFAULT_ENABLED 947 bool "Automatically enable NUMA aware memory/task placement" 948 default y 949 depends on NUMA_BALANCING 950 help 951 If set, automatic NUMA balancing will be enabled if running on a NUMA 952 machine. 953 954config SLAB_OBJ_EXT 955 bool 956 957menuconfig CGROUPS 958 bool "Control Group support" 959 select KERNFS 960 help 961 This option adds support for grouping sets of processes together, for 962 use with process control subsystems such as Cpusets, CFS, memory 963 controls or device isolation. 964 See 965 - Documentation/scheduler/sched-design-CFS.rst (CFS) 966 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 967 and resource control) 968 969 Say N if unsure. 970 971if CGROUPS 972 973config PAGE_COUNTER 974 bool 975 976config CGROUP_FAVOR_DYNMODS 977 bool "Favor dynamic modification latency reduction by default" 978 help 979 This option enables the "favordynmods" mount option by default 980 which reduces the latencies of dynamic cgroup modifications such 981 as task migrations and controller on/offs at the cost of making 982 hot path operations such as forks and exits more expensive. 983 984 Say N if unsure. 985 986config MEMCG 987 bool "Memory controller" 988 select PAGE_COUNTER 989 select EVENTFD 990 select SLAB_OBJ_EXT 991 help 992 Provides control over the memory footprint of tasks in a cgroup. 993 994config MEMCG_V1 995 bool "Legacy cgroup v1 memory controller" 996 depends on MEMCG 997 default n 998 help 999 Legacy cgroup v1 memory controller which has been deprecated by 1000 cgroup v2 implementation. The v1 is there for legacy applications 1001 which haven't migrated to the new cgroup v2 interface yet. If you 1002 do not have any such application then you are completely fine leaving 1003 this option disabled. 1004 1005 Please note that feature set of the legacy memory controller is likely 1006 going to shrink due to deprecation process. New deployments with v1 1007 controller are highly discouraged. 1008 1009 Say N if unsure. 1010 1011config BLK_CGROUP 1012 bool "IO controller" 1013 depends on BLOCK 1014 default n 1015 help 1016 Generic block IO controller cgroup interface. This is the common 1017 cgroup interface which should be used by various IO controlling 1018 policies. 1019 1020 Currently, CFQ IO scheduler uses it to recognize task groups and 1021 control disk bandwidth allocation (proportional time slice allocation) 1022 to such task groups. It is also used by bio throttling logic in 1023 block layer to implement upper limit in IO rates on a device. 1024 1025 This option only enables generic Block IO controller infrastructure. 1026 One needs to also enable actual IO controlling logic/policy. For 1027 enabling proportional weight division of disk bandwidth in CFQ, set 1028 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1029 CONFIG_BLK_DEV_THROTTLING=y. 1030 1031 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1032 1033config CGROUP_WRITEBACK 1034 bool 1035 depends on MEMCG && BLK_CGROUP 1036 default y 1037 1038menuconfig CGROUP_SCHED 1039 bool "CPU controller" 1040 default n 1041 help 1042 This feature lets CPU scheduler recognize task groups and control CPU 1043 bandwidth allocation to such task groups. It uses cgroups to group 1044 tasks. 1045 1046if CGROUP_SCHED 1047config GROUP_SCHED_WEIGHT 1048 def_bool n 1049 1050config FAIR_GROUP_SCHED 1051 bool "Group scheduling for SCHED_OTHER" 1052 depends on CGROUP_SCHED 1053 select GROUP_SCHED_WEIGHT 1054 default CGROUP_SCHED 1055 1056config CFS_BANDWIDTH 1057 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1058 depends on FAIR_GROUP_SCHED 1059 default n 1060 help 1061 This option allows users to define CPU bandwidth rates (limits) for 1062 tasks running within the fair group scheduler. Groups with no limit 1063 set are considered to be unconstrained and will run with no 1064 restriction. 1065 See Documentation/scheduler/sched-bwc.rst for more information. 1066 1067config RT_GROUP_SCHED 1068 bool "Group scheduling for SCHED_RR/FIFO" 1069 depends on CGROUP_SCHED 1070 default n 1071 help 1072 This feature lets you explicitly allocate real CPU bandwidth 1073 to task groups. If enabled, it will also make it impossible to 1074 schedule realtime tasks for non-root users until you allocate 1075 realtime bandwidth for them. 1076 See Documentation/scheduler/sched-rt-group.rst for more information. 1077 1078config EXT_GROUP_SCHED 1079 bool 1080 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1081 select GROUP_SCHED_WEIGHT 1082 default y 1083 1084endif #CGROUP_SCHED 1085 1086config SCHED_MM_CID 1087 def_bool y 1088 depends on SMP && RSEQ 1089 1090config UCLAMP_TASK_GROUP 1091 bool "Utilization clamping per group of tasks" 1092 depends on CGROUP_SCHED 1093 depends on UCLAMP_TASK 1094 default n 1095 help 1096 This feature enables the scheduler to track the clamped utilization 1097 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1098 1099 When this option is enabled, the user can specify a min and max 1100 CPU bandwidth which is allowed for each single task in a group. 1101 The max bandwidth allows to clamp the maximum frequency a task 1102 can use, while the min bandwidth allows to define a minimum 1103 frequency a task will always use. 1104 1105 When task group based utilization clamping is enabled, an eventually 1106 specified task-specific clamp value is constrained by the cgroup 1107 specified clamp value. Both minimum and maximum task clamping cannot 1108 be bigger than the corresponding clamping defined at task group level. 1109 1110 If in doubt, say N. 1111 1112config CGROUP_PIDS 1113 bool "PIDs controller" 1114 help 1115 Provides enforcement of process number limits in the scope of a 1116 cgroup. Any attempt to fork more processes than is allowed in the 1117 cgroup will fail. PIDs are fundamentally a global resource because it 1118 is fairly trivial to reach PID exhaustion before you reach even a 1119 conservative kmemcg limit. As a result, it is possible to grind a 1120 system to halt without being limited by other cgroup policies. The 1121 PIDs controller is designed to stop this from happening. 1122 1123 It should be noted that organisational operations (such as attaching 1124 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1125 since the PIDs limit only affects a process's ability to fork, not to 1126 attach to a cgroup. 1127 1128config CGROUP_RDMA 1129 bool "RDMA controller" 1130 help 1131 Provides enforcement of RDMA resources defined by IB stack. 1132 It is fairly easy for consumers to exhaust RDMA resources, which 1133 can result into resource unavailability to other consumers. 1134 RDMA controller is designed to stop this from happening. 1135 Attaching processes with active RDMA resources to the cgroup 1136 hierarchy is allowed even if can cross the hierarchy's limit. 1137 1138config CGROUP_DMEM 1139 bool "Device memory controller (DMEM)" 1140 select PAGE_COUNTER 1141 help 1142 The DMEM controller allows compatible devices to restrict device 1143 memory usage based on the cgroup hierarchy. 1144 1145 As an example, it allows you to restrict VRAM usage for applications 1146 in the DRM subsystem. 1147 1148config CGROUP_FREEZER 1149 bool "Freezer controller" 1150 help 1151 Provides a way to freeze and unfreeze all tasks in a 1152 cgroup. 1153 1154 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1155 controller includes important in-kernel memory consumers per default. 1156 1157 If you're using cgroup2, say N. 1158 1159config CGROUP_HUGETLB 1160 bool "HugeTLB controller" 1161 depends on HUGETLB_PAGE 1162 select PAGE_COUNTER 1163 default n 1164 help 1165 Provides a cgroup controller for HugeTLB pages. 1166 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1167 The limit is enforced during page fault. Since HugeTLB doesn't 1168 support page reclaim, enforcing the limit at page fault time implies 1169 that, the application will get SIGBUS signal if it tries to access 1170 HugeTLB pages beyond its limit. This requires the application to know 1171 beforehand how much HugeTLB pages it would require for its use. The 1172 control group is tracked in the third page lru pointer. This means 1173 that we cannot use the controller with huge page less than 3 pages. 1174 1175config CPUSETS 1176 bool "Cpuset controller" 1177 depends on SMP 1178 select UNION_FIND 1179 help 1180 This option will let you create and manage CPUSETs which 1181 allow dynamically partitioning a system into sets of CPUs and 1182 Memory Nodes and assigning tasks to run only within those sets. 1183 This is primarily useful on large SMP or NUMA systems. 1184 1185 Say N if unsure. 1186 1187config CPUSETS_V1 1188 bool "Legacy cgroup v1 cpusets controller" 1189 depends on CPUSETS 1190 default n 1191 help 1192 Legacy cgroup v1 cpusets controller which has been deprecated by 1193 cgroup v2 implementation. The v1 is there for legacy applications 1194 which haven't migrated to the new cgroup v2 interface yet. Legacy 1195 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1196 do not have any such application then you are completely fine leaving 1197 this option disabled. 1198 1199 Say N if unsure. 1200 1201config PROC_PID_CPUSET 1202 bool "Include legacy /proc/<pid>/cpuset file" 1203 depends on CPUSETS_V1 1204 default y 1205 1206config CGROUP_DEVICE 1207 bool "Device controller" 1208 help 1209 Provides a cgroup controller implementing whitelists for 1210 devices which a process in the cgroup can mknod or open. 1211 1212config CGROUP_CPUACCT 1213 bool "Simple CPU accounting controller" 1214 help 1215 Provides a simple controller for monitoring the 1216 total CPU consumed by the tasks in a cgroup. 1217 1218config CGROUP_PERF 1219 bool "Perf controller" 1220 depends on PERF_EVENTS 1221 help 1222 This option extends the perf per-cpu mode to restrict monitoring 1223 to threads which belong to the cgroup specified and run on the 1224 designated cpu. Or this can be used to have cgroup ID in samples 1225 so that it can monitor performance events among cgroups. 1226 1227 Say N if unsure. 1228 1229config CGROUP_BPF 1230 bool "Support for eBPF programs attached to cgroups" 1231 depends on BPF_SYSCALL 1232 select SOCK_CGROUP_DATA 1233 help 1234 Allow attaching eBPF programs to a cgroup using the bpf(2) 1235 syscall command BPF_PROG_ATTACH. 1236 1237 In which context these programs are accessed depends on the type 1238 of attachment. For instance, programs that are attached using 1239 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1240 inet sockets. 1241 1242config CGROUP_MISC 1243 bool "Misc resource controller" 1244 default n 1245 help 1246 Provides a controller for miscellaneous resources on a host. 1247 1248 Miscellaneous scalar resources are the resources on the host system 1249 which cannot be abstracted like the other cgroups. This controller 1250 tracks and limits the miscellaneous resources used by a process 1251 attached to a cgroup hierarchy. 1252 1253 For more information, please check misc cgroup section in 1254 /Documentation/admin-guide/cgroup-v2.rst. 1255 1256config CGROUP_DEBUG 1257 bool "Debug controller" 1258 default n 1259 depends on DEBUG_KERNEL 1260 help 1261 This option enables a simple controller that exports 1262 debugging information about the cgroups framework. This 1263 controller is for control cgroup debugging only. Its 1264 interfaces are not stable. 1265 1266 Say N. 1267 1268config SOCK_CGROUP_DATA 1269 bool 1270 default n 1271 1272endif # CGROUPS 1273 1274menuconfig NAMESPACES 1275 bool "Namespaces support" if EXPERT 1276 depends on MULTIUSER 1277 default !EXPERT 1278 help 1279 Provides the way to make tasks work with different objects using 1280 the same id. For example same IPC id may refer to different objects 1281 or same user id or pid may refer to different tasks when used in 1282 different namespaces. 1283 1284if NAMESPACES 1285 1286config UTS_NS 1287 bool "UTS namespace" 1288 default y 1289 help 1290 In this namespace tasks see different info provided with the 1291 uname() system call 1292 1293config TIME_NS 1294 bool "TIME namespace" 1295 depends on GENERIC_VDSO_TIME_NS 1296 default y 1297 help 1298 In this namespace boottime and monotonic clocks can be set. 1299 The time will keep going with the same pace. 1300 1301config IPC_NS 1302 bool "IPC namespace" 1303 depends on (SYSVIPC || POSIX_MQUEUE) 1304 default y 1305 help 1306 In this namespace tasks work with IPC ids which correspond to 1307 different IPC objects in different namespaces. 1308 1309config USER_NS 1310 bool "User namespace" 1311 default n 1312 help 1313 This allows containers, i.e. vservers, to use user namespaces 1314 to provide different user info for different servers. 1315 1316 When user namespaces are enabled in the kernel it is 1317 recommended that the MEMCG option also be enabled and that 1318 user-space use the memory control groups to limit the amount 1319 of memory a memory unprivileged users can use. 1320 1321 If unsure, say N. 1322 1323config PID_NS 1324 bool "PID Namespaces" 1325 default y 1326 help 1327 Support process id namespaces. This allows having multiple 1328 processes with the same pid as long as they are in different 1329 pid namespaces. This is a building block of containers. 1330 1331config NET_NS 1332 bool "Network namespace" 1333 depends on NET 1334 default y 1335 help 1336 Allow user space to create what appear to be multiple instances 1337 of the network stack. 1338 1339endif # NAMESPACES 1340 1341config CHECKPOINT_RESTORE 1342 bool "Checkpoint/restore support" 1343 depends on PROC_FS 1344 select PROC_CHILDREN 1345 select KCMP 1346 default n 1347 help 1348 Enables additional kernel features in a sake of checkpoint/restore. 1349 In particular it adds auxiliary prctl codes to setup process text, 1350 data and heap segment sizes, and a few additional /proc filesystem 1351 entries. 1352 1353 If unsure, say N here. 1354 1355config SCHED_AUTOGROUP 1356 bool "Automatic process group scheduling" 1357 select CGROUPS 1358 select CGROUP_SCHED 1359 select FAIR_GROUP_SCHED 1360 help 1361 This option optimizes the scheduler for common desktop workloads by 1362 automatically creating and populating task groups. This separation 1363 of workloads isolates aggressive CPU burners (like build jobs) from 1364 desktop applications. Task group autogeneration is currently based 1365 upon task session. 1366 1367config RELAY 1368 bool "Kernel->user space relay support (formerly relayfs)" 1369 select IRQ_WORK 1370 help 1371 This option enables support for relay interface support in 1372 certain file systems (such as debugfs). 1373 It is designed to provide an efficient mechanism for tools and 1374 facilities to relay large amounts of data from kernel space to 1375 user space. 1376 1377 If unsure, say N. 1378 1379config BLK_DEV_INITRD 1380 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1381 help 1382 The initial RAM filesystem is a ramfs which is loaded by the 1383 boot loader (loadlin or lilo) and that is mounted as root 1384 before the normal boot procedure. It is typically used to 1385 load modules needed to mount the "real" root file system, 1386 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1387 1388 If RAM disk support (BLK_DEV_RAM) is also included, this 1389 also enables initial RAM disk (initrd) support and adds 1390 15 Kbytes (more on some other architectures) to the kernel size. 1391 1392 If unsure say Y. 1393 1394if BLK_DEV_INITRD 1395 1396source "usr/Kconfig" 1397 1398endif 1399 1400config BOOT_CONFIG 1401 bool "Boot config support" 1402 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1403 help 1404 Extra boot config allows system admin to pass a config file as 1405 complemental extension of kernel cmdline when booting. 1406 The boot config file must be attached at the end of initramfs 1407 with checksum, size and magic word. 1408 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1409 1410 If unsure, say Y. 1411 1412config BOOT_CONFIG_FORCE 1413 bool "Force unconditional bootconfig processing" 1414 depends on BOOT_CONFIG 1415 default y if BOOT_CONFIG_EMBED 1416 help 1417 With this Kconfig option set, BOOT_CONFIG processing is carried 1418 out even when the "bootconfig" kernel-boot parameter is omitted. 1419 In fact, with this Kconfig option set, there is no way to 1420 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1421 parameters. 1422 1423 If unsure, say N. 1424 1425config BOOT_CONFIG_EMBED 1426 bool "Embed bootconfig file in the kernel" 1427 depends on BOOT_CONFIG 1428 help 1429 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1430 kernel. Usually, the bootconfig file is loaded with the initrd 1431 image. But if the system doesn't support initrd, this option will 1432 help you by embedding a bootconfig file while building the kernel. 1433 1434 If unsure, say N. 1435 1436config BOOT_CONFIG_EMBED_FILE 1437 string "Embedded bootconfig file path" 1438 depends on BOOT_CONFIG_EMBED 1439 help 1440 Specify a bootconfig file which will be embedded to the kernel. 1441 This bootconfig will be used if there is no initrd or no other 1442 bootconfig in the initrd. 1443 1444config INITRAMFS_PRESERVE_MTIME 1445 bool "Preserve cpio archive mtimes in initramfs" 1446 default y 1447 help 1448 Each entry in an initramfs cpio archive carries an mtime value. When 1449 enabled, extracted cpio items take this mtime, with directory mtime 1450 setting deferred until after creation of any child entries. 1451 1452 If unsure, say Y. 1453 1454config INITRAMFS_TEST 1455 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1456 depends on BLK_DEV_INITRD && KUNIT=y 1457 default KUNIT_ALL_TESTS 1458 help 1459 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1460 1461choice 1462 prompt "Compiler optimization level" 1463 default CC_OPTIMIZE_FOR_PERFORMANCE 1464 1465config CC_OPTIMIZE_FOR_PERFORMANCE 1466 bool "Optimize for performance (-O2)" 1467 help 1468 This is the default optimization level for the kernel, building 1469 with the "-O2" compiler flag for best performance and most 1470 helpful compile-time warnings. 1471 1472config CC_OPTIMIZE_FOR_SIZE 1473 bool "Optimize for size (-Os)" 1474 help 1475 Choosing this option will pass "-Os" to your compiler resulting 1476 in a smaller kernel. 1477 1478endchoice 1479 1480config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1481 bool 1482 help 1483 This requires that the arch annotates or otherwise protects 1484 its external entry points from being discarded. Linker scripts 1485 must also merge .text.*, .data.*, and .bss.* correctly into 1486 output sections. Care must be taken not to pull in unrelated 1487 sections (e.g., '.text.init'). Typically '.' in section names 1488 is used to distinguish them from label names / C identifiers. 1489 1490config LD_DEAD_CODE_DATA_ELIMINATION 1491 bool "Dead code and data elimination (EXPERIMENTAL)" 1492 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1493 depends on EXPERT 1494 depends on $(cc-option,-ffunction-sections -fdata-sections) 1495 depends on $(ld-option,--gc-sections) 1496 help 1497 Enable this if you want to do dead code and data elimination with 1498 the linker by compiling with -ffunction-sections -fdata-sections, 1499 and linking with --gc-sections. 1500 1501 This can reduce on disk and in-memory size of the kernel 1502 code and static data, particularly for small configs and 1503 on small systems. This has the possibility of introducing 1504 silently broken kernel if the required annotations are not 1505 present. This option is not well tested yet, so use at your 1506 own risk. 1507 1508config LD_ORPHAN_WARN 1509 def_bool y 1510 depends on ARCH_WANT_LD_ORPHAN_WARN 1511 depends on $(ld-option,--orphan-handling=warn) 1512 depends on $(ld-option,--orphan-handling=error) 1513 1514config LD_ORPHAN_WARN_LEVEL 1515 string 1516 depends on LD_ORPHAN_WARN 1517 default "error" if WERROR 1518 default "warn" 1519 1520config SYSCTL 1521 bool 1522 1523config HAVE_UID16 1524 bool 1525 1526config SYSCTL_EXCEPTION_TRACE 1527 bool 1528 help 1529 Enable support for /proc/sys/debug/exception-trace. 1530 1531config SYSCTL_ARCH_UNALIGN_NO_WARN 1532 bool 1533 help 1534 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1535 Allows arch to define/use @no_unaligned_warning to possibly warn 1536 about unaligned access emulation going on under the hood. 1537 1538config SYSCTL_ARCH_UNALIGN_ALLOW 1539 bool 1540 help 1541 Enable support for /proc/sys/kernel/unaligned-trap 1542 Allows arches to define/use @unaligned_enabled to runtime toggle 1543 the unaligned access emulation. 1544 see arch/parisc/kernel/unaligned.c for reference 1545 1546config SYSFS_SYSCALL 1547 bool "Sysfs syscall support" 1548 default n 1549 help 1550 sys_sysfs is an obsolete system call no longer supported in libc. 1551 Note that disabling this option is more secure but might break 1552 compatibility with some systems. 1553 1554 If unsure say N here. 1555 1556config HAVE_PCSPKR_PLATFORM 1557 bool 1558 1559menuconfig EXPERT 1560 bool "Configure standard kernel features (expert users)" 1561 # Unhide debug options, to make the on-by-default options visible 1562 select DEBUG_KERNEL 1563 help 1564 This option allows certain base kernel options and settings 1565 to be disabled or tweaked. This is for specialized 1566 environments which can tolerate a "non-standard" kernel. 1567 Only use this if you really know what you are doing. 1568 1569config UID16 1570 bool "Enable 16-bit UID system calls" if EXPERT 1571 depends on HAVE_UID16 && MULTIUSER 1572 default y 1573 help 1574 This enables the legacy 16-bit UID syscall wrappers. 1575 1576config MULTIUSER 1577 bool "Multiple users, groups and capabilities support" if EXPERT 1578 default y 1579 help 1580 This option enables support for non-root users, groups and 1581 capabilities. 1582 1583 If you say N here, all processes will run with UID 0, GID 0, and all 1584 possible capabilities. Saying N here also compiles out support for 1585 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1586 setgid, and capset. 1587 1588 If unsure, say Y here. 1589 1590config SGETMASK_SYSCALL 1591 bool "sgetmask/ssetmask syscalls support" if EXPERT 1592 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1593 help 1594 sys_sgetmask and sys_ssetmask are obsolete system calls 1595 no longer supported in libc but still enabled by default in some 1596 architectures. 1597 1598 If unsure, leave the default option here. 1599 1600config FHANDLE 1601 bool "open by fhandle syscalls" if EXPERT 1602 select EXPORTFS 1603 default y 1604 help 1605 If you say Y here, a user level program will be able to map 1606 file names to handle and then later use the handle for 1607 different file system operations. This is useful in implementing 1608 userspace file servers, which now track files using handles instead 1609 of names. The handle would remain the same even if file names 1610 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1611 syscalls. 1612 1613config POSIX_TIMERS 1614 bool "Posix Clocks & timers" if EXPERT 1615 default y 1616 help 1617 This includes native support for POSIX timers to the kernel. 1618 Some embedded systems have no use for them and therefore they 1619 can be configured out to reduce the size of the kernel image. 1620 1621 When this option is disabled, the following syscalls won't be 1622 available: timer_create, timer_gettime: timer_getoverrun, 1623 timer_settime, timer_delete, clock_adjtime, getitimer, 1624 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1625 clock_getres and clock_nanosleep syscalls will be limited to 1626 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1627 1628 If unsure say y. 1629 1630config PRINTK 1631 default y 1632 bool "Enable support for printk" if EXPERT 1633 select IRQ_WORK 1634 help 1635 This option enables normal printk support. Removing it 1636 eliminates most of the message strings from the kernel image 1637 and makes the kernel more or less silent. As this makes it 1638 very difficult to diagnose system problems, saying N here is 1639 strongly discouraged. 1640 1641config BUG 1642 bool "BUG() support" if EXPERT 1643 default y 1644 help 1645 Disabling this option eliminates support for BUG and WARN, reducing 1646 the size of your kernel image and potentially quietly ignoring 1647 numerous fatal conditions. You should only consider disabling this 1648 option for embedded systems with no facilities for reporting errors. 1649 Just say Y. 1650 1651config ELF_CORE 1652 depends on COREDUMP 1653 default y 1654 bool "Enable ELF core dumps" if EXPERT 1655 help 1656 Enable support for generating core dumps. Disabling saves about 4k. 1657 1658 1659config PCSPKR_PLATFORM 1660 bool "Enable PC-Speaker support" if EXPERT 1661 depends on HAVE_PCSPKR_PLATFORM 1662 select I8253_LOCK 1663 default y 1664 help 1665 This option allows to disable the internal PC-Speaker 1666 support, saving some memory. 1667 1668config BASE_SMALL 1669 bool "Enable smaller-sized data structures for core" if EXPERT 1670 help 1671 Enabling this option reduces the size of miscellaneous core 1672 kernel data structures. This saves memory on small machines, 1673 but may reduce performance. 1674 1675config FUTEX 1676 bool "Enable futex support" if EXPERT 1677 depends on !(SPARC32 && SMP) 1678 default y 1679 imply RT_MUTEXES 1680 help 1681 Disabling this option will cause the kernel to be built without 1682 support for "fast userspace mutexes". The resulting kernel may not 1683 run glibc-based applications correctly. 1684 1685config FUTEX_PI 1686 bool 1687 depends on FUTEX && RT_MUTEXES 1688 default y 1689 1690config EPOLL 1691 bool "Enable eventpoll support" if EXPERT 1692 default y 1693 help 1694 Disabling this option will cause the kernel to be built without 1695 support for epoll family of system calls. 1696 1697config SIGNALFD 1698 bool "Enable signalfd() system call" if EXPERT 1699 default y 1700 help 1701 Enable the signalfd() system call that allows to receive signals 1702 on a file descriptor. 1703 1704 If unsure, say Y. 1705 1706config TIMERFD 1707 bool "Enable timerfd() system call" if EXPERT 1708 default y 1709 help 1710 Enable the timerfd() system call that allows to receive timer 1711 events on a file descriptor. 1712 1713 If unsure, say Y. 1714 1715config EVENTFD 1716 bool "Enable eventfd() system call" if EXPERT 1717 default y 1718 help 1719 Enable the eventfd() system call that allows to receive both 1720 kernel notification (ie. KAIO) or userspace notifications. 1721 1722 If unsure, say Y. 1723 1724config SHMEM 1725 bool "Use full shmem filesystem" if EXPERT 1726 default y 1727 depends on MMU 1728 help 1729 The shmem is an internal filesystem used to manage shared memory. 1730 It is backed by swap and manages resource limits. It is also exported 1731 to userspace as tmpfs if TMPFS is enabled. Disabling this 1732 option replaces shmem and tmpfs with the much simpler ramfs code, 1733 which may be appropriate on small systems without swap. 1734 1735config AIO 1736 bool "Enable AIO support" if EXPERT 1737 default y 1738 help 1739 This option enables POSIX asynchronous I/O which may by used 1740 by some high performance threaded applications. Disabling 1741 this option saves about 7k. 1742 1743config IO_URING 1744 bool "Enable IO uring support" if EXPERT 1745 select IO_WQ 1746 default y 1747 help 1748 This option enables support for the io_uring interface, enabling 1749 applications to submit and complete IO through submission and 1750 completion rings that are shared between the kernel and application. 1751 1752config GCOV_PROFILE_URING 1753 bool "Enable GCOV profiling on the io_uring subsystem" 1754 depends on GCOV_KERNEL 1755 help 1756 Enable GCOV profiling on the io_uring subsystem, to facilitate 1757 code coverage testing. 1758 1759 If unsure, say N. 1760 1761 Note that this will have a negative impact on the performance of 1762 the io_uring subsystem, hence this should only be enabled for 1763 specific test purposes. 1764 1765config ADVISE_SYSCALLS 1766 bool "Enable madvise/fadvise syscalls" if EXPERT 1767 default y 1768 help 1769 This option enables the madvise and fadvise syscalls, used by 1770 applications to advise the kernel about their future memory or file 1771 usage, improving performance. If building an embedded system where no 1772 applications use these syscalls, you can disable this option to save 1773 space. 1774 1775config MEMBARRIER 1776 bool "Enable membarrier() system call" if EXPERT 1777 default y 1778 help 1779 Enable the membarrier() system call that allows issuing memory 1780 barriers across all running threads, which can be used to distribute 1781 the cost of user-space memory barriers asymmetrically by transforming 1782 pairs of memory barriers into pairs consisting of membarrier() and a 1783 compiler barrier. 1784 1785 If unsure, say Y. 1786 1787config KCMP 1788 bool "Enable kcmp() system call" if EXPERT 1789 help 1790 Enable the kernel resource comparison system call. It provides 1791 user-space with the ability to compare two processes to see if they 1792 share a common resource, such as a file descriptor or even virtual 1793 memory space. 1794 1795 If unsure, say N. 1796 1797config RSEQ 1798 bool "Enable rseq() system call" if EXPERT 1799 default y 1800 depends on HAVE_RSEQ 1801 select MEMBARRIER 1802 help 1803 Enable the restartable sequences system call. It provides a 1804 user-space cache for the current CPU number value, which 1805 speeds up getting the current CPU number from user-space, 1806 as well as an ABI to speed up user-space operations on 1807 per-CPU data. 1808 1809 If unsure, say Y. 1810 1811config DEBUG_RSEQ 1812 default n 1813 bool "Enable debugging of rseq() system call" if EXPERT 1814 depends on RSEQ && DEBUG_KERNEL 1815 help 1816 Enable extra debugging checks for the rseq system call. 1817 1818 If unsure, say N. 1819 1820config CACHESTAT_SYSCALL 1821 bool "Enable cachestat() system call" if EXPERT 1822 default y 1823 help 1824 Enable the cachestat system call, which queries the page cache 1825 statistics of a file (number of cached pages, dirty pages, 1826 pages marked for writeback, (recently) evicted pages). 1827 1828 If unsure say Y here. 1829 1830config PC104 1831 bool "PC/104 support" if EXPERT 1832 help 1833 Expose PC/104 form factor device drivers and options available for 1834 selection and configuration. Enable this option if your target 1835 machine has a PC/104 bus. 1836 1837config KALLSYMS 1838 bool "Load all symbols for debugging/ksymoops" if EXPERT 1839 default y 1840 help 1841 Say Y here to let the kernel print out symbolic crash information and 1842 symbolic stack backtraces. This increases the size of the kernel 1843 somewhat, as all symbols have to be loaded into the kernel image. 1844 1845config KALLSYMS_SELFTEST 1846 bool "Test the basic functions and performance of kallsyms" 1847 depends on KALLSYMS 1848 default n 1849 help 1850 Test the basic functions and performance of some interfaces, such as 1851 kallsyms_lookup_name. It also calculates the compression rate of the 1852 kallsyms compression algorithm for the current symbol set. 1853 1854 Start self-test automatically after system startup. Suggest executing 1855 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 1856 displayed in the last line, indicating that the test is complete. 1857 1858config KALLSYMS_ALL 1859 bool "Include all symbols in kallsyms" 1860 depends on DEBUG_KERNEL && KALLSYMS 1861 help 1862 Normally kallsyms only contains the symbols of functions for nicer 1863 OOPS messages and backtraces (i.e., symbols from the text and inittext 1864 sections). This is sufficient for most cases. And only if you want to 1865 enable kernel live patching, or other less common use cases (e.g., 1866 when a debugger is used) all symbols are required (i.e., names of 1867 variables from the data sections, etc). 1868 1869 This option makes sure that all symbols are loaded into the kernel 1870 image (i.e., symbols from all sections) in cost of increased kernel 1871 size (depending on the kernel configuration, it may be 300KiB or 1872 something like this). 1873 1874 Say N unless you really need all symbols, or kernel live patching. 1875 1876# end of the "standard kernel features (expert users)" menu 1877 1878config ARCH_HAS_MEMBARRIER_CALLBACKS 1879 bool 1880 1881config ARCH_HAS_MEMBARRIER_SYNC_CORE 1882 bool 1883 1884config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 1885 bool 1886 help 1887 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 1888 1889 A 64-bit kernel is required for the memory sealing feature. 1890 No specific hardware features from the CPU are needed. 1891 1892 To enable this feature, the architecture needs to update their 1893 special mappings calls to include the sealing flag and confirm 1894 that it doesn't unmap/remap system mappings during the life 1895 time of the process. The existence of this flag for an architecture 1896 implies that it does not require the remapping of the system 1897 mappings during process lifetime, so sealing these mappings is safe 1898 from a kernel perspective. 1899 1900 After the architecture enables this, a distribution can set 1901 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 1902 1903 For complete descriptions of memory sealing, please see 1904 Documentation/userspace-api/mseal.rst 1905 1906config HAVE_PERF_EVENTS 1907 bool 1908 help 1909 See tools/perf/design.txt for details. 1910 1911config GUEST_PERF_EVENTS 1912 bool 1913 depends on HAVE_PERF_EVENTS 1914 1915config PERF_USE_VMALLOC 1916 bool 1917 help 1918 See tools/perf/design.txt for details 1919 1920menu "Kernel Performance Events And Counters" 1921 1922config PERF_EVENTS 1923 bool "Kernel performance events and counters" 1924 default y if PROFILING 1925 depends on HAVE_PERF_EVENTS 1926 select IRQ_WORK 1927 help 1928 Enable kernel support for various performance events provided 1929 by software and hardware. 1930 1931 Software events are supported either built-in or via the 1932 use of generic tracepoints. 1933 1934 Most modern CPUs support performance events via performance 1935 counter registers. These registers count the number of certain 1936 types of hw events: such as instructions executed, cachemisses 1937 suffered, or branches mis-predicted - without slowing down the 1938 kernel or applications. These registers can also trigger interrupts 1939 when a threshold number of events have passed - and can thus be 1940 used to profile the code that runs on that CPU. 1941 1942 The Linux Performance Event subsystem provides an abstraction of 1943 these software and hardware event capabilities, available via a 1944 system call and used by the "perf" utility in tools/perf/. It 1945 provides per task and per CPU counters, and it provides event 1946 capabilities on top of those. 1947 1948 Say Y if unsure. 1949 1950config DEBUG_PERF_USE_VMALLOC 1951 default n 1952 bool "Debug: use vmalloc to back perf mmap() buffers" 1953 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 1954 select PERF_USE_VMALLOC 1955 help 1956 Use vmalloc memory to back perf mmap() buffers. 1957 1958 Mostly useful for debugging the vmalloc code on platforms 1959 that don't require it. 1960 1961 Say N if unsure. 1962 1963endmenu 1964 1965config SYSTEM_DATA_VERIFICATION 1966 def_bool n 1967 select SYSTEM_TRUSTED_KEYRING 1968 select KEYS 1969 select CRYPTO 1970 select CRYPTO_RSA 1971 select ASYMMETRIC_KEY_TYPE 1972 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1973 select ASN1 1974 select OID_REGISTRY 1975 select X509_CERTIFICATE_PARSER 1976 select PKCS7_MESSAGE_PARSER 1977 help 1978 Provide PKCS#7 message verification using the contents of the system 1979 trusted keyring to provide public keys. This then can be used for 1980 module verification, kexec image verification and firmware blob 1981 verification. 1982 1983config PROFILING 1984 bool "Profiling support" 1985 help 1986 Say Y here to enable the extended profiling support mechanisms used 1987 by profilers. 1988 1989config RUST 1990 bool "Rust support" 1991 depends on HAVE_RUST 1992 depends on RUST_IS_AVAILABLE 1993 select EXTENDED_MODVERSIONS if MODVERSIONS 1994 depends on !MODVERSIONS || GENDWARFKSYMS 1995 depends on !GCC_PLUGIN_RANDSTRUCT 1996 depends on !RANDSTRUCT 1997 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 1998 depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 1999 select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG 2000 depends on !CALL_PADDING || RUSTC_VERSION >= 108100 2001 depends on !KASAN_SW_TAGS 2002 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300 2003 help 2004 Enables Rust support in the kernel. 2005 2006 This allows other Rust-related options, like drivers written in Rust, 2007 to be selected. 2008 2009 It is also required to be able to load external kernel modules 2010 written in Rust. 2011 2012 See Documentation/rust/ for more information. 2013 2014 If unsure, say N. 2015 2016config RUSTC_VERSION_TEXT 2017 string 2018 depends on RUST 2019 default "$(RUSTC_VERSION_TEXT)" 2020 help 2021 See `CC_VERSION_TEXT`. 2022 2023config BINDGEN_VERSION_TEXT 2024 string 2025 depends on RUST 2026 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0 2027 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0 2028 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed 2029 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1 2030 # both fixed the issue). 2031 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)" 2032 2033# 2034# Place an empty function call at each tracepoint site. Can be 2035# dynamically changed for a probe function. 2036# 2037config TRACEPOINTS 2038 bool 2039 select TASKS_TRACE_RCU 2040 2041source "kernel/Kconfig.kexec" 2042 2043endmenu # General setup 2044 2045source "arch/Kconfig" 2046 2047config RT_MUTEXES 2048 bool 2049 default y if PREEMPT_RT 2050 2051config MODULE_SIG_FORMAT 2052 def_bool n 2053 select SYSTEM_DATA_VERIFICATION 2054 2055source "kernel/module/Kconfig" 2056 2057config INIT_ALL_POSSIBLE 2058 bool 2059 help 2060 Back when each arch used to define their own cpu_online_mask and 2061 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2062 with all 1s, and others with all 0s. When they were centralised, 2063 it was better to provide this option than to break all the archs 2064 and have several arch maintainers pursuing me down dark alleys. 2065 2066source "block/Kconfig" 2067 2068config PREEMPT_NOTIFIERS 2069 bool 2070 2071config PADATA 2072 depends on SMP 2073 bool 2074 2075config ASN1 2076 tristate 2077 help 2078 Build a simple ASN.1 grammar compiler that produces a bytecode output 2079 that can be interpreted by the ASN.1 stream decoder and used to 2080 inform it as to what tags are to be expected in a stream and what 2081 functions to call on what tags. 2082 2083source "kernel/Kconfig.locks" 2084 2085config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2086 bool 2087 2088config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2089 bool 2090 2091config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2092 bool 2093 2094# It may be useful for an architecture to override the definitions of the 2095# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2096# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2097# different calling convention for syscalls. They can also override the 2098# macros for not-implemented syscalls in kernel/sys_ni.c and 2099# kernel/time/posix-stubs.c. All these overrides need to be available in 2100# <asm/syscall_wrapper.h>. 2101config ARCH_HAS_SYSCALL_WRAPPER 2102 def_bool n 2103