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 90config CC_CAN_LINK_STATIC 91 bool 92 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT 93 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static) 94 95# Fixed in GCC 14, 13.3, 12.4 and 11.5 96# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 97config GCC_ASM_GOTO_OUTPUT_BROKEN 98 bool 99 depends on CC_IS_GCC 100 default y if GCC_VERSION < 110500 101 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400 102 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300 103 104config CC_HAS_ASM_GOTO_OUTPUT 105 def_bool y 106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN 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 109config CC_HAS_ASM_GOTO_TIED_OUTPUT 110 depends on CC_HAS_ASM_GOTO_OUTPUT 111 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 112 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) 113 114config TOOLS_SUPPORT_RELR 115 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 116 117config CC_HAS_ASM_INLINE 118 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 119 120config CC_HAS_NO_PROFILE_FN_ATTR 121 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 122 123config CC_HAS_COUNTED_BY 124 # TODO: when gcc 15 is released remove the build test and add 125 # a gcc version check 126 def_bool $(success,echo 'struct flex { int count; int array[] __attribute__((__counted_by__(count))); };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 127 # clang needs to be at least 19.1.3 to avoid __bdos miscalculations 128 # https://github.com/llvm/llvm-project/pull/110497 129 # https://github.com/llvm/llvm-project/pull/112636 130 depends on !(CC_IS_CLANG && CLANG_VERSION < 190103) 131 132config CC_HAS_MULTIDIMENSIONAL_NONSTRING 133 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 134 135config RUSTC_HAS_COERCE_POINTEE 136 def_bool RUSTC_VERSION >= 108400 137 138config PAHOLE_VERSION 139 int 140 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) 141 142config CONSTRUCTORS 143 bool 144 145config IRQ_WORK 146 def_bool y if SMP 147 148config BUILDTIME_TABLE_SORT 149 bool 150 151config THREAD_INFO_IN_TASK 152 bool 153 help 154 Select this to move thread_info off the stack into task_struct. To 155 make this work, an arch will need to remove all thread_info fields 156 except flags and fix any runtime bugs. 157 158 One subtle change that will be needed is to use try_get_task_stack() 159 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 160 161menu "General setup" 162 163config BROKEN 164 bool 165 166config BROKEN_ON_SMP 167 bool 168 depends on BROKEN || !SMP 169 default y 170 171config INIT_ENV_ARG_LIMIT 172 int 173 default 32 if !UML 174 default 128 if UML 175 help 176 Maximum of each of the number of arguments and environment 177 variables passed to init from the kernel command line. 178 179config COMPILE_TEST 180 bool "Compile also drivers which will not load" 181 depends on HAS_IOMEM 182 help 183 Some drivers can be compiled on a different platform than they are 184 intended to be run on. Despite they cannot be loaded there (or even 185 when they load they cannot be used due to missing HW support), 186 developers still, opposing to distributors, might want to build such 187 drivers to compile-test them. 188 189 If you are a developer and want to build everything available, say Y 190 here. If you are a user/distributor, say N here to exclude useless 191 drivers to be distributed. 192 193config WERROR 194 bool "Compile the kernel with warnings as errors" 195 default COMPILE_TEST 196 help 197 A kernel build should not cause any compiler warnings, and this 198 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 199 to enforce that rule by default. Certain warnings from other tools 200 such as the linker may be upgraded to errors with this option as 201 well. 202 203 However, if you have a new (or very old) compiler or linker with odd 204 and unusual warnings, or you have some architecture with problems, 205 you may need to disable this config option in order to 206 successfully build the kernel. 207 208 If in doubt, say Y. 209 210config UAPI_HEADER_TEST 211 bool "Compile test UAPI headers" 212 depends on HEADERS_INSTALL && CC_CAN_LINK 213 help 214 Compile test headers exported to user-space to ensure they are 215 self-contained, i.e. compilable as standalone units. 216 217 If you are a developer or tester and want to ensure the exported 218 headers are self-contained, say Y here. Otherwise, choose N. 219 220config LOCALVERSION 221 string "Local version - append to kernel release" 222 help 223 Append an extra string to the end of your kernel version. 224 This will show up when you type uname, for example. 225 The string you set here will be appended after the contents of 226 any files with a filename matching localversion* in your 227 object and source tree, in that order. Your total string can 228 be a maximum of 64 characters. 229 230config LOCALVERSION_AUTO 231 bool "Automatically append version information to the version string" 232 default y 233 depends on !COMPILE_TEST 234 help 235 This will try to automatically determine if the current tree is a 236 release tree by looking for git tags that belong to the current 237 top of tree revision. 238 239 A string of the format -gxxxxxxxx will be added to the localversion 240 if a git-based tree is found. The string generated by this will be 241 appended after any matching localversion* files, and after the value 242 set in CONFIG_LOCALVERSION. 243 244 (The actual string used here is the first 12 characters produced 245 by running the command: 246 247 $ git rev-parse --verify HEAD 248 249 which is done within the script "scripts/setlocalversion".) 250 251config BUILD_SALT 252 string "Build ID Salt" 253 default "" 254 help 255 The build ID is used to link binaries and their debug info. Setting 256 this option will use the value in the calculation of the build id. 257 This is mostly useful for distributions which want to ensure the 258 build is unique between builds. It's safe to leave the default. 259 260config HAVE_KERNEL_GZIP 261 bool 262 263config HAVE_KERNEL_BZIP2 264 bool 265 266config HAVE_KERNEL_LZMA 267 bool 268 269config HAVE_KERNEL_XZ 270 bool 271 272config HAVE_KERNEL_LZO 273 bool 274 275config HAVE_KERNEL_LZ4 276 bool 277 278config HAVE_KERNEL_ZSTD 279 bool 280 281config HAVE_KERNEL_UNCOMPRESSED 282 bool 283 284choice 285 prompt "Kernel compression mode" 286 default KERNEL_GZIP 287 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 288 help 289 The linux kernel is a kind of self-extracting executable. 290 Several compression algorithms are available, which differ 291 in efficiency, compression and decompression speed. 292 Compression speed is only relevant when building a kernel. 293 Decompression speed is relevant at each boot. 294 295 If you have any problems with bzip2 or lzma compressed 296 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 297 version of this functionality (bzip2 only), for 2.4, was 298 supplied by Christian Ludwig) 299 300 High compression options are mostly useful for users, who 301 are low on disk space (embedded systems), but for whom ram 302 size matters less. 303 304 If in doubt, select 'gzip' 305 306config KERNEL_GZIP 307 bool "Gzip" 308 depends on HAVE_KERNEL_GZIP 309 help 310 The old and tried gzip compression. It provides a good balance 311 between compression ratio and decompression speed. 312 313config KERNEL_BZIP2 314 bool "Bzip2" 315 depends on HAVE_KERNEL_BZIP2 316 help 317 Its compression ratio and speed is intermediate. 318 Decompression speed is slowest among the choices. The kernel 319 size is about 10% smaller with bzip2, in comparison to gzip. 320 Bzip2 uses a large amount of memory. For modern kernels you 321 will need at least 8MB RAM or more for booting. 322 323config KERNEL_LZMA 324 bool "LZMA" 325 depends on HAVE_KERNEL_LZMA 326 help 327 This compression algorithm's ratio is best. Decompression speed 328 is between gzip and bzip2. Compression is slowest. 329 The kernel size is about 33% smaller with LZMA in comparison to gzip. 330 331config KERNEL_XZ 332 bool "XZ" 333 depends on HAVE_KERNEL_XZ 334 help 335 XZ uses the LZMA2 algorithm and instruction set specific 336 BCJ filters which can improve compression ratio of executable 337 code. The size of the kernel is about 30% smaller with XZ in 338 comparison to gzip. On architectures for which there is a BCJ 339 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 340 and SPARC), XZ will create a few percent smaller kernel than 341 plain LZMA. 342 343 The speed is about the same as with LZMA: The decompression 344 speed of XZ is better than that of bzip2 but worse than gzip 345 and LZO. Compression is slow. 346 347config KERNEL_LZO 348 bool "LZO" 349 depends on HAVE_KERNEL_LZO 350 help 351 Its compression ratio is the poorest among the choices. The kernel 352 size is about 10% bigger than gzip; however its speed 353 (both compression and decompression) is the fastest. 354 355config KERNEL_LZ4 356 bool "LZ4" 357 depends on HAVE_KERNEL_LZ4 358 help 359 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 360 A preliminary version of LZ4 de/compression tool is available at 361 <https://code.google.com/p/lz4/>. 362 363 Its compression ratio is worse than LZO. The size of the kernel 364 is about 8% bigger than LZO. But the decompression speed is 365 faster than LZO. 366 367config KERNEL_ZSTD 368 bool "ZSTD" 369 depends on HAVE_KERNEL_ZSTD 370 help 371 ZSTD is a compression algorithm targeting intermediate compression 372 with fast decompression speed. It will compress better than GZIP and 373 decompress around the same speed as LZO, but slower than LZ4. You 374 will need at least 192 KB RAM or more for booting. The zstd command 375 line tool is required for compression. 376 377config KERNEL_UNCOMPRESSED 378 bool "None" 379 depends on HAVE_KERNEL_UNCOMPRESSED 380 help 381 Produce uncompressed kernel image. This option is usually not what 382 you want. It is useful for debugging the kernel in slow simulation 383 environments, where decompressing and moving the kernel is awfully 384 slow. This option allows early boot code to skip the decompressor 385 and jump right at uncompressed kernel image. 386 387endchoice 388 389config DEFAULT_INIT 390 string "Default init path" 391 default "" 392 help 393 This option determines the default init for the system if no init= 394 option is passed on the kernel command line. If the requested path is 395 not present, we will still then move on to attempting further 396 locations (e.g. /sbin/init, etc). If this is empty, we will just use 397 the fallback list when init= is not passed. 398 399config DEFAULT_HOSTNAME 400 string "Default hostname" 401 default "(none)" 402 help 403 This option determines the default system hostname before userspace 404 calls sethostname(2). The kernel traditionally uses "(none)" here, 405 but you may wish to use a different default here to make a minimal 406 system more usable with less configuration. 407 408config SYSVIPC 409 bool "System V IPC" 410 help 411 Inter Process Communication is a suite of library functions and 412 system calls which let processes (running programs) synchronize and 413 exchange information. It is generally considered to be a good thing, 414 and some programs won't run unless you say Y here. In particular, if 415 you want to run the DOS emulator dosemu under Linux (read the 416 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 417 you'll need to say Y here. 418 419 You can find documentation about IPC with "info ipc" and also in 420 section 6.4 of the Linux Programmer's Guide, available from 421 <http://www.tldp.org/guides.html>. 422 423config SYSVIPC_SYSCTL 424 bool 425 depends on SYSVIPC 426 depends on SYSCTL 427 default y 428 429config SYSVIPC_COMPAT 430 def_bool y 431 depends on COMPAT && SYSVIPC 432 433config POSIX_MQUEUE 434 bool "POSIX Message Queues" 435 depends on NET 436 help 437 POSIX variant of message queues is a part of IPC. In POSIX message 438 queues every message has a priority which decides about succession 439 of receiving it by a process. If you want to compile and run 440 programs written e.g. for Solaris with use of its POSIX message 441 queues (functions mq_*) say Y here. 442 443 POSIX message queues are visible as a filesystem called 'mqueue' 444 and can be mounted somewhere if you want to do filesystem 445 operations on message queues. 446 447 If unsure, say Y. 448 449config POSIX_MQUEUE_SYSCTL 450 bool 451 depends on POSIX_MQUEUE 452 depends on SYSCTL 453 default y 454 455config WATCH_QUEUE 456 bool "General notification queue" 457 default n 458 help 459 460 This is a general notification queue for the kernel to pass events to 461 userspace by splicing them into pipes. It can be used in conjunction 462 with watches for key/keyring change notifications and device 463 notifications. 464 465 See Documentation/core-api/watch_queue.rst 466 467config CROSS_MEMORY_ATTACH 468 bool "Enable process_vm_readv/writev syscalls" 469 depends on MMU 470 default y 471 help 472 Enabling this option adds the system calls process_vm_readv and 473 process_vm_writev which allow a process with the correct privileges 474 to directly read from or write to another process' address space. 475 See the man page for more details. 476 477config USELIB 478 bool "uselib syscall (for libc5 and earlier)" 479 default ALPHA || M68K || SPARC 480 help 481 This option enables the uselib syscall, a system call used in the 482 dynamic linker from libc5 and earlier. glibc does not use this 483 system call. If you intend to run programs built on libc5 or 484 earlier, you may need to enable this syscall. Current systems 485 running glibc can safely disable this. 486 487config AUDIT 488 bool "Auditing support" 489 depends on NET 490 help 491 Enable auditing infrastructure that can be used with another 492 kernel subsystem, such as SELinux (which requires this for 493 logging of avc messages output). System call auditing is included 494 on architectures which support it. 495 496config HAVE_ARCH_AUDITSYSCALL 497 bool 498 499config AUDITSYSCALL 500 def_bool y 501 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 502 select FSNOTIFY 503 504source "kernel/irq/Kconfig" 505source "kernel/time/Kconfig" 506source "kernel/bpf/Kconfig" 507source "kernel/Kconfig.preempt" 508 509menu "CPU/Task time and stats accounting" 510 511config VIRT_CPU_ACCOUNTING 512 bool 513 514choice 515 prompt "Cputime accounting" 516 default TICK_CPU_ACCOUNTING 517 518# Kind of a stub config for the pure tick based cputime accounting 519config TICK_CPU_ACCOUNTING 520 bool "Simple tick based cputime accounting" 521 depends on !S390 && !NO_HZ_FULL 522 help 523 This is the basic tick based cputime accounting that maintains 524 statistics about user, system and idle time spent on per jiffies 525 granularity. 526 527 If unsure, say Y. 528 529config VIRT_CPU_ACCOUNTING_NATIVE 530 bool "Deterministic task and CPU time accounting" 531 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 532 select VIRT_CPU_ACCOUNTING 533 help 534 Select this option to enable more accurate task and CPU time 535 accounting. This is done by reading a CPU counter on each 536 kernel entry and exit and on transitions within the kernel 537 between system, softirq and hardirq state, so there is a 538 small performance impact. In the case of s390 or IBM POWER > 5, 539 this also enables accounting of stolen time on logically-partitioned 540 systems. 541 542config VIRT_CPU_ACCOUNTING_GEN 543 bool "Full dynticks CPU time accounting" 544 depends on HAVE_CONTEXT_TRACKING_USER 545 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 546 depends on GENERIC_CLOCKEVENTS 547 select VIRT_CPU_ACCOUNTING 548 select CONTEXT_TRACKING_USER 549 help 550 Select this option to enable task and CPU time accounting on full 551 dynticks systems. This accounting is implemented by watching every 552 kernel-user boundaries using the context tracking subsystem. 553 The accounting is thus performed at the expense of some significant 554 overhead. 555 556 For now this is only useful if you are working on the full 557 dynticks subsystem development. 558 559 If unsure, say N. 560 561endchoice 562 563config IRQ_TIME_ACCOUNTING 564 bool "Fine granularity task level IRQ time accounting" 565 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 566 help 567 Select this option to enable fine granularity task irq time 568 accounting. This is done by reading a timestamp on each 569 transitions between softirq and hardirq state, so there can be a 570 small performance impact. 571 572 If in doubt, say N here. 573 574config HAVE_SCHED_AVG_IRQ 575 def_bool y 576 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 577 depends on SMP 578 579config SCHED_HW_PRESSURE 580 bool 581 default y if ARM && ARM_CPU_TOPOLOGY 582 default y if ARM64 583 depends on SMP 584 depends on CPU_FREQ_THERMAL 585 help 586 Select this option to enable HW pressure accounting in the 587 scheduler. HW pressure is the value conveyed to the scheduler 588 that reflects the reduction in CPU compute capacity resulted from 589 HW throttling. HW throttling occurs when the performance of 590 a CPU is capped due to high operating temperatures as an example. 591 592 If selected, the scheduler will be able to balance tasks accordingly, 593 i.e. put less load on throttled CPUs than on non/less throttled ones. 594 595 This requires the architecture to implement 596 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 597 598config BSD_PROCESS_ACCT 599 bool "BSD Process Accounting" 600 depends on MULTIUSER 601 help 602 If you say Y here, a user level program will be able to instruct the 603 kernel (via a special system call) to write process accounting 604 information to a file: whenever a process exits, information about 605 that process will be appended to the file by the kernel. The 606 information includes things such as creation time, owning user, 607 command name, memory usage, controlling terminal etc. (the complete 608 list is in the struct acct in <file:include/linux/acct.h>). It is 609 up to the user level program to do useful things with this 610 information. This is generally a good idea, so say Y. 611 612config BSD_PROCESS_ACCT_V3 613 bool "BSD Process Accounting version 3 file format" 614 depends on BSD_PROCESS_ACCT 615 default n 616 help 617 If you say Y here, the process accounting information is written 618 in a new file format that also logs the process IDs of each 619 process and its parent. Note that this file format is incompatible 620 with previous v0/v1/v2 file formats, so you will need updated tools 621 for processing it. A preliminary version of these tools is available 622 at <http://www.gnu.org/software/acct/>. 623 624config TASKSTATS 625 bool "Export task/process statistics through netlink" 626 depends on NET 627 depends on MULTIUSER 628 default n 629 help 630 Export selected statistics for tasks/processes through the 631 generic netlink interface. Unlike BSD process accounting, the 632 statistics are available during the lifetime of tasks/processes as 633 responses to commands. Like BSD accounting, they are sent to user 634 space on task exit. 635 636 Say N if unsure. 637 638config TASK_DELAY_ACCT 639 bool "Enable per-task delay accounting" 640 depends on TASKSTATS 641 select SCHED_INFO 642 help 643 Collect information on time spent by a task waiting for system 644 resources like cpu, synchronous block I/O completion and swapping 645 in pages. Such statistics can help in setting a task's priorities 646 relative to other tasks for cpu, io, rss limits etc. 647 648 Say N if unsure. 649 650config TASK_XACCT 651 bool "Enable extended accounting over taskstats" 652 depends on TASKSTATS 653 help 654 Collect extended task accounting data and send the data 655 to userland for processing over the taskstats interface. 656 657 Say N if unsure. 658 659config TASK_IO_ACCOUNTING 660 bool "Enable per-task storage I/O accounting" 661 depends on TASK_XACCT 662 help 663 Collect information on the number of bytes of storage I/O which this 664 task has caused. 665 666 Say N if unsure. 667 668config PSI 669 bool "Pressure stall information tracking" 670 select KERNFS 671 help 672 Collect metrics that indicate how overcommitted the CPU, memory, 673 and IO capacity are in the system. 674 675 If you say Y here, the kernel will create /proc/pressure/ with the 676 pressure statistics files cpu, memory, and io. These will indicate 677 the share of walltime in which some or all tasks in the system are 678 delayed due to contention of the respective resource. 679 680 In kernels with cgroup support, cgroups (cgroup2 only) will 681 have cpu.pressure, memory.pressure, and io.pressure files, 682 which aggregate pressure stalls for the grouped tasks only. 683 684 For more details see Documentation/accounting/psi.rst. 685 686 Say N if unsure. 687 688config PSI_DEFAULT_DISABLED 689 bool "Require boot parameter to enable pressure stall information tracking" 690 default n 691 depends on PSI 692 help 693 If set, pressure stall information tracking will be disabled 694 per default but can be enabled through passing psi=1 on the 695 kernel commandline during boot. 696 697 This feature adds some code to the task wakeup and sleep 698 paths of the scheduler. The overhead is too low to affect 699 common scheduling-intense workloads in practice (such as 700 webservers, memcache), but it does show up in artificial 701 scheduler stress tests, such as hackbench. 702 703 If you are paranoid and not sure what the kernel will be 704 used for, say Y. 705 706 Say N if unsure. 707 708endmenu # "CPU/Task time and stats accounting" 709 710config CPU_ISOLATION 711 bool "CPU isolation" 712 depends on SMP || COMPILE_TEST 713 default y 714 help 715 Make sure that CPUs running critical tasks are not disturbed by 716 any source of "noise" such as unbound workqueues, timers, kthreads... 717 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 718 the "isolcpus=" boot parameter. 719 720 Say Y if unsure. 721 722source "kernel/rcu/Kconfig" 723 724config IKCONFIG 725 tristate "Kernel .config support" 726 help 727 This option enables the complete Linux kernel ".config" file 728 contents to be saved in the kernel. It provides documentation 729 of which kernel options are used in a running kernel or in an 730 on-disk kernel. This information can be extracted from the kernel 731 image file with the script scripts/extract-ikconfig and used as 732 input to rebuild the current kernel or to build another kernel. 733 It can also be extracted from a running kernel by reading 734 /proc/config.gz if enabled (below). 735 736config IKCONFIG_PROC 737 bool "Enable access to .config through /proc/config.gz" 738 depends on IKCONFIG && PROC_FS 739 help 740 This option enables access to the kernel configuration file 741 through /proc/config.gz. 742 743config IKHEADERS 744 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 745 depends on SYSFS 746 help 747 This option enables access to the in-kernel headers that are generated during 748 the build process. These can be used to build eBPF tracing programs, 749 or similar programs. If you build the headers as a module, a module called 750 kheaders.ko is built which can be loaded on-demand to get access to headers. 751 752config LOG_BUF_SHIFT 753 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 754 range 12 25 755 default 17 756 depends on PRINTK 757 help 758 Select the minimal kernel log buffer size as a power of 2. 759 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 760 parameter, see below. Any higher size also might be forced 761 by "log_buf_len" boot parameter. 762 763 Examples: 764 17 => 128 KB 765 16 => 64 KB 766 15 => 32 KB 767 14 => 16 KB 768 13 => 8 KB 769 12 => 4 KB 770 771config LOG_CPU_MAX_BUF_SHIFT 772 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 773 depends on SMP 774 range 0 21 775 default 0 if BASE_SMALL 776 default 12 777 depends on PRINTK 778 help 779 This option allows to increase the default ring buffer size 780 according to the number of CPUs. The value defines the contribution 781 of each CPU as a power of 2. The used space is typically only few 782 lines however it might be much more when problems are reported, 783 e.g. backtraces. 784 785 The increased size means that a new buffer has to be allocated and 786 the original static one is unused. It makes sense only on systems 787 with more CPUs. Therefore this value is used only when the sum of 788 contributions is greater than the half of the default kernel ring 789 buffer as defined by LOG_BUF_SHIFT. The default values are set 790 so that more than 16 CPUs are needed to trigger the allocation. 791 792 Also this option is ignored when "log_buf_len" kernel parameter is 793 used as it forces an exact (power of two) size of the ring buffer. 794 795 The number of possible CPUs is used for this computation ignoring 796 hotplugging making the computation optimal for the worst case 797 scenario while allowing a simple algorithm to be used from bootup. 798 799 Examples shift values and their meaning: 800 17 => 128 KB for each CPU 801 16 => 64 KB for each CPU 802 15 => 32 KB for each CPU 803 14 => 16 KB for each CPU 804 13 => 8 KB for each CPU 805 12 => 4 KB for each CPU 806 807config PRINTK_INDEX 808 bool "Printk indexing debugfs interface" 809 depends on PRINTK && DEBUG_FS 810 help 811 Add support for indexing of all printk formats known at compile time 812 at <debugfs>/printk/index/<module>. 813 814 This can be used as part of maintaining daemons which monitor 815 /dev/kmsg, as it permits auditing the printk formats present in a 816 kernel, allowing detection of cases where monitored printks are 817 changed or no longer present. 818 819 There is no additional runtime cost to printk with this enabled. 820 821# 822# Architectures with an unreliable sched_clock() should select this: 823# 824config HAVE_UNSTABLE_SCHED_CLOCK 825 bool 826 827config GENERIC_SCHED_CLOCK 828 bool 829 830menu "Scheduler features" 831 832config UCLAMP_TASK 833 bool "Enable utilization clamping for RT/FAIR tasks" 834 depends on CPU_FREQ_GOV_SCHEDUTIL 835 help 836 This feature enables the scheduler to track the clamped utilization 837 of each CPU based on RUNNABLE tasks scheduled on that CPU. 838 839 With this option, the user can specify the min and max CPU 840 utilization allowed for RUNNABLE tasks. The max utilization defines 841 the maximum frequency a task should use while the min utilization 842 defines the minimum frequency it should use. 843 844 Both min and max utilization clamp values are hints to the scheduler, 845 aiming at improving its frequency selection policy, but they do not 846 enforce or grant any specific bandwidth for tasks. 847 848 If in doubt, say N. 849 850config UCLAMP_BUCKETS_COUNT 851 int "Number of supported utilization clamp buckets" 852 range 5 20 853 default 5 854 depends on UCLAMP_TASK 855 help 856 Defines the number of clamp buckets to use. The range of each bucket 857 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 858 number of clamp buckets the finer their granularity and the higher 859 the precision of clamping aggregation and tracking at run-time. 860 861 For example, with the minimum configuration value we will have 5 862 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 863 be refcounted in the [20..39]% bucket and will set the bucket clamp 864 effective value to 25%. 865 If a second 30% boosted task should be co-scheduled on the same CPU, 866 that task will be refcounted in the same bucket of the first task and 867 it will boost the bucket clamp effective value to 30%. 868 The clamp effective value of a bucket is reset to its nominal value 869 (20% in the example above) when there are no more tasks refcounted in 870 that bucket. 871 872 An additional boost/capping margin can be added to some tasks. In the 873 example above the 25% task will be boosted to 30% until it exits the 874 CPU. If that should be considered not acceptable on certain systems, 875 it's always possible to reduce the margin by increasing the number of 876 clamp buckets to trade off used memory for run-time tracking 877 precision. 878 879 If in doubt, use the default value. 880 881endmenu 882 883# 884# For architectures that want to enable the support for NUMA-affine scheduler 885# balancing logic: 886# 887config ARCH_SUPPORTS_NUMA_BALANCING 888 bool 889 890# 891# For architectures that prefer to flush all TLBs after a number of pages 892# are unmapped instead of sending one IPI per page to flush. The architecture 893# must provide guarantees on what happens if a clean TLB cache entry is 894# written after the unmap. Details are in mm/rmap.c near the check for 895# should_defer_flush. The architecture should also consider if the full flush 896# and the refill costs are offset by the savings of sending fewer IPIs. 897config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 898 bool 899 900config CC_HAS_INT128 901 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 902 903config CC_IMPLICIT_FALLTHROUGH 904 string 905 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 906 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 907 908# Currently, disable gcc-10+ array-bounds globally. 909# It's still broken in gcc-13, so no upper bound yet. 910config GCC10_NO_ARRAY_BOUNDS 911 def_bool y 912 913config CC_NO_ARRAY_BOUNDS 914 bool 915 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 916 917# Currently, disable -Wstringop-overflow for GCC globally. 918config GCC_NO_STRINGOP_OVERFLOW 919 def_bool y 920 921config CC_NO_STRINGOP_OVERFLOW 922 bool 923 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 924 925config CC_STRINGOP_OVERFLOW 926 bool 927 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 928 929# 930# For architectures that know their GCC __int128 support is sound 931# 932config ARCH_SUPPORTS_INT128 933 bool 934 935# For architectures that (ab)use NUMA to represent different memory regions 936# all cpu-local but of different latencies, such as SuperH. 937# 938config ARCH_WANT_NUMA_VARIABLE_LOCALITY 939 bool 940 941config NUMA_BALANCING 942 bool "Memory placement aware NUMA scheduler" 943 depends on ARCH_SUPPORTS_NUMA_BALANCING 944 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 945 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 946 help 947 This option adds support for automatic NUMA aware memory/task placement. 948 The mechanism is quite primitive and is based on migrating memory when 949 it has references to the node the task is running on. 950 951 This system will be inactive on UMA systems. 952 953config NUMA_BALANCING_DEFAULT_ENABLED 954 bool "Automatically enable NUMA aware memory/task placement" 955 default y 956 depends on NUMA_BALANCING 957 help 958 If set, automatic NUMA balancing will be enabled if running on a NUMA 959 machine. 960 961config SLAB_OBJ_EXT 962 bool 963 964menuconfig CGROUPS 965 bool "Control Group support" 966 select KERNFS 967 help 968 This option adds support for grouping sets of processes together, for 969 use with process control subsystems such as Cpusets, CFS, memory 970 controls or device isolation. 971 See 972 - Documentation/scheduler/sched-design-CFS.rst (CFS) 973 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 974 and resource control) 975 976 Say N if unsure. 977 978if CGROUPS 979 980config PAGE_COUNTER 981 bool 982 983config CGROUP_FAVOR_DYNMODS 984 bool "Favor dynamic modification latency reduction by default" 985 help 986 This option enables the "favordynmods" mount option by default 987 which reduces the latencies of dynamic cgroup modifications such 988 as task migrations and controller on/offs at the cost of making 989 hot path operations such as forks and exits more expensive. 990 991 Say N if unsure. 992 993config MEMCG 994 bool "Memory controller" 995 select PAGE_COUNTER 996 select EVENTFD 997 select SLAB_OBJ_EXT 998 help 999 Provides control over the memory footprint of tasks in a cgroup. 1000 1001config MEMCG_V1 1002 bool "Legacy cgroup v1 memory controller" 1003 depends on MEMCG 1004 default n 1005 help 1006 Legacy cgroup v1 memory controller which has been deprecated by 1007 cgroup v2 implementation. The v1 is there for legacy applications 1008 which haven't migrated to the new cgroup v2 interface yet. If you 1009 do not have any such application then you are completely fine leaving 1010 this option disabled. 1011 1012 Please note that feature set of the legacy memory controller is likely 1013 going to shrink due to deprecation process. New deployments with v1 1014 controller are highly discouraged. 1015 1016 Say N if unsure. 1017 1018config BLK_CGROUP 1019 bool "IO controller" 1020 depends on BLOCK 1021 default n 1022 help 1023 Generic block IO controller cgroup interface. This is the common 1024 cgroup interface which should be used by various IO controlling 1025 policies. 1026 1027 Currently, CFQ IO scheduler uses it to recognize task groups and 1028 control disk bandwidth allocation (proportional time slice allocation) 1029 to such task groups. It is also used by bio throttling logic in 1030 block layer to implement upper limit in IO rates on a device. 1031 1032 This option only enables generic Block IO controller infrastructure. 1033 One needs to also enable actual IO controlling logic/policy. For 1034 enabling proportional weight division of disk bandwidth in CFQ, set 1035 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1036 CONFIG_BLK_DEV_THROTTLING=y. 1037 1038 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1039 1040config CGROUP_WRITEBACK 1041 bool 1042 depends on MEMCG && BLK_CGROUP 1043 default y 1044 1045menuconfig CGROUP_SCHED 1046 bool "CPU controller" 1047 default n 1048 help 1049 This feature lets CPU scheduler recognize task groups and control CPU 1050 bandwidth allocation to such task groups. It uses cgroups to group 1051 tasks. 1052 1053if CGROUP_SCHED 1054config GROUP_SCHED_WEIGHT 1055 def_bool n 1056 1057config FAIR_GROUP_SCHED 1058 bool "Group scheduling for SCHED_OTHER" 1059 depends on CGROUP_SCHED 1060 select GROUP_SCHED_WEIGHT 1061 default CGROUP_SCHED 1062 1063config CFS_BANDWIDTH 1064 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1065 depends on FAIR_GROUP_SCHED 1066 default n 1067 help 1068 This option allows users to define CPU bandwidth rates (limits) for 1069 tasks running within the fair group scheduler. Groups with no limit 1070 set are considered to be unconstrained and will run with no 1071 restriction. 1072 See Documentation/scheduler/sched-bwc.rst for more information. 1073 1074config RT_GROUP_SCHED 1075 bool "Group scheduling for SCHED_RR/FIFO" 1076 depends on CGROUP_SCHED 1077 default n 1078 help 1079 This feature lets you explicitly allocate real CPU bandwidth 1080 to task groups. If enabled, it will also make it impossible to 1081 schedule realtime tasks for non-root users until you allocate 1082 realtime bandwidth for them. 1083 See Documentation/scheduler/sched-rt-group.rst for more information. 1084 1085config EXT_GROUP_SCHED 1086 bool 1087 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1088 select GROUP_SCHED_WEIGHT 1089 default y 1090 1091endif #CGROUP_SCHED 1092 1093config SCHED_MM_CID 1094 def_bool y 1095 depends on SMP && RSEQ 1096 1097config UCLAMP_TASK_GROUP 1098 bool "Utilization clamping per group of tasks" 1099 depends on CGROUP_SCHED 1100 depends on UCLAMP_TASK 1101 default n 1102 help 1103 This feature enables the scheduler to track the clamped utilization 1104 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1105 1106 When this option is enabled, the user can specify a min and max 1107 CPU bandwidth which is allowed for each single task in a group. 1108 The max bandwidth allows to clamp the maximum frequency a task 1109 can use, while the min bandwidth allows to define a minimum 1110 frequency a task will always use. 1111 1112 When task group based utilization clamping is enabled, an eventually 1113 specified task-specific clamp value is constrained by the cgroup 1114 specified clamp value. Both minimum and maximum task clamping cannot 1115 be bigger than the corresponding clamping defined at task group level. 1116 1117 If in doubt, say N. 1118 1119config CGROUP_PIDS 1120 bool "PIDs controller" 1121 help 1122 Provides enforcement of process number limits in the scope of a 1123 cgroup. Any attempt to fork more processes than is allowed in the 1124 cgroup will fail. PIDs are fundamentally a global resource because it 1125 is fairly trivial to reach PID exhaustion before you reach even a 1126 conservative kmemcg limit. As a result, it is possible to grind a 1127 system to halt without being limited by other cgroup policies. The 1128 PIDs controller is designed to stop this from happening. 1129 1130 It should be noted that organisational operations (such as attaching 1131 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1132 since the PIDs limit only affects a process's ability to fork, not to 1133 attach to a cgroup. 1134 1135config CGROUP_RDMA 1136 bool "RDMA controller" 1137 help 1138 Provides enforcement of RDMA resources defined by IB stack. 1139 It is fairly easy for consumers to exhaust RDMA resources, which 1140 can result into resource unavailability to other consumers. 1141 RDMA controller is designed to stop this from happening. 1142 Attaching processes with active RDMA resources to the cgroup 1143 hierarchy is allowed even if can cross the hierarchy's limit. 1144 1145config CGROUP_DMEM 1146 bool "Device memory controller (DMEM)" 1147 select PAGE_COUNTER 1148 help 1149 The DMEM controller allows compatible devices to restrict device 1150 memory usage based on the cgroup hierarchy. 1151 1152 As an example, it allows you to restrict VRAM usage for applications 1153 in the DRM subsystem. 1154 1155config CGROUP_FREEZER 1156 bool "Freezer controller" 1157 help 1158 Provides a way to freeze and unfreeze all tasks in a 1159 cgroup. 1160 1161 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1162 controller includes important in-kernel memory consumers per default. 1163 1164 If you're using cgroup2, say N. 1165 1166config CGROUP_HUGETLB 1167 bool "HugeTLB controller" 1168 depends on HUGETLB_PAGE 1169 select PAGE_COUNTER 1170 default n 1171 help 1172 Provides a cgroup controller for HugeTLB pages. 1173 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1174 The limit is enforced during page fault. Since HugeTLB doesn't 1175 support page reclaim, enforcing the limit at page fault time implies 1176 that, the application will get SIGBUS signal if it tries to access 1177 HugeTLB pages beyond its limit. This requires the application to know 1178 beforehand how much HugeTLB pages it would require for its use. The 1179 control group is tracked in the third page lru pointer. This means 1180 that we cannot use the controller with huge page less than 3 pages. 1181 1182config CPUSETS 1183 bool "Cpuset controller" 1184 depends on SMP 1185 select UNION_FIND 1186 help 1187 This option will let you create and manage CPUSETs which 1188 allow dynamically partitioning a system into sets of CPUs and 1189 Memory Nodes and assigning tasks to run only within those sets. 1190 This is primarily useful on large SMP or NUMA systems. 1191 1192 Say N if unsure. 1193 1194config CPUSETS_V1 1195 bool "Legacy cgroup v1 cpusets controller" 1196 depends on CPUSETS 1197 default n 1198 help 1199 Legacy cgroup v1 cpusets controller which has been deprecated by 1200 cgroup v2 implementation. The v1 is there for legacy applications 1201 which haven't migrated to the new cgroup v2 interface yet. Legacy 1202 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1203 do not have any such application then you are completely fine leaving 1204 this option disabled. 1205 1206 Say N if unsure. 1207 1208config PROC_PID_CPUSET 1209 bool "Include legacy /proc/<pid>/cpuset file" 1210 depends on CPUSETS_V1 1211 default y 1212 1213config CGROUP_DEVICE 1214 bool "Device controller" 1215 help 1216 Provides a cgroup controller implementing whitelists for 1217 devices which a process in the cgroup can mknod or open. 1218 1219config CGROUP_CPUACCT 1220 bool "Simple CPU accounting controller" 1221 help 1222 Provides a simple controller for monitoring the 1223 total CPU consumed by the tasks in a cgroup. 1224 1225config CGROUP_PERF 1226 bool "Perf controller" 1227 depends on PERF_EVENTS 1228 help 1229 This option extends the perf per-cpu mode to restrict monitoring 1230 to threads which belong to the cgroup specified and run on the 1231 designated cpu. Or this can be used to have cgroup ID in samples 1232 so that it can monitor performance events among cgroups. 1233 1234 Say N if unsure. 1235 1236config CGROUP_BPF 1237 bool "Support for eBPF programs attached to cgroups" 1238 depends on BPF_SYSCALL 1239 select SOCK_CGROUP_DATA 1240 help 1241 Allow attaching eBPF programs to a cgroup using the bpf(2) 1242 syscall command BPF_PROG_ATTACH. 1243 1244 In which context these programs are accessed depends on the type 1245 of attachment. For instance, programs that are attached using 1246 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1247 inet sockets. 1248 1249config CGROUP_MISC 1250 bool "Misc resource controller" 1251 default n 1252 help 1253 Provides a controller for miscellaneous resources on a host. 1254 1255 Miscellaneous scalar resources are the resources on the host system 1256 which cannot be abstracted like the other cgroups. This controller 1257 tracks and limits the miscellaneous resources used by a process 1258 attached to a cgroup hierarchy. 1259 1260 For more information, please check misc cgroup section in 1261 /Documentation/admin-guide/cgroup-v2.rst. 1262 1263config CGROUP_DEBUG 1264 bool "Debug controller" 1265 default n 1266 depends on DEBUG_KERNEL 1267 help 1268 This option enables a simple controller that exports 1269 debugging information about the cgroups framework. This 1270 controller is for control cgroup debugging only. Its 1271 interfaces are not stable. 1272 1273 Say N. 1274 1275config SOCK_CGROUP_DATA 1276 bool 1277 default n 1278 1279endif # CGROUPS 1280 1281menuconfig NAMESPACES 1282 bool "Namespaces support" if EXPERT 1283 depends on MULTIUSER 1284 default !EXPERT 1285 help 1286 Provides the way to make tasks work with different objects using 1287 the same id. For example same IPC id may refer to different objects 1288 or same user id or pid may refer to different tasks when used in 1289 different namespaces. 1290 1291if NAMESPACES 1292 1293config UTS_NS 1294 bool "UTS namespace" 1295 default y 1296 help 1297 In this namespace tasks see different info provided with the 1298 uname() system call 1299 1300config TIME_NS 1301 bool "TIME namespace" 1302 depends on GENERIC_VDSO_TIME_NS 1303 default y 1304 help 1305 In this namespace boottime and monotonic clocks can be set. 1306 The time will keep going with the same pace. 1307 1308config IPC_NS 1309 bool "IPC namespace" 1310 depends on (SYSVIPC || POSIX_MQUEUE) 1311 default y 1312 help 1313 In this namespace tasks work with IPC ids which correspond to 1314 different IPC objects in different namespaces. 1315 1316config USER_NS 1317 bool "User namespace" 1318 default n 1319 help 1320 This allows containers, i.e. vservers, to use user namespaces 1321 to provide different user info for different servers. 1322 1323 When user namespaces are enabled in the kernel it is 1324 recommended that the MEMCG option also be enabled and that 1325 user-space use the memory control groups to limit the amount 1326 of memory a memory unprivileged users can use. 1327 1328 If unsure, say N. 1329 1330config PID_NS 1331 bool "PID Namespaces" 1332 default y 1333 help 1334 Support process id namespaces. This allows having multiple 1335 processes with the same pid as long as they are in different 1336 pid namespaces. This is a building block of containers. 1337 1338config NET_NS 1339 bool "Network namespace" 1340 depends on NET 1341 default y 1342 help 1343 Allow user space to create what appear to be multiple instances 1344 of the network stack. 1345 1346endif # NAMESPACES 1347 1348config CHECKPOINT_RESTORE 1349 bool "Checkpoint/restore support" 1350 depends on PROC_FS 1351 select PROC_CHILDREN 1352 select KCMP 1353 default n 1354 help 1355 Enables additional kernel features in a sake of checkpoint/restore. 1356 In particular it adds auxiliary prctl codes to setup process text, 1357 data and heap segment sizes, and a few additional /proc filesystem 1358 entries. 1359 1360 If unsure, say N here. 1361 1362config SCHED_AUTOGROUP 1363 bool "Automatic process group scheduling" 1364 select CGROUPS 1365 select CGROUP_SCHED 1366 select FAIR_GROUP_SCHED 1367 help 1368 This option optimizes the scheduler for common desktop workloads by 1369 automatically creating and populating task groups. This separation 1370 of workloads isolates aggressive CPU burners (like build jobs) from 1371 desktop applications. Task group autogeneration is currently based 1372 upon task session. 1373 1374config RELAY 1375 bool "Kernel->user space relay support (formerly relayfs)" 1376 select IRQ_WORK 1377 help 1378 This option enables support for relay interface support in 1379 certain file systems (such as debugfs). 1380 It is designed to provide an efficient mechanism for tools and 1381 facilities to relay large amounts of data from kernel space to 1382 user space. 1383 1384 If unsure, say N. 1385 1386config BLK_DEV_INITRD 1387 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1388 help 1389 The initial RAM filesystem is a ramfs which is loaded by the 1390 boot loader (loadlin or lilo) and that is mounted as root 1391 before the normal boot procedure. It is typically used to 1392 load modules needed to mount the "real" root file system, 1393 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1394 1395 If RAM disk support (BLK_DEV_RAM) is also included, this 1396 also enables initial RAM disk (initrd) support and adds 1397 15 Kbytes (more on some other architectures) to the kernel size. 1398 1399 If unsure say Y. 1400 1401if BLK_DEV_INITRD 1402 1403source "usr/Kconfig" 1404 1405endif 1406 1407config BOOT_CONFIG 1408 bool "Boot config support" 1409 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1410 help 1411 Extra boot config allows system admin to pass a config file as 1412 complemental extension of kernel cmdline when booting. 1413 The boot config file must be attached at the end of initramfs 1414 with checksum, size and magic word. 1415 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1416 1417 If unsure, say Y. 1418 1419config BOOT_CONFIG_FORCE 1420 bool "Force unconditional bootconfig processing" 1421 depends on BOOT_CONFIG 1422 default y if BOOT_CONFIG_EMBED 1423 help 1424 With this Kconfig option set, BOOT_CONFIG processing is carried 1425 out even when the "bootconfig" kernel-boot parameter is omitted. 1426 In fact, with this Kconfig option set, there is no way to 1427 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1428 parameters. 1429 1430 If unsure, say N. 1431 1432config BOOT_CONFIG_EMBED 1433 bool "Embed bootconfig file in the kernel" 1434 depends on BOOT_CONFIG 1435 help 1436 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1437 kernel. Usually, the bootconfig file is loaded with the initrd 1438 image. But if the system doesn't support initrd, this option will 1439 help you by embedding a bootconfig file while building the kernel. 1440 1441 If unsure, say N. 1442 1443config BOOT_CONFIG_EMBED_FILE 1444 string "Embedded bootconfig file path" 1445 depends on BOOT_CONFIG_EMBED 1446 help 1447 Specify a bootconfig file which will be embedded to the kernel. 1448 This bootconfig will be used if there is no initrd or no other 1449 bootconfig in the initrd. 1450 1451config INITRAMFS_PRESERVE_MTIME 1452 bool "Preserve cpio archive mtimes in initramfs" 1453 default y 1454 help 1455 Each entry in an initramfs cpio archive carries an mtime value. When 1456 enabled, extracted cpio items take this mtime, with directory mtime 1457 setting deferred until after creation of any child entries. 1458 1459 If unsure, say Y. 1460 1461config INITRAMFS_TEST 1462 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1463 depends on BLK_DEV_INITRD && KUNIT=y 1464 default KUNIT_ALL_TESTS 1465 help 1466 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1467 1468choice 1469 prompt "Compiler optimization level" 1470 default CC_OPTIMIZE_FOR_PERFORMANCE 1471 1472config CC_OPTIMIZE_FOR_PERFORMANCE 1473 bool "Optimize for performance (-O2)" 1474 help 1475 This is the default optimization level for the kernel, building 1476 with the "-O2" compiler flag for best performance and most 1477 helpful compile-time warnings. 1478 1479config CC_OPTIMIZE_FOR_SIZE 1480 bool "Optimize for size (-Os)" 1481 help 1482 Choosing this option will pass "-Os" to your compiler resulting 1483 in a smaller kernel. 1484 1485endchoice 1486 1487config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1488 bool 1489 help 1490 This requires that the arch annotates or otherwise protects 1491 its external entry points from being discarded. Linker scripts 1492 must also merge .text.*, .data.*, and .bss.* correctly into 1493 output sections. Care must be taken not to pull in unrelated 1494 sections (e.g., '.text.init'). Typically '.' in section names 1495 is used to distinguish them from label names / C identifiers. 1496 1497config LD_DEAD_CODE_DATA_ELIMINATION 1498 bool "Dead code and data elimination (EXPERIMENTAL)" 1499 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1500 depends on EXPERT 1501 depends on $(cc-option,-ffunction-sections -fdata-sections) 1502 depends on $(ld-option,--gc-sections) 1503 help 1504 Enable this if you want to do dead code and data elimination with 1505 the linker by compiling with -ffunction-sections -fdata-sections, 1506 and linking with --gc-sections. 1507 1508 This can reduce on disk and in-memory size of the kernel 1509 code and static data, particularly for small configs and 1510 on small systems. This has the possibility of introducing 1511 silently broken kernel if the required annotations are not 1512 present. This option is not well tested yet, so use at your 1513 own risk. 1514 1515config LD_ORPHAN_WARN 1516 def_bool y 1517 depends on ARCH_WANT_LD_ORPHAN_WARN 1518 depends on $(ld-option,--orphan-handling=warn) 1519 depends on $(ld-option,--orphan-handling=error) 1520 1521config LD_ORPHAN_WARN_LEVEL 1522 string 1523 depends on LD_ORPHAN_WARN 1524 default "error" if WERROR 1525 default "warn" 1526 1527config SYSCTL 1528 bool 1529 1530config HAVE_UID16 1531 bool 1532 1533config SYSCTL_EXCEPTION_TRACE 1534 bool 1535 help 1536 Enable support for /proc/sys/debug/exception-trace. 1537 1538config SYSCTL_ARCH_UNALIGN_NO_WARN 1539 bool 1540 help 1541 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1542 Allows arch to define/use @no_unaligned_warning to possibly warn 1543 about unaligned access emulation going on under the hood. 1544 1545config SYSCTL_ARCH_UNALIGN_ALLOW 1546 bool 1547 help 1548 Enable support for /proc/sys/kernel/unaligned-trap 1549 Allows arches to define/use @unaligned_enabled to runtime toggle 1550 the unaligned access emulation. 1551 see arch/parisc/kernel/unaligned.c for reference 1552 1553config HAVE_PCSPKR_PLATFORM 1554 bool 1555 1556menuconfig EXPERT 1557 bool "Configure standard kernel features (expert users)" 1558 # Unhide debug options, to make the on-by-default options visible 1559 select DEBUG_KERNEL 1560 help 1561 This option allows certain base kernel options and settings 1562 to be disabled or tweaked. This is for specialized 1563 environments which can tolerate a "non-standard" kernel. 1564 Only use this if you really know what you are doing. 1565 1566config UID16 1567 bool "Enable 16-bit UID system calls" if EXPERT 1568 depends on HAVE_UID16 && MULTIUSER 1569 default y 1570 help 1571 This enables the legacy 16-bit UID syscall wrappers. 1572 1573config MULTIUSER 1574 bool "Multiple users, groups and capabilities support" if EXPERT 1575 default y 1576 help 1577 This option enables support for non-root users, groups and 1578 capabilities. 1579 1580 If you say N here, all processes will run with UID 0, GID 0, and all 1581 possible capabilities. Saying N here also compiles out support for 1582 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1583 setgid, and capset. 1584 1585 If unsure, say Y here. 1586 1587config SGETMASK_SYSCALL 1588 bool "sgetmask/ssetmask syscalls support" if EXPERT 1589 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1590 help 1591 sys_sgetmask and sys_ssetmask are obsolete system calls 1592 no longer supported in libc but still enabled by default in some 1593 architectures. 1594 1595 If unsure, leave the default option here. 1596 1597config SYSFS_SYSCALL 1598 bool "Sysfs syscall support" if EXPERT 1599 default y 1600 help 1601 sys_sysfs is an obsolete system call no longer supported in libc. 1602 Note that disabling this option is more secure but might break 1603 compatibility with some systems. 1604 1605 If unsure say Y here. 1606 1607config FHANDLE 1608 bool "open by fhandle syscalls" if EXPERT 1609 select EXPORTFS 1610 default y 1611 help 1612 If you say Y here, a user level program will be able to map 1613 file names to handle and then later use the handle for 1614 different file system operations. This is useful in implementing 1615 userspace file servers, which now track files using handles instead 1616 of names. The handle would remain the same even if file names 1617 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1618 syscalls. 1619 1620config POSIX_TIMERS 1621 bool "Posix Clocks & timers" if EXPERT 1622 default y 1623 help 1624 This includes native support for POSIX timers to the kernel. 1625 Some embedded systems have no use for them and therefore they 1626 can be configured out to reduce the size of the kernel image. 1627 1628 When this option is disabled, the following syscalls won't be 1629 available: timer_create, timer_gettime: timer_getoverrun, 1630 timer_settime, timer_delete, clock_adjtime, getitimer, 1631 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1632 clock_getres and clock_nanosleep syscalls will be limited to 1633 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1634 1635 If unsure say y. 1636 1637config PRINTK 1638 default y 1639 bool "Enable support for printk" if EXPERT 1640 select IRQ_WORK 1641 help 1642 This option enables normal printk support. Removing it 1643 eliminates most of the message strings from the kernel image 1644 and makes the kernel more or less silent. As this makes it 1645 very difficult to diagnose system problems, saying N here is 1646 strongly discouraged. 1647 1648config BUG 1649 bool "BUG() support" if EXPERT 1650 default y 1651 help 1652 Disabling this option eliminates support for BUG and WARN, reducing 1653 the size of your kernel image and potentially quietly ignoring 1654 numerous fatal conditions. You should only consider disabling this 1655 option for embedded systems with no facilities for reporting errors. 1656 Just say Y. 1657 1658config ELF_CORE 1659 depends on COREDUMP 1660 default y 1661 bool "Enable ELF core dumps" if EXPERT 1662 help 1663 Enable support for generating core dumps. Disabling saves about 4k. 1664 1665 1666config PCSPKR_PLATFORM 1667 bool "Enable PC-Speaker support" if EXPERT 1668 depends on HAVE_PCSPKR_PLATFORM 1669 select I8253_LOCK 1670 default y 1671 help 1672 This option allows to disable the internal PC-Speaker 1673 support, saving some memory. 1674 1675config BASE_SMALL 1676 bool "Enable smaller-sized data structures for core" if EXPERT 1677 help 1678 Enabling this option reduces the size of miscellaneous core 1679 kernel data structures. This saves memory on small machines, 1680 but may reduce performance. 1681 1682config FUTEX 1683 bool "Enable futex support" if EXPERT 1684 depends on !(SPARC32 && SMP) 1685 default y 1686 imply RT_MUTEXES 1687 help 1688 Disabling this option will cause the kernel to be built without 1689 support for "fast userspace mutexes". The resulting kernel may not 1690 run glibc-based applications correctly. 1691 1692config FUTEX_PI 1693 bool 1694 depends on FUTEX && RT_MUTEXES 1695 default y 1696 1697config EPOLL 1698 bool "Enable eventpoll support" if EXPERT 1699 default y 1700 help 1701 Disabling this option will cause the kernel to be built without 1702 support for epoll family of system calls. 1703 1704config SIGNALFD 1705 bool "Enable signalfd() system call" if EXPERT 1706 default y 1707 help 1708 Enable the signalfd() system call that allows to receive signals 1709 on a file descriptor. 1710 1711 If unsure, say Y. 1712 1713config TIMERFD 1714 bool "Enable timerfd() system call" if EXPERT 1715 default y 1716 help 1717 Enable the timerfd() system call that allows to receive timer 1718 events on a file descriptor. 1719 1720 If unsure, say Y. 1721 1722config EVENTFD 1723 bool "Enable eventfd() system call" if EXPERT 1724 default y 1725 help 1726 Enable the eventfd() system call that allows to receive both 1727 kernel notification (ie. KAIO) or userspace notifications. 1728 1729 If unsure, say Y. 1730 1731config SHMEM 1732 bool "Use full shmem filesystem" if EXPERT 1733 default y 1734 depends on MMU 1735 help 1736 The shmem is an internal filesystem used to manage shared memory. 1737 It is backed by swap and manages resource limits. It is also exported 1738 to userspace as tmpfs if TMPFS is enabled. Disabling this 1739 option replaces shmem and tmpfs with the much simpler ramfs code, 1740 which may be appropriate on small systems without swap. 1741 1742config AIO 1743 bool "Enable AIO support" if EXPERT 1744 default y 1745 help 1746 This option enables POSIX asynchronous I/O which may by used 1747 by some high performance threaded applications. Disabling 1748 this option saves about 7k. 1749 1750config IO_URING 1751 bool "Enable IO uring support" if EXPERT 1752 select IO_WQ 1753 default y 1754 help 1755 This option enables support for the io_uring interface, enabling 1756 applications to submit and complete IO through submission and 1757 completion rings that are shared between the kernel and application. 1758 1759config GCOV_PROFILE_URING 1760 bool "Enable GCOV profiling on the io_uring subsystem" 1761 depends on GCOV_KERNEL 1762 help 1763 Enable GCOV profiling on the io_uring subsystem, to facilitate 1764 code coverage testing. 1765 1766 If unsure, say N. 1767 1768 Note that this will have a negative impact on the performance of 1769 the io_uring subsystem, hence this should only be enabled for 1770 specific test purposes. 1771 1772config ADVISE_SYSCALLS 1773 bool "Enable madvise/fadvise syscalls" if EXPERT 1774 default y 1775 help 1776 This option enables the madvise and fadvise syscalls, used by 1777 applications to advise the kernel about their future memory or file 1778 usage, improving performance. If building an embedded system where no 1779 applications use these syscalls, you can disable this option to save 1780 space. 1781 1782config MEMBARRIER 1783 bool "Enable membarrier() system call" if EXPERT 1784 default y 1785 help 1786 Enable the membarrier() system call that allows issuing memory 1787 barriers across all running threads, which can be used to distribute 1788 the cost of user-space memory barriers asymmetrically by transforming 1789 pairs of memory barriers into pairs consisting of membarrier() and a 1790 compiler barrier. 1791 1792 If unsure, say Y. 1793 1794config KCMP 1795 bool "Enable kcmp() system call" if EXPERT 1796 help 1797 Enable the kernel resource comparison system call. It provides 1798 user-space with the ability to compare two processes to see if they 1799 share a common resource, such as a file descriptor or even virtual 1800 memory space. 1801 1802 If unsure, say N. 1803 1804config RSEQ 1805 bool "Enable rseq() system call" if EXPERT 1806 default y 1807 depends on HAVE_RSEQ 1808 select MEMBARRIER 1809 help 1810 Enable the restartable sequences system call. It provides a 1811 user-space cache for the current CPU number value, which 1812 speeds up getting the current CPU number from user-space, 1813 as well as an ABI to speed up user-space operations on 1814 per-CPU data. 1815 1816 If unsure, say Y. 1817 1818config DEBUG_RSEQ 1819 default n 1820 bool "Enable debugging of rseq() system call" if EXPERT 1821 depends on RSEQ && DEBUG_KERNEL 1822 help 1823 Enable extra debugging checks for the rseq system call. 1824 1825 If unsure, say N. 1826 1827config CACHESTAT_SYSCALL 1828 bool "Enable cachestat() system call" if EXPERT 1829 default y 1830 help 1831 Enable the cachestat system call, which queries the page cache 1832 statistics of a file (number of cached pages, dirty pages, 1833 pages marked for writeback, (recently) evicted pages). 1834 1835 If unsure say Y here. 1836 1837config PC104 1838 bool "PC/104 support" if EXPERT 1839 help 1840 Expose PC/104 form factor device drivers and options available for 1841 selection and configuration. Enable this option if your target 1842 machine has a PC/104 bus. 1843 1844config KALLSYMS 1845 bool "Load all symbols for debugging/ksymoops" if EXPERT 1846 default y 1847 help 1848 Say Y here to let the kernel print out symbolic crash information and 1849 symbolic stack backtraces. This increases the size of the kernel 1850 somewhat, as all symbols have to be loaded into the kernel image. 1851 1852config KALLSYMS_SELFTEST 1853 bool "Test the basic functions and performance of kallsyms" 1854 depends on KALLSYMS 1855 default n 1856 help 1857 Test the basic functions and performance of some interfaces, such as 1858 kallsyms_lookup_name. It also calculates the compression rate of the 1859 kallsyms compression algorithm for the current symbol set. 1860 1861 Start self-test automatically after system startup. Suggest executing 1862 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 1863 displayed in the last line, indicating that the test is complete. 1864 1865config KALLSYMS_ALL 1866 bool "Include all symbols in kallsyms" 1867 depends on DEBUG_KERNEL && KALLSYMS 1868 help 1869 Normally kallsyms only contains the symbols of functions for nicer 1870 OOPS messages and backtraces (i.e., symbols from the text and inittext 1871 sections). This is sufficient for most cases. And only if you want to 1872 enable kernel live patching, or other less common use cases (e.g., 1873 when a debugger is used) all symbols are required (i.e., names of 1874 variables from the data sections, etc). 1875 1876 This option makes sure that all symbols are loaded into the kernel 1877 image (i.e., symbols from all sections) in cost of increased kernel 1878 size (depending on the kernel configuration, it may be 300KiB or 1879 something like this). 1880 1881 Say N unless you really need all symbols, or kernel live patching. 1882 1883# end of the "standard kernel features (expert users)" menu 1884 1885config ARCH_HAS_MEMBARRIER_CALLBACKS 1886 bool 1887 1888config ARCH_HAS_MEMBARRIER_SYNC_CORE 1889 bool 1890 1891config HAVE_PERF_EVENTS 1892 bool 1893 help 1894 See tools/perf/design.txt for details. 1895 1896config GUEST_PERF_EVENTS 1897 bool 1898 depends on HAVE_PERF_EVENTS 1899 1900config PERF_USE_VMALLOC 1901 bool 1902 help 1903 See tools/perf/design.txt for details 1904 1905menu "Kernel Performance Events And Counters" 1906 1907config PERF_EVENTS 1908 bool "Kernel performance events and counters" 1909 default y if PROFILING 1910 depends on HAVE_PERF_EVENTS 1911 select IRQ_WORK 1912 help 1913 Enable kernel support for various performance events provided 1914 by software and hardware. 1915 1916 Software events are supported either built-in or via the 1917 use of generic tracepoints. 1918 1919 Most modern CPUs support performance events via performance 1920 counter registers. These registers count the number of certain 1921 types of hw events: such as instructions executed, cachemisses 1922 suffered, or branches mis-predicted - without slowing down the 1923 kernel or applications. These registers can also trigger interrupts 1924 when a threshold number of events have passed - and can thus be 1925 used to profile the code that runs on that CPU. 1926 1927 The Linux Performance Event subsystem provides an abstraction of 1928 these software and hardware event capabilities, available via a 1929 system call and used by the "perf" utility in tools/perf/. It 1930 provides per task and per CPU counters, and it provides event 1931 capabilities on top of those. 1932 1933 Say Y if unsure. 1934 1935config DEBUG_PERF_USE_VMALLOC 1936 default n 1937 bool "Debug: use vmalloc to back perf mmap() buffers" 1938 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 1939 select PERF_USE_VMALLOC 1940 help 1941 Use vmalloc memory to back perf mmap() buffers. 1942 1943 Mostly useful for debugging the vmalloc code on platforms 1944 that don't require it. 1945 1946 Say N if unsure. 1947 1948endmenu 1949 1950config SYSTEM_DATA_VERIFICATION 1951 def_bool n 1952 select SYSTEM_TRUSTED_KEYRING 1953 select KEYS 1954 select CRYPTO 1955 select CRYPTO_RSA 1956 select ASYMMETRIC_KEY_TYPE 1957 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1958 select ASN1 1959 select OID_REGISTRY 1960 select X509_CERTIFICATE_PARSER 1961 select PKCS7_MESSAGE_PARSER 1962 help 1963 Provide PKCS#7 message verification using the contents of the system 1964 trusted keyring to provide public keys. This then can be used for 1965 module verification, kexec image verification and firmware blob 1966 verification. 1967 1968config PROFILING 1969 bool "Profiling support" 1970 help 1971 Say Y here to enable the extended profiling support mechanisms used 1972 by profilers. 1973 1974config RUST 1975 bool "Rust support" 1976 depends on HAVE_RUST 1977 depends on RUST_IS_AVAILABLE 1978 select EXTENDED_MODVERSIONS if MODVERSIONS 1979 depends on !MODVERSIONS || GENDWARFKSYMS 1980 depends on !GCC_PLUGIN_RANDSTRUCT 1981 depends on !RANDSTRUCT 1982 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 1983 depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 1984 select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG 1985 depends on !CALL_PADDING || RUSTC_VERSION >= 108100 1986 depends on !KASAN_SW_TAGS 1987 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300 1988 help 1989 Enables Rust support in the kernel. 1990 1991 This allows other Rust-related options, like drivers written in Rust, 1992 to be selected. 1993 1994 It is also required to be able to load external kernel modules 1995 written in Rust. 1996 1997 See Documentation/rust/ for more information. 1998 1999 If unsure, say N. 2000 2001config RUSTC_VERSION_TEXT 2002 string 2003 depends on RUST 2004 default "$(RUSTC_VERSION_TEXT)" 2005 help 2006 See `CC_VERSION_TEXT`. 2007 2008config BINDGEN_VERSION_TEXT 2009 string 2010 depends on RUST 2011 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0 2012 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0 2013 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed 2014 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1 2015 # both fixed the issue). 2016 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)" 2017 2018# 2019# Place an empty function call at each tracepoint site. Can be 2020# dynamically changed for a probe function. 2021# 2022config TRACEPOINTS 2023 bool 2024 select TASKS_TRACE_RCU 2025 2026source "kernel/Kconfig.kexec" 2027 2028endmenu # General setup 2029 2030source "arch/Kconfig" 2031 2032config RT_MUTEXES 2033 bool 2034 default y if PREEMPT_RT 2035 2036config MODULE_SIG_FORMAT 2037 def_bool n 2038 select SYSTEM_DATA_VERIFICATION 2039 2040source "kernel/module/Kconfig" 2041 2042config INIT_ALL_POSSIBLE 2043 bool 2044 help 2045 Back when each arch used to define their own cpu_online_mask and 2046 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2047 with all 1s, and others with all 0s. When they were centralised, 2048 it was better to provide this option than to break all the archs 2049 and have several arch maintainers pursuing me down dark alleys. 2050 2051source "block/Kconfig" 2052 2053config PREEMPT_NOTIFIERS 2054 bool 2055 2056config PADATA 2057 depends on SMP 2058 bool 2059 2060config ASN1 2061 tristate 2062 help 2063 Build a simple ASN.1 grammar compiler that produces a bytecode output 2064 that can be interpreted by the ASN.1 stream decoder and used to 2065 inform it as to what tags are to be expected in a stream and what 2066 functions to call on what tags. 2067 2068source "kernel/Kconfig.locks" 2069 2070config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2071 bool 2072 2073config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2074 bool 2075 2076config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2077 bool 2078 2079# It may be useful for an architecture to override the definitions of the 2080# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2081# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2082# different calling convention for syscalls. They can also override the 2083# macros for not-implemented syscalls in kernel/sys_ni.c and 2084# kernel/time/posix-stubs.c. All these overrides need to be available in 2085# <asm/syscall_wrapper.h>. 2086config ARCH_HAS_SYSCALL_WRAPPER 2087 def_bool n 2088