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