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 LD_CAN_USE_KEEP_IN_OVERLAY 133 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 134 # https://github.com/llvm/llvm-project/pull/130661 135 def_bool LD_IS_BFD || LLD_VERSION >= 210000 136 137config RUSTC_HAS_COERCE_POINTEE 138 def_bool RUSTC_VERSION >= 108400 139 140config PAHOLE_VERSION 141 int 142 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) 143 144config CONSTRUCTORS 145 bool 146 147config IRQ_WORK 148 def_bool y if SMP 149 150config BUILDTIME_TABLE_SORT 151 bool 152 153config THREAD_INFO_IN_TASK 154 bool 155 help 156 Select this to move thread_info off the stack into task_struct. To 157 make this work, an arch will need to remove all thread_info fields 158 except flags and fix any runtime bugs. 159 160 One subtle change that will be needed is to use try_get_task_stack() 161 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 162 163menu "General setup" 164 165config BROKEN 166 bool 167 168config BROKEN_ON_SMP 169 bool 170 depends on BROKEN || !SMP 171 default y 172 173config INIT_ENV_ARG_LIMIT 174 int 175 default 32 if !UML 176 default 128 if UML 177 help 178 Maximum of each of the number of arguments and environment 179 variables passed to init from the kernel command line. 180 181config COMPILE_TEST 182 bool "Compile also drivers which will not load" 183 depends on HAS_IOMEM 184 help 185 Some drivers can be compiled on a different platform than they are 186 intended to be run on. Despite they cannot be loaded there (or even 187 when they load they cannot be used due to missing HW support), 188 developers still, opposing to distributors, might want to build such 189 drivers to compile-test them. 190 191 If you are a developer and want to build everything available, say Y 192 here. If you are a user/distributor, say N here to exclude useless 193 drivers to be distributed. 194 195config WERROR 196 bool "Compile the kernel with warnings as errors" 197 default COMPILE_TEST 198 help 199 A kernel build should not cause any compiler warnings, and this 200 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 201 to enforce that rule by default. Certain warnings from other tools 202 such as the linker may be upgraded to errors with this option as 203 well. 204 205 However, if you have a new (or very old) compiler or linker with odd 206 and unusual warnings, or you have some architecture with problems, 207 you may need to disable this config option in order to 208 successfully build the kernel. 209 210 If in doubt, say Y. 211 212config UAPI_HEADER_TEST 213 bool "Compile test UAPI headers" 214 depends on HEADERS_INSTALL && CC_CAN_LINK 215 help 216 Compile test headers exported to user-space to ensure they are 217 self-contained, i.e. compilable as standalone units. 218 219 If you are a developer or tester and want to ensure the exported 220 headers are self-contained, say Y here. Otherwise, choose N. 221 222config LOCALVERSION 223 string "Local version - append to kernel release" 224 help 225 Append an extra string to the end of your kernel version. 226 This will show up when you type uname, for example. 227 The string you set here will be appended after the contents of 228 any files with a filename matching localversion* in your 229 object and source tree, in that order. Your total string can 230 be a maximum of 64 characters. 231 232config LOCALVERSION_AUTO 233 bool "Automatically append version information to the version string" 234 default y 235 depends on !COMPILE_TEST 236 help 237 This will try to automatically determine if the current tree is a 238 release tree by looking for git tags that belong to the current 239 top of tree revision. 240 241 A string of the format -gxxxxxxxx will be added to the localversion 242 if a git-based tree is found. The string generated by this will be 243 appended after any matching localversion* files, and after the value 244 set in CONFIG_LOCALVERSION. 245 246 (The actual string used here is the first 12 characters produced 247 by running the command: 248 249 $ git rev-parse --verify HEAD 250 251 which is done within the script "scripts/setlocalversion".) 252 253config BUILD_SALT 254 string "Build ID Salt" 255 default "" 256 help 257 The build ID is used to link binaries and their debug info. Setting 258 this option will use the value in the calculation of the build id. 259 This is mostly useful for distributions which want to ensure the 260 build is unique between builds. It's safe to leave the default. 261 262config HAVE_KERNEL_GZIP 263 bool 264 265config HAVE_KERNEL_BZIP2 266 bool 267 268config HAVE_KERNEL_LZMA 269 bool 270 271config HAVE_KERNEL_XZ 272 bool 273 274config HAVE_KERNEL_LZO 275 bool 276 277config HAVE_KERNEL_LZ4 278 bool 279 280config HAVE_KERNEL_ZSTD 281 bool 282 283config HAVE_KERNEL_UNCOMPRESSED 284 bool 285 286choice 287 prompt "Kernel compression mode" 288 default KERNEL_GZIP 289 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 290 help 291 The linux kernel is a kind of self-extracting executable. 292 Several compression algorithms are available, which differ 293 in efficiency, compression and decompression speed. 294 Compression speed is only relevant when building a kernel. 295 Decompression speed is relevant at each boot. 296 297 If you have any problems with bzip2 or lzma compressed 298 kernels, mail me (Alain Knaff) <[email protected]>. (An older 299 version of this functionality (bzip2 only), for 2.4, was 300 supplied by Christian Ludwig) 301 302 High compression options are mostly useful for users, who 303 are low on disk space (embedded systems), but for whom ram 304 size matters less. 305 306 If in doubt, select 'gzip' 307 308config KERNEL_GZIP 309 bool "Gzip" 310 depends on HAVE_KERNEL_GZIP 311 help 312 The old and tried gzip compression. It provides a good balance 313 between compression ratio and decompression speed. 314 315config KERNEL_BZIP2 316 bool "Bzip2" 317 depends on HAVE_KERNEL_BZIP2 318 help 319 Its compression ratio and speed is intermediate. 320 Decompression speed is slowest among the choices. The kernel 321 size is about 10% smaller with bzip2, in comparison to gzip. 322 Bzip2 uses a large amount of memory. For modern kernels you 323 will need at least 8MB RAM or more for booting. 324 325config KERNEL_LZMA 326 bool "LZMA" 327 depends on HAVE_KERNEL_LZMA 328 help 329 This compression algorithm's ratio is best. Decompression speed 330 is between gzip and bzip2. Compression is slowest. 331 The kernel size is about 33% smaller with LZMA in comparison to gzip. 332 333config KERNEL_XZ 334 bool "XZ" 335 depends on HAVE_KERNEL_XZ 336 help 337 XZ uses the LZMA2 algorithm and instruction set specific 338 BCJ filters which can improve compression ratio of executable 339 code. The size of the kernel is about 30% smaller with XZ in 340 comparison to gzip. On architectures for which there is a BCJ 341 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 342 and SPARC), XZ will create a few percent smaller kernel than 343 plain LZMA. 344 345 The speed is about the same as with LZMA: The decompression 346 speed of XZ is better than that of bzip2 but worse than gzip 347 and LZO. Compression is slow. 348 349config KERNEL_LZO 350 bool "LZO" 351 depends on HAVE_KERNEL_LZO 352 help 353 Its compression ratio is the poorest among the choices. The kernel 354 size is about 10% bigger than gzip; however its speed 355 (both compression and decompression) is the fastest. 356 357config KERNEL_LZ4 358 bool "LZ4" 359 depends on HAVE_KERNEL_LZ4 360 help 361 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 362 A preliminary version of LZ4 de/compression tool is available at 363 <https://code.google.com/p/lz4/>. 364 365 Its compression ratio is worse than LZO. The size of the kernel 366 is about 8% bigger than LZO. But the decompression speed is 367 faster than LZO. 368 369config KERNEL_ZSTD 370 bool "ZSTD" 371 depends on HAVE_KERNEL_ZSTD 372 help 373 ZSTD is a compression algorithm targeting intermediate compression 374 with fast decompression speed. It will compress better than GZIP and 375 decompress around the same speed as LZO, but slower than LZ4. You 376 will need at least 192 KB RAM or more for booting. The zstd command 377 line tool is required for compression. 378 379config KERNEL_UNCOMPRESSED 380 bool "None" 381 depends on HAVE_KERNEL_UNCOMPRESSED 382 help 383 Produce uncompressed kernel image. This option is usually not what 384 you want. It is useful for debugging the kernel in slow simulation 385 environments, where decompressing and moving the kernel is awfully 386 slow. This option allows early boot code to skip the decompressor 387 and jump right at uncompressed kernel image. 388 389endchoice 390 391config DEFAULT_INIT 392 string "Default init path" 393 default "" 394 help 395 This option determines the default init for the system if no init= 396 option is passed on the kernel command line. If the requested path is 397 not present, we will still then move on to attempting further 398 locations (e.g. /sbin/init, etc). If this is empty, we will just use 399 the fallback list when init= is not passed. 400 401config DEFAULT_HOSTNAME 402 string "Default hostname" 403 default "(none)" 404 help 405 This option determines the default system hostname before userspace 406 calls sethostname(2). The kernel traditionally uses "(none)" here, 407 but you may wish to use a different default here to make a minimal 408 system more usable with less configuration. 409 410config SYSVIPC 411 bool "System V IPC" 412 help 413 Inter Process Communication is a suite of library functions and 414 system calls which let processes (running programs) synchronize and 415 exchange information. It is generally considered to be a good thing, 416 and some programs won't run unless you say Y here. In particular, if 417 you want to run the DOS emulator dosemu under Linux (read the 418 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 419 you'll need to say Y here. 420 421 You can find documentation about IPC with "info ipc" and also in 422 section 6.4 of the Linux Programmer's Guide, available from 423 <http://www.tldp.org/guides.html>. 424 425config SYSVIPC_SYSCTL 426 bool 427 depends on SYSVIPC 428 depends on SYSCTL 429 default y 430 431config SYSVIPC_COMPAT 432 def_bool y 433 depends on COMPAT && SYSVIPC 434 435config POSIX_MQUEUE 436 bool "POSIX Message Queues" 437 depends on NET 438 help 439 POSIX variant of message queues is a part of IPC. In POSIX message 440 queues every message has a priority which decides about succession 441 of receiving it by a process. If you want to compile and run 442 programs written e.g. for Solaris with use of its POSIX message 443 queues (functions mq_*) say Y here. 444 445 POSIX message queues are visible as a filesystem called 'mqueue' 446 and can be mounted somewhere if you want to do filesystem 447 operations on message queues. 448 449 If unsure, say Y. 450 451config POSIX_MQUEUE_SYSCTL 452 bool 453 depends on POSIX_MQUEUE 454 depends on SYSCTL 455 default y 456 457config WATCH_QUEUE 458 bool "General notification queue" 459 default n 460 help 461 462 This is a general notification queue for the kernel to pass events to 463 userspace by splicing them into pipes. It can be used in conjunction 464 with watches for key/keyring change notifications and device 465 notifications. 466 467 See Documentation/core-api/watch_queue.rst 468 469config CROSS_MEMORY_ATTACH 470 bool "Enable process_vm_readv/writev syscalls" 471 depends on MMU 472 default y 473 help 474 Enabling this option adds the system calls process_vm_readv and 475 process_vm_writev which allow a process with the correct privileges 476 to directly read from or write to another process' address space. 477 See the man page for more details. 478 479config USELIB 480 bool "uselib syscall (for libc5 and earlier)" 481 default ALPHA || M68K || SPARC 482 help 483 This option enables the uselib syscall, a system call used in the 484 dynamic linker from libc5 and earlier. glibc does not use this 485 system call. If you intend to run programs built on libc5 or 486 earlier, you may need to enable this syscall. Current systems 487 running glibc can safely disable this. 488 489config AUDIT 490 bool "Auditing support" 491 depends on NET 492 help 493 Enable auditing infrastructure that can be used with another 494 kernel subsystem, such as SELinux (which requires this for 495 logging of avc messages output). System call auditing is included 496 on architectures which support it. 497 498config HAVE_ARCH_AUDITSYSCALL 499 bool 500 501config AUDITSYSCALL 502 def_bool y 503 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 504 select FSNOTIFY 505 506source "kernel/irq/Kconfig" 507source "kernel/time/Kconfig" 508source "kernel/bpf/Kconfig" 509source "kernel/Kconfig.preempt" 510 511menu "CPU/Task time and stats accounting" 512 513config VIRT_CPU_ACCOUNTING 514 bool 515 516choice 517 prompt "Cputime accounting" 518 default TICK_CPU_ACCOUNTING 519 520# Kind of a stub config for the pure tick based cputime accounting 521config TICK_CPU_ACCOUNTING 522 bool "Simple tick based cputime accounting" 523 depends on !S390 && !NO_HZ_FULL 524 help 525 This is the basic tick based cputime accounting that maintains 526 statistics about user, system and idle time spent on per jiffies 527 granularity. 528 529 If unsure, say Y. 530 531config VIRT_CPU_ACCOUNTING_NATIVE 532 bool "Deterministic task and CPU time accounting" 533 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 534 select VIRT_CPU_ACCOUNTING 535 help 536 Select this option to enable more accurate task and CPU time 537 accounting. This is done by reading a CPU counter on each 538 kernel entry and exit and on transitions within the kernel 539 between system, softirq and hardirq state, so there is a 540 small performance impact. In the case of s390 or IBM POWER > 5, 541 this also enables accounting of stolen time on logically-partitioned 542 systems. 543 544config VIRT_CPU_ACCOUNTING_GEN 545 bool "Full dynticks CPU time accounting" 546 depends on HAVE_CONTEXT_TRACKING_USER 547 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 548 depends on GENERIC_CLOCKEVENTS 549 select VIRT_CPU_ACCOUNTING 550 select CONTEXT_TRACKING_USER 551 help 552 Select this option to enable task and CPU time accounting on full 553 dynticks systems. This accounting is implemented by watching every 554 kernel-user boundaries using the context tracking subsystem. 555 The accounting is thus performed at the expense of some significant 556 overhead. 557 558 For now this is only useful if you are working on the full 559 dynticks subsystem development. 560 561 If unsure, say N. 562 563endchoice 564 565config IRQ_TIME_ACCOUNTING 566 bool "Fine granularity task level IRQ time accounting" 567 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 568 help 569 Select this option to enable fine granularity task irq time 570 accounting. This is done by reading a timestamp on each 571 transitions between softirq and hardirq state, so there can be a 572 small performance impact. 573 574 If in doubt, say N here. 575 576config HAVE_SCHED_AVG_IRQ 577 def_bool y 578 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 579 depends on SMP 580 581config SCHED_HW_PRESSURE 582 bool 583 default y if ARM && ARM_CPU_TOPOLOGY 584 default y if ARM64 585 depends on SMP 586 depends on CPU_FREQ_THERMAL 587 help 588 Select this option to enable HW pressure accounting in the 589 scheduler. HW pressure is the value conveyed to the scheduler 590 that reflects the reduction in CPU compute capacity resulted from 591 HW throttling. HW throttling occurs when the performance of 592 a CPU is capped due to high operating temperatures as an example. 593 594 If selected, the scheduler will be able to balance tasks accordingly, 595 i.e. put less load on throttled CPUs than on non/less throttled ones. 596 597 This requires the architecture to implement 598 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 599 600config BSD_PROCESS_ACCT 601 bool "BSD Process Accounting" 602 depends on MULTIUSER 603 help 604 If you say Y here, a user level program will be able to instruct the 605 kernel (via a special system call) to write process accounting 606 information to a file: whenever a process exits, information about 607 that process will be appended to the file by the kernel. The 608 information includes things such as creation time, owning user, 609 command name, memory usage, controlling terminal etc. (the complete 610 list is in the struct acct in <file:include/linux/acct.h>). It is 611 up to the user level program to do useful things with this 612 information. This is generally a good idea, so say Y. 613 614config BSD_PROCESS_ACCT_V3 615 bool "BSD Process Accounting version 3 file format" 616 depends on BSD_PROCESS_ACCT 617 default n 618 help 619 If you say Y here, the process accounting information is written 620 in a new file format that also logs the process IDs of each 621 process and its parent. Note that this file format is incompatible 622 with previous v0/v1/v2 file formats, so you will need updated tools 623 for processing it. A preliminary version of these tools is available 624 at <http://www.gnu.org/software/acct/>. 625 626config TASKSTATS 627 bool "Export task/process statistics through netlink" 628 depends on NET 629 depends on MULTIUSER 630 default n 631 help 632 Export selected statistics for tasks/processes through the 633 generic netlink interface. Unlike BSD process accounting, the 634 statistics are available during the lifetime of tasks/processes as 635 responses to commands. Like BSD accounting, they are sent to user 636 space on task exit. 637 638 Say N if unsure. 639 640config TASK_DELAY_ACCT 641 bool "Enable per-task delay accounting" 642 depends on TASKSTATS 643 select SCHED_INFO 644 help 645 Collect information on time spent by a task waiting for system 646 resources like cpu, synchronous block I/O completion and swapping 647 in pages. Such statistics can help in setting a task's priorities 648 relative to other tasks for cpu, io, rss limits etc. 649 650 Say N if unsure. 651 652config TASK_XACCT 653 bool "Enable extended accounting over taskstats" 654 depends on TASKSTATS 655 help 656 Collect extended task accounting data and send the data 657 to userland for processing over the taskstats interface. 658 659 Say N if unsure. 660 661config TASK_IO_ACCOUNTING 662 bool "Enable per-task storage I/O accounting" 663 depends on TASK_XACCT 664 help 665 Collect information on the number of bytes of storage I/O which this 666 task has caused. 667 668 Say N if unsure. 669 670config PSI 671 bool "Pressure stall information tracking" 672 select KERNFS 673 help 674 Collect metrics that indicate how overcommitted the CPU, memory, 675 and IO capacity are in the system. 676 677 If you say Y here, the kernel will create /proc/pressure/ with the 678 pressure statistics files cpu, memory, and io. These will indicate 679 the share of walltime in which some or all tasks in the system are 680 delayed due to contention of the respective resource. 681 682 In kernels with cgroup support, cgroups (cgroup2 only) will 683 have cpu.pressure, memory.pressure, and io.pressure files, 684 which aggregate pressure stalls for the grouped tasks only. 685 686 For more details see Documentation/accounting/psi.rst. 687 688 Say N if unsure. 689 690config PSI_DEFAULT_DISABLED 691 bool "Require boot parameter to enable pressure stall information tracking" 692 default n 693 depends on PSI 694 help 695 If set, pressure stall information tracking will be disabled 696 per default but can be enabled through passing psi=1 on the 697 kernel commandline during boot. 698 699 This feature adds some code to the task wakeup and sleep 700 paths of the scheduler. The overhead is too low to affect 701 common scheduling-intense workloads in practice (such as 702 webservers, memcache), but it does show up in artificial 703 scheduler stress tests, such as hackbench. 704 705 If you are paranoid and not sure what the kernel will be 706 used for, say Y. 707 708 Say N if unsure. 709 710endmenu # "CPU/Task time and stats accounting" 711 712config CPU_ISOLATION 713 bool "CPU isolation" 714 depends on SMP || COMPILE_TEST 715 default y 716 help 717 Make sure that CPUs running critical tasks are not disturbed by 718 any source of "noise" such as unbound workqueues, timers, kthreads... 719 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 720 the "isolcpus=" boot parameter. 721 722 Say Y if unsure. 723 724source "kernel/rcu/Kconfig" 725 726config IKCONFIG 727 tristate "Kernel .config support" 728 help 729 This option enables the complete Linux kernel ".config" file 730 contents to be saved in the kernel. It provides documentation 731 of which kernel options are used in a running kernel or in an 732 on-disk kernel. This information can be extracted from the kernel 733 image file with the script scripts/extract-ikconfig and used as 734 input to rebuild the current kernel or to build another kernel. 735 It can also be extracted from a running kernel by reading 736 /proc/config.gz if enabled (below). 737 738config IKCONFIG_PROC 739 bool "Enable access to .config through /proc/config.gz" 740 depends on IKCONFIG && PROC_FS 741 help 742 This option enables access to the kernel configuration file 743 through /proc/config.gz. 744 745config IKHEADERS 746 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 747 depends on SYSFS 748 help 749 This option enables access to the in-kernel headers that are generated during 750 the build process. These can be used to build eBPF tracing programs, 751 or similar programs. If you build the headers as a module, a module called 752 kheaders.ko is built which can be loaded on-demand to get access to headers. 753 754config LOG_BUF_SHIFT 755 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 756 range 12 25 757 default 17 758 depends on PRINTK 759 help 760 Select the minimal kernel log buffer size as a power of 2. 761 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 762 parameter, see below. Any higher size also might be forced 763 by "log_buf_len" boot parameter. 764 765 Examples: 766 17 => 128 KB 767 16 => 64 KB 768 15 => 32 KB 769 14 => 16 KB 770 13 => 8 KB 771 12 => 4 KB 772 773config LOG_CPU_MAX_BUF_SHIFT 774 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 775 depends on SMP 776 range 0 21 777 default 0 if BASE_SMALL 778 default 12 779 depends on PRINTK 780 help 781 This option allows to increase the default ring buffer size 782 according to the number of CPUs. The value defines the contribution 783 of each CPU as a power of 2. The used space is typically only few 784 lines however it might be much more when problems are reported, 785 e.g. backtraces. 786 787 The increased size means that a new buffer has to be allocated and 788 the original static one is unused. It makes sense only on systems 789 with more CPUs. Therefore this value is used only when the sum of 790 contributions is greater than the half of the default kernel ring 791 buffer as defined by LOG_BUF_SHIFT. The default values are set 792 so that more than 16 CPUs are needed to trigger the allocation. 793 794 Also this option is ignored when "log_buf_len" kernel parameter is 795 used as it forces an exact (power of two) size of the ring buffer. 796 797 The number of possible CPUs is used for this computation ignoring 798 hotplugging making the computation optimal for the worst case 799 scenario while allowing a simple algorithm to be used from bootup. 800 801 Examples shift values and their meaning: 802 17 => 128 KB for each CPU 803 16 => 64 KB for each CPU 804 15 => 32 KB for each CPU 805 14 => 16 KB for each CPU 806 13 => 8 KB for each CPU 807 12 => 4 KB for each CPU 808 809config PRINTK_INDEX 810 bool "Printk indexing debugfs interface" 811 depends on PRINTK && DEBUG_FS 812 help 813 Add support for indexing of all printk formats known at compile time 814 at <debugfs>/printk/index/<module>. 815 816 This can be used as part of maintaining daemons which monitor 817 /dev/kmsg, as it permits auditing the printk formats present in a 818 kernel, allowing detection of cases where monitored printks are 819 changed or no longer present. 820 821 There is no additional runtime cost to printk with this enabled. 822 823# 824# Architectures with an unreliable sched_clock() should select this: 825# 826config HAVE_UNSTABLE_SCHED_CLOCK 827 bool 828 829config GENERIC_SCHED_CLOCK 830 bool 831 832menu "Scheduler features" 833 834config UCLAMP_TASK 835 bool "Enable utilization clamping for RT/FAIR tasks" 836 depends on CPU_FREQ_GOV_SCHEDUTIL 837 help 838 This feature enables the scheduler to track the clamped utilization 839 of each CPU based on RUNNABLE tasks scheduled on that CPU. 840 841 With this option, the user can specify the min and max CPU 842 utilization allowed for RUNNABLE tasks. The max utilization defines 843 the maximum frequency a task should use while the min utilization 844 defines the minimum frequency it should use. 845 846 Both min and max utilization clamp values are hints to the scheduler, 847 aiming at improving its frequency selection policy, but they do not 848 enforce or grant any specific bandwidth for tasks. 849 850 If in doubt, say N. 851 852config UCLAMP_BUCKETS_COUNT 853 int "Number of supported utilization clamp buckets" 854 range 5 20 855 default 5 856 depends on UCLAMP_TASK 857 help 858 Defines the number of clamp buckets to use. The range of each bucket 859 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 860 number of clamp buckets the finer their granularity and the higher 861 the precision of clamping aggregation and tracking at run-time. 862 863 For example, with the minimum configuration value we will have 5 864 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 865 be refcounted in the [20..39]% bucket and will set the bucket clamp 866 effective value to 25%. 867 If a second 30% boosted task should be co-scheduled on the same CPU, 868 that task will be refcounted in the same bucket of the first task and 869 it will boost the bucket clamp effective value to 30%. 870 The clamp effective value of a bucket is reset to its nominal value 871 (20% in the example above) when there are no more tasks refcounted in 872 that bucket. 873 874 An additional boost/capping margin can be added to some tasks. In the 875 example above the 25% task will be boosted to 30% until it exits the 876 CPU. If that should be considered not acceptable on certain systems, 877 it's always possible to reduce the margin by increasing the number of 878 clamp buckets to trade off used memory for run-time tracking 879 precision. 880 881 If in doubt, use the default value. 882 883endmenu 884 885# 886# For architectures that want to enable the support for NUMA-affine scheduler 887# balancing logic: 888# 889config ARCH_SUPPORTS_NUMA_BALANCING 890 bool 891 892# 893# For architectures that prefer to flush all TLBs after a number of pages 894# are unmapped instead of sending one IPI per page to flush. The architecture 895# must provide guarantees on what happens if a clean TLB cache entry is 896# written after the unmap. Details are in mm/rmap.c near the check for 897# should_defer_flush. The architecture should also consider if the full flush 898# and the refill costs are offset by the savings of sending fewer IPIs. 899config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 900 bool 901 902config CC_HAS_INT128 903 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 904 905config CC_IMPLICIT_FALLTHROUGH 906 string 907 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 908 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 909 910# Currently, disable gcc-10+ array-bounds globally. 911# It's still broken in gcc-13, so no upper bound yet. 912config GCC10_NO_ARRAY_BOUNDS 913 def_bool y 914 915config CC_NO_ARRAY_BOUNDS 916 bool 917 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 918 919# Currently, disable -Wstringop-overflow for GCC globally. 920config GCC_NO_STRINGOP_OVERFLOW 921 def_bool y 922 923config CC_NO_STRINGOP_OVERFLOW 924 bool 925 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 926 927config CC_STRINGOP_OVERFLOW 928 bool 929 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 930 931# 932# For architectures that know their GCC __int128 support is sound 933# 934config ARCH_SUPPORTS_INT128 935 bool 936 937# For architectures that (ab)use NUMA to represent different memory regions 938# all cpu-local but of different latencies, such as SuperH. 939# 940config ARCH_WANT_NUMA_VARIABLE_LOCALITY 941 bool 942 943config NUMA_BALANCING 944 bool "Memory placement aware NUMA scheduler" 945 depends on ARCH_SUPPORTS_NUMA_BALANCING 946 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 947 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 948 help 949 This option adds support for automatic NUMA aware memory/task placement. 950 The mechanism is quite primitive and is based on migrating memory when 951 it has references to the node the task is running on. 952 953 This system will be inactive on UMA systems. 954 955config NUMA_BALANCING_DEFAULT_ENABLED 956 bool "Automatically enable NUMA aware memory/task placement" 957 default y 958 depends on NUMA_BALANCING 959 help 960 If set, automatic NUMA balancing will be enabled if running on a NUMA 961 machine. 962 963config SLAB_OBJ_EXT 964 bool 965 966menuconfig CGROUPS 967 bool "Control Group support" 968 select KERNFS 969 help 970 This option adds support for grouping sets of processes together, for 971 use with process control subsystems such as Cpusets, CFS, memory 972 controls or device isolation. 973 See 974 - Documentation/scheduler/sched-design-CFS.rst (CFS) 975 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 976 and resource control) 977 978 Say N if unsure. 979 980if CGROUPS 981 982config PAGE_COUNTER 983 bool 984 985config CGROUP_FAVOR_DYNMODS 986 bool "Favor dynamic modification latency reduction by default" 987 help 988 This option enables the "favordynmods" mount option by default 989 which reduces the latencies of dynamic cgroup modifications such 990 as task migrations and controller on/offs at the cost of making 991 hot path operations such as forks and exits more expensive. 992 993 Say N if unsure. 994 995config MEMCG 996 bool "Memory controller" 997 select PAGE_COUNTER 998 select EVENTFD 999 select SLAB_OBJ_EXT 1000 help 1001 Provides control over the memory footprint of tasks in a cgroup. 1002 1003config MEMCG_V1 1004 bool "Legacy cgroup v1 memory controller" 1005 depends on MEMCG 1006 default n 1007 help 1008 Legacy cgroup v1 memory controller which has been deprecated by 1009 cgroup v2 implementation. The v1 is there for legacy applications 1010 which haven't migrated to the new cgroup v2 interface yet. If you 1011 do not have any such application then you are completely fine leaving 1012 this option disabled. 1013 1014 Please note that feature set of the legacy memory controller is likely 1015 going to shrink due to deprecation process. New deployments with v1 1016 controller are highly discouraged. 1017 1018 Say N if unsure. 1019 1020config BLK_CGROUP 1021 bool "IO controller" 1022 depends on BLOCK 1023 default n 1024 help 1025 Generic block IO controller cgroup interface. This is the common 1026 cgroup interface which should be used by various IO controlling 1027 policies. 1028 1029 Currently, CFQ IO scheduler uses it to recognize task groups and 1030 control disk bandwidth allocation (proportional time slice allocation) 1031 to such task groups. It is also used by bio throttling logic in 1032 block layer to implement upper limit in IO rates on a device. 1033 1034 This option only enables generic Block IO controller infrastructure. 1035 One needs to also enable actual IO controlling logic/policy. For 1036 enabling proportional weight division of disk bandwidth in CFQ, set 1037 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1038 CONFIG_BLK_DEV_THROTTLING=y. 1039 1040 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1041 1042config CGROUP_WRITEBACK 1043 bool 1044 depends on MEMCG && BLK_CGROUP 1045 default y 1046 1047menuconfig CGROUP_SCHED 1048 bool "CPU controller" 1049 default n 1050 help 1051 This feature lets CPU scheduler recognize task groups and control CPU 1052 bandwidth allocation to such task groups. It uses cgroups to group 1053 tasks. 1054 1055if CGROUP_SCHED 1056config GROUP_SCHED_WEIGHT 1057 def_bool n 1058 1059config FAIR_GROUP_SCHED 1060 bool "Group scheduling for SCHED_OTHER" 1061 depends on CGROUP_SCHED 1062 select GROUP_SCHED_WEIGHT 1063 default CGROUP_SCHED 1064 1065config CFS_BANDWIDTH 1066 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1067 depends on FAIR_GROUP_SCHED 1068 default n 1069 help 1070 This option allows users to define CPU bandwidth rates (limits) for 1071 tasks running within the fair group scheduler. Groups with no limit 1072 set are considered to be unconstrained and will run with no 1073 restriction. 1074 See Documentation/scheduler/sched-bwc.rst for more information. 1075 1076config RT_GROUP_SCHED 1077 bool "Group scheduling for SCHED_RR/FIFO" 1078 depends on CGROUP_SCHED 1079 default n 1080 help 1081 This feature lets you explicitly allocate real CPU bandwidth 1082 to task groups. If enabled, it will also make it impossible to 1083 schedule realtime tasks for non-root users until you allocate 1084 realtime bandwidth for them. 1085 See Documentation/scheduler/sched-rt-group.rst for more information. 1086 1087config EXT_GROUP_SCHED 1088 bool 1089 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1090 select GROUP_SCHED_WEIGHT 1091 default y 1092 1093endif #CGROUP_SCHED 1094 1095config SCHED_MM_CID 1096 def_bool y 1097 depends on SMP && RSEQ 1098 1099config UCLAMP_TASK_GROUP 1100 bool "Utilization clamping per group of tasks" 1101 depends on CGROUP_SCHED 1102 depends on UCLAMP_TASK 1103 default n 1104 help 1105 This feature enables the scheduler to track the clamped utilization 1106 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1107 1108 When this option is enabled, the user can specify a min and max 1109 CPU bandwidth which is allowed for each single task in a group. 1110 The max bandwidth allows to clamp the maximum frequency a task 1111 can use, while the min bandwidth allows to define a minimum 1112 frequency a task will always use. 1113 1114 When task group based utilization clamping is enabled, an eventually 1115 specified task-specific clamp value is constrained by the cgroup 1116 specified clamp value. Both minimum and maximum task clamping cannot 1117 be bigger than the corresponding clamping defined at task group level. 1118 1119 If in doubt, say N. 1120 1121config CGROUP_PIDS 1122 bool "PIDs controller" 1123 help 1124 Provides enforcement of process number limits in the scope of a 1125 cgroup. Any attempt to fork more processes than is allowed in the 1126 cgroup will fail. PIDs are fundamentally a global resource because it 1127 is fairly trivial to reach PID exhaustion before you reach even a 1128 conservative kmemcg limit. As a result, it is possible to grind a 1129 system to halt without being limited by other cgroup policies. The 1130 PIDs controller is designed to stop this from happening. 1131 1132 It should be noted that organisational operations (such as attaching 1133 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1134 since the PIDs limit only affects a process's ability to fork, not to 1135 attach to a cgroup. 1136 1137config CGROUP_RDMA 1138 bool "RDMA controller" 1139 help 1140 Provides enforcement of RDMA resources defined by IB stack. 1141 It is fairly easy for consumers to exhaust RDMA resources, which 1142 can result into resource unavailability to other consumers. 1143 RDMA controller is designed to stop this from happening. 1144 Attaching processes with active RDMA resources to the cgroup 1145 hierarchy is allowed even if can cross the hierarchy's limit. 1146 1147config CGROUP_DMEM 1148 bool "Device memory controller (DMEM)" 1149 select PAGE_COUNTER 1150 help 1151 The DMEM controller allows compatible devices to restrict device 1152 memory usage based on the cgroup hierarchy. 1153 1154 As an example, it allows you to restrict VRAM usage for applications 1155 in the DRM subsystem. 1156 1157config CGROUP_FREEZER 1158 bool "Freezer controller" 1159 help 1160 Provides a way to freeze and unfreeze all tasks in a 1161 cgroup. 1162 1163 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1164 controller includes important in-kernel memory consumers per default. 1165 1166 If you're using cgroup2, say N. 1167 1168config CGROUP_HUGETLB 1169 bool "HugeTLB controller" 1170 depends on HUGETLB_PAGE 1171 select PAGE_COUNTER 1172 default n 1173 help 1174 Provides a cgroup controller for HugeTLB pages. 1175 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1176 The limit is enforced during page fault. Since HugeTLB doesn't 1177 support page reclaim, enforcing the limit at page fault time implies 1178 that, the application will get SIGBUS signal if it tries to access 1179 HugeTLB pages beyond its limit. This requires the application to know 1180 beforehand how much HugeTLB pages it would require for its use. The 1181 control group is tracked in the third page lru pointer. This means 1182 that we cannot use the controller with huge page less than 3 pages. 1183 1184config CPUSETS 1185 bool "Cpuset controller" 1186 depends on SMP 1187 select UNION_FIND 1188 help 1189 This option will let you create and manage CPUSETs which 1190 allow dynamically partitioning a system into sets of CPUs and 1191 Memory Nodes and assigning tasks to run only within those sets. 1192 This is primarily useful on large SMP or NUMA systems. 1193 1194 Say N if unsure. 1195 1196config CPUSETS_V1 1197 bool "Legacy cgroup v1 cpusets controller" 1198 depends on CPUSETS 1199 default n 1200 help 1201 Legacy cgroup v1 cpusets controller which has been deprecated by 1202 cgroup v2 implementation. The v1 is there for legacy applications 1203 which haven't migrated to the new cgroup v2 interface yet. If you 1204 do not have any such application then you are completely fine leaving 1205 this option disabled. 1206 1207 Say N if unsure. 1208 1209config PROC_PID_CPUSET 1210 bool "Include legacy /proc/<pid>/cpuset file" 1211 depends on CPUSETS 1212 default y 1213 1214config CGROUP_DEVICE 1215 bool "Device controller" 1216 help 1217 Provides a cgroup controller implementing whitelists for 1218 devices which a process in the cgroup can mknod or open. 1219 1220config CGROUP_CPUACCT 1221 bool "Simple CPU accounting controller" 1222 help 1223 Provides a simple controller for monitoring the 1224 total CPU consumed by the tasks in a cgroup. 1225 1226config CGROUP_PERF 1227 bool "Perf controller" 1228 depends on PERF_EVENTS 1229 help 1230 This option extends the perf per-cpu mode to restrict monitoring 1231 to threads which belong to the cgroup specified and run on the 1232 designated cpu. Or this can be used to have cgroup ID in samples 1233 so that it can monitor performance events among cgroups. 1234 1235 Say N if unsure. 1236 1237config CGROUP_BPF 1238 bool "Support for eBPF programs attached to cgroups" 1239 depends on BPF_SYSCALL 1240 select SOCK_CGROUP_DATA 1241 help 1242 Allow attaching eBPF programs to a cgroup using the bpf(2) 1243 syscall command BPF_PROG_ATTACH. 1244 1245 In which context these programs are accessed depends on the type 1246 of attachment. For instance, programs that are attached using 1247 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1248 inet sockets. 1249 1250config CGROUP_MISC 1251 bool "Misc resource controller" 1252 default n 1253 help 1254 Provides a controller for miscellaneous resources on a host. 1255 1256 Miscellaneous scalar resources are the resources on the host system 1257 which cannot be abstracted like the other cgroups. This controller 1258 tracks and limits the miscellaneous resources used by a process 1259 attached to a cgroup hierarchy. 1260 1261 For more information, please check misc cgroup section in 1262 /Documentation/admin-guide/cgroup-v2.rst. 1263 1264config CGROUP_DEBUG 1265 bool "Debug controller" 1266 default n 1267 depends on DEBUG_KERNEL 1268 help 1269 This option enables a simple controller that exports 1270 debugging information about the cgroups framework. This 1271 controller is for control cgroup debugging only. Its 1272 interfaces are not stable. 1273 1274 Say N. 1275 1276config SOCK_CGROUP_DATA 1277 bool 1278 default n 1279 1280endif # CGROUPS 1281 1282menuconfig NAMESPACES 1283 bool "Namespaces support" if EXPERT 1284 depends on MULTIUSER 1285 default !EXPERT 1286 help 1287 Provides the way to make tasks work with different objects using 1288 the same id. For example same IPC id may refer to different objects 1289 or same user id or pid may refer to different tasks when used in 1290 different namespaces. 1291 1292if NAMESPACES 1293 1294config UTS_NS 1295 bool "UTS namespace" 1296 default y 1297 help 1298 In this namespace tasks see different info provided with the 1299 uname() system call 1300 1301config TIME_NS 1302 bool "TIME namespace" 1303 depends on GENERIC_VDSO_TIME_NS 1304 default y 1305 help 1306 In this namespace boottime and monotonic clocks can be set. 1307 The time will keep going with the same pace. 1308 1309config IPC_NS 1310 bool "IPC namespace" 1311 depends on (SYSVIPC || POSIX_MQUEUE) 1312 default y 1313 help 1314 In this namespace tasks work with IPC ids which correspond to 1315 different IPC objects in different namespaces. 1316 1317config USER_NS 1318 bool "User namespace" 1319 default n 1320 help 1321 This allows containers, i.e. vservers, to use user namespaces 1322 to provide different user info for different servers. 1323 1324 When user namespaces are enabled in the kernel it is 1325 recommended that the MEMCG option also be enabled and that 1326 user-space use the memory control groups to limit the amount 1327 of memory a memory unprivileged users can use. 1328 1329 If unsure, say N. 1330 1331config PID_NS 1332 bool "PID Namespaces" 1333 default y 1334 help 1335 Support process id namespaces. This allows having multiple 1336 processes with the same pid as long as they are in different 1337 pid namespaces. This is a building block of containers. 1338 1339config NET_NS 1340 bool "Network namespace" 1341 depends on NET 1342 default y 1343 help 1344 Allow user space to create what appear to be multiple instances 1345 of the network stack. 1346 1347endif # NAMESPACES 1348 1349config CHECKPOINT_RESTORE 1350 bool "Checkpoint/restore support" 1351 depends on PROC_FS 1352 select PROC_CHILDREN 1353 select KCMP 1354 default n 1355 help 1356 Enables additional kernel features in a sake of checkpoint/restore. 1357 In particular it adds auxiliary prctl codes to setup process text, 1358 data and heap segment sizes, and a few additional /proc filesystem 1359 entries. 1360 1361 If unsure, say N here. 1362 1363config SCHED_AUTOGROUP 1364 bool "Automatic process group scheduling" 1365 select CGROUPS 1366 select CGROUP_SCHED 1367 select FAIR_GROUP_SCHED 1368 help 1369 This option optimizes the scheduler for common desktop workloads by 1370 automatically creating and populating task groups. This separation 1371 of workloads isolates aggressive CPU burners (like build jobs) from 1372 desktop applications. Task group autogeneration is currently based 1373 upon task session. 1374 1375config RELAY 1376 bool "Kernel->user space relay support (formerly relayfs)" 1377 select IRQ_WORK 1378 help 1379 This option enables support for relay interface support in 1380 certain file systems (such as debugfs). 1381 It is designed to provide an efficient mechanism for tools and 1382 facilities to relay large amounts of data from kernel space to 1383 user space. 1384 1385 If unsure, say N. 1386 1387config BLK_DEV_INITRD 1388 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1389 help 1390 The initial RAM filesystem is a ramfs which is loaded by the 1391 boot loader (loadlin or lilo) and that is mounted as root 1392 before the normal boot procedure. It is typically used to 1393 load modules needed to mount the "real" root file system, 1394 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1395 1396 If RAM disk support (BLK_DEV_RAM) is also included, this 1397 also enables initial RAM disk (initrd) support and adds 1398 15 Kbytes (more on some other architectures) to the kernel size. 1399 1400 If unsure say Y. 1401 1402if BLK_DEV_INITRD 1403 1404source "usr/Kconfig" 1405 1406endif 1407 1408config BOOT_CONFIG 1409 bool "Boot config support" 1410 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1411 help 1412 Extra boot config allows system admin to pass a config file as 1413 complemental extension of kernel cmdline when booting. 1414 The boot config file must be attached at the end of initramfs 1415 with checksum, size and magic word. 1416 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1417 1418 If unsure, say Y. 1419 1420config BOOT_CONFIG_FORCE 1421 bool "Force unconditional bootconfig processing" 1422 depends on BOOT_CONFIG 1423 default y if BOOT_CONFIG_EMBED 1424 help 1425 With this Kconfig option set, BOOT_CONFIG processing is carried 1426 out even when the "bootconfig" kernel-boot parameter is omitted. 1427 In fact, with this Kconfig option set, there is no way to 1428 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1429 parameters. 1430 1431 If unsure, say N. 1432 1433config BOOT_CONFIG_EMBED 1434 bool "Embed bootconfig file in the kernel" 1435 depends on BOOT_CONFIG 1436 help 1437 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1438 kernel. Usually, the bootconfig file is loaded with the initrd 1439 image. But if the system doesn't support initrd, this option will 1440 help you by embedding a bootconfig file while building the kernel. 1441 1442 If unsure, say N. 1443 1444config BOOT_CONFIG_EMBED_FILE 1445 string "Embedded bootconfig file path" 1446 depends on BOOT_CONFIG_EMBED 1447 help 1448 Specify a bootconfig file which will be embedded to the kernel. 1449 This bootconfig will be used if there is no initrd or no other 1450 bootconfig in the initrd. 1451 1452config INITRAMFS_PRESERVE_MTIME 1453 bool "Preserve cpio archive mtimes in initramfs" 1454 default y 1455 help 1456 Each entry in an initramfs cpio archive carries an mtime value. When 1457 enabled, extracted cpio items take this mtime, with directory mtime 1458 setting deferred until after creation of any child entries. 1459 1460 If unsure, say Y. 1461 1462choice 1463 prompt "Compiler optimization level" 1464 default CC_OPTIMIZE_FOR_PERFORMANCE 1465 1466config CC_OPTIMIZE_FOR_PERFORMANCE 1467 bool "Optimize for performance (-O2)" 1468 help 1469 This is the default optimization level for the kernel, building 1470 with the "-O2" compiler flag for best performance and most 1471 helpful compile-time warnings. 1472 1473config CC_OPTIMIZE_FOR_SIZE 1474 bool "Optimize for size (-Os)" 1475 help 1476 Choosing this option will pass "-Os" to your compiler resulting 1477 in a smaller kernel. 1478 1479endchoice 1480 1481config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1482 bool 1483 help 1484 This requires that the arch annotates or otherwise protects 1485 its external entry points from being discarded. Linker scripts 1486 must also merge .text.*, .data.*, and .bss.* correctly into 1487 output sections. Care must be taken not to pull in unrelated 1488 sections (e.g., '.text.init'). Typically '.' in section names 1489 is used to distinguish them from label names / C identifiers. 1490 1491config LD_DEAD_CODE_DATA_ELIMINATION 1492 bool "Dead code and data elimination (EXPERIMENTAL)" 1493 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1494 depends on EXPERT 1495 depends on $(cc-option,-ffunction-sections -fdata-sections) 1496 depends on $(ld-option,--gc-sections) 1497 help 1498 Enable this if you want to do dead code and data elimination with 1499 the linker by compiling with -ffunction-sections -fdata-sections, 1500 and linking with --gc-sections. 1501 1502 This can reduce on disk and in-memory size of the kernel 1503 code and static data, particularly for small configs and 1504 on small systems. This has the possibility of introducing 1505 silently broken kernel if the required annotations are not 1506 present. This option is not well tested yet, so use at your 1507 own risk. 1508 1509config LD_ORPHAN_WARN 1510 def_bool y 1511 depends on ARCH_WANT_LD_ORPHAN_WARN 1512 depends on $(ld-option,--orphan-handling=warn) 1513 depends on $(ld-option,--orphan-handling=error) 1514 1515config LD_ORPHAN_WARN_LEVEL 1516 string 1517 depends on LD_ORPHAN_WARN 1518 default "error" if WERROR 1519 default "warn" 1520 1521config SYSCTL 1522 bool 1523 1524config HAVE_UID16 1525 bool 1526 1527config SYSCTL_EXCEPTION_TRACE 1528 bool 1529 help 1530 Enable support for /proc/sys/debug/exception-trace. 1531 1532config SYSCTL_ARCH_UNALIGN_NO_WARN 1533 bool 1534 help 1535 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1536 Allows arch to define/use @no_unaligned_warning to possibly warn 1537 about unaligned access emulation going on under the hood. 1538 1539config SYSCTL_ARCH_UNALIGN_ALLOW 1540 bool 1541 help 1542 Enable support for /proc/sys/kernel/unaligned-trap 1543 Allows arches to define/use @unaligned_enabled to runtime toggle 1544 the unaligned access emulation. 1545 see arch/parisc/kernel/unaligned.c for reference 1546 1547config HAVE_PCSPKR_PLATFORM 1548 bool 1549 1550menuconfig EXPERT 1551 bool "Configure standard kernel features (expert users)" 1552 # Unhide debug options, to make the on-by-default options visible 1553 select DEBUG_KERNEL 1554 help 1555 This option allows certain base kernel options and settings 1556 to be disabled or tweaked. This is for specialized 1557 environments which can tolerate a "non-standard" kernel. 1558 Only use this if you really know what you are doing. 1559 1560config UID16 1561 bool "Enable 16-bit UID system calls" if EXPERT 1562 depends on HAVE_UID16 && MULTIUSER 1563 default y 1564 help 1565 This enables the legacy 16-bit UID syscall wrappers. 1566 1567config MULTIUSER 1568 bool "Multiple users, groups and capabilities support" if EXPERT 1569 default y 1570 help 1571 This option enables support for non-root users, groups and 1572 capabilities. 1573 1574 If you say N here, all processes will run with UID 0, GID 0, and all 1575 possible capabilities. Saying N here also compiles out support for 1576 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1577 setgid, and capset. 1578 1579 If unsure, say Y here. 1580 1581config SGETMASK_SYSCALL 1582 bool "sgetmask/ssetmask syscalls support" if EXPERT 1583 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1584 help 1585 sys_sgetmask and sys_ssetmask are obsolete system calls 1586 no longer supported in libc but still enabled by default in some 1587 architectures. 1588 1589 If unsure, leave the default option here. 1590 1591config SYSFS_SYSCALL 1592 bool "Sysfs syscall support" if EXPERT 1593 default y 1594 help 1595 sys_sysfs is an obsolete system call no longer supported in libc. 1596 Note that disabling this option is more secure but might break 1597 compatibility with some systems. 1598 1599 If unsure say Y here. 1600 1601config FHANDLE 1602 bool "open by fhandle syscalls" if EXPERT 1603 select EXPORTFS 1604 default y 1605 help 1606 If you say Y here, a user level program will be able to map 1607 file names to handle and then later use the handle for 1608 different file system operations. This is useful in implementing 1609 userspace file servers, which now track files using handles instead 1610 of names. The handle would remain the same even if file names 1611 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1612 syscalls. 1613 1614config POSIX_TIMERS 1615 bool "Posix Clocks & timers" if EXPERT 1616 default y 1617 help 1618 This includes native support for POSIX timers to the kernel. 1619 Some embedded systems have no use for them and therefore they 1620 can be configured out to reduce the size of the kernel image. 1621 1622 When this option is disabled, the following syscalls won't be 1623 available: timer_create, timer_gettime: timer_getoverrun, 1624 timer_settime, timer_delete, clock_adjtime, getitimer, 1625 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1626 clock_getres and clock_nanosleep syscalls will be limited to 1627 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1628 1629 If unsure say y. 1630 1631config PRINTK 1632 default y 1633 bool "Enable support for printk" if EXPERT 1634 select IRQ_WORK 1635 help 1636 This option enables normal printk support. Removing it 1637 eliminates most of the message strings from the kernel image 1638 and makes the kernel more or less silent. As this makes it 1639 very difficult to diagnose system problems, saying N here is 1640 strongly discouraged. 1641 1642config BUG 1643 bool "BUG() support" if EXPERT 1644 default y 1645 help 1646 Disabling this option eliminates support for BUG and WARN, reducing 1647 the size of your kernel image and potentially quietly ignoring 1648 numerous fatal conditions. You should only consider disabling this 1649 option for embedded systems with no facilities for reporting errors. 1650 Just say Y. 1651 1652config ELF_CORE 1653 depends on COREDUMP 1654 default y 1655 bool "Enable ELF core dumps" if EXPERT 1656 help 1657 Enable support for generating core dumps. Disabling saves about 4k. 1658 1659 1660config PCSPKR_PLATFORM 1661 bool "Enable PC-Speaker support" if EXPERT 1662 depends on HAVE_PCSPKR_PLATFORM 1663 select I8253_LOCK 1664 default y 1665 help 1666 This option allows to disable the internal PC-Speaker 1667 support, saving some memory. 1668 1669config BASE_SMALL 1670 bool "Enable smaller-sized data structures for core" if EXPERT 1671 help 1672 Enabling this option reduces the size of miscellaneous core 1673 kernel data structures. This saves memory on small machines, 1674 but may reduce performance. 1675 1676config FUTEX 1677 bool "Enable futex support" if EXPERT 1678 depends on !(SPARC32 && SMP) 1679 default y 1680 imply RT_MUTEXES 1681 help 1682 Disabling this option will cause the kernel to be built without 1683 support for "fast userspace mutexes". The resulting kernel may not 1684 run glibc-based applications correctly. 1685 1686config FUTEX_PI 1687 bool 1688 depends on FUTEX && RT_MUTEXES 1689 default y 1690 1691config EPOLL 1692 bool "Enable eventpoll support" if EXPERT 1693 default y 1694 help 1695 Disabling this option will cause the kernel to be built without 1696 support for epoll family of system calls. 1697 1698config SIGNALFD 1699 bool "Enable signalfd() system call" if EXPERT 1700 default y 1701 help 1702 Enable the signalfd() system call that allows to receive signals 1703 on a file descriptor. 1704 1705 If unsure, say Y. 1706 1707config TIMERFD 1708 bool "Enable timerfd() system call" if EXPERT 1709 default y 1710 help 1711 Enable the timerfd() system call that allows to receive timer 1712 events on a file descriptor. 1713 1714 If unsure, say Y. 1715 1716config EVENTFD 1717 bool "Enable eventfd() system call" if EXPERT 1718 default y 1719 help 1720 Enable the eventfd() system call that allows to receive both 1721 kernel notification (ie. KAIO) or userspace notifications. 1722 1723 If unsure, say Y. 1724 1725config SHMEM 1726 bool "Use full shmem filesystem" if EXPERT 1727 default y 1728 depends on MMU 1729 help 1730 The shmem is an internal filesystem used to manage shared memory. 1731 It is backed by swap and manages resource limits. It is also exported 1732 to userspace as tmpfs if TMPFS is enabled. Disabling this 1733 option replaces shmem and tmpfs with the much simpler ramfs code, 1734 which may be appropriate on small systems without swap. 1735 1736config AIO 1737 bool "Enable AIO support" if EXPERT 1738 default y 1739 help 1740 This option enables POSIX asynchronous I/O which may by used 1741 by some high performance threaded applications. Disabling 1742 this option saves about 7k. 1743 1744config IO_URING 1745 bool "Enable IO uring support" if EXPERT 1746 select IO_WQ 1747 default y 1748 help 1749 This option enables support for the io_uring interface, enabling 1750 applications to submit and complete IO through submission and 1751 completion rings that are shared between the kernel and application. 1752 1753config GCOV_PROFILE_URING 1754 bool "Enable GCOV profiling on the io_uring subsystem" 1755 depends on GCOV_KERNEL 1756 help 1757 Enable GCOV profiling on the io_uring subsystem, to facilitate 1758 code coverage testing. 1759 1760 If unsure, say N. 1761 1762 Note that this will have a negative impact on the performance of 1763 the io_uring subsystem, hence this should only be enabled for 1764 specific test purposes. 1765 1766config ADVISE_SYSCALLS 1767 bool "Enable madvise/fadvise syscalls" if EXPERT 1768 default y 1769 help 1770 This option enables the madvise and fadvise syscalls, used by 1771 applications to advise the kernel about their future memory or file 1772 usage, improving performance. If building an embedded system where no 1773 applications use these syscalls, you can disable this option to save 1774 space. 1775 1776config MEMBARRIER 1777 bool "Enable membarrier() system call" if EXPERT 1778 default y 1779 help 1780 Enable the membarrier() system call that allows issuing memory 1781 barriers across all running threads, which can be used to distribute 1782 the cost of user-space memory barriers asymmetrically by transforming 1783 pairs of memory barriers into pairs consisting of membarrier() and a 1784 compiler barrier. 1785 1786 If unsure, say Y. 1787 1788config KCMP 1789 bool "Enable kcmp() system call" if EXPERT 1790 help 1791 Enable the kernel resource comparison system call. It provides 1792 user-space with the ability to compare two processes to see if they 1793 share a common resource, such as a file descriptor or even virtual 1794 memory space. 1795 1796 If unsure, say N. 1797 1798config RSEQ 1799 bool "Enable rseq() system call" if EXPERT 1800 default y 1801 depends on HAVE_RSEQ 1802 select MEMBARRIER 1803 help 1804 Enable the restartable sequences system call. It provides a 1805 user-space cache for the current CPU number value, which 1806 speeds up getting the current CPU number from user-space, 1807 as well as an ABI to speed up user-space operations on 1808 per-CPU data. 1809 1810 If unsure, say Y. 1811 1812config DEBUG_RSEQ 1813 default n 1814 bool "Enable debugging of rseq() system call" if EXPERT 1815 depends on RSEQ && DEBUG_KERNEL 1816 help 1817 Enable extra debugging checks for the rseq system call. 1818 1819 If unsure, say N. 1820 1821config CACHESTAT_SYSCALL 1822 bool "Enable cachestat() system call" if EXPERT 1823 default y 1824 help 1825 Enable the cachestat system call, which queries the page cache 1826 statistics of a file (number of cached pages, dirty pages, 1827 pages marked for writeback, (recently) evicted pages). 1828 1829 If unsure say Y here. 1830 1831config PC104 1832 bool "PC/104 support" if EXPERT 1833 help 1834 Expose PC/104 form factor device drivers and options available for 1835 selection and configuration. Enable this option if your target 1836 machine has a PC/104 bus. 1837 1838config KALLSYMS 1839 bool "Load all symbols for debugging/ksymoops" if EXPERT 1840 default y 1841 help 1842 Say Y here to let the kernel print out symbolic crash information and 1843 symbolic stack backtraces. This increases the size of the kernel 1844 somewhat, as all symbols have to be loaded into the kernel image. 1845 1846config KALLSYMS_SELFTEST 1847 bool "Test the basic functions and performance of kallsyms" 1848 depends on KALLSYMS 1849 default n 1850 help 1851 Test the basic functions and performance of some interfaces, such as 1852 kallsyms_lookup_name. It also calculates the compression rate of the 1853 kallsyms compression algorithm for the current symbol set. 1854 1855 Start self-test automatically after system startup. Suggest executing 1856 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 1857 displayed in the last line, indicating that the test is complete. 1858 1859config KALLSYMS_ALL 1860 bool "Include all symbols in kallsyms" 1861 depends on DEBUG_KERNEL && KALLSYMS 1862 help 1863 Normally kallsyms only contains the symbols of functions for nicer 1864 OOPS messages and backtraces (i.e., symbols from the text and inittext 1865 sections). This is sufficient for most cases. And only if you want to 1866 enable kernel live patching, or other less common use cases (e.g., 1867 when a debugger is used) all symbols are required (i.e., names of 1868 variables from the data sections, etc). 1869 1870 This option makes sure that all symbols are loaded into the kernel 1871 image (i.e., symbols from all sections) in cost of increased kernel 1872 size (depending on the kernel configuration, it may be 300KiB or 1873 something like this). 1874 1875 Say N unless you really need all symbols, or kernel live patching. 1876 1877config KALLSYMS_ABSOLUTE_PERCPU 1878 bool 1879 depends on KALLSYMS 1880 default X86_64 && SMP 1881 1882# end of the "standard kernel features (expert users)" menu 1883 1884config ARCH_HAS_MEMBARRIER_CALLBACKS 1885 bool 1886 1887config ARCH_HAS_MEMBARRIER_SYNC_CORE 1888 bool 1889 1890config HAVE_PERF_EVENTS 1891 bool 1892 help 1893 See tools/perf/design.txt for details. 1894 1895config GUEST_PERF_EVENTS 1896 bool 1897 depends on HAVE_PERF_EVENTS 1898 1899config PERF_USE_VMALLOC 1900 bool 1901 help 1902 See tools/perf/design.txt for details 1903 1904menu "Kernel Performance Events And Counters" 1905 1906config PERF_EVENTS 1907 bool "Kernel performance events and counters" 1908 default y if PROFILING 1909 depends on HAVE_PERF_EVENTS 1910 select IRQ_WORK 1911 help 1912 Enable kernel support for various performance events provided 1913 by software and hardware. 1914 1915 Software events are supported either built-in or via the 1916 use of generic tracepoints. 1917 1918 Most modern CPUs support performance events via performance 1919 counter registers. These registers count the number of certain 1920 types of hw events: such as instructions executed, cachemisses 1921 suffered, or branches mis-predicted - without slowing down the 1922 kernel or applications. These registers can also trigger interrupts 1923 when a threshold number of events have passed - and can thus be 1924 used to profile the code that runs on that CPU. 1925 1926 The Linux Performance Event subsystem provides an abstraction of 1927 these software and hardware event capabilities, available via a 1928 system call and used by the "perf" utility in tools/perf/. It 1929 provides per task and per CPU counters, and it provides event 1930 capabilities on top of those. 1931 1932 Say Y if unsure. 1933 1934config DEBUG_PERF_USE_VMALLOC 1935 default n 1936 bool "Debug: use vmalloc to back perf mmap() buffers" 1937 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 1938 select PERF_USE_VMALLOC 1939 help 1940 Use vmalloc memory to back perf mmap() buffers. 1941 1942 Mostly useful for debugging the vmalloc code on platforms 1943 that don't require it. 1944 1945 Say N if unsure. 1946 1947endmenu 1948 1949config SYSTEM_DATA_VERIFICATION 1950 def_bool n 1951 select SYSTEM_TRUSTED_KEYRING 1952 select KEYS 1953 select CRYPTO 1954 select CRYPTO_RSA 1955 select ASYMMETRIC_KEY_TYPE 1956 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1957 select ASN1 1958 select OID_REGISTRY 1959 select X509_CERTIFICATE_PARSER 1960 select PKCS7_MESSAGE_PARSER 1961 help 1962 Provide PKCS#7 message verification using the contents of the system 1963 trusted keyring to provide public keys. This then can be used for 1964 module verification, kexec image verification and firmware blob 1965 verification. 1966 1967config PROFILING 1968 bool "Profiling support" 1969 help 1970 Say Y here to enable the extended profiling support mechanisms used 1971 by profilers. 1972 1973config RUST 1974 bool "Rust support" 1975 depends on HAVE_RUST 1976 depends on RUST_IS_AVAILABLE 1977 select EXTENDED_MODVERSIONS if MODVERSIONS 1978 depends on !MODVERSIONS || GENDWARFKSYMS 1979 depends on !GCC_PLUGIN_RANDSTRUCT 1980 depends on !RANDSTRUCT 1981 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 1982 depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 1983 select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG 1984 depends on !CALL_PADDING || RUSTC_VERSION >= 108100 1985 depends on !KASAN_SW_TAGS 1986 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300 1987 help 1988 Enables Rust support in the kernel. 1989 1990 This allows other Rust-related options, like drivers written in Rust, 1991 to be selected. 1992 1993 It is also required to be able to load external kernel modules 1994 written in Rust. 1995 1996 See Documentation/rust/ for more information. 1997 1998 If unsure, say N. 1999 2000config RUSTC_VERSION_TEXT 2001 string 2002 depends on RUST 2003 default "$(RUSTC_VERSION_TEXT)" 2004 help 2005 See `CC_VERSION_TEXT`. 2006 2007config BINDGEN_VERSION_TEXT 2008 string 2009 depends on RUST 2010 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0 2011 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0 2012 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed 2013 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1 2014 # both fixed the issue). 2015 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)" 2016 2017# 2018# Place an empty function call at each tracepoint site. Can be 2019# dynamically changed for a probe function. 2020# 2021config TRACEPOINTS 2022 bool 2023 select TASKS_TRACE_RCU 2024 2025source "kernel/Kconfig.kexec" 2026 2027endmenu # General setup 2028 2029source "arch/Kconfig" 2030 2031config RT_MUTEXES 2032 bool 2033 default y if PREEMPT_RT 2034 2035config MODULE_SIG_FORMAT 2036 def_bool n 2037 select SYSTEM_DATA_VERIFICATION 2038 2039source "kernel/module/Kconfig" 2040 2041config INIT_ALL_POSSIBLE 2042 bool 2043 help 2044 Back when each arch used to define their own cpu_online_mask and 2045 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2046 with all 1s, and others with all 0s. When they were centralised, 2047 it was better to provide this option than to break all the archs 2048 and have several arch maintainers pursuing me down dark alleys. 2049 2050source "block/Kconfig" 2051 2052config PREEMPT_NOTIFIERS 2053 bool 2054 2055config PADATA 2056 depends on SMP 2057 bool 2058 2059config ASN1 2060 tristate 2061 help 2062 Build a simple ASN.1 grammar compiler that produces a bytecode output 2063 that can be interpreted by the ASN.1 stream decoder and used to 2064 inform it as to what tags are to be expected in a stream and what 2065 functions to call on what tags. 2066 2067source "kernel/Kconfig.locks" 2068 2069config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2070 bool 2071 2072config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2073 bool 2074 2075config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2076 bool 2077 2078# It may be useful for an architecture to override the definitions of the 2079# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2080# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2081# different calling convention for syscalls. They can also override the 2082# macros for not-implemented syscalls in kernel/sys_ni.c and 2083# kernel/time/posix-stubs.c. All these overrides need to be available in 2084# <asm/syscall_wrapper.h>. 2085config ARCH_HAS_SYSCALL_WRAPPER 2086 def_bool n 2087