1# SPDX-License-Identifier: GPL-2.0-only 2config CC_VERSION_TEXT 3 string 4 default "$(CC_VERSION_TEXT)" 5 help 6 This is used in unclear ways: 7 8 - Re-run Kconfig when the compiler is updated 9 The 'default' property references the environment variable, 10 CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd. 11 When the compiler is updated, Kconfig will be invoked. 12 13 - Ensure full rebuild when the compiler is updated 14 include/linux/compiler-version.h contains this option in the comment 15 line so fixdep adds include/config/CC_VERSION_TEXT into the 16 auto-generated dependency. When the compiler is updated, syncconfig 17 will touch it and then every file will be rebuilt. 18 19config CC_IS_GCC 20 def_bool $(success,test "$(cc-name)" = GCC) 21 22config GCC_VERSION 23 int 24 default $(cc-version) if CC_IS_GCC 25 default 0 26 27config CC_IS_CLANG 28 def_bool $(success,test "$(cc-name)" = Clang) 29 30config CLANG_VERSION 31 int 32 default $(cc-version) if CC_IS_CLANG 33 default 0 34 35config AS_IS_GNU 36 def_bool $(success,test "$(as-name)" = GNU) 37 38config AS_IS_LLVM 39 def_bool $(success,test "$(as-name)" = LLVM) 40 41config AS_VERSION 42 int 43 # Use clang version if this is the integrated assembler 44 default CLANG_VERSION if AS_IS_LLVM 45 default $(as-version) 46 47config LD_IS_BFD 48 def_bool $(success,test "$(ld-name)" = BFD) 49 50config LD_VERSION 51 int 52 default $(ld-version) if LD_IS_BFD 53 default 0 54 55config LD_IS_LLD 56 def_bool $(success,test "$(ld-name)" = LLD) 57 58config LLD_VERSION 59 int 60 default $(ld-version) if LD_IS_LLD 61 default 0 62 63config RUSTC_VERSION 64 int 65 default $(rustc-version) 66 help 67 It does not depend on `RUST` since that one may need to use the version 68 in a `depends on`. 69 70config RUST_IS_AVAILABLE 71 def_bool $(success,$(srctree)/scripts/rust_is_available.sh) 72 help 73 This shows whether a suitable Rust toolchain is available (found). 74 75 Please see Documentation/rust/quick-start.rst for instructions on how 76 to satisfy the build requirements of Rust support. 77 78 In particular, the Makefile target 'rustavailable' is useful to check 79 why the Rust toolchain is not being detected. 80 81config RUSTC_LLVM_VERSION 82 int 83 default $(rustc-llvm-version) 84 85config CC_CAN_LINK 86 bool 87 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT 88 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag)) 89 90# Fixed in GCC 14, 13.3, 12.4 and 11.5 91# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 92config GCC_ASM_GOTO_OUTPUT_BROKEN 93 bool 94 depends on CC_IS_GCC 95 default y if GCC_VERSION < 110500 96 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400 97 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300 98 99config CC_HAS_ASM_GOTO_OUTPUT 100 def_bool y 101 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN 102 depends on $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null) 103 104config CC_HAS_ASM_GOTO_TIED_OUTPUT 105 depends on CC_HAS_ASM_GOTO_OUTPUT 106 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 107 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null) 108 109config TOOLS_SUPPORT_RELR 110 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 111 112config CC_HAS_ASM_INLINE 113 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 114 115config CC_HAS_NO_PROFILE_FN_ATTR 116 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 117 118config CC_HAS_COUNTED_BY 119 # TODO: when gcc 15 is released remove the build test and add 120 # a gcc version check 121 def_bool $(success,echo 'struct flex { int count; int array[] __attribute__((__counted_by__(count))); };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 122 # clang needs to be at least 19.1.3 to avoid __bdos miscalculations 123 # https://github.com/llvm/llvm-project/pull/110497 124 # https://github.com/llvm/llvm-project/pull/112636 125 depends on !(CC_IS_CLANG && CLANG_VERSION < 190103) 126 127config CC_HAS_MULTIDIMENSIONAL_NONSTRING 128 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 129 130config LD_CAN_USE_KEEP_IN_OVERLAY 131 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 132 # https://github.com/llvm/llvm-project/pull/130661 133 def_bool LD_IS_BFD || LLD_VERSION >= 210000 134 135config RUSTC_HAS_COERCE_POINTEE 136 def_bool RUSTC_VERSION >= 108400 137 138config RUSTC_HAS_UNNECESSARY_TRANSMUTES 139 def_bool RUSTC_VERSION >= 108800 140 141config PAHOLE_VERSION 142 int 143 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) 144 145config CONSTRUCTORS 146 bool 147 148config IRQ_WORK 149 def_bool y if SMP 150 151config BUILDTIME_TABLE_SORT 152 bool 153 154config THREAD_INFO_IN_TASK 155 bool 156 help 157 Select this to move thread_info off the stack into task_struct. To 158 make this work, an arch will need to remove all thread_info fields 159 except flags and fix any runtime bugs. 160 161 One subtle change that will be needed is to use try_get_task_stack() 162 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 163 164menu "General setup" 165 166config BROKEN 167 bool 168 169config BROKEN_ON_SMP 170 bool 171 depends on BROKEN || !SMP 172 default y 173 174config INIT_ENV_ARG_LIMIT 175 int 176 default 32 if !UML 177 default 128 if UML 178 help 179 Maximum of each of the number of arguments and environment 180 variables passed to init from the kernel command line. 181 182config COMPILE_TEST 183 bool "Compile also drivers which will not load" 184 depends on HAS_IOMEM 185 help 186 Some drivers can be compiled on a different platform than they are 187 intended to be run on. Despite they cannot be loaded there (or even 188 when they load they cannot be used due to missing HW support), 189 developers still, opposing to distributors, might want to build such 190 drivers to compile-test them. 191 192 If you are a developer and want to build everything available, say Y 193 here. If you are a user/distributor, say N here to exclude useless 194 drivers to be distributed. 195 196config WERROR 197 bool "Compile the kernel with warnings as errors" 198 default COMPILE_TEST 199 help 200 A kernel build should not cause any compiler warnings, and this 201 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 202 to enforce that rule by default. Certain warnings from other tools 203 such as the linker may be upgraded to errors with this option as 204 well. 205 206 However, if you have a new (or very old) compiler or linker with odd 207 and unusual warnings, or you have some architecture with problems, 208 you may need to disable this config option in order to 209 successfully build the kernel. 210 211 If in doubt, say Y. 212 213config UAPI_HEADER_TEST 214 bool "Compile test UAPI headers" 215 depends on HEADERS_INSTALL && CC_CAN_LINK 216 help 217 Compile test headers exported to user-space to ensure they are 218 self-contained, i.e. compilable as standalone units. 219 220 If you are a developer or tester and want to ensure the exported 221 headers are self-contained, say Y here. Otherwise, choose N. 222 223config LOCALVERSION 224 string "Local version - append to kernel release" 225 help 226 Append an extra string to the end of your kernel version. 227 This will show up when you type uname, for example. 228 The string you set here will be appended after the contents of 229 any files with a filename matching localversion* in your 230 object and source tree, in that order. Your total string can 231 be a maximum of 64 characters. 232 233config LOCALVERSION_AUTO 234 bool "Automatically append version information to the version string" 235 default y 236 depends on !COMPILE_TEST 237 help 238 This will try to automatically determine if the current tree is a 239 release tree by looking for git tags that belong to the current 240 top of tree revision. 241 242 A string of the format -gxxxxxxxx will be added to the localversion 243 if a git-based tree is found. The string generated by this will be 244 appended after any matching localversion* files, and after the value 245 set in CONFIG_LOCALVERSION. 246 247 (The actual string used here is the first 12 characters produced 248 by running the command: 249 250 $ git rev-parse --verify HEAD 251 252 which is done within the script "scripts/setlocalversion".) 253 254config BUILD_SALT 255 string "Build ID Salt" 256 default "" 257 help 258 The build ID is used to link binaries and their debug info. Setting 259 this option will use the value in the calculation of the build id. 260 This is mostly useful for distributions which want to ensure the 261 build is unique between builds. It's safe to leave the default. 262 263config HAVE_KERNEL_GZIP 264 bool 265 266config HAVE_KERNEL_BZIP2 267 bool 268 269config HAVE_KERNEL_LZMA 270 bool 271 272config HAVE_KERNEL_XZ 273 bool 274 275config HAVE_KERNEL_LZO 276 bool 277 278config HAVE_KERNEL_LZ4 279 bool 280 281config HAVE_KERNEL_ZSTD 282 bool 283 284config HAVE_KERNEL_UNCOMPRESSED 285 bool 286 287choice 288 prompt "Kernel compression mode" 289 default KERNEL_GZIP 290 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED 291 help 292 The linux kernel is a kind of self-extracting executable. 293 Several compression algorithms are available, which differ 294 in efficiency, compression and decompression speed. 295 Compression speed is only relevant when building a kernel. 296 Decompression speed is relevant at each boot. 297 298 If you have any problems with bzip2 or lzma compressed 299 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 300 version of this functionality (bzip2 only), for 2.4, was 301 supplied by Christian Ludwig) 302 303 High compression options are mostly useful for users, who 304 are low on disk space (embedded systems), but for whom ram 305 size matters less. 306 307 If in doubt, select 'gzip' 308 309config KERNEL_GZIP 310 bool "Gzip" 311 depends on HAVE_KERNEL_GZIP 312 help 313 The old and tried gzip compression. It provides a good balance 314 between compression ratio and decompression speed. 315 316config KERNEL_BZIP2 317 bool "Bzip2" 318 depends on HAVE_KERNEL_BZIP2 319 help 320 Its compression ratio and speed is intermediate. 321 Decompression speed is slowest among the choices. The kernel 322 size is about 10% smaller with bzip2, in comparison to gzip. 323 Bzip2 uses a large amount of memory. For modern kernels you 324 will need at least 8MB RAM or more for booting. 325 326config KERNEL_LZMA 327 bool "LZMA" 328 depends on HAVE_KERNEL_LZMA 329 help 330 This compression algorithm's ratio is best. Decompression speed 331 is between gzip and bzip2. Compression is slowest. 332 The kernel size is about 33% smaller with LZMA in comparison to gzip. 333 334config KERNEL_XZ 335 bool "XZ" 336 depends on HAVE_KERNEL_XZ 337 help 338 XZ uses the LZMA2 algorithm and instruction set specific 339 BCJ filters which can improve compression ratio of executable 340 code. The size of the kernel is about 30% smaller with XZ in 341 comparison to gzip. On architectures for which there is a BCJ 342 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 343 and SPARC), XZ will create a few percent smaller kernel than 344 plain LZMA. 345 346 The speed is about the same as with LZMA: The decompression 347 speed of XZ is better than that of bzip2 but worse than gzip 348 and LZO. Compression is slow. 349 350config KERNEL_LZO 351 bool "LZO" 352 depends on HAVE_KERNEL_LZO 353 help 354 Its compression ratio is the poorest among the choices. The kernel 355 size is about 10% bigger than gzip; however its speed 356 (both compression and decompression) is the fastest. 357 358config KERNEL_LZ4 359 bool "LZ4" 360 depends on HAVE_KERNEL_LZ4 361 help 362 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 363 A preliminary version of LZ4 de/compression tool is available at 364 <https://code.google.com/p/lz4/>. 365 366 Its compression ratio is worse than LZO. The size of the kernel 367 is about 8% bigger than LZO. But the decompression speed is 368 faster than LZO. 369 370config KERNEL_ZSTD 371 bool "ZSTD" 372 depends on HAVE_KERNEL_ZSTD 373 help 374 ZSTD is a compression algorithm targeting intermediate compression 375 with fast decompression speed. It will compress better than GZIP and 376 decompress around the same speed as LZO, but slower than LZ4. You 377 will need at least 192 KB RAM or more for booting. The zstd command 378 line tool is required for compression. 379 380config KERNEL_UNCOMPRESSED 381 bool "None" 382 depends on HAVE_KERNEL_UNCOMPRESSED 383 help 384 Produce uncompressed kernel image. This option is usually not what 385 you want. It is useful for debugging the kernel in slow simulation 386 environments, where decompressing and moving the kernel is awfully 387 slow. This option allows early boot code to skip the decompressor 388 and jump right at uncompressed kernel image. 389 390endchoice 391 392config DEFAULT_INIT 393 string "Default init path" 394 default "" 395 help 396 This option determines the default init for the system if no init= 397 option is passed on the kernel command line. If the requested path is 398 not present, we will still then move on to attempting further 399 locations (e.g. /sbin/init, etc). If this is empty, we will just use 400 the fallback list when init= is not passed. 401 402config DEFAULT_HOSTNAME 403 string "Default hostname" 404 default "(none)" 405 help 406 This option determines the default system hostname before userspace 407 calls sethostname(2). The kernel traditionally uses "(none)" here, 408 but you may wish to use a different default here to make a minimal 409 system more usable with less configuration. 410 411config SYSVIPC 412 bool "System V IPC" 413 help 414 Inter Process Communication is a suite of library functions and 415 system calls which let processes (running programs) synchronize and 416 exchange information. It is generally considered to be a good thing, 417 and some programs won't run unless you say Y here. In particular, if 418 you want to run the DOS emulator dosemu under Linux (read the 419 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 420 you'll need to say Y here. 421 422 You can find documentation about IPC with "info ipc" and also in 423 section 6.4 of the Linux Programmer's Guide, available from 424 <http://www.tldp.org/guides.html>. 425 426config SYSVIPC_SYSCTL 427 bool 428 depends on SYSVIPC 429 depends on SYSCTL 430 default y 431 432config SYSVIPC_COMPAT 433 def_bool y 434 depends on COMPAT && SYSVIPC 435 436config POSIX_MQUEUE 437 bool "POSIX Message Queues" 438 depends on NET 439 help 440 POSIX variant of message queues is a part of IPC. In POSIX message 441 queues every message has a priority which decides about succession 442 of receiving it by a process. If you want to compile and run 443 programs written e.g. for Solaris with use of its POSIX message 444 queues (functions mq_*) say Y here. 445 446 POSIX message queues are visible as a filesystem called 'mqueue' 447 and can be mounted somewhere if you want to do filesystem 448 operations on message queues. 449 450 If unsure, say Y. 451 452config POSIX_MQUEUE_SYSCTL 453 bool 454 depends on POSIX_MQUEUE 455 depends on SYSCTL 456 default y 457 458config WATCH_QUEUE 459 bool "General notification queue" 460 default n 461 help 462 463 This is a general notification queue for the kernel to pass events to 464 userspace by splicing them into pipes. It can be used in conjunction 465 with watches for key/keyring change notifications and device 466 notifications. 467 468 See Documentation/core-api/watch_queue.rst 469 470config CROSS_MEMORY_ATTACH 471 bool "Enable process_vm_readv/writev syscalls" 472 depends on MMU 473 default y 474 help 475 Enabling this option adds the system calls process_vm_readv and 476 process_vm_writev which allow a process with the correct privileges 477 to directly read from or write to another process' address space. 478 See the man page for more details. 479 480config USELIB 481 bool "uselib syscall (for libc5 and earlier)" 482 default ALPHA || M68K || SPARC 483 help 484 This option enables the uselib syscall, a system call used in the 485 dynamic linker from libc5 and earlier. glibc does not use this 486 system call. If you intend to run programs built on libc5 or 487 earlier, you may need to enable this syscall. Current systems 488 running glibc can safely disable this. 489 490config AUDIT 491 bool "Auditing support" 492 depends on NET 493 help 494 Enable auditing infrastructure that can be used with another 495 kernel subsystem, such as SELinux (which requires this for 496 logging of avc messages output). System call auditing is included 497 on architectures which support it. 498 499config HAVE_ARCH_AUDITSYSCALL 500 bool 501 502config AUDITSYSCALL 503 def_bool y 504 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 505 select FSNOTIFY 506 507source "kernel/irq/Kconfig" 508source "kernel/time/Kconfig" 509source "kernel/bpf/Kconfig" 510source "kernel/Kconfig.preempt" 511 512menu "CPU/Task time and stats accounting" 513 514config VIRT_CPU_ACCOUNTING 515 bool 516 517choice 518 prompt "Cputime accounting" 519 default TICK_CPU_ACCOUNTING 520 521# Kind of a stub config for the pure tick based cputime accounting 522config TICK_CPU_ACCOUNTING 523 bool "Simple tick based cputime accounting" 524 depends on !S390 && !NO_HZ_FULL 525 help 526 This is the basic tick based cputime accounting that maintains 527 statistics about user, system and idle time spent on per jiffies 528 granularity. 529 530 If unsure, say Y. 531 532config VIRT_CPU_ACCOUNTING_NATIVE 533 bool "Deterministic task and CPU time accounting" 534 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 535 select VIRT_CPU_ACCOUNTING 536 help 537 Select this option to enable more accurate task and CPU time 538 accounting. This is done by reading a CPU counter on each 539 kernel entry and exit and on transitions within the kernel 540 between system, softirq and hardirq state, so there is a 541 small performance impact. In the case of s390 or IBM POWER > 5, 542 this also enables accounting of stolen time on logically-partitioned 543 systems. 544 545config VIRT_CPU_ACCOUNTING_GEN 546 bool "Full dynticks CPU time accounting" 547 depends on HAVE_CONTEXT_TRACKING_USER 548 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 549 depends on GENERIC_CLOCKEVENTS 550 select VIRT_CPU_ACCOUNTING 551 select CONTEXT_TRACKING_USER 552 help 553 Select this option to enable task and CPU time accounting on full 554 dynticks systems. This accounting is implemented by watching every 555 kernel-user boundaries using the context tracking subsystem. 556 The accounting is thus performed at the expense of some significant 557 overhead. 558 559 For now this is only useful if you are working on the full 560 dynticks subsystem development. 561 562 If unsure, say N. 563 564endchoice 565 566config IRQ_TIME_ACCOUNTING 567 bool "Fine granularity task level IRQ time accounting" 568 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 569 help 570 Select this option to enable fine granularity task irq time 571 accounting. This is done by reading a timestamp on each 572 transitions between softirq and hardirq state, so there can be a 573 small performance impact. 574 575 If in doubt, say N here. 576 577config HAVE_SCHED_AVG_IRQ 578 def_bool y 579 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 580 depends on SMP 581 582config SCHED_HW_PRESSURE 583 bool 584 default y if ARM && ARM_CPU_TOPOLOGY 585 default y if ARM64 586 depends on SMP 587 depends on CPU_FREQ_THERMAL 588 help 589 Select this option to enable HW pressure accounting in the 590 scheduler. HW pressure is the value conveyed to the scheduler 591 that reflects the reduction in CPU compute capacity resulted from 592 HW throttling. HW throttling occurs when the performance of 593 a CPU is capped due to high operating temperatures as an example. 594 595 If selected, the scheduler will be able to balance tasks accordingly, 596 i.e. put less load on throttled CPUs than on non/less throttled ones. 597 598 This requires the architecture to implement 599 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 600 601config BSD_PROCESS_ACCT 602 bool "BSD Process Accounting" 603 depends on MULTIUSER 604 help 605 If you say Y here, a user level program will be able to instruct the 606 kernel (via a special system call) to write process accounting 607 information to a file: whenever a process exits, information about 608 that process will be appended to the file by the kernel. The 609 information includes things such as creation time, owning user, 610 command name, memory usage, controlling terminal etc. (the complete 611 list is in the struct acct in <file:include/linux/acct.h>). It is 612 up to the user level program to do useful things with this 613 information. This is generally a good idea, so say Y. 614 615config BSD_PROCESS_ACCT_V3 616 bool "BSD Process Accounting version 3 file format" 617 depends on BSD_PROCESS_ACCT 618 default n 619 help 620 If you say Y here, the process accounting information is written 621 in a new file format that also logs the process IDs of each 622 process and its parent. Note that this file format is incompatible 623 with previous v0/v1/v2 file formats, so you will need updated tools 624 for processing it. A preliminary version of these tools is available 625 at <http://www.gnu.org/software/acct/>. 626 627config TASKSTATS 628 bool "Export task/process statistics through netlink" 629 depends on NET 630 depends on MULTIUSER 631 default n 632 help 633 Export selected statistics for tasks/processes through the 634 generic netlink interface. Unlike BSD process accounting, the 635 statistics are available during the lifetime of tasks/processes as 636 responses to commands. Like BSD accounting, they are sent to user 637 space on task exit. 638 639 Say N if unsure. 640 641config TASK_DELAY_ACCT 642 bool "Enable per-task delay accounting" 643 depends on TASKSTATS 644 select SCHED_INFO 645 help 646 Collect information on time spent by a task waiting for system 647 resources like cpu, synchronous block I/O completion and swapping 648 in pages. Such statistics can help in setting a task's priorities 649 relative to other tasks for cpu, io, rss limits etc. 650 651 Say N if unsure. 652 653config TASK_XACCT 654 bool "Enable extended accounting over taskstats" 655 depends on TASKSTATS 656 help 657 Collect extended task accounting data and send the data 658 to userland for processing over the taskstats interface. 659 660 Say N if unsure. 661 662config TASK_IO_ACCOUNTING 663 bool "Enable per-task storage I/O accounting" 664 depends on TASK_XACCT 665 help 666 Collect information on the number of bytes of storage I/O which this 667 task has caused. 668 669 Say N if unsure. 670 671config PSI 672 bool "Pressure stall information tracking" 673 select KERNFS 674 help 675 Collect metrics that indicate how overcommitted the CPU, memory, 676 and IO capacity are in the system. 677 678 If you say Y here, the kernel will create /proc/pressure/ with the 679 pressure statistics files cpu, memory, and io. These will indicate 680 the share of walltime in which some or all tasks in the system are 681 delayed due to contention of the respective resource. 682 683 In kernels with cgroup support, cgroups (cgroup2 only) will 684 have cpu.pressure, memory.pressure, and io.pressure files, 685 which aggregate pressure stalls for the grouped tasks only. 686 687 For more details see Documentation/accounting/psi.rst. 688 689 Say N if unsure. 690 691config PSI_DEFAULT_DISABLED 692 bool "Require boot parameter to enable pressure stall information tracking" 693 default n 694 depends on PSI 695 help 696 If set, pressure stall information tracking will be disabled 697 per default but can be enabled through passing psi=1 on the 698 kernel commandline during boot. 699 700 This feature adds some code to the task wakeup and sleep 701 paths of the scheduler. The overhead is too low to affect 702 common scheduling-intense workloads in practice (such as 703 webservers, memcache), but it does show up in artificial 704 scheduler stress tests, such as hackbench. 705 706 If you are paranoid and not sure what the kernel will be 707 used for, say Y. 708 709 Say N if unsure. 710 711endmenu # "CPU/Task time and stats accounting" 712 713config CPU_ISOLATION 714 bool "CPU isolation" 715 depends on SMP 716 default y 717 help 718 Make sure that CPUs running critical tasks are not disturbed by 719 any source of "noise" such as unbound workqueues, timers, kthreads... 720 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 721 the "isolcpus=" boot parameter. 722 723 Say Y if unsure. 724 725source "kernel/rcu/Kconfig" 726 727config IKCONFIG 728 tristate "Kernel .config support" 729 help 730 This option enables the complete Linux kernel ".config" file 731 contents to be saved in the kernel. It provides documentation 732 of which kernel options are used in a running kernel or in an 733 on-disk kernel. This information can be extracted from the kernel 734 image file with the script scripts/extract-ikconfig and used as 735 input to rebuild the current kernel or to build another kernel. 736 It can also be extracted from a running kernel by reading 737 /proc/config.gz if enabled (below). 738 739config IKCONFIG_PROC 740 bool "Enable access to .config through /proc/config.gz" 741 depends on IKCONFIG && PROC_FS 742 help 743 This option enables access to the kernel configuration file 744 through /proc/config.gz. 745 746config IKHEADERS 747 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 748 depends on SYSFS 749 help 750 This option enables access to the in-kernel headers that are generated during 751 the build process. These can be used to build eBPF tracing programs, 752 or similar programs. If you build the headers as a module, a module called 753 kheaders.ko is built which can be loaded on-demand to get access to headers. 754 755config LOG_BUF_SHIFT 756 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 757 range 12 25 758 default 17 759 depends on PRINTK 760 help 761 Select the minimal kernel log buffer size as a power of 2. 762 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 763 parameter, see below. Any higher size also might be forced 764 by "log_buf_len" boot parameter. 765 766 Examples: 767 17 => 128 KB 768 16 => 64 KB 769 15 => 32 KB 770 14 => 16 KB 771 13 => 8 KB 772 12 => 4 KB 773 774config LOG_CPU_MAX_BUF_SHIFT 775 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 776 depends on SMP 777 range 0 21 778 default 0 if BASE_SMALL 779 default 12 780 depends on PRINTK 781 help 782 This option allows to increase the default ring buffer size 783 according to the number of CPUs. The value defines the contribution 784 of each CPU as a power of 2. The used space is typically only few 785 lines however it might be much more when problems are reported, 786 e.g. backtraces. 787 788 The increased size means that a new buffer has to be allocated and 789 the original static one is unused. It makes sense only on systems 790 with more CPUs. Therefore this value is used only when the sum of 791 contributions is greater than the half of the default kernel ring 792 buffer as defined by LOG_BUF_SHIFT. The default values are set 793 so that more than 16 CPUs are needed to trigger the allocation. 794 795 Also this option is ignored when "log_buf_len" kernel parameter is 796 used as it forces an exact (power of two) size of the ring buffer. 797 798 The number of possible CPUs is used for this computation ignoring 799 hotplugging making the computation optimal for the worst case 800 scenario while allowing a simple algorithm to be used from bootup. 801 802 Examples shift values and their meaning: 803 17 => 128 KB for each CPU 804 16 => 64 KB for each CPU 805 15 => 32 KB for each CPU 806 14 => 16 KB for each CPU 807 13 => 8 KB for each CPU 808 12 => 4 KB for each CPU 809 810config PRINTK_INDEX 811 bool "Printk indexing debugfs interface" 812 depends on PRINTK && DEBUG_FS 813 help 814 Add support for indexing of all printk formats known at compile time 815 at <debugfs>/printk/index/<module>. 816 817 This can be used as part of maintaining daemons which monitor 818 /dev/kmsg, as it permits auditing the printk formats present in a 819 kernel, allowing detection of cases where monitored printks are 820 changed or no longer present. 821 822 There is no additional runtime cost to printk with this enabled. 823 824# 825# Architectures with an unreliable sched_clock() should select this: 826# 827config HAVE_UNSTABLE_SCHED_CLOCK 828 bool 829 830config GENERIC_SCHED_CLOCK 831 bool 832 833menu "Scheduler features" 834 835config UCLAMP_TASK 836 bool "Enable utilization clamping for RT/FAIR tasks" 837 depends on CPU_FREQ_GOV_SCHEDUTIL 838 help 839 This feature enables the scheduler to track the clamped utilization 840 of each CPU based on RUNNABLE tasks scheduled on that CPU. 841 842 With this option, the user can specify the min and max CPU 843 utilization allowed for RUNNABLE tasks. The max utilization defines 844 the maximum frequency a task should use while the min utilization 845 defines the minimum frequency it should use. 846 847 Both min and max utilization clamp values are hints to the scheduler, 848 aiming at improving its frequency selection policy, but they do not 849 enforce or grant any specific bandwidth for tasks. 850 851 If in doubt, say N. 852 853config UCLAMP_BUCKETS_COUNT 854 int "Number of supported utilization clamp buckets" 855 range 5 20 856 default 5 857 depends on UCLAMP_TASK 858 help 859 Defines the number of clamp buckets to use. The range of each bucket 860 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 861 number of clamp buckets the finer their granularity and the higher 862 the precision of clamping aggregation and tracking at run-time. 863 864 For example, with the minimum configuration value we will have 5 865 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 866 be refcounted in the [20..39]% bucket and will set the bucket clamp 867 effective value to 25%. 868 If a second 30% boosted task should be co-scheduled on the same CPU, 869 that task will be refcounted in the same bucket of the first task and 870 it will boost the bucket clamp effective value to 30%. 871 The clamp effective value of a bucket is reset to its nominal value 872 (20% in the example above) when there are no more tasks refcounted in 873 that bucket. 874 875 An additional boost/capping margin can be added to some tasks. In the 876 example above the 25% task will be boosted to 30% until it exits the 877 CPU. If that should be considered not acceptable on certain systems, 878 it's always possible to reduce the margin by increasing the number of 879 clamp buckets to trade off used memory for run-time tracking 880 precision. 881 882 If in doubt, use the default value. 883 884endmenu 885 886# 887# For architectures that want to enable the support for NUMA-affine scheduler 888# balancing logic: 889# 890config ARCH_SUPPORTS_NUMA_BALANCING 891 bool 892 893# 894# For architectures that prefer to flush all TLBs after a number of pages 895# are unmapped instead of sending one IPI per page to flush. The architecture 896# must provide guarantees on what happens if a clean TLB cache entry is 897# written after the unmap. Details are in mm/rmap.c near the check for 898# should_defer_flush. The architecture should also consider if the full flush 899# and the refill costs are offset by the savings of sending fewer IPIs. 900config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 901 bool 902 903config CC_HAS_INT128 904 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 905 906config CC_IMPLICIT_FALLTHROUGH 907 string 908 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 909 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 910 911# Currently, disable gcc-10+ array-bounds globally. 912# It's still broken in gcc-13, so no upper bound yet. 913config GCC10_NO_ARRAY_BOUNDS 914 def_bool y 915 916config CC_NO_ARRAY_BOUNDS 917 bool 918 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 919 920# Currently, disable -Wstringop-overflow for GCC globally. 921config GCC_NO_STRINGOP_OVERFLOW 922 def_bool y 923 924config CC_NO_STRINGOP_OVERFLOW 925 bool 926 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 927 928config CC_STRINGOP_OVERFLOW 929 bool 930 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 931 932# 933# For architectures that know their GCC __int128 support is sound 934# 935config ARCH_SUPPORTS_INT128 936 bool 937 938# For architectures that (ab)use NUMA to represent different memory regions 939# all cpu-local but of different latencies, such as SuperH. 940# 941config ARCH_WANT_NUMA_VARIABLE_LOCALITY 942 bool 943 944config NUMA_BALANCING 945 bool "Memory placement aware NUMA scheduler" 946 depends on ARCH_SUPPORTS_NUMA_BALANCING 947 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 948 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 949 help 950 This option adds support for automatic NUMA aware memory/task placement. 951 The mechanism is quite primitive and is based on migrating memory when 952 it has references to the node the task is running on. 953 954 This system will be inactive on UMA systems. 955 956config NUMA_BALANCING_DEFAULT_ENABLED 957 bool "Automatically enable NUMA aware memory/task placement" 958 default y 959 depends on NUMA_BALANCING 960 help 961 If set, automatic NUMA balancing will be enabled if running on a NUMA 962 machine. 963 964config SLAB_OBJ_EXT 965 bool 966 967menuconfig CGROUPS 968 bool "Control Group support" 969 select KERNFS 970 help 971 This option adds support for grouping sets of processes together, for 972 use with process control subsystems such as Cpusets, CFS, memory 973 controls or device isolation. 974 See 975 - Documentation/scheduler/sched-design-CFS.rst (CFS) 976 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 977 and resource control) 978 979 Say N if unsure. 980 981if CGROUPS 982 983config PAGE_COUNTER 984 bool 985 986config CGROUP_FAVOR_DYNMODS 987 bool "Favor dynamic modification latency reduction by default" 988 help 989 This option enables the "favordynmods" mount option by default 990 which reduces the latencies of dynamic cgroup modifications such 991 as task migrations and controller on/offs at the cost of making 992 hot path operations such as forks and exits more expensive. 993 994 Say N if unsure. 995 996config MEMCG 997 bool "Memory controller" 998 select PAGE_COUNTER 999 select EVENTFD 1000 select SLAB_OBJ_EXT 1001 help 1002 Provides control over the memory footprint of tasks in a cgroup. 1003 1004config MEMCG_V1 1005 bool "Legacy cgroup v1 memory controller" 1006 depends on MEMCG 1007 default n 1008 help 1009 Legacy cgroup v1 memory controller which has been deprecated by 1010 cgroup v2 implementation. The v1 is there for legacy applications 1011 which haven't migrated to the new cgroup v2 interface yet. If you 1012 do not have any such application then you are completely fine leaving 1013 this option disabled. 1014 1015 Please note that feature set of the legacy memory controller is likely 1016 going to shrink due to deprecation process. New deployments with v1 1017 controller are highly discouraged. 1018 1019 Say N if unsure. 1020 1021config BLK_CGROUP 1022 bool "IO controller" 1023 depends on BLOCK 1024 default n 1025 help 1026 Generic block IO controller cgroup interface. This is the common 1027 cgroup interface which should be used by various IO controlling 1028 policies. 1029 1030 Currently, CFQ IO scheduler uses it to recognize task groups and 1031 control disk bandwidth allocation (proportional time slice allocation) 1032 to such task groups. It is also used by bio throttling logic in 1033 block layer to implement upper limit in IO rates on a device. 1034 1035 This option only enables generic Block IO controller infrastructure. 1036 One needs to also enable actual IO controlling logic/policy. For 1037 enabling proportional weight division of disk bandwidth in CFQ, set 1038 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1039 CONFIG_BLK_DEV_THROTTLING=y. 1040 1041 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1042 1043config CGROUP_WRITEBACK 1044 bool 1045 depends on MEMCG && BLK_CGROUP 1046 default y 1047 1048menuconfig CGROUP_SCHED 1049 bool "CPU controller" 1050 default n 1051 help 1052 This feature lets CPU scheduler recognize task groups and control CPU 1053 bandwidth allocation to such task groups. It uses cgroups to group 1054 tasks. 1055 1056if CGROUP_SCHED 1057config GROUP_SCHED_WEIGHT 1058 def_bool n 1059 1060config FAIR_GROUP_SCHED 1061 bool "Group scheduling for SCHED_OTHER" 1062 depends on CGROUP_SCHED 1063 select GROUP_SCHED_WEIGHT 1064 default CGROUP_SCHED 1065 1066config CFS_BANDWIDTH 1067 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1068 depends on FAIR_GROUP_SCHED 1069 default n 1070 help 1071 This option allows users to define CPU bandwidth rates (limits) for 1072 tasks running within the fair group scheduler. Groups with no limit 1073 set are considered to be unconstrained and will run with no 1074 restriction. 1075 See Documentation/scheduler/sched-bwc.rst for more information. 1076 1077config RT_GROUP_SCHED 1078 bool "Group scheduling for SCHED_RR/FIFO" 1079 depends on CGROUP_SCHED 1080 default n 1081 help 1082 This feature lets you explicitly allocate real CPU bandwidth 1083 to task groups. If enabled, it will also make it impossible to 1084 schedule realtime tasks for non-root users until you allocate 1085 realtime bandwidth for them. 1086 See Documentation/scheduler/sched-rt-group.rst for more information. 1087 1088config EXT_GROUP_SCHED 1089 bool 1090 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1091 select GROUP_SCHED_WEIGHT 1092 default y 1093 1094endif #CGROUP_SCHED 1095 1096config SCHED_MM_CID 1097 def_bool y 1098 depends on SMP && RSEQ 1099 1100config UCLAMP_TASK_GROUP 1101 bool "Utilization clamping per group of tasks" 1102 depends on CGROUP_SCHED 1103 depends on UCLAMP_TASK 1104 default n 1105 help 1106 This feature enables the scheduler to track the clamped utilization 1107 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1108 1109 When this option is enabled, the user can specify a min and max 1110 CPU bandwidth which is allowed for each single task in a group. 1111 The max bandwidth allows to clamp the maximum frequency a task 1112 can use, while the min bandwidth allows to define a minimum 1113 frequency a task will always use. 1114 1115 When task group based utilization clamping is enabled, an eventually 1116 specified task-specific clamp value is constrained by the cgroup 1117 specified clamp value. Both minimum and maximum task clamping cannot 1118 be bigger than the corresponding clamping defined at task group level. 1119 1120 If in doubt, say N. 1121 1122config CGROUP_PIDS 1123 bool "PIDs controller" 1124 help 1125 Provides enforcement of process number limits in the scope of a 1126 cgroup. Any attempt to fork more processes than is allowed in the 1127 cgroup will fail. PIDs are fundamentally a global resource because it 1128 is fairly trivial to reach PID exhaustion before you reach even a 1129 conservative kmemcg limit. As a result, it is possible to grind a 1130 system to halt without being limited by other cgroup policies. The 1131 PIDs controller is designed to stop this from happening. 1132 1133 It should be noted that organisational operations (such as attaching 1134 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1135 since the PIDs limit only affects a process's ability to fork, not to 1136 attach to a cgroup. 1137 1138config CGROUP_RDMA 1139 bool "RDMA controller" 1140 help 1141 Provides enforcement of RDMA resources defined by IB stack. 1142 It is fairly easy for consumers to exhaust RDMA resources, which 1143 can result into resource unavailability to other consumers. 1144 RDMA controller is designed to stop this from happening. 1145 Attaching processes with active RDMA resources to the cgroup 1146 hierarchy is allowed even if can cross the hierarchy's limit. 1147 1148config CGROUP_DMEM 1149 bool "Device memory controller (DMEM)" 1150 select PAGE_COUNTER 1151 help 1152 The DMEM controller allows compatible devices to restrict device 1153 memory usage based on the cgroup hierarchy. 1154 1155 As an example, it allows you to restrict VRAM usage for applications 1156 in the DRM subsystem. 1157 1158config CGROUP_FREEZER 1159 bool "Freezer controller" 1160 help 1161 Provides a way to freeze and unfreeze all tasks in a 1162 cgroup. 1163 1164 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1165 controller includes important in-kernel memory consumers per default. 1166 1167 If you're using cgroup2, say N. 1168 1169config CGROUP_HUGETLB 1170 bool "HugeTLB controller" 1171 depends on HUGETLB_PAGE 1172 select PAGE_COUNTER 1173 default n 1174 help 1175 Provides a cgroup controller for HugeTLB pages. 1176 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1177 The limit is enforced during page fault. Since HugeTLB doesn't 1178 support page reclaim, enforcing the limit at page fault time implies 1179 that, the application will get SIGBUS signal if it tries to access 1180 HugeTLB pages beyond its limit. This requires the application to know 1181 beforehand how much HugeTLB pages it would require for its use. The 1182 control group is tracked in the third page lru pointer. This means 1183 that we cannot use the controller with huge page less than 3 pages. 1184 1185config CPUSETS 1186 bool "Cpuset controller" 1187 depends on SMP 1188 select UNION_FIND 1189 help 1190 This option will let you create and manage CPUSETs which 1191 allow dynamically partitioning a system into sets of CPUs and 1192 Memory Nodes and assigning tasks to run only within those sets. 1193 This is primarily useful on large SMP or NUMA systems. 1194 1195 Say N if unsure. 1196 1197config CPUSETS_V1 1198 bool "Legacy cgroup v1 cpusets controller" 1199 depends on CPUSETS 1200 default n 1201 help 1202 Legacy cgroup v1 cpusets controller which has been deprecated by 1203 cgroup v2 implementation. The v1 is there for legacy applications 1204 which haven't migrated to the new cgroup v2 interface yet. Legacy 1205 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1206 do not have any such application then you are completely fine leaving 1207 this option disabled. 1208 1209 Say N if unsure. 1210 1211config PROC_PID_CPUSET 1212 bool "Include legacy /proc/<pid>/cpuset file" 1213 depends on CPUSETS_V1 1214 default y 1215 1216config CGROUP_DEVICE 1217 bool "Device controller" 1218 help 1219 Provides a cgroup controller implementing whitelists for 1220 devices which a process in the cgroup can mknod or open. 1221 1222config CGROUP_CPUACCT 1223 bool "Simple CPU accounting controller" 1224 help 1225 Provides a simple controller for monitoring the 1226 total CPU consumed by the tasks in a cgroup. 1227 1228config CGROUP_PERF 1229 bool "Perf controller" 1230 depends on PERF_EVENTS 1231 help 1232 This option extends the perf per-cpu mode to restrict monitoring 1233 to threads which belong to the cgroup specified and run on the 1234 designated cpu. Or this can be used to have cgroup ID in samples 1235 so that it can monitor performance events among cgroups. 1236 1237 Say N if unsure. 1238 1239config CGROUP_BPF 1240 bool "Support for eBPF programs attached to cgroups" 1241 depends on BPF_SYSCALL 1242 select SOCK_CGROUP_DATA 1243 help 1244 Allow attaching eBPF programs to a cgroup using the bpf(2) 1245 syscall command BPF_PROG_ATTACH. 1246 1247 In which context these programs are accessed depends on the type 1248 of attachment. For instance, programs that are attached using 1249 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1250 inet sockets. 1251 1252config CGROUP_MISC 1253 bool "Misc resource controller" 1254 default n 1255 help 1256 Provides a controller for miscellaneous resources on a host. 1257 1258 Miscellaneous scalar resources are the resources on the host system 1259 which cannot be abstracted like the other cgroups. This controller 1260 tracks and limits the miscellaneous resources used by a process 1261 attached to a cgroup hierarchy. 1262 1263 For more information, please check misc cgroup section in 1264 /Documentation/admin-guide/cgroup-v2.rst. 1265 1266config CGROUP_DEBUG 1267 bool "Debug controller" 1268 default n 1269 depends on DEBUG_KERNEL 1270 help 1271 This option enables a simple controller that exports 1272 debugging information about the cgroups framework. This 1273 controller is for control cgroup debugging only. Its 1274 interfaces are not stable. 1275 1276 Say N. 1277 1278config SOCK_CGROUP_DATA 1279 bool 1280 default n 1281 1282endif # CGROUPS 1283 1284menuconfig NAMESPACES 1285 bool "Namespaces support" if EXPERT 1286 depends on MULTIUSER 1287 default !EXPERT 1288 help 1289 Provides the way to make tasks work with different objects using 1290 the same id. For example same IPC id may refer to different objects 1291 or same user id or pid may refer to different tasks when used in 1292 different namespaces. 1293 1294if NAMESPACES 1295 1296config UTS_NS 1297 bool "UTS namespace" 1298 default y 1299 help 1300 In this namespace tasks see different info provided with the 1301 uname() system call 1302 1303config TIME_NS 1304 bool "TIME namespace" 1305 depends on GENERIC_VDSO_TIME_NS 1306 default y 1307 help 1308 In this namespace boottime and monotonic clocks can be set. 1309 The time will keep going with the same pace. 1310 1311config IPC_NS 1312 bool "IPC namespace" 1313 depends on (SYSVIPC || POSIX_MQUEUE) 1314 default y 1315 help 1316 In this namespace tasks work with IPC ids which correspond to 1317 different IPC objects in different namespaces. 1318 1319config USER_NS 1320 bool "User namespace" 1321 default n 1322 help 1323 This allows containers, i.e. vservers, to use user namespaces 1324 to provide different user info for different servers. 1325 1326 When user namespaces are enabled in the kernel it is 1327 recommended that the MEMCG option also be enabled and that 1328 user-space use the memory control groups to limit the amount 1329 of memory a memory unprivileged users can use. 1330 1331 If unsure, say N. 1332 1333config PID_NS 1334 bool "PID Namespaces" 1335 default y 1336 help 1337 Support process id namespaces. This allows having multiple 1338 processes with the same pid as long as they are in different 1339 pid namespaces. This is a building block of containers. 1340 1341config NET_NS 1342 bool "Network namespace" 1343 depends on NET 1344 default y 1345 help 1346 Allow user space to create what appear to be multiple instances 1347 of the network stack. 1348 1349endif # NAMESPACES 1350 1351config CHECKPOINT_RESTORE 1352 bool "Checkpoint/restore support" 1353 depends on PROC_FS 1354 select PROC_CHILDREN 1355 select KCMP 1356 default n 1357 help 1358 Enables additional kernel features in a sake of checkpoint/restore. 1359 In particular it adds auxiliary prctl codes to setup process text, 1360 data and heap segment sizes, and a few additional /proc filesystem 1361 entries. 1362 1363 If unsure, say N here. 1364 1365config SCHED_AUTOGROUP 1366 bool "Automatic process group scheduling" 1367 select CGROUPS 1368 select CGROUP_SCHED 1369 select FAIR_GROUP_SCHED 1370 help 1371 This option optimizes the scheduler for common desktop workloads by 1372 automatically creating and populating task groups. This separation 1373 of workloads isolates aggressive CPU burners (like build jobs) from 1374 desktop applications. Task group autogeneration is currently based 1375 upon task session. 1376 1377config RELAY 1378 bool "Kernel->user space relay support (formerly relayfs)" 1379 select IRQ_WORK 1380 help 1381 This option enables support for relay interface support in 1382 certain file systems (such as debugfs). 1383 It is designed to provide an efficient mechanism for tools and 1384 facilities to relay large amounts of data from kernel space to 1385 user space. 1386 1387 If unsure, say N. 1388 1389config BLK_DEV_INITRD 1390 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1391 help 1392 The initial RAM filesystem is a ramfs which is loaded by the 1393 boot loader (loadlin or lilo) and that is mounted as root 1394 before the normal boot procedure. It is typically used to 1395 load modules needed to mount the "real" root file system, 1396 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1397 1398 If RAM disk support (BLK_DEV_RAM) is also included, this 1399 also enables initial RAM disk (initrd) support and adds 1400 15 Kbytes (more on some other architectures) to the kernel size. 1401 1402 If unsure say Y. 1403 1404if BLK_DEV_INITRD 1405 1406source "usr/Kconfig" 1407 1408endif 1409 1410config BOOT_CONFIG 1411 bool "Boot config support" 1412 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1413 help 1414 Extra boot config allows system admin to pass a config file as 1415 complemental extension of kernel cmdline when booting. 1416 The boot config file must be attached at the end of initramfs 1417 with checksum, size and magic word. 1418 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1419 1420 If unsure, say Y. 1421 1422config BOOT_CONFIG_FORCE 1423 bool "Force unconditional bootconfig processing" 1424 depends on BOOT_CONFIG 1425 default y if BOOT_CONFIG_EMBED 1426 help 1427 With this Kconfig option set, BOOT_CONFIG processing is carried 1428 out even when the "bootconfig" kernel-boot parameter is omitted. 1429 In fact, with this Kconfig option set, there is no way to 1430 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1431 parameters. 1432 1433 If unsure, say N. 1434 1435config BOOT_CONFIG_EMBED 1436 bool "Embed bootconfig file in the kernel" 1437 depends on BOOT_CONFIG 1438 help 1439 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1440 kernel. Usually, the bootconfig file is loaded with the initrd 1441 image. But if the system doesn't support initrd, this option will 1442 help you by embedding a bootconfig file while building the kernel. 1443 1444 If unsure, say N. 1445 1446config BOOT_CONFIG_EMBED_FILE 1447 string "Embedded bootconfig file path" 1448 depends on BOOT_CONFIG_EMBED 1449 help 1450 Specify a bootconfig file which will be embedded to the kernel. 1451 This bootconfig will be used if there is no initrd or no other 1452 bootconfig in the initrd. 1453 1454config INITRAMFS_PRESERVE_MTIME 1455 bool "Preserve cpio archive mtimes in initramfs" 1456 default y 1457 help 1458 Each entry in an initramfs cpio archive carries an mtime value. When 1459 enabled, extracted cpio items take this mtime, with directory mtime 1460 setting deferred until after creation of any child entries. 1461 1462 If unsure, say Y. 1463 1464config INITRAMFS_TEST 1465 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1466 depends on BLK_DEV_INITRD && KUNIT=y 1467 default KUNIT_ALL_TESTS 1468 help 1469 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1470 1471choice 1472 prompt "Compiler optimization level" 1473 default CC_OPTIMIZE_FOR_PERFORMANCE 1474 1475config CC_OPTIMIZE_FOR_PERFORMANCE 1476 bool "Optimize for performance (-O2)" 1477 help 1478 This is the default optimization level for the kernel, building 1479 with the "-O2" compiler flag for best performance and most 1480 helpful compile-time warnings. 1481 1482config CC_OPTIMIZE_FOR_SIZE 1483 bool "Optimize for size (-Os)" 1484 help 1485 Choosing this option will pass "-Os" to your compiler resulting 1486 in a smaller kernel. 1487 1488endchoice 1489 1490config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1491 bool 1492 help 1493 This requires that the arch annotates or otherwise protects 1494 its external entry points from being discarded. Linker scripts 1495 must also merge .text.*, .data.*, and .bss.* correctly into 1496 output sections. Care must be taken not to pull in unrelated 1497 sections (e.g., '.text.init'). Typically '.' in section names 1498 is used to distinguish them from label names / C identifiers. 1499 1500config LD_DEAD_CODE_DATA_ELIMINATION 1501 bool "Dead code and data elimination (EXPERIMENTAL)" 1502 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1503 depends on EXPERT 1504 depends on $(cc-option,-ffunction-sections -fdata-sections) 1505 depends on $(ld-option,--gc-sections) 1506 help 1507 Enable this if you want to do dead code and data elimination with 1508 the linker by compiling with -ffunction-sections -fdata-sections, 1509 and linking with --gc-sections. 1510 1511 This can reduce on disk and in-memory size of the kernel 1512 code and static data, particularly for small configs and 1513 on small systems. This has the possibility of introducing 1514 silently broken kernel if the required annotations are not 1515 present. This option is not well tested yet, so use at your 1516 own risk. 1517 1518config LD_ORPHAN_WARN 1519 def_bool y 1520 depends on ARCH_WANT_LD_ORPHAN_WARN 1521 depends on $(ld-option,--orphan-handling=warn) 1522 depends on $(ld-option,--orphan-handling=error) 1523 1524config LD_ORPHAN_WARN_LEVEL 1525 string 1526 depends on LD_ORPHAN_WARN 1527 default "error" if WERROR 1528 default "warn" 1529 1530config SYSCTL 1531 bool 1532 1533config HAVE_UID16 1534 bool 1535 1536config SYSCTL_EXCEPTION_TRACE 1537 bool 1538 help 1539 Enable support for /proc/sys/debug/exception-trace. 1540 1541config SYSCTL_ARCH_UNALIGN_NO_WARN 1542 bool 1543 help 1544 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1545 Allows arch to define/use @no_unaligned_warning to possibly warn 1546 about unaligned access emulation going on under the hood. 1547 1548config SYSCTL_ARCH_UNALIGN_ALLOW 1549 bool 1550 help 1551 Enable support for /proc/sys/kernel/unaligned-trap 1552 Allows arches to define/use @unaligned_enabled to runtime toggle 1553 the unaligned access emulation. 1554 see arch/parisc/kernel/unaligned.c for reference 1555 1556config SYSFS_SYSCALL 1557 bool "Sysfs syscall support" 1558 default n 1559 help 1560 sys_sysfs is an obsolete system call no longer supported in libc. 1561 Note that disabling this option is more secure but might break 1562 compatibility with some systems. 1563 1564 If unsure say N here. 1565 1566config HAVE_PCSPKR_PLATFORM 1567 bool 1568 1569menuconfig EXPERT 1570 bool "Configure standard kernel features (expert users)" 1571 # Unhide debug options, to make the on-by-default options visible 1572 select DEBUG_KERNEL 1573 help 1574 This option allows certain base kernel options and settings 1575 to be disabled or tweaked. This is for specialized 1576 environments which can tolerate a "non-standard" kernel. 1577 Only use this if you really know what you are doing. 1578 1579config UID16 1580 bool "Enable 16-bit UID system calls" if EXPERT 1581 depends on HAVE_UID16 && MULTIUSER 1582 default y 1583 help 1584 This enables the legacy 16-bit UID syscall wrappers. 1585 1586config MULTIUSER 1587 bool "Multiple users, groups and capabilities support" if EXPERT 1588 default y 1589 help 1590 This option enables support for non-root users, groups and 1591 capabilities. 1592 1593 If you say N here, all processes will run with UID 0, GID 0, and all 1594 possible capabilities. Saying N here also compiles out support for 1595 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1596 setgid, and capset. 1597 1598 If unsure, say Y here. 1599 1600config SGETMASK_SYSCALL 1601 bool "sgetmask/ssetmask syscalls support" if EXPERT 1602 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1603 help 1604 sys_sgetmask and sys_ssetmask are obsolete system calls 1605 no longer supported in libc but still enabled by default in some 1606 architectures. 1607 1608 If unsure, leave the default option here. 1609 1610config FHANDLE 1611 bool "open by fhandle syscalls" if EXPERT 1612 select EXPORTFS 1613 default y 1614 help 1615 If you say Y here, a user level program will be able to map 1616 file names to handle and then later use the handle for 1617 different file system operations. This is useful in implementing 1618 userspace file servers, which now track files using handles instead 1619 of names. The handle would remain the same even if file names 1620 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1621 syscalls. 1622 1623config POSIX_TIMERS 1624 bool "Posix Clocks & timers" if EXPERT 1625 default y 1626 help 1627 This includes native support for POSIX timers to the kernel. 1628 Some embedded systems have no use for them and therefore they 1629 can be configured out to reduce the size of the kernel image. 1630 1631 When this option is disabled, the following syscalls won't be 1632 available: timer_create, timer_gettime: timer_getoverrun, 1633 timer_settime, timer_delete, clock_adjtime, getitimer, 1634 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1635 clock_getres and clock_nanosleep syscalls will be limited to 1636 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1637 1638 If unsure say y. 1639 1640config PRINTK 1641 default y 1642 bool "Enable support for printk" if EXPERT 1643 select IRQ_WORK 1644 help 1645 This option enables normal printk support. Removing it 1646 eliminates most of the message strings from the kernel image 1647 and makes the kernel more or less silent. As this makes it 1648 very difficult to diagnose system problems, saying N here is 1649 strongly discouraged. 1650 1651config BUG 1652 bool "BUG() support" if EXPERT 1653 default y 1654 help 1655 Disabling this option eliminates support for BUG and WARN, reducing 1656 the size of your kernel image and potentially quietly ignoring 1657 numerous fatal conditions. You should only consider disabling this 1658 option for embedded systems with no facilities for reporting errors. 1659 Just say Y. 1660 1661config ELF_CORE 1662 depends on COREDUMP 1663 default y 1664 bool "Enable ELF core dumps" if EXPERT 1665 help 1666 Enable support for generating core dumps. Disabling saves about 4k. 1667 1668 1669config PCSPKR_PLATFORM 1670 bool "Enable PC-Speaker support" if EXPERT 1671 depends on HAVE_PCSPKR_PLATFORM 1672 select I8253_LOCK 1673 default y 1674 help 1675 This option allows to disable the internal PC-Speaker 1676 support, saving some memory. 1677 1678config BASE_SMALL 1679 bool "Enable smaller-sized data structures for core" if EXPERT 1680 help 1681 Enabling this option reduces the size of miscellaneous core 1682 kernel data structures. This saves memory on small machines, 1683 but may reduce performance. 1684 1685config FUTEX 1686 bool "Enable futex support" if EXPERT 1687 depends on !(SPARC32 && SMP) 1688 default y 1689 imply RT_MUTEXES 1690 help 1691 Disabling this option will cause the kernel to be built without 1692 support for "fast userspace mutexes". The resulting kernel may not 1693 run glibc-based applications correctly. 1694 1695config FUTEX_PI 1696 bool 1697 depends on FUTEX && RT_MUTEXES 1698 default y 1699 1700config EPOLL 1701 bool "Enable eventpoll support" if EXPERT 1702 default y 1703 help 1704 Disabling this option will cause the kernel to be built without 1705 support for epoll family of system calls. 1706 1707config SIGNALFD 1708 bool "Enable signalfd() system call" if EXPERT 1709 default y 1710 help 1711 Enable the signalfd() system call that allows to receive signals 1712 on a file descriptor. 1713 1714 If unsure, say Y. 1715 1716config TIMERFD 1717 bool "Enable timerfd() system call" if EXPERT 1718 default y 1719 help 1720 Enable the timerfd() system call that allows to receive timer 1721 events on a file descriptor. 1722 1723 If unsure, say Y. 1724 1725config EVENTFD 1726 bool "Enable eventfd() system call" if EXPERT 1727 default y 1728 help 1729 Enable the eventfd() system call that allows to receive both 1730 kernel notification (ie. KAIO) or userspace notifications. 1731 1732 If unsure, say Y. 1733 1734config SHMEM 1735 bool "Use full shmem filesystem" if EXPERT 1736 default y 1737 depends on MMU 1738 help 1739 The shmem is an internal filesystem used to manage shared memory. 1740 It is backed by swap and manages resource limits. It is also exported 1741 to userspace as tmpfs if TMPFS is enabled. Disabling this 1742 option replaces shmem and tmpfs with the much simpler ramfs code, 1743 which may be appropriate on small systems without swap. 1744 1745config AIO 1746 bool "Enable AIO support" if EXPERT 1747 default y 1748 help 1749 This option enables POSIX asynchronous I/O which may by used 1750 by some high performance threaded applications. Disabling 1751 this option saves about 7k. 1752 1753config IO_URING 1754 bool "Enable IO uring support" if EXPERT 1755 select IO_WQ 1756 default y 1757 help 1758 This option enables support for the io_uring interface, enabling 1759 applications to submit and complete IO through submission and 1760 completion rings that are shared between the kernel and application. 1761 1762config GCOV_PROFILE_URING 1763 bool "Enable GCOV profiling on the io_uring subsystem" 1764 depends on GCOV_KERNEL 1765 help 1766 Enable GCOV profiling on the io_uring subsystem, to facilitate 1767 code coverage testing. 1768 1769 If unsure, say N. 1770 1771 Note that this will have a negative impact on the performance of 1772 the io_uring subsystem, hence this should only be enabled for 1773 specific test purposes. 1774 1775config ADVISE_SYSCALLS 1776 bool "Enable madvise/fadvise syscalls" if EXPERT 1777 default y 1778 help 1779 This option enables the madvise and fadvise syscalls, used by 1780 applications to advise the kernel about their future memory or file 1781 usage, improving performance. If building an embedded system where no 1782 applications use these syscalls, you can disable this option to save 1783 space. 1784 1785config MEMBARRIER 1786 bool "Enable membarrier() system call" if EXPERT 1787 default y 1788 help 1789 Enable the membarrier() system call that allows issuing memory 1790 barriers across all running threads, which can be used to distribute 1791 the cost of user-space memory barriers asymmetrically by transforming 1792 pairs of memory barriers into pairs consisting of membarrier() and a 1793 compiler barrier. 1794 1795 If unsure, say Y. 1796 1797config KCMP 1798 bool "Enable kcmp() system call" if EXPERT 1799 help 1800 Enable the kernel resource comparison system call. It provides 1801 user-space with the ability to compare two processes to see if they 1802 share a common resource, such as a file descriptor or even virtual 1803 memory space. 1804 1805 If unsure, say N. 1806 1807config RSEQ 1808 bool "Enable rseq() system call" if EXPERT 1809 default y 1810 depends on HAVE_RSEQ 1811 select MEMBARRIER 1812 help 1813 Enable the restartable sequences system call. It provides a 1814 user-space cache for the current CPU number value, which 1815 speeds up getting the current CPU number from user-space, 1816 as well as an ABI to speed up user-space operations on 1817 per-CPU data. 1818 1819 If unsure, say Y. 1820 1821config DEBUG_RSEQ 1822 default n 1823 bool "Enable debugging of rseq() system call" if EXPERT 1824 depends on RSEQ && DEBUG_KERNEL 1825 help 1826 Enable extra debugging checks for the rseq system call. 1827 1828 If unsure, say N. 1829 1830config CACHESTAT_SYSCALL 1831 bool "Enable cachestat() system call" if EXPERT 1832 default y 1833 help 1834 Enable the cachestat system call, which queries the page cache 1835 statistics of a file (number of cached pages, dirty pages, 1836 pages marked for writeback, (recently) evicted pages). 1837 1838 If unsure say Y here. 1839 1840config PC104 1841 bool "PC/104 support" if EXPERT 1842 help 1843 Expose PC/104 form factor device drivers and options available for 1844 selection and configuration. Enable this option if your target 1845 machine has a PC/104 bus. 1846 1847config KALLSYMS 1848 bool "Load all symbols for debugging/ksymoops" if EXPERT 1849 default y 1850 help 1851 Say Y here to let the kernel print out symbolic crash information and 1852 symbolic stack backtraces. This increases the size of the kernel 1853 somewhat, as all symbols have to be loaded into the kernel image. 1854 1855config KALLSYMS_SELFTEST 1856 bool "Test the basic functions and performance of kallsyms" 1857 depends on KALLSYMS 1858 default n 1859 help 1860 Test the basic functions and performance of some interfaces, such as 1861 kallsyms_lookup_name. It also calculates the compression rate of the 1862 kallsyms compression algorithm for the current symbol set. 1863 1864 Start self-test automatically after system startup. Suggest executing 1865 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 1866 displayed in the last line, indicating that the test is complete. 1867 1868config KALLSYMS_ALL 1869 bool "Include all symbols in kallsyms" 1870 depends on DEBUG_KERNEL && KALLSYMS 1871 help 1872 Normally kallsyms only contains the symbols of functions for nicer 1873 OOPS messages and backtraces (i.e., symbols from the text and inittext 1874 sections). This is sufficient for most cases. And only if you want to 1875 enable kernel live patching, or other less common use cases (e.g., 1876 when a debugger is used) all symbols are required (i.e., names of 1877 variables from the data sections, etc). 1878 1879 This option makes sure that all symbols are loaded into the kernel 1880 image (i.e., symbols from all sections) in cost of increased kernel 1881 size (depending on the kernel configuration, it may be 300KiB or 1882 something like this). 1883 1884 Say N unless you really need all symbols, or kernel live patching. 1885 1886# end of the "standard kernel features (expert users)" menu 1887 1888config ARCH_HAS_MEMBARRIER_CALLBACKS 1889 bool 1890 1891config ARCH_HAS_MEMBARRIER_SYNC_CORE 1892 bool 1893 1894config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 1895 bool 1896 help 1897 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 1898 1899 A 64-bit kernel is required for the memory sealing feature. 1900 No specific hardware features from the CPU are needed. 1901 1902 To enable this feature, the architecture needs to update their 1903 special mappings calls to include the sealing flag and confirm 1904 that it doesn't unmap/remap system mappings during the life 1905 time of the process. The existence of this flag for an architecture 1906 implies that it does not require the remapping of the system 1907 mappings during process lifetime, so sealing these mappings is safe 1908 from a kernel perspective. 1909 1910 After the architecture enables this, a distribution can set 1911 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 1912 1913 For complete descriptions of memory sealing, please see 1914 Documentation/userspace-api/mseal.rst 1915 1916config HAVE_PERF_EVENTS 1917 bool 1918 help 1919 See tools/perf/design.txt for details. 1920 1921config GUEST_PERF_EVENTS 1922 bool 1923 depends on HAVE_PERF_EVENTS 1924 1925config PERF_USE_VMALLOC 1926 bool 1927 help 1928 See tools/perf/design.txt for details 1929 1930menu "Kernel Performance Events And Counters" 1931 1932config PERF_EVENTS 1933 bool "Kernel performance events and counters" 1934 default y if PROFILING 1935 depends on HAVE_PERF_EVENTS 1936 select IRQ_WORK 1937 help 1938 Enable kernel support for various performance events provided 1939 by software and hardware. 1940 1941 Software events are supported either built-in or via the 1942 use of generic tracepoints. 1943 1944 Most modern CPUs support performance events via performance 1945 counter registers. These registers count the number of certain 1946 types of hw events: such as instructions executed, cachemisses 1947 suffered, or branches mis-predicted - without slowing down the 1948 kernel or applications. These registers can also trigger interrupts 1949 when a threshold number of events have passed - and can thus be 1950 used to profile the code that runs on that CPU. 1951 1952 The Linux Performance Event subsystem provides an abstraction of 1953 these software and hardware event capabilities, available via a 1954 system call and used by the "perf" utility in tools/perf/. It 1955 provides per task and per CPU counters, and it provides event 1956 capabilities on top of those. 1957 1958 Say Y if unsure. 1959 1960config DEBUG_PERF_USE_VMALLOC 1961 default n 1962 bool "Debug: use vmalloc to back perf mmap() buffers" 1963 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 1964 select PERF_USE_VMALLOC 1965 help 1966 Use vmalloc memory to back perf mmap() buffers. 1967 1968 Mostly useful for debugging the vmalloc code on platforms 1969 that don't require it. 1970 1971 Say N if unsure. 1972 1973endmenu 1974 1975config SYSTEM_DATA_VERIFICATION 1976 def_bool n 1977 select SYSTEM_TRUSTED_KEYRING 1978 select KEYS 1979 select CRYPTO 1980 select CRYPTO_RSA 1981 select ASYMMETRIC_KEY_TYPE 1982 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1983 select ASN1 1984 select OID_REGISTRY 1985 select X509_CERTIFICATE_PARSER 1986 select PKCS7_MESSAGE_PARSER 1987 help 1988 Provide PKCS#7 message verification using the contents of the system 1989 trusted keyring to provide public keys. This then can be used for 1990 module verification, kexec image verification and firmware blob 1991 verification. 1992 1993config PROFILING 1994 bool "Profiling support" 1995 help 1996 Say Y here to enable the extended profiling support mechanisms used 1997 by profilers. 1998 1999config RUST 2000 bool "Rust support" 2001 depends on HAVE_RUST 2002 depends on RUST_IS_AVAILABLE 2003 select EXTENDED_MODVERSIONS if MODVERSIONS 2004 depends on !MODVERSIONS || GENDWARFKSYMS 2005 depends on !GCC_PLUGIN_RANDSTRUCT 2006 depends on !RANDSTRUCT 2007 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2008 depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2009 select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG 2010 depends on !CALL_PADDING || RUSTC_VERSION >= 108100 2011 depends on !KASAN_SW_TAGS 2012 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300 2013 help 2014 Enables Rust support in the kernel. 2015 2016 This allows other Rust-related options, like drivers written in Rust, 2017 to be selected. 2018 2019 It is also required to be able to load external kernel modules 2020 written in Rust. 2021 2022 See Documentation/rust/ for more information. 2023 2024 If unsure, say N. 2025 2026config RUSTC_VERSION_TEXT 2027 string 2028 depends on RUST 2029 default "$(RUSTC_VERSION_TEXT)" 2030 help 2031 See `CC_VERSION_TEXT`. 2032 2033config BINDGEN_VERSION_TEXT 2034 string 2035 depends on RUST 2036 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0 2037 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0 2038 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed 2039 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1 2040 # both fixed the issue). 2041 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)" 2042 2043# 2044# Place an empty function call at each tracepoint site. Can be 2045# dynamically changed for a probe function. 2046# 2047config TRACEPOINTS 2048 bool 2049 select TASKS_TRACE_RCU 2050 2051source "kernel/Kconfig.kexec" 2052 2053endmenu # General setup 2054 2055source "arch/Kconfig" 2056 2057config RT_MUTEXES 2058 bool 2059 default y if PREEMPT_RT 2060 2061config MODULE_SIG_FORMAT 2062 def_bool n 2063 select SYSTEM_DATA_VERIFICATION 2064 2065source "kernel/module/Kconfig" 2066 2067config INIT_ALL_POSSIBLE 2068 bool 2069 help 2070 Back when each arch used to define their own cpu_online_mask and 2071 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2072 with all 1s, and others with all 0s. When they were centralised, 2073 it was better to provide this option than to break all the archs 2074 and have several arch maintainers pursuing me down dark alleys. 2075 2076source "block/Kconfig" 2077 2078config PREEMPT_NOTIFIERS 2079 bool 2080 2081config PADATA 2082 depends on SMP 2083 bool 2084 2085config ASN1 2086 tristate 2087 help 2088 Build a simple ASN.1 grammar compiler that produces a bytecode output 2089 that can be interpreted by the ASN.1 stream decoder and used to 2090 inform it as to what tags are to be expected in a stream and what 2091 functions to call on what tags. 2092 2093source "kernel/Kconfig.locks" 2094 2095config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2096 bool 2097 2098config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2099 bool 2100 2101config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2102 bool 2103 2104# It may be useful for an architecture to override the definitions of the 2105# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2106# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2107# different calling convention for syscalls. They can also override the 2108# macros for not-implemented syscalls in kernel/sys_ni.c and 2109# kernel/time/posix-stubs.c. All these overrides need to be available in 2110# <asm/syscall_wrapper.h>. 2111config ARCH_HAS_SYSCALL_WRAPPER 2112 def_bool n 2113