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 ARCH_HAS_CC_CAN_LINK 86 bool 87 88config CC_CAN_LINK 89 bool 90 default ARCH_CC_CAN_LINK if ARCH_HAS_CC_CAN_LINK 91 default $(cc_can_link_user,$(m64-flag)) if 64BIT 92 default $(cc_can_link_user,$(m32-flag)) 93 94# Fixed in GCC 14, 13.3, 12.4 and 11.5 95# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 96config GCC_ASM_GOTO_OUTPUT_BROKEN 97 bool 98 depends on CC_IS_GCC 99 default y if GCC_VERSION < 110500 100 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400 101 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300 102 103config CC_HAS_ASM_GOTO_OUTPUT 104 def_bool y 105 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN 106 # Detect basic support 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 # Detect clang (< v17) scoped label issues 109 depends on $(success,echo 'void b(void **);void* c(void);int f(void){{asm goto(""::::l0);return 0;l0:return 1;}void *x __attribute__((cleanup(b)))=c();{asm goto(""::::l1);return 2;l1:return 3;}}' | $(CC) -x c - -c -o /dev/null) 110 111config CC_HAS_ASM_GOTO_TIED_OUTPUT 112 depends on CC_HAS_ASM_GOTO_OUTPUT 113 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 114 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) 115 116config TOOLS_SUPPORT_RELR 117 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 118 119config CC_HAS_ASM_INLINE 120 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 121 122config CC_HAS_ASSUME 123 bool 124 # clang needs to be at least 19.1.0 since the meaning of the assume 125 # attribute changed: 126 # https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17 127 default y if CC_IS_CLANG && CLANG_VERSION >= 190100 128 # supported since gcc 13.1.0 129 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654 130 default y if CC_IS_GCC && GCC_VERSION >= 130100 131 132config CC_HAS_NO_PROFILE_FN_ATTR 133 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 134 135config CC_HAS_COUNTED_BY 136 bool 137 # clang needs to be at least 20.1.0 to avoid potential crashes 138 # when building structures that contain __counted_by 139 # https://github.com/ClangBuiltLinux/linux/issues/2114 140 # https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489 141 default y if CC_IS_CLANG && CLANG_VERSION >= 200100 142 # supported since gcc 15.1.0 143 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 144 default y if CC_IS_GCC && GCC_VERSION >= 150100 145 146config CC_HAS_COUNTED_BY_PTR 147 bool 148 # supported since clang 22 149 default y if CC_IS_CLANG && CLANG_VERSION >= 220000 150 # supported since gcc 16.0.0 151 default y if CC_IS_GCC && GCC_VERSION >= 160000 152 153config CC_HAS_MULTIDIMENSIONAL_NONSTRING 154 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 155 156config LD_CAN_USE_KEEP_IN_OVERLAY 157 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 158 # https://github.com/llvm/llvm-project/pull/130661 159 def_bool LD_IS_BFD || LLD_VERSION >= 210000 160 161config RUSTC_HAS_SLICE_AS_FLATTENED 162 def_bool RUSTC_VERSION >= 108000 163 164config RUSTC_HAS_COERCE_POINTEE 165 def_bool RUSTC_VERSION >= 108400 166 167config RUSTC_HAS_SPAN_FILE 168 def_bool RUSTC_VERSION >= 108800 169 170config RUSTC_HAS_UNNECESSARY_TRANSMUTES 171 def_bool RUSTC_VERSION >= 108800 172 173config RUSTC_HAS_FILE_WITH_NUL 174 def_bool RUSTC_VERSION >= 108900 175 176config RUSTC_HAS_FILE_AS_C_STR 177 def_bool RUSTC_VERSION >= 109100 178 179config PAHOLE_VERSION 180 int 181 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) 182 183config CONSTRUCTORS 184 bool 185 186config IRQ_WORK 187 def_bool y if SMP 188 189config BUILDTIME_TABLE_SORT 190 bool 191 192config THREAD_INFO_IN_TASK 193 bool 194 help 195 Select this to move thread_info off the stack into task_struct. To 196 make this work, an arch will need to remove all thread_info fields 197 except flags and fix any runtime bugs. 198 199 One subtle change that will be needed is to use try_get_task_stack() 200 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 201 202menu "General setup" 203 204config BROKEN 205 bool 206 help 207 This option allows you to choose whether you want to try to 208 compile (and fix) old drivers that haven't been updated to 209 new infrastructure. 210 211config BROKEN_ON_SMP 212 bool 213 depends on BROKEN || !SMP 214 default y 215 216config INIT_ENV_ARG_LIMIT 217 int 218 default 32 if !UML 219 default 128 if UML 220 help 221 Maximum of each of the number of arguments and environment 222 variables passed to init from the kernel command line. 223 224config COMPILE_TEST 225 bool "Compile also drivers which will not load" 226 depends on HAS_IOMEM 227 help 228 Some drivers can be compiled on a different platform than they are 229 intended to be run on. Despite they cannot be loaded there (or even 230 when they load they cannot be used due to missing HW support), 231 developers still, opposing to distributors, might want to build such 232 drivers to compile-test them. 233 234 If you are a developer and want to build everything available, say Y 235 here. If you are a user/distributor, say N here to exclude useless 236 drivers to be distributed. 237 238config WERROR 239 bool "Compile the kernel with warnings as errors" 240 default COMPILE_TEST 241 help 242 A kernel build should not cause any compiler warnings, and this 243 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 244 to enforce that rule by default. Certain warnings from other tools 245 such as the linker may be upgraded to errors with this option as 246 well. 247 248 However, if you have a new (or very old) compiler or linker with odd 249 and unusual warnings, or you have some architecture with problems, 250 you may need to disable this config option in order to 251 successfully build the kernel. 252 253 If in doubt, say Y. 254 255config UAPI_HEADER_TEST 256 bool "Compile test UAPI headers" 257 depends on HEADERS_INSTALL && CC_CAN_LINK 258 help 259 Compile test headers exported to user-space to ensure they are 260 self-contained, i.e. compilable as standalone units. 261 262 If you are a developer or tester and want to ensure the exported 263 headers are self-contained, say Y here. Otherwise, choose N. 264 265config LOCALVERSION 266 string "Local version - append to kernel release" 267 help 268 Append an extra string to the end of your kernel version. 269 This will show up when you type uname, for example. 270 The string you set here will be appended after the contents of 271 any files with a filename matching localversion* in your 272 object and source tree, in that order. Your total string can 273 be a maximum of 64 characters. 274 275config LOCALVERSION_AUTO 276 bool "Automatically append version information to the version string" 277 default y 278 depends on !COMPILE_TEST 279 help 280 This will try to automatically determine if the current tree is a 281 release tree by looking for git tags that belong to the current 282 top of tree revision. 283 284 A string of the format -gxxxxxxxx will be added to the localversion 285 if a git-based tree is found. The string generated by this will be 286 appended after any matching localversion* files, and after the value 287 set in CONFIG_LOCALVERSION. 288 289 (The actual string used here is the first 12 characters produced 290 by running the command: 291 292 $ git rev-parse --verify HEAD 293 294 which is done within the script "scripts/setlocalversion".) 295 296config BUILD_SALT 297 string "Build ID Salt" 298 default "" 299 help 300 The build ID is used to link binaries and their debug info. Setting 301 this option will use the value in the calculation of the build id. 302 This is mostly useful for distributions which want to ensure the 303 build is unique between builds. It's safe to leave the default. 304 305config HAVE_KERNEL_GZIP 306 bool 307 308config HAVE_KERNEL_BZIP2 309 bool 310 311config HAVE_KERNEL_LZMA 312 bool 313 314config HAVE_KERNEL_XZ 315 bool 316 317config HAVE_KERNEL_LZO 318 bool 319 320config HAVE_KERNEL_LZ4 321 bool 322 323config HAVE_KERNEL_ZSTD 324 bool 325 326config HAVE_KERNEL_UNCOMPRESSED 327 bool 328 329choice 330 prompt "Kernel compression mode" 331 default KERNEL_GZIP 332 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 333 help 334 The linux kernel is a kind of self-extracting executable. 335 Several compression algorithms are available, which differ 336 in efficiency, compression and decompression speed. 337 Compression speed is only relevant when building a kernel. 338 Decompression speed is relevant at each boot. 339 340 If you have any problems with bzip2 or lzma compressed 341 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 342 version of this functionality (bzip2 only), for 2.4, was 343 supplied by Christian Ludwig) 344 345 High compression options are mostly useful for users, who 346 are low on disk space (embedded systems), but for whom ram 347 size matters less. 348 349 If in doubt, select 'gzip' 350 351config KERNEL_GZIP 352 bool "Gzip" 353 depends on HAVE_KERNEL_GZIP 354 help 355 The old and tried gzip compression. It provides a good balance 356 between compression ratio and decompression speed. 357 358config KERNEL_BZIP2 359 bool "Bzip2" 360 depends on HAVE_KERNEL_BZIP2 361 help 362 Its compression ratio and speed is intermediate. 363 Decompression speed is slowest among the choices. The kernel 364 size is about 10% smaller with bzip2, in comparison to gzip. 365 Bzip2 uses a large amount of memory. For modern kernels you 366 will need at least 8MB RAM or more for booting. 367 368config KERNEL_LZMA 369 bool "LZMA" 370 depends on HAVE_KERNEL_LZMA 371 help 372 This compression algorithm's ratio is best. Decompression speed 373 is between gzip and bzip2. Compression is slowest. 374 The kernel size is about 33% smaller with LZMA in comparison to gzip. 375 376config KERNEL_XZ 377 bool "XZ" 378 depends on HAVE_KERNEL_XZ 379 help 380 XZ uses the LZMA2 algorithm and instruction set specific 381 BCJ filters which can improve compression ratio of executable 382 code. The size of the kernel is about 30% smaller with XZ in 383 comparison to gzip. On architectures for which there is a BCJ 384 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 385 and SPARC), XZ will create a few percent smaller kernel than 386 plain LZMA. 387 388 The speed is about the same as with LZMA: The decompression 389 speed of XZ is better than that of bzip2 but worse than gzip 390 and LZO. Compression is slow. 391 392config KERNEL_LZO 393 bool "LZO" 394 depends on HAVE_KERNEL_LZO 395 help 396 Its compression ratio is the poorest among the choices. The kernel 397 size is about 10% bigger than gzip; however its speed 398 (both compression and decompression) is the fastest. 399 400config KERNEL_LZ4 401 bool "LZ4" 402 depends on HAVE_KERNEL_LZ4 403 help 404 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 405 A preliminary version of LZ4 de/compression tool is available at 406 <https://code.google.com/p/lz4/>. 407 408 Its compression ratio is worse than LZO. The size of the kernel 409 is about 8% bigger than LZO. But the decompression speed is 410 faster than LZO. 411 412config KERNEL_ZSTD 413 bool "ZSTD" 414 depends on HAVE_KERNEL_ZSTD 415 help 416 ZSTD is a compression algorithm targeting intermediate compression 417 with fast decompression speed. It will compress better than GZIP and 418 decompress around the same speed as LZO, but slower than LZ4. You 419 will need at least 192 KB RAM or more for booting. The zstd command 420 line tool is required for compression. 421 422config KERNEL_UNCOMPRESSED 423 bool "None" 424 depends on HAVE_KERNEL_UNCOMPRESSED 425 help 426 Produce uncompressed kernel image. This option is usually not what 427 you want. It is useful for debugging the kernel in slow simulation 428 environments, where decompressing and moving the kernel is awfully 429 slow. This option allows early boot code to skip the decompressor 430 and jump right at uncompressed kernel image. 431 432endchoice 433 434config DEFAULT_INIT 435 string "Default init path" 436 default "" 437 help 438 This option determines the default init for the system if no init= 439 option is passed on the kernel command line. If the requested path is 440 not present, we will still then move on to attempting further 441 locations (e.g. /sbin/init, etc). If this is empty, we will just use 442 the fallback list when init= is not passed. 443 444config DEFAULT_HOSTNAME 445 string "Default hostname" 446 default "(none)" 447 help 448 This option determines the default system hostname before userspace 449 calls sethostname(2). The kernel traditionally uses "(none)" here, 450 but you may wish to use a different default here to make a minimal 451 system more usable with less configuration. 452 453config SYSVIPC 454 bool "System V IPC" 455 help 456 Inter Process Communication is a suite of library functions and 457 system calls which let processes (running programs) synchronize and 458 exchange information. It is generally considered to be a good thing, 459 and some programs won't run unless you say Y here. In particular, if 460 you want to run the DOS emulator dosemu under Linux (read the 461 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 462 you'll need to say Y here. 463 464 You can find documentation about IPC with "info ipc" and also in 465 section 6.4 of the Linux Programmer's Guide, available from 466 <http://www.tldp.org/guides.html>. 467 468config SYSVIPC_SYSCTL 469 bool 470 depends on SYSVIPC 471 depends on SYSCTL 472 default y 473 474config SYSVIPC_COMPAT 475 def_bool y 476 depends on COMPAT && SYSVIPC 477 478config POSIX_MQUEUE 479 bool "POSIX Message Queues" 480 depends on NET 481 help 482 POSIX variant of message queues is a part of IPC. In POSIX message 483 queues every message has a priority which decides about succession 484 of receiving it by a process. If you want to compile and run 485 programs written e.g. for Solaris with use of its POSIX message 486 queues (functions mq_*) say Y here. 487 488 POSIX message queues are visible as a filesystem called 'mqueue' 489 and can be mounted somewhere if you want to do filesystem 490 operations on message queues. 491 492 If unsure, say Y. 493 494config POSIX_MQUEUE_SYSCTL 495 bool 496 depends on POSIX_MQUEUE 497 depends on SYSCTL 498 default y 499 500config WATCH_QUEUE 501 bool "General notification queue" 502 default n 503 help 504 505 This is a general notification queue for the kernel to pass events to 506 userspace by splicing them into pipes. It can be used in conjunction 507 with watches for key/keyring change notifications and device 508 notifications. 509 510 See Documentation/core-api/watch_queue.rst 511 512config CROSS_MEMORY_ATTACH 513 bool "Enable process_vm_readv/writev syscalls" 514 depends on MMU 515 default y 516 help 517 Enabling this option adds the system calls process_vm_readv and 518 process_vm_writev which allow a process with the correct privileges 519 to directly read from or write to another process' address space. 520 See the man page for more details. 521 522config AUDIT 523 bool "Auditing support" 524 depends on NET 525 help 526 Enable auditing infrastructure that can be used with another 527 kernel subsystem, such as SELinux (which requires this for 528 logging of avc messages output). System call auditing is included 529 on architectures which support it. 530 531config HAVE_ARCH_AUDITSYSCALL 532 bool 533 534config AUDITSYSCALL 535 def_bool y 536 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 537 select FSNOTIFY 538 539source "kernel/irq/Kconfig" 540source "kernel/time/Kconfig" 541source "kernel/bpf/Kconfig" 542source "kernel/Kconfig.preempt" 543 544menu "CPU/Task time and stats accounting" 545 546config VIRT_CPU_ACCOUNTING 547 bool 548 549choice 550 prompt "Cputime accounting" 551 default TICK_CPU_ACCOUNTING 552 553# Kind of a stub config for the pure tick based cputime accounting 554config TICK_CPU_ACCOUNTING 555 bool "Simple tick based cputime accounting" 556 depends on !S390 && !NO_HZ_FULL 557 help 558 This is the basic tick based cputime accounting that maintains 559 statistics about user, system and idle time spent on per jiffies 560 granularity. 561 562 If unsure, say Y. 563 564config VIRT_CPU_ACCOUNTING_NATIVE 565 bool "Deterministic task and CPU time accounting" 566 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 567 select VIRT_CPU_ACCOUNTING 568 help 569 Select this option to enable more accurate task and CPU time 570 accounting. This is done by reading a CPU counter on each 571 kernel entry and exit and on transitions within the kernel 572 between system, softirq and hardirq state, so there is a 573 small performance impact. In the case of s390 or IBM POWER > 5, 574 this also enables accounting of stolen time on logically-partitioned 575 systems. 576 577config VIRT_CPU_ACCOUNTING_GEN 578 bool "Full dynticks CPU time accounting" 579 depends on HAVE_CONTEXT_TRACKING_USER 580 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 581 depends on GENERIC_CLOCKEVENTS 582 select VIRT_CPU_ACCOUNTING 583 select CONTEXT_TRACKING_USER 584 help 585 Select this option to enable task and CPU time accounting on full 586 dynticks systems. This accounting is implemented by watching every 587 kernel-user boundaries using the context tracking subsystem. 588 The accounting is thus performed at the expense of some significant 589 overhead. 590 591 For now this is only useful if you are working on the full 592 dynticks subsystem development. 593 594 If unsure, say N. 595 596endchoice 597 598config IRQ_TIME_ACCOUNTING 599 bool "Fine granularity task level IRQ time accounting" 600 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 601 help 602 Select this option to enable fine granularity task irq time 603 accounting. This is done by reading a timestamp on each 604 transitions between softirq and hardirq state, so there can be a 605 small performance impact. 606 607 If in doubt, say N here. 608 609config HAVE_SCHED_AVG_IRQ 610 def_bool y 611 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 612 depends on SMP 613 614config SCHED_HW_PRESSURE 615 bool 616 default y if ARM && ARM_CPU_TOPOLOGY 617 default y if ARM64 618 depends on SMP 619 depends on CPU_FREQ_THERMAL 620 help 621 Select this option to enable HW pressure accounting in the 622 scheduler. HW pressure is the value conveyed to the scheduler 623 that reflects the reduction in CPU compute capacity resulted from 624 HW throttling. HW throttling occurs when the performance of 625 a CPU is capped due to high operating temperatures as an example. 626 627 If selected, the scheduler will be able to balance tasks accordingly, 628 i.e. put less load on throttled CPUs than on non/less throttled ones. 629 630 This requires the architecture to implement 631 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 632 633config BSD_PROCESS_ACCT 634 bool "BSD Process Accounting" 635 depends on MULTIUSER 636 help 637 If you say Y here, a user level program will be able to instruct the 638 kernel (via a special system call) to write process accounting 639 information to a file: whenever a process exits, information about 640 that process will be appended to the file by the kernel. The 641 information includes things such as creation time, owning user, 642 command name, memory usage, controlling terminal etc. (the complete 643 list is in the struct acct in <file:include/linux/acct.h>). It is 644 up to the user level program to do useful things with this 645 information. This is generally a good idea, so say Y. 646 647config BSD_PROCESS_ACCT_V3 648 bool "BSD Process Accounting version 3 file format" 649 depends on BSD_PROCESS_ACCT 650 default n 651 help 652 If you say Y here, the process accounting information is written 653 in a new file format that also logs the process IDs of each 654 process and its parent. Note that this file format is incompatible 655 with previous v0/v1/v2 file formats, so you will need updated tools 656 for processing it. A preliminary version of these tools is available 657 at <http://www.gnu.org/software/acct/>. 658 659config TASKSTATS 660 bool "Export task/process statistics through netlink" 661 depends on NET 662 depends on MULTIUSER 663 default n 664 help 665 Export selected statistics for tasks/processes through the 666 generic netlink interface. Unlike BSD process accounting, the 667 statistics are available during the lifetime of tasks/processes as 668 responses to commands. Like BSD accounting, they are sent to user 669 space on task exit. 670 671 Say N if unsure. 672 673config TASK_DELAY_ACCT 674 bool "Enable per-task delay accounting" 675 depends on TASKSTATS 676 select SCHED_INFO 677 help 678 Collect information on time spent by a task waiting for system 679 resources like cpu, synchronous block I/O completion and swapping 680 in pages. Such statistics can help in setting a task's priorities 681 relative to other tasks for cpu, io, rss limits etc. 682 683 Say N if unsure. 684 685config TASK_XACCT 686 bool "Enable extended accounting over taskstats" 687 depends on TASKSTATS 688 help 689 Collect extended task accounting data and send the data 690 to userland for processing over the taskstats interface. 691 692 Say N if unsure. 693 694config TASK_IO_ACCOUNTING 695 bool "Enable per-task storage I/O accounting" 696 depends on TASK_XACCT 697 help 698 Collect information on the number of bytes of storage I/O which this 699 task has caused. 700 701 Say N if unsure. 702 703config PSI 704 bool "Pressure stall information tracking" 705 select KERNFS 706 help 707 Collect metrics that indicate how overcommitted the CPU, memory, 708 and IO capacity are in the system. 709 710 If you say Y here, the kernel will create /proc/pressure/ with the 711 pressure statistics files cpu, memory, and io. These will indicate 712 the share of walltime in which some or all tasks in the system are 713 delayed due to contention of the respective resource. 714 715 In kernels with cgroup support, cgroups (cgroup2 only) will 716 have cpu.pressure, memory.pressure, and io.pressure files, 717 which aggregate pressure stalls for the grouped tasks only. 718 719 For more details see Documentation/accounting/psi.rst. 720 721 Say N if unsure. 722 723config PSI_DEFAULT_DISABLED 724 bool "Require boot parameter to enable pressure stall information tracking" 725 default n 726 depends on PSI 727 help 728 If set, pressure stall information tracking will be disabled 729 per default but can be enabled through passing psi=1 on the 730 kernel commandline during boot. 731 732 This feature adds some code to the task wakeup and sleep 733 paths of the scheduler. The overhead is too low to affect 734 common scheduling-intense workloads in practice (such as 735 webservers, memcache), but it does show up in artificial 736 scheduler stress tests, such as hackbench. 737 738 If you are paranoid and not sure what the kernel will be 739 used for, say Y. 740 741 Say N if unsure. 742 743endmenu # "CPU/Task time and stats accounting" 744 745config CPU_ISOLATION 746 bool "CPU isolation" 747 depends on SMP 748 default y 749 help 750 Make sure that CPUs running critical tasks are not disturbed by 751 any source of "noise" such as unbound workqueues, timers, kthreads... 752 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 753 the "isolcpus=" boot parameter. 754 755 Say Y if unsure. 756 757source "kernel/rcu/Kconfig" 758 759config IKCONFIG 760 tristate "Kernel .config support" 761 help 762 This option enables the complete Linux kernel ".config" file 763 contents to be saved in the kernel. It provides documentation 764 of which kernel options are used in a running kernel or in an 765 on-disk kernel. This information can be extracted from the kernel 766 image file with the script scripts/extract-ikconfig and used as 767 input to rebuild the current kernel or to build another kernel. 768 It can also be extracted from a running kernel by reading 769 /proc/config.gz if enabled (below). 770 771config IKCONFIG_PROC 772 bool "Enable access to .config through /proc/config.gz" 773 depends on IKCONFIG && PROC_FS 774 help 775 This option enables access to the kernel configuration file 776 through /proc/config.gz. 777 778config IKHEADERS 779 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 780 depends on SYSFS 781 help 782 This option enables access to the in-kernel headers that are generated during 783 the build process. These can be used to build eBPF tracing programs, 784 or similar programs. If you build the headers as a module, a module called 785 kheaders.ko is built which can be loaded on-demand to get access to headers. 786 787config LOG_BUF_SHIFT 788 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 789 range 12 25 790 default 17 791 depends on PRINTK 792 help 793 Select the minimal kernel log buffer size as a power of 2. 794 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 795 parameter, see below. Any higher size also might be forced 796 by "log_buf_len" boot parameter. 797 798 Examples: 799 17 => 128 KB 800 16 => 64 KB 801 15 => 32 KB 802 14 => 16 KB 803 13 => 8 KB 804 12 => 4 KB 805 806config LOG_CPU_MAX_BUF_SHIFT 807 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 808 depends on SMP 809 range 0 21 810 default 0 if BASE_SMALL 811 default 12 812 depends on PRINTK 813 help 814 This option allows to increase the default ring buffer size 815 according to the number of CPUs. The value defines the contribution 816 of each CPU as a power of 2. The used space is typically only few 817 lines however it might be much more when problems are reported, 818 e.g. backtraces. 819 820 The increased size means that a new buffer has to be allocated and 821 the original static one is unused. It makes sense only on systems 822 with more CPUs. Therefore this value is used only when the sum of 823 contributions is greater than the half of the default kernel ring 824 buffer as defined by LOG_BUF_SHIFT. The default values are set 825 so that more than 16 CPUs are needed to trigger the allocation. 826 827 Also this option is ignored when "log_buf_len" kernel parameter is 828 used as it forces an exact (power of two) size of the ring buffer. 829 830 The number of possible CPUs is used for this computation ignoring 831 hotplugging making the computation optimal for the worst case 832 scenario while allowing a simple algorithm to be used from bootup. 833 834 Examples shift values and their meaning: 835 17 => 128 KB for each CPU 836 16 => 64 KB for each CPU 837 15 => 32 KB for each CPU 838 14 => 16 KB for each CPU 839 13 => 8 KB for each CPU 840 12 => 4 KB for each CPU 841 842config PRINTK_INDEX 843 bool "Printk indexing debugfs interface" 844 depends on PRINTK && DEBUG_FS 845 help 846 Add support for indexing of all printk formats known at compile time 847 at <debugfs>/printk/index/<module>. 848 849 This can be used as part of maintaining daemons which monitor 850 /dev/kmsg, as it permits auditing the printk formats present in a 851 kernel, allowing detection of cases where monitored printks are 852 changed or no longer present. 853 854 There is no additional runtime cost to printk with this enabled. 855 856# 857# Architectures with an unreliable sched_clock() should select this: 858# 859config HAVE_UNSTABLE_SCHED_CLOCK 860 bool 861 862config GENERIC_SCHED_CLOCK 863 bool 864 865menu "Scheduler features" 866 867config UCLAMP_TASK 868 bool "Enable utilization clamping for RT/FAIR tasks" 869 depends on CPU_FREQ_GOV_SCHEDUTIL 870 help 871 This feature enables the scheduler to track the clamped utilization 872 of each CPU based on RUNNABLE tasks scheduled on that CPU. 873 874 With this option, the user can specify the min and max CPU 875 utilization allowed for RUNNABLE tasks. The max utilization defines 876 the maximum frequency a task should use while the min utilization 877 defines the minimum frequency it should use. 878 879 Both min and max utilization clamp values are hints to the scheduler, 880 aiming at improving its frequency selection policy, but they do not 881 enforce or grant any specific bandwidth for tasks. 882 883 If in doubt, say N. 884 885config UCLAMP_BUCKETS_COUNT 886 int "Number of supported utilization clamp buckets" 887 range 5 20 888 default 5 889 depends on UCLAMP_TASK 890 help 891 Defines the number of clamp buckets to use. The range of each bucket 892 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 893 number of clamp buckets the finer their granularity and the higher 894 the precision of clamping aggregation and tracking at run-time. 895 896 For example, with the minimum configuration value we will have 5 897 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 898 be refcounted in the [20..39]% bucket and will set the bucket clamp 899 effective value to 25%. 900 If a second 30% boosted task should be co-scheduled on the same CPU, 901 that task will be refcounted in the same bucket of the first task and 902 it will boost the bucket clamp effective value to 30%. 903 The clamp effective value of a bucket is reset to its nominal value 904 (20% in the example above) when there are no more tasks refcounted in 905 that bucket. 906 907 An additional boost/capping margin can be added to some tasks. In the 908 example above the 25% task will be boosted to 30% until it exits the 909 CPU. If that should be considered not acceptable on certain systems, 910 it's always possible to reduce the margin by increasing the number of 911 clamp buckets to trade off used memory for run-time tracking 912 precision. 913 914 If in doubt, use the default value. 915 916config SCHED_PROXY_EXEC 917 bool "Proxy Execution" 918 # Avoid some build failures w/ PREEMPT_RT until it can be fixed 919 depends on !PREEMPT_RT 920 # Need to investigate how to inform sched_ext of split contexts 921 depends on !SCHED_CLASS_EXT 922 # Not particularly useful until we get to multi-rq proxying 923 depends on EXPERT 924 help 925 This option enables proxy execution, a mechanism for mutex-owning 926 tasks to inherit the scheduling context of higher priority waiters. 927 928endmenu 929 930# 931# For architectures that want to enable the support for NUMA-affine scheduler 932# balancing logic: 933# 934config ARCH_SUPPORTS_NUMA_BALANCING 935 bool 936 937# 938# For architectures that prefer to flush all TLBs after a number of pages 939# are unmapped instead of sending one IPI per page to flush. The architecture 940# must provide guarantees on what happens if a clean TLB cache entry is 941# written after the unmap. Details are in mm/rmap.c near the check for 942# should_defer_flush. The architecture should also consider if the full flush 943# and the refill costs are offset by the savings of sending fewer IPIs. 944config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 945 bool 946 947config CC_HAS_INT128 948 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 949 950config CC_IMPLICIT_FALLTHROUGH 951 string 952 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 953 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 954 955# Currently, disable gcc-10+ array-bounds globally. 956# It's still broken in gcc-13, so no upper bound yet. 957config GCC10_NO_ARRAY_BOUNDS 958 def_bool y 959 960config CC_NO_ARRAY_BOUNDS 961 bool 962 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 963 964# Currently, disable -Wstringop-overflow for GCC globally. 965config GCC_NO_STRINGOP_OVERFLOW 966 def_bool y 967 968config CC_NO_STRINGOP_OVERFLOW 969 bool 970 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 971 972config CC_STRINGOP_OVERFLOW 973 bool 974 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 975 976# 977# For architectures that know their GCC __int128 support is sound 978# 979config ARCH_SUPPORTS_INT128 980 bool 981 982# For architectures that (ab)use NUMA to represent different memory regions 983# all cpu-local but of different latencies, such as SuperH. 984# 985config ARCH_WANT_NUMA_VARIABLE_LOCALITY 986 bool 987 988config NUMA_BALANCING 989 bool "Memory placement aware NUMA scheduler" 990 depends on ARCH_SUPPORTS_NUMA_BALANCING 991 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 992 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 993 help 994 This option adds support for automatic NUMA aware memory/task placement. 995 The mechanism is quite primitive and is based on migrating memory when 996 it has references to the node the task is running on. 997 998 This system will be inactive on UMA systems. 999 1000config NUMA_BALANCING_DEFAULT_ENABLED 1001 bool "Automatically enable NUMA aware memory/task placement" 1002 default y 1003 depends on NUMA_BALANCING 1004 help 1005 If set, automatic NUMA balancing will be enabled if running on a NUMA 1006 machine. 1007 1008config SLAB_OBJ_EXT 1009 bool 1010 1011menuconfig CGROUPS 1012 bool "Control Group support" 1013 select KERNFS 1014 help 1015 This option adds support for grouping sets of processes together, for 1016 use with process control subsystems such as Cpusets, CFS, memory 1017 controls or device isolation. 1018 See 1019 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1020 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1021 and resource control) 1022 1023 Say N if unsure. 1024 1025if CGROUPS 1026 1027config PAGE_COUNTER 1028 bool 1029 1030config CGROUP_FAVOR_DYNMODS 1031 bool "Favor dynamic modification latency reduction by default" 1032 help 1033 This option enables the "favordynmods" mount option by default 1034 which reduces the latencies of dynamic cgroup modifications such 1035 as task migrations and controller on/offs at the cost of making 1036 hot path operations such as forks and exits more expensive. 1037 1038 Say N if unsure. 1039 1040config MEMCG 1041 bool "Memory controller" 1042 select PAGE_COUNTER 1043 select EVENTFD 1044 select SLAB_OBJ_EXT 1045 select VM_EVENT_COUNTERS 1046 help 1047 Provides control over the memory footprint of tasks in a cgroup. 1048 1049config MEMCG_NMI_UNSAFE 1050 bool 1051 depends on MEMCG 1052 depends on HAVE_NMI 1053 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1054 default y 1055 1056config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1057 bool 1058 depends on MEMCG 1059 depends on HAVE_NMI 1060 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1061 default y 1062 1063config MEMCG_V1 1064 bool "Legacy cgroup v1 memory controller" 1065 depends on MEMCG 1066 default n 1067 help 1068 Legacy cgroup v1 memory controller which has been deprecated by 1069 cgroup v2 implementation. The v1 is there for legacy applications 1070 which haven't migrated to the new cgroup v2 interface yet. If you 1071 do not have any such application then you are completely fine leaving 1072 this option disabled. 1073 1074 Please note that feature set of the legacy memory controller is likely 1075 going to shrink due to deprecation process. New deployments with v1 1076 controller are highly discouraged. 1077 1078 Say N if unsure. 1079 1080config BLK_CGROUP 1081 bool "IO controller" 1082 depends on BLOCK 1083 default n 1084 help 1085 Generic block IO controller cgroup interface. This is the common 1086 cgroup interface which should be used by various IO controlling 1087 policies. 1088 1089 Currently, CFQ IO scheduler uses it to recognize task groups and 1090 control disk bandwidth allocation (proportional time slice allocation) 1091 to such task groups. It is also used by bio throttling logic in 1092 block layer to implement upper limit in IO rates on a device. 1093 1094 This option only enables generic Block IO controller infrastructure. 1095 One needs to also enable actual IO controlling logic/policy. For 1096 enabling proportional weight division of disk bandwidth in CFQ, set 1097 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1098 CONFIG_BLK_DEV_THROTTLING=y. 1099 1100 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1101 1102config CGROUP_WRITEBACK 1103 bool 1104 depends on MEMCG && BLK_CGROUP 1105 default y 1106 1107menuconfig CGROUP_SCHED 1108 bool "CPU controller" 1109 default n 1110 help 1111 This feature lets CPU scheduler recognize task groups and control CPU 1112 bandwidth allocation to such task groups. It uses cgroups to group 1113 tasks. 1114 1115if CGROUP_SCHED 1116config GROUP_SCHED_WEIGHT 1117 def_bool n 1118 1119config GROUP_SCHED_BANDWIDTH 1120 def_bool n 1121 1122config FAIR_GROUP_SCHED 1123 bool "Group scheduling for SCHED_OTHER" 1124 depends on CGROUP_SCHED 1125 select GROUP_SCHED_WEIGHT 1126 default CGROUP_SCHED 1127 1128config CFS_BANDWIDTH 1129 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1130 depends on FAIR_GROUP_SCHED 1131 select GROUP_SCHED_BANDWIDTH 1132 default n 1133 help 1134 This option allows users to define CPU bandwidth rates (limits) for 1135 tasks running within the fair group scheduler. Groups with no limit 1136 set are considered to be unconstrained and will run with no 1137 restriction. 1138 See Documentation/scheduler/sched-bwc.rst for more information. 1139 1140config RT_GROUP_SCHED 1141 bool "Group scheduling for SCHED_RR/FIFO" 1142 depends on CGROUP_SCHED 1143 default n 1144 help 1145 This feature lets you explicitly allocate real CPU bandwidth 1146 to task groups. If enabled, it will also make it impossible to 1147 schedule realtime tasks for non-root users until you allocate 1148 realtime bandwidth for them. 1149 See Documentation/scheduler/sched-rt-group.rst for more information. 1150 1151config RT_GROUP_SCHED_DEFAULT_DISABLED 1152 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1153 depends on RT_GROUP_SCHED 1154 default n 1155 help 1156 When set, the RT group scheduling is disabled by default. The option 1157 is in inverted form so that mere RT_GROUP_SCHED enables the group 1158 scheduling. 1159 1160 Say N if unsure. 1161 1162config EXT_GROUP_SCHED 1163 bool 1164 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1165 select GROUP_SCHED_WEIGHT 1166 select GROUP_SCHED_BANDWIDTH 1167 default y 1168 1169endif #CGROUP_SCHED 1170 1171config SCHED_MM_CID 1172 def_bool y 1173 depends on SMP && RSEQ 1174 1175config UCLAMP_TASK_GROUP 1176 bool "Utilization clamping per group of tasks" 1177 depends on CGROUP_SCHED 1178 depends on UCLAMP_TASK 1179 default n 1180 help 1181 This feature enables the scheduler to track the clamped utilization 1182 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1183 1184 When this option is enabled, the user can specify a min and max 1185 CPU bandwidth which is allowed for each single task in a group. 1186 The max bandwidth allows to clamp the maximum frequency a task 1187 can use, while the min bandwidth allows to define a minimum 1188 frequency a task will always use. 1189 1190 When task group based utilization clamping is enabled, an eventually 1191 specified task-specific clamp value is constrained by the cgroup 1192 specified clamp value. Both minimum and maximum task clamping cannot 1193 be bigger than the corresponding clamping defined at task group level. 1194 1195 If in doubt, say N. 1196 1197config CGROUP_PIDS 1198 bool "PIDs controller" 1199 help 1200 Provides enforcement of process number limits in the scope of a 1201 cgroup. Any attempt to fork more processes than is allowed in the 1202 cgroup will fail. PIDs are fundamentally a global resource because it 1203 is fairly trivial to reach PID exhaustion before you reach even a 1204 conservative kmemcg limit. As a result, it is possible to grind a 1205 system to halt without being limited by other cgroup policies. The 1206 PIDs controller is designed to stop this from happening. 1207 1208 It should be noted that organisational operations (such as attaching 1209 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1210 since the PIDs limit only affects a process's ability to fork, not to 1211 attach to a cgroup. 1212 1213config CGROUP_RDMA 1214 bool "RDMA controller" 1215 help 1216 Provides enforcement of RDMA resources defined by IB stack. 1217 It is fairly easy for consumers to exhaust RDMA resources, which 1218 can result into resource unavailability to other consumers. 1219 RDMA controller is designed to stop this from happening. 1220 Attaching processes with active RDMA resources to the cgroup 1221 hierarchy is allowed even if can cross the hierarchy's limit. 1222 1223config CGROUP_DMEM 1224 bool "Device memory controller (DMEM)" 1225 select PAGE_COUNTER 1226 help 1227 The DMEM controller allows compatible devices to restrict device 1228 memory usage based on the cgroup hierarchy. 1229 1230 As an example, it allows you to restrict VRAM usage for applications 1231 in the DRM subsystem. 1232 1233config CGROUP_FREEZER 1234 bool "Freezer controller" 1235 help 1236 Provides a way to freeze and unfreeze all tasks in a 1237 cgroup. 1238 1239 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1240 controller includes important in-kernel memory consumers per default. 1241 1242 If you're using cgroup2, say N. 1243 1244config CGROUP_HUGETLB 1245 bool "HugeTLB controller" 1246 depends on HUGETLB_PAGE 1247 select PAGE_COUNTER 1248 default n 1249 help 1250 Provides a cgroup controller for HugeTLB pages. 1251 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1252 The limit is enforced during page fault. Since HugeTLB doesn't 1253 support page reclaim, enforcing the limit at page fault time implies 1254 that, the application will get SIGBUS signal if it tries to access 1255 HugeTLB pages beyond its limit. This requires the application to know 1256 beforehand how much HugeTLB pages it would require for its use. The 1257 control group is tracked in the third page lru pointer. This means 1258 that we cannot use the controller with huge page less than 3 pages. 1259 1260config CPUSETS 1261 bool "Cpuset controller" 1262 depends on SMP 1263 select UNION_FIND 1264 help 1265 This option will let you create and manage CPUSETs which 1266 allow dynamically partitioning a system into sets of CPUs and 1267 Memory Nodes and assigning tasks to run only within those sets. 1268 This is primarily useful on large SMP or NUMA systems. 1269 1270 Say N if unsure. 1271 1272config CPUSETS_V1 1273 bool "Legacy cgroup v1 cpusets controller" 1274 depends on CPUSETS 1275 default n 1276 help 1277 Legacy cgroup v1 cpusets controller which has been deprecated by 1278 cgroup v2 implementation. The v1 is there for legacy applications 1279 which haven't migrated to the new cgroup v2 interface yet. Legacy 1280 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1281 do not have any such application then you are completely fine leaving 1282 this option disabled. 1283 1284 Say N if unsure. 1285 1286config PROC_PID_CPUSET 1287 bool "Include legacy /proc/<pid>/cpuset file" 1288 depends on CPUSETS_V1 1289 default y 1290 1291config CGROUP_DEVICE 1292 bool "Device controller" 1293 help 1294 Provides a cgroup controller implementing whitelists for 1295 devices which a process in the cgroup can mknod or open. 1296 1297config CGROUP_CPUACCT 1298 bool "Simple CPU accounting controller" 1299 help 1300 Provides a simple controller for monitoring the 1301 total CPU consumed by the tasks in a cgroup. 1302 1303config CGROUP_PERF 1304 bool "Perf controller" 1305 depends on PERF_EVENTS 1306 help 1307 This option extends the perf per-cpu mode to restrict monitoring 1308 to threads which belong to the cgroup specified and run on the 1309 designated cpu. Or this can be used to have cgroup ID in samples 1310 so that it can monitor performance events among cgroups. 1311 1312 Say N if unsure. 1313 1314config CGROUP_BPF 1315 bool "Support for eBPF programs attached to cgroups" 1316 depends on BPF_SYSCALL 1317 select SOCK_CGROUP_DATA 1318 help 1319 Allow attaching eBPF programs to a cgroup using the bpf(2) 1320 syscall command BPF_PROG_ATTACH. 1321 1322 In which context these programs are accessed depends on the type 1323 of attachment. For instance, programs that are attached using 1324 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1325 inet sockets. 1326 1327config CGROUP_MISC 1328 bool "Misc resource controller" 1329 default n 1330 help 1331 Provides a controller for miscellaneous resources on a host. 1332 1333 Miscellaneous scalar resources are the resources on the host system 1334 which cannot be abstracted like the other cgroups. This controller 1335 tracks and limits the miscellaneous resources used by a process 1336 attached to a cgroup hierarchy. 1337 1338 For more information, please check misc cgroup section in 1339 /Documentation/admin-guide/cgroup-v2.rst. 1340 1341config CGROUP_DEBUG 1342 bool "Debug controller" 1343 default n 1344 depends on DEBUG_KERNEL 1345 help 1346 This option enables a simple controller that exports 1347 debugging information about the cgroups framework. This 1348 controller is for control cgroup debugging only. Its 1349 interfaces are not stable. 1350 1351 Say N. 1352 1353config SOCK_CGROUP_DATA 1354 bool 1355 default n 1356 1357endif # CGROUPS 1358 1359menuconfig NAMESPACES 1360 bool "Namespaces support" if EXPERT 1361 depends on MULTIUSER 1362 default !EXPERT 1363 help 1364 Provides the way to make tasks work with different objects using 1365 the same id. For example same IPC id may refer to different objects 1366 or same user id or pid may refer to different tasks when used in 1367 different namespaces. 1368 1369if NAMESPACES 1370 1371config UTS_NS 1372 bool "UTS namespace" 1373 default y 1374 help 1375 In this namespace tasks see different info provided with the 1376 uname() system call 1377 1378config TIME_NS 1379 bool "TIME namespace" 1380 depends on GENERIC_GETTIMEOFDAY 1381 default y 1382 help 1383 In this namespace boottime and monotonic clocks can be set. 1384 The time will keep going with the same pace. 1385 1386config IPC_NS 1387 bool "IPC namespace" 1388 depends on (SYSVIPC || POSIX_MQUEUE) 1389 default y 1390 help 1391 In this namespace tasks work with IPC ids which correspond to 1392 different IPC objects in different namespaces. 1393 1394config USER_NS 1395 bool "User namespace" 1396 default n 1397 help 1398 This allows containers, i.e. vservers, to use user namespaces 1399 to provide different user info for different servers. 1400 1401 When user namespaces are enabled in the kernel it is 1402 recommended that the MEMCG option also be enabled and that 1403 user-space use the memory control groups to limit the amount 1404 of memory a memory unprivileged users can use. 1405 1406 If unsure, say N. 1407 1408config PID_NS 1409 bool "PID Namespaces" 1410 default y 1411 help 1412 Support process id namespaces. This allows having multiple 1413 processes with the same pid as long as they are in different 1414 pid namespaces. This is a building block of containers. 1415 1416config NET_NS 1417 bool "Network namespace" 1418 depends on NET 1419 default y 1420 help 1421 Allow user space to create what appear to be multiple instances 1422 of the network stack. 1423 1424endif # NAMESPACES 1425 1426config CHECKPOINT_RESTORE 1427 bool "Checkpoint/restore support" 1428 depends on PROC_FS 1429 select PROC_CHILDREN 1430 select KCMP 1431 default n 1432 help 1433 Enables additional kernel features in a sake of checkpoint/restore. 1434 In particular it adds auxiliary prctl codes to setup process text, 1435 data and heap segment sizes, and a few additional /proc filesystem 1436 entries. 1437 1438 If unsure, say N here. 1439 1440config SCHED_AUTOGROUP 1441 bool "Automatic process group scheduling" 1442 select CGROUPS 1443 select CGROUP_SCHED 1444 select FAIR_GROUP_SCHED 1445 help 1446 This option optimizes the scheduler for common desktop workloads by 1447 automatically creating and populating task groups. This separation 1448 of workloads isolates aggressive CPU burners (like build jobs) from 1449 desktop applications. Task group autogeneration is currently based 1450 upon task session. 1451 1452config RELAY 1453 bool "Kernel->user space relay support (formerly relayfs)" 1454 select IRQ_WORK 1455 help 1456 This option enables support for relay interface support in 1457 certain file systems (such as debugfs). 1458 It is designed to provide an efficient mechanism for tools and 1459 facilities to relay large amounts of data from kernel space to 1460 user space. 1461 1462 If unsure, say N. 1463 1464config BLK_DEV_INITRD 1465 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1466 help 1467 The initial RAM filesystem is a ramfs which is loaded by the 1468 boot loader (loadlin or lilo) and that is mounted as root 1469 before the normal boot procedure. It is typically used to 1470 load modules needed to mount the "real" root file system, 1471 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1472 1473 If RAM disk support (BLK_DEV_RAM) is also included, this 1474 also enables initial RAM disk (initrd) support and adds 1475 15 Kbytes (more on some other architectures) to the kernel size. 1476 1477 If unsure say Y. 1478 1479if BLK_DEV_INITRD 1480 1481source "usr/Kconfig" 1482 1483endif 1484 1485config BOOT_CONFIG 1486 bool "Boot config support" 1487 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1488 help 1489 Extra boot config allows system admin to pass a config file as 1490 complemental extension of kernel cmdline when booting. 1491 The boot config file must be attached at the end of initramfs 1492 with checksum, size and magic word. 1493 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1494 1495 If unsure, say Y. 1496 1497config BOOT_CONFIG_FORCE 1498 bool "Force unconditional bootconfig processing" 1499 depends on BOOT_CONFIG 1500 default y if BOOT_CONFIG_EMBED 1501 help 1502 With this Kconfig option set, BOOT_CONFIG processing is carried 1503 out even when the "bootconfig" kernel-boot parameter is omitted. 1504 In fact, with this Kconfig option set, there is no way to 1505 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1506 parameters. 1507 1508 If unsure, say N. 1509 1510config BOOT_CONFIG_EMBED 1511 bool "Embed bootconfig file in the kernel" 1512 depends on BOOT_CONFIG 1513 help 1514 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1515 kernel. Usually, the bootconfig file is loaded with the initrd 1516 image. But if the system doesn't support initrd, this option will 1517 help you by embedding a bootconfig file while building the kernel. 1518 1519 If unsure, say N. 1520 1521config BOOT_CONFIG_EMBED_FILE 1522 string "Embedded bootconfig file path" 1523 depends on BOOT_CONFIG_EMBED 1524 help 1525 Specify a bootconfig file which will be embedded to the kernel. 1526 This bootconfig will be used if there is no initrd or no other 1527 bootconfig in the initrd. 1528 1529config CMDLINE_LOG_WRAP_IDEAL_LEN 1530 int "Length to try to wrap the cmdline when logged at boot" 1531 default 1021 1532 range 0 1021 1533 help 1534 At boot time, the kernel command line is logged to the console. 1535 The log message will start with the prefix "Kernel command line: ". 1536 The log message will attempt to be wrapped (split into multiple log 1537 messages) at spaces based on CMDLINE_LOG_WRAP_IDEAL_LEN characters. 1538 If wrapping happens, each log message will start with the prefix and 1539 all but the last message will end with " \". Messages may exceed the 1540 ideal length if a place to wrap isn't found before the specified 1541 number of characters. 1542 1543 A value of 0 disables wrapping, though be warned that the maximum 1544 length of a log message (1021 characters) may cause the cmdline to 1545 be truncated. 1546 1547config INITRAMFS_PRESERVE_MTIME 1548 bool "Preserve cpio archive mtimes in initramfs" 1549 depends on BLK_DEV_INITRD 1550 default y 1551 help 1552 Each entry in an initramfs cpio archive carries an mtime value. When 1553 enabled, extracted cpio items take this mtime, with directory mtime 1554 setting deferred until after creation of any child entries. 1555 1556 If unsure, say Y. 1557 1558config INITRAMFS_TEST 1559 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1560 depends on BLK_DEV_INITRD && KUNIT=y 1561 default KUNIT_ALL_TESTS 1562 help 1563 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1564 1565choice 1566 prompt "Compiler optimization level" 1567 default CC_OPTIMIZE_FOR_PERFORMANCE 1568 1569config CC_OPTIMIZE_FOR_PERFORMANCE 1570 bool "Optimize for performance (-O2)" 1571 help 1572 This is the default optimization level for the kernel, building 1573 with the "-O2" compiler flag for best performance and most 1574 helpful compile-time warnings. 1575 1576config CC_OPTIMIZE_FOR_SIZE 1577 bool "Optimize for size (-Os)" 1578 help 1579 Choosing this option will pass "-Os" to your compiler resulting 1580 in a smaller kernel. 1581 1582endchoice 1583 1584config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1585 bool 1586 help 1587 This requires that the arch annotates or otherwise protects 1588 its external entry points from being discarded. Linker scripts 1589 must also merge .text.*, .data.*, and .bss.* correctly into 1590 output sections. Care must be taken not to pull in unrelated 1591 sections (e.g., '.text.init'). Typically '.' in section names 1592 is used to distinguish them from label names / C identifiers. 1593 1594config LD_DEAD_CODE_DATA_ELIMINATION 1595 bool "Dead code and data elimination (EXPERIMENTAL)" 1596 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1597 depends on EXPERT 1598 depends on $(cc-option,-ffunction-sections -fdata-sections) 1599 depends on $(ld-option,--gc-sections) 1600 help 1601 Enable this if you want to do dead code and data elimination with 1602 the linker by compiling with -ffunction-sections -fdata-sections, 1603 and linking with --gc-sections. 1604 1605 This can reduce on disk and in-memory size of the kernel 1606 code and static data, particularly for small configs and 1607 on small systems. This has the possibility of introducing 1608 silently broken kernel if the required annotations are not 1609 present. This option is not well tested yet, so use at your 1610 own risk. 1611 1612config LD_ORPHAN_WARN 1613 def_bool y 1614 depends on ARCH_WANT_LD_ORPHAN_WARN 1615 depends on $(ld-option,--orphan-handling=warn) 1616 depends on $(ld-option,--orphan-handling=error) 1617 1618config LD_ORPHAN_WARN_LEVEL 1619 string 1620 depends on LD_ORPHAN_WARN 1621 default "error" if WERROR 1622 default "warn" 1623 1624config SYSCTL 1625 bool 1626 1627config HAVE_UID16 1628 bool 1629 1630config SYSCTL_EXCEPTION_TRACE 1631 bool 1632 help 1633 Enable support for /proc/sys/debug/exception-trace. 1634 1635config SYSCTL_ARCH_UNALIGN_NO_WARN 1636 bool 1637 help 1638 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1639 Allows arch to define/use @no_unaligned_warning to possibly warn 1640 about unaligned access emulation going on under the hood. 1641 1642config SYSCTL_ARCH_UNALIGN_ALLOW 1643 bool 1644 help 1645 Enable support for /proc/sys/kernel/unaligned-trap 1646 Allows arches to define/use @unaligned_enabled to runtime toggle 1647 the unaligned access emulation. 1648 see arch/parisc/kernel/unaligned.c for reference 1649 1650config SYSFS_SYSCALL 1651 bool "Sysfs syscall support" 1652 default n 1653 help 1654 sys_sysfs is an obsolete system call no longer supported in libc. 1655 Note that disabling this option is more secure but might break 1656 compatibility with some systems. 1657 1658 If unsure say N here. 1659 1660config HAVE_PCSPKR_PLATFORM 1661 bool 1662 1663menuconfig EXPERT 1664 bool "Configure standard kernel features (expert users)" 1665 # Unhide debug options, to make the on-by-default options visible 1666 select DEBUG_KERNEL 1667 help 1668 This option allows certain base kernel options and settings 1669 to be disabled or tweaked. This is for specialized 1670 environments which can tolerate a "non-standard" kernel. 1671 Only use this if you really know what you are doing. 1672 1673config UID16 1674 bool "Enable 16-bit UID system calls" if EXPERT 1675 depends on HAVE_UID16 && MULTIUSER 1676 default y 1677 help 1678 This enables the legacy 16-bit UID syscall wrappers. 1679 1680config MULTIUSER 1681 bool "Multiple users, groups and capabilities support" if EXPERT 1682 default y 1683 help 1684 This option enables support for non-root users, groups and 1685 capabilities. 1686 1687 If you say N here, all processes will run with UID 0, GID 0, and all 1688 possible capabilities. Saying N here also compiles out support for 1689 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1690 setgid, and capset. 1691 1692 If unsure, say Y here. 1693 1694config SGETMASK_SYSCALL 1695 bool "sgetmask/ssetmask syscalls support" if EXPERT 1696 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1697 help 1698 sys_sgetmask and sys_ssetmask are obsolete system calls 1699 no longer supported in libc but still enabled by default in some 1700 architectures. 1701 1702 If unsure, leave the default option here. 1703 1704config FHANDLE 1705 bool "open by fhandle syscalls" if EXPERT 1706 select EXPORTFS 1707 default y 1708 help 1709 If you say Y here, a user level program will be able to map 1710 file names to handle and then later use the handle for 1711 different file system operations. This is useful in implementing 1712 userspace file servers, which now track files using handles instead 1713 of names. The handle would remain the same even if file names 1714 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1715 syscalls. 1716 1717config POSIX_TIMERS 1718 bool "Posix Clocks & timers" if EXPERT 1719 default y 1720 help 1721 This includes native support for POSIX timers to the kernel. 1722 Some embedded systems have no use for them and therefore they 1723 can be configured out to reduce the size of the kernel image. 1724 1725 When this option is disabled, the following syscalls won't be 1726 available: timer_create, timer_gettime: timer_getoverrun, 1727 timer_settime, timer_delete, clock_adjtime, getitimer, 1728 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1729 clock_getres and clock_nanosleep syscalls will be limited to 1730 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1731 1732 If unsure say y. 1733 1734config PRINTK 1735 default y 1736 bool "Enable support for printk" if EXPERT 1737 select IRQ_WORK 1738 help 1739 This option enables normal printk support. Removing it 1740 eliminates most of the message strings from the kernel image 1741 and makes the kernel more or less silent. As this makes it 1742 very difficult to diagnose system problems, saying N here is 1743 strongly discouraged. 1744 1745config PRINTK_RINGBUFFER_KUNIT_TEST 1746 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1747 depends on PRINTK && KUNIT 1748 default KUNIT_ALL_TESTS 1749 help 1750 This builds the printk ringbuffer KUnit test suite. 1751 1752 For more information on KUnit and unit tests in general, please refer 1753 to the KUnit documentation. 1754 1755 If unsure, say N. 1756 1757config BUG 1758 bool "BUG() support" if EXPERT 1759 default y 1760 help 1761 Disabling this option eliminates support for BUG and WARN, reducing 1762 the size of your kernel image and potentially quietly ignoring 1763 numerous fatal conditions. You should only consider disabling this 1764 option for embedded systems with no facilities for reporting errors. 1765 Just say Y. 1766 1767config ELF_CORE 1768 depends on COREDUMP 1769 default y 1770 bool "Enable ELF core dumps" if EXPERT 1771 help 1772 Enable support for generating core dumps. Disabling saves about 4k. 1773 1774 1775config PCSPKR_PLATFORM 1776 bool "Enable PC-Speaker support" if EXPERT 1777 depends on HAVE_PCSPKR_PLATFORM 1778 select I8253_LOCK 1779 default y 1780 help 1781 This option allows to disable the internal PC-Speaker 1782 support, saving some memory. 1783 1784config BASE_SMALL 1785 bool "Enable smaller-sized data structures for core" if EXPERT 1786 help 1787 Enabling this option reduces the size of miscellaneous core 1788 kernel data structures. This saves memory on small machines, 1789 but may reduce performance. 1790 1791config FUTEX 1792 bool "Enable futex support" if EXPERT 1793 depends on !(SPARC32 && SMP) 1794 default y 1795 imply RT_MUTEXES 1796 help 1797 Disabling this option will cause the kernel to be built without 1798 support for "fast userspace mutexes". The resulting kernel may not 1799 run glibc-based applications correctly. 1800 1801config FUTEX_PI 1802 bool 1803 depends on FUTEX && RT_MUTEXES 1804 default y 1805 1806config FUTEX_PRIVATE_HASH 1807 bool 1808 depends on FUTEX && !BASE_SMALL && MMU 1809 default y 1810 1811config FUTEX_MPOL 1812 bool 1813 depends on FUTEX && NUMA 1814 default y 1815 1816config EPOLL 1817 bool "Enable eventpoll support" if EXPERT 1818 default y 1819 help 1820 Disabling this option will cause the kernel to be built without 1821 support for epoll family of system calls. 1822 1823config SIGNALFD 1824 bool "Enable signalfd() system call" if EXPERT 1825 default y 1826 help 1827 Enable the signalfd() system call that allows to receive signals 1828 on a file descriptor. 1829 1830 If unsure, say Y. 1831 1832config TIMERFD 1833 bool "Enable timerfd() system call" if EXPERT 1834 default y 1835 help 1836 Enable the timerfd() system call that allows to receive timer 1837 events on a file descriptor. 1838 1839 If unsure, say Y. 1840 1841config EVENTFD 1842 bool "Enable eventfd() system call" if EXPERT 1843 default y 1844 help 1845 Enable the eventfd() system call that allows to receive both 1846 kernel notification (ie. KAIO) or userspace notifications. 1847 1848 If unsure, say Y. 1849 1850config SHMEM 1851 bool "Use full shmem filesystem" if EXPERT 1852 default y 1853 depends on MMU 1854 help 1855 The shmem is an internal filesystem used to manage shared memory. 1856 It is backed by swap and manages resource limits. It is also exported 1857 to userspace as tmpfs if TMPFS is enabled. Disabling this 1858 option replaces shmem and tmpfs with the much simpler ramfs code, 1859 which may be appropriate on small systems without swap. 1860 1861config AIO 1862 bool "Enable AIO support" if EXPERT 1863 default y 1864 help 1865 This option enables POSIX asynchronous I/O which may by used 1866 by some high performance threaded applications. Disabling 1867 this option saves about 7k. 1868 1869config IO_URING 1870 bool "Enable IO uring support" if EXPERT 1871 select IO_WQ 1872 default y 1873 help 1874 This option enables support for the io_uring interface, enabling 1875 applications to submit and complete IO through submission and 1876 completion rings that are shared between the kernel and application. 1877 1878config GCOV_PROFILE_URING 1879 bool "Enable GCOV profiling on the io_uring subsystem" 1880 depends on IO_URING && GCOV_KERNEL 1881 help 1882 Enable GCOV profiling on the io_uring subsystem, to facilitate 1883 code coverage testing. 1884 1885 If unsure, say N. 1886 1887 Note that this will have a negative impact on the performance of 1888 the io_uring subsystem, hence this should only be enabled for 1889 specific test purposes. 1890 1891config IO_URING_MOCK_FILE 1892 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1893 default n 1894 depends on IO_URING 1895 help 1896 Enable mock files for io_uring subststem testing. The ABI might 1897 still change, so it's still experimental and should only be enabled 1898 for specific test purposes. 1899 1900 If unsure, say N. 1901 1902config ADVISE_SYSCALLS 1903 bool "Enable madvise/fadvise syscalls" if EXPERT 1904 default y 1905 help 1906 This option enables the madvise and fadvise syscalls, used by 1907 applications to advise the kernel about their future memory or file 1908 usage, improving performance. If building an embedded system where no 1909 applications use these syscalls, you can disable this option to save 1910 space. 1911 1912config MEMBARRIER 1913 bool "Enable membarrier() system call" if EXPERT 1914 default y 1915 help 1916 Enable the membarrier() system call that allows issuing memory 1917 barriers across all running threads, which can be used to distribute 1918 the cost of user-space memory barriers asymmetrically by transforming 1919 pairs of memory barriers into pairs consisting of membarrier() and a 1920 compiler barrier. 1921 1922 If unsure, say Y. 1923 1924config KCMP 1925 bool "Enable kcmp() system call" if EXPERT 1926 help 1927 Enable the kernel resource comparison system call. It provides 1928 user-space with the ability to compare two processes to see if they 1929 share a common resource, such as a file descriptor or even virtual 1930 memory space. 1931 1932 If unsure, say N. 1933 1934config RSEQ 1935 bool "Enable rseq() system call" if EXPERT 1936 default y 1937 depends on HAVE_RSEQ 1938 select MEMBARRIER 1939 help 1940 Enable the restartable sequences system call. It provides a 1941 user-space cache for the current CPU number value, which 1942 speeds up getting the current CPU number from user-space, 1943 as well as an ABI to speed up user-space operations on 1944 per-CPU data. 1945 1946 If unsure, say Y. 1947 1948config RSEQ_STATS 1949 default n 1950 bool "Enable lightweight statistics of restartable sequences" if EXPERT 1951 depends on RSEQ && DEBUG_FS 1952 help 1953 Enable lightweight counters which expose information about the 1954 frequency of RSEQ operations via debugfs. Mostly interesting for 1955 kernel debugging or performance analysis. While lightweight it's 1956 still adding code into the user/kernel mode transitions. 1957 1958 If unsure, say N. 1959 1960config RSEQ_DEBUG_DEFAULT_ENABLE 1961 default n 1962 bool "Enable restartable sequences debug mode by default" if EXPERT 1963 depends on RSEQ 1964 help 1965 This enables the static branch for debug mode of restartable 1966 sequences. 1967 1968 This also can be controlled on the kernel command line via the 1969 command line parameter "rseq_debug=0/1" and through debugfs. 1970 1971 If unsure, say N. 1972 1973config DEBUG_RSEQ 1974 default n 1975 bool "Enable debugging of rseq() system call" if EXPERT 1976 depends on RSEQ && DEBUG_KERNEL && !GENERIC_ENTRY 1977 select RSEQ_DEBUG_DEFAULT_ENABLE 1978 help 1979 Enable extra debugging checks for the rseq system call. 1980 1981 If unsure, say N. 1982 1983config CACHESTAT_SYSCALL 1984 bool "Enable cachestat() system call" if EXPERT 1985 default y 1986 help 1987 Enable the cachestat system call, which queries the page cache 1988 statistics of a file (number of cached pages, dirty pages, 1989 pages marked for writeback, (recently) evicted pages). 1990 1991 If unsure say Y here. 1992 1993config KALLSYMS 1994 bool "Load all symbols for debugging/ksymoops" if EXPERT 1995 default y 1996 help 1997 Say Y here to let the kernel print out symbolic crash information and 1998 symbolic stack backtraces. This increases the size of the kernel 1999 somewhat, as all symbols have to be loaded into the kernel image. 2000 2001config KALLSYMS_SELFTEST 2002 bool "Test the basic functions and performance of kallsyms" 2003 depends on KALLSYMS 2004 default n 2005 help 2006 Test the basic functions and performance of some interfaces, such as 2007 kallsyms_lookup_name. It also calculates the compression rate of the 2008 kallsyms compression algorithm for the current symbol set. 2009 2010 Start self-test automatically after system startup. Suggest executing 2011 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 2012 displayed in the last line, indicating that the test is complete. 2013 2014config KALLSYMS_ALL 2015 bool "Include all symbols in kallsyms" 2016 depends on DEBUG_KERNEL && KALLSYMS 2017 help 2018 Normally kallsyms only contains the symbols of functions for nicer 2019 OOPS messages and backtraces (i.e., symbols from the text and inittext 2020 sections). This is sufficient for most cases. And only if you want to 2021 enable kernel live patching, or other less common use cases (e.g., 2022 when a debugger is used) all symbols are required (i.e., names of 2023 variables from the data sections, etc). 2024 2025 This option makes sure that all symbols are loaded into the kernel 2026 image (i.e., symbols from all sections) in cost of increased kernel 2027 size (depending on the kernel configuration, it may be 300KiB or 2028 something like this). 2029 2030 Say N unless you really need all symbols, or kernel live patching. 2031 2032# end of the "standard kernel features (expert users)" menu 2033 2034config ARCH_HAS_MEMBARRIER_CALLBACKS 2035 bool 2036 2037config ARCH_HAS_MEMBARRIER_SYNC_CORE 2038 bool 2039 2040config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 2041 bool 2042 help 2043 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 2044 2045 A 64-bit kernel is required for the memory sealing feature. 2046 No specific hardware features from the CPU are needed. 2047 2048 To enable this feature, the architecture needs to update their 2049 special mappings calls to include the sealing flag and confirm 2050 that it doesn't unmap/remap system mappings during the life 2051 time of the process. The existence of this flag for an architecture 2052 implies that it does not require the remapping of the system 2053 mappings during process lifetime, so sealing these mappings is safe 2054 from a kernel perspective. 2055 2056 After the architecture enables this, a distribution can set 2057 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 2058 2059 For complete descriptions of memory sealing, please see 2060 Documentation/userspace-api/mseal.rst 2061 2062config HAVE_PERF_EVENTS 2063 bool 2064 help 2065 See tools/perf/design.txt for details. 2066 2067config GUEST_PERF_EVENTS 2068 bool 2069 depends on HAVE_PERF_EVENTS 2070 2071config PERF_USE_VMALLOC 2072 bool 2073 help 2074 See tools/perf/design.txt for details 2075 2076menu "Kernel Performance Events And Counters" 2077 2078config PERF_EVENTS 2079 bool "Kernel performance events and counters" 2080 default y if PROFILING 2081 depends on HAVE_PERF_EVENTS 2082 select IRQ_WORK 2083 help 2084 Enable kernel support for various performance events provided 2085 by software and hardware. 2086 2087 Software events are supported either built-in or via the 2088 use of generic tracepoints. 2089 2090 Most modern CPUs support performance events via performance 2091 counter registers. These registers count the number of certain 2092 types of hw events: such as instructions executed, cachemisses 2093 suffered, or branches mis-predicted - without slowing down the 2094 kernel or applications. These registers can also trigger interrupts 2095 when a threshold number of events have passed - and can thus be 2096 used to profile the code that runs on that CPU. 2097 2098 The Linux Performance Event subsystem provides an abstraction of 2099 these software and hardware event capabilities, available via a 2100 system call and used by the "perf" utility in tools/perf/. It 2101 provides per task and per CPU counters, and it provides event 2102 capabilities on top of those. 2103 2104 Say Y if unsure. 2105 2106config DEBUG_PERF_USE_VMALLOC 2107 default n 2108 bool "Debug: use vmalloc to back perf mmap() buffers" 2109 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2110 select PERF_USE_VMALLOC 2111 help 2112 Use vmalloc memory to back perf mmap() buffers. 2113 2114 Mostly useful for debugging the vmalloc code on platforms 2115 that don't require it. 2116 2117 Say N if unsure. 2118 2119endmenu 2120 2121config SYSTEM_DATA_VERIFICATION 2122 def_bool n 2123 select SYSTEM_TRUSTED_KEYRING 2124 select KEYS 2125 select CRYPTO 2126 select CRYPTO_RSA 2127 select ASYMMETRIC_KEY_TYPE 2128 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2129 select ASN1 2130 select OID_REGISTRY 2131 select X509_CERTIFICATE_PARSER 2132 select PKCS7_MESSAGE_PARSER 2133 help 2134 Provide PKCS#7 message verification using the contents of the system 2135 trusted keyring to provide public keys. This then can be used for 2136 module verification, kexec image verification and firmware blob 2137 verification. 2138 2139config PROFILING 2140 bool "Profiling support" 2141 help 2142 Say Y here to enable the extended profiling support mechanisms used 2143 by profilers. 2144 2145config RUST 2146 bool "Rust support" 2147 depends on HAVE_RUST 2148 depends on RUST_IS_AVAILABLE 2149 select EXTENDED_MODVERSIONS if MODVERSIONS 2150 depends on !MODVERSIONS || GENDWARFKSYMS 2151 depends on !GCC_PLUGIN_RANDSTRUCT 2152 depends on !RANDSTRUCT 2153 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2154 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2155 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2156 depends on !CALL_PADDING || RUSTC_VERSION >= 108100 2157 depends on !KASAN_SW_TAGS 2158 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300 2159 help 2160 Enables Rust support in the kernel. 2161 2162 This allows other Rust-related options, like drivers written in Rust, 2163 to be selected. 2164 2165 It is also required to be able to load external kernel modules 2166 written in Rust. 2167 2168 See Documentation/rust/ for more information. 2169 2170 If unsure, say N. 2171 2172config RUSTC_VERSION_TEXT 2173 string 2174 depends on RUST 2175 default "$(RUSTC_VERSION_TEXT)" 2176 help 2177 See `CC_VERSION_TEXT`. 2178 2179config BINDGEN_VERSION_TEXT 2180 string 2181 depends on RUST 2182 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0 2183 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0 2184 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed 2185 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1 2186 # both fixed the issue). 2187 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)" 2188 2189# 2190# Place an empty function call at each tracepoint site. Can be 2191# dynamically changed for a probe function. 2192# 2193config TRACEPOINTS 2194 bool 2195 select TASKS_TRACE_RCU 2196 2197source "kernel/Kconfig.kexec" 2198 2199source "kernel/liveupdate/Kconfig" 2200 2201endmenu # General setup 2202 2203source "arch/Kconfig" 2204 2205config RT_MUTEXES 2206 bool 2207 default y if PREEMPT_RT 2208 2209config MODULE_SIG_FORMAT 2210 def_bool n 2211 select SYSTEM_DATA_VERIFICATION 2212 2213source "kernel/module/Kconfig" 2214 2215config INIT_ALL_POSSIBLE 2216 bool 2217 help 2218 Back when each arch used to define their own cpu_online_mask and 2219 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2220 with all 1s, and others with all 0s. When they were centralised, 2221 it was better to provide this option than to break all the archs 2222 and have several arch maintainers pursuing me down dark alleys. 2223 2224source "block/Kconfig" 2225 2226config PREEMPT_NOTIFIERS 2227 bool 2228 2229config PADATA 2230 depends on SMP 2231 bool 2232 2233config ASN1 2234 tristate 2235 help 2236 Build a simple ASN.1 grammar compiler that produces a bytecode output 2237 that can be interpreted by the ASN.1 stream decoder and used to 2238 inform it as to what tags are to be expected in a stream and what 2239 functions to call on what tags. 2240 2241source "kernel/Kconfig.locks" 2242 2243config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2244 bool 2245 2246config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2247 bool 2248 2249config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2250 bool 2251 2252# It may be useful for an architecture to override the definitions of the 2253# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2254# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2255# different calling convention for syscalls. They can also override the 2256# macros for not-implemented syscalls in kernel/sys_ni.c and 2257# kernel/time/posix-stubs.c. All these overrides need to be available in 2258# <asm/syscall_wrapper.h>. 2259config ARCH_HAS_SYSCALL_WRAPPER 2260 def_bool n 2261