1# SPDX-License-Identifier: GPL-2.0-only 2config CC_VERSION_TEXT 3 string 4 default "$(CC_VERSION_TEXT)" 5 help 6 This is used in unclear ways: 7 8 - Re-run Kconfig when the compiler is updated 9 The 'default' property references the environment variable, 10 CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd. 11 When the compiler is updated, Kconfig will be invoked. 12 13 - Ensure full rebuild when the compiler is updated 14 include/linux/compiler-version.h contains this option in the comment 15 line so fixdep adds include/config/CC_VERSION_TEXT into the 16 auto-generated dependency. When the compiler is updated, syncconfig 17 will touch it and then every file will be rebuilt. 18 19config CC_IS_GCC 20 def_bool $(success,test "$(cc-name)" = GCC) 21 22config GCC_VERSION 23 int 24 default $(cc-version) if CC_IS_GCC 25 default 0 26 27config CC_IS_CLANG 28 def_bool $(success,test "$(cc-name)" = Clang) 29 30config CLANG_VERSION 31 int 32 default $(cc-version) if CC_IS_CLANG 33 default 0 34 35config AS_IS_GNU 36 def_bool $(success,test "$(as-name)" = GNU) 37 38config AS_IS_LLVM 39 def_bool $(success,test "$(as-name)" = LLVM) 40 41config AS_VERSION 42 int 43 # Use clang version if this is the integrated assembler 44 default CLANG_VERSION if AS_IS_LLVM 45 default $(as-version) 46 47config LD_IS_BFD 48 def_bool $(success,test "$(ld-name)" = BFD) 49 50config LD_VERSION 51 int 52 default $(ld-version) if LD_IS_BFD 53 default 0 54 55config LD_IS_LLD 56 def_bool $(success,test "$(ld-name)" = LLD) 57 58config LLD_VERSION 59 int 60 default $(ld-version) if LD_IS_LLD 61 default 0 62 63config RUSTC_VERSION 64 int 65 default $(rustc-version) 66 help 67 It does not depend on `RUST` since that one may need to use the version 68 in a `depends on`. 69 70config RUST_IS_AVAILABLE 71 def_bool $(success,$(srctree)/scripts/rust_is_available.sh) 72 help 73 This shows whether a suitable Rust toolchain is available (found). 74 75 Please see Documentation/rust/quick-start.rst for instructions on how 76 to satisfy the build requirements of Rust support. 77 78 In particular, the Makefile target 'rustavailable' is useful to check 79 why the Rust toolchain is not being detected. 80 81config RUSTC_LLVM_VERSION 82 int 83 default $(rustc-llvm-version) 84 85config CC_CAN_LINK 86 bool 87 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT 88 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag)) 89 90# Fixed in GCC 14, 13.3, 12.4 and 11.5 91# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 92config GCC_ASM_GOTO_OUTPUT_BROKEN 93 bool 94 depends on CC_IS_GCC 95 default y if GCC_VERSION < 110500 96 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400 97 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300 98 99config CC_HAS_ASM_GOTO_OUTPUT 100 def_bool y 101 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN 102 # Detect basic support 103 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) 104 # Detect clang (< v17) scoped label issues 105 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) 106 107config CC_HAS_ASM_GOTO_TIED_OUTPUT 108 depends on CC_HAS_ASM_GOTO_OUTPUT 109 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 110 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) 111 112config TOOLS_SUPPORT_RELR 113 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 114 115config CC_HAS_ASM_INLINE 116 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 117 118config CC_HAS_ASSUME 119 bool 120 # clang needs to be at least 19.1.0 since the meaning of the assume 121 # attribute changed: 122 # https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17 123 default y if CC_IS_CLANG && CLANG_VERSION >= 190100 124 # supported since gcc 13.1.0 125 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654 126 default y if CC_IS_GCC && GCC_VERSION >= 130100 127 128config CC_HAS_NO_PROFILE_FN_ATTR 129 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 130 131config CC_HAS_COUNTED_BY 132 bool 133 # clang needs to be at least 20.1.0 to avoid potential crashes 134 # when building structures that contain __counted_by 135 # https://github.com/ClangBuiltLinux/linux/issues/2114 136 # https://github.com/llvm/llvm-project/commit/160fb1121cdf703c3ef5e61fb26c5659eb581489 137 default y if CC_IS_CLANG && CLANG_VERSION >= 200100 138 # supported since gcc 15.1.0 139 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 140 default y if CC_IS_GCC && GCC_VERSION >= 150100 141 142config CC_HAS_MULTIDIMENSIONAL_NONSTRING 143 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) 144 145config LD_CAN_USE_KEEP_IN_OVERLAY 146 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description 147 # https://github.com/llvm/llvm-project/pull/130661 148 def_bool LD_IS_BFD || LLD_VERSION >= 210000 149 150config RUSTC_HAS_COERCE_POINTEE 151 def_bool RUSTC_VERSION >= 108400 152 153config RUSTC_HAS_SPAN_FILE 154 def_bool RUSTC_VERSION >= 108800 155 156config RUSTC_HAS_UNNECESSARY_TRANSMUTES 157 def_bool RUSTC_VERSION >= 108800 158 159config RUSTC_HAS_FILE_WITH_NUL 160 def_bool RUSTC_VERSION >= 108900 161 162config RUSTC_HAS_FILE_AS_C_STR 163 def_bool RUSTC_VERSION >= 109100 164 165config PAHOLE_VERSION 166 int 167 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) 168 169config CONSTRUCTORS 170 bool 171 172config IRQ_WORK 173 def_bool y if SMP 174 175config BUILDTIME_TABLE_SORT 176 bool 177 178config THREAD_INFO_IN_TASK 179 bool 180 help 181 Select this to move thread_info off the stack into task_struct. To 182 make this work, an arch will need to remove all thread_info fields 183 except flags and fix any runtime bugs. 184 185 One subtle change that will be needed is to use try_get_task_stack() 186 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 187 188menu "General setup" 189 190config BROKEN 191 bool 192 help 193 This option allows you to choose whether you want to try to 194 compile (and fix) old drivers that haven't been updated to 195 new infrastructure. 196 197config BROKEN_ON_SMP 198 bool 199 depends on BROKEN || !SMP 200 default y 201 202config INIT_ENV_ARG_LIMIT 203 int 204 default 32 if !UML 205 default 128 if UML 206 help 207 Maximum of each of the number of arguments and environment 208 variables passed to init from the kernel command line. 209 210config COMPILE_TEST 211 bool "Compile also drivers which will not load" 212 depends on HAS_IOMEM 213 help 214 Some drivers can be compiled on a different platform than they are 215 intended to be run on. Despite they cannot be loaded there (or even 216 when they load they cannot be used due to missing HW support), 217 developers still, opposing to distributors, might want to build such 218 drivers to compile-test them. 219 220 If you are a developer and want to build everything available, say Y 221 here. If you are a user/distributor, say N here to exclude useless 222 drivers to be distributed. 223 224config WERROR 225 bool "Compile the kernel with warnings as errors" 226 default COMPILE_TEST 227 help 228 A kernel build should not cause any compiler warnings, and this 229 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags 230 to enforce that rule by default. Certain warnings from other tools 231 such as the linker may be upgraded to errors with this option as 232 well. 233 234 However, if you have a new (or very old) compiler or linker with odd 235 and unusual warnings, or you have some architecture with problems, 236 you may need to disable this config option in order to 237 successfully build the kernel. 238 239 If in doubt, say Y. 240 241config UAPI_HEADER_TEST 242 bool "Compile test UAPI headers" 243 depends on HEADERS_INSTALL && CC_CAN_LINK 244 help 245 Compile test headers exported to user-space to ensure they are 246 self-contained, i.e. compilable as standalone units. 247 248 If you are a developer or tester and want to ensure the exported 249 headers are self-contained, say Y here. Otherwise, choose N. 250 251config LOCALVERSION 252 string "Local version - append to kernel release" 253 help 254 Append an extra string to the end of your kernel version. 255 This will show up when you type uname, for example. 256 The string you set here will be appended after the contents of 257 any files with a filename matching localversion* in your 258 object and source tree, in that order. Your total string can 259 be a maximum of 64 characters. 260 261config LOCALVERSION_AUTO 262 bool "Automatically append version information to the version string" 263 default y 264 depends on !COMPILE_TEST 265 help 266 This will try to automatically determine if the current tree is a 267 release tree by looking for git tags that belong to the current 268 top of tree revision. 269 270 A string of the format -gxxxxxxxx will be added to the localversion 271 if a git-based tree is found. The string generated by this will be 272 appended after any matching localversion* files, and after the value 273 set in CONFIG_LOCALVERSION. 274 275 (The actual string used here is the first 12 characters produced 276 by running the command: 277 278 $ git rev-parse --verify HEAD 279 280 which is done within the script "scripts/setlocalversion".) 281 282config BUILD_SALT 283 string "Build ID Salt" 284 default "" 285 help 286 The build ID is used to link binaries and their debug info. Setting 287 this option will use the value in the calculation of the build id. 288 This is mostly useful for distributions which want to ensure the 289 build is unique between builds. It's safe to leave the default. 290 291config HAVE_KERNEL_GZIP 292 bool 293 294config HAVE_KERNEL_BZIP2 295 bool 296 297config HAVE_KERNEL_LZMA 298 bool 299 300config HAVE_KERNEL_XZ 301 bool 302 303config HAVE_KERNEL_LZO 304 bool 305 306config HAVE_KERNEL_LZ4 307 bool 308 309config HAVE_KERNEL_ZSTD 310 bool 311 312config HAVE_KERNEL_UNCOMPRESSED 313 bool 314 315choice 316 prompt "Kernel compression mode" 317 default KERNEL_GZIP 318 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 319 help 320 The linux kernel is a kind of self-extracting executable. 321 Several compression algorithms are available, which differ 322 in efficiency, compression and decompression speed. 323 Compression speed is only relevant when building a kernel. 324 Decompression speed is relevant at each boot. 325 326 If you have any problems with bzip2 or lzma compressed 327 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 328 version of this functionality (bzip2 only), for 2.4, was 329 supplied by Christian Ludwig) 330 331 High compression options are mostly useful for users, who 332 are low on disk space (embedded systems), but for whom ram 333 size matters less. 334 335 If in doubt, select 'gzip' 336 337config KERNEL_GZIP 338 bool "Gzip" 339 depends on HAVE_KERNEL_GZIP 340 help 341 The old and tried gzip compression. It provides a good balance 342 between compression ratio and decompression speed. 343 344config KERNEL_BZIP2 345 bool "Bzip2" 346 depends on HAVE_KERNEL_BZIP2 347 help 348 Its compression ratio and speed is intermediate. 349 Decompression speed is slowest among the choices. The kernel 350 size is about 10% smaller with bzip2, in comparison to gzip. 351 Bzip2 uses a large amount of memory. For modern kernels you 352 will need at least 8MB RAM or more for booting. 353 354config KERNEL_LZMA 355 bool "LZMA" 356 depends on HAVE_KERNEL_LZMA 357 help 358 This compression algorithm's ratio is best. Decompression speed 359 is between gzip and bzip2. Compression is slowest. 360 The kernel size is about 33% smaller with LZMA in comparison to gzip. 361 362config KERNEL_XZ 363 bool "XZ" 364 depends on HAVE_KERNEL_XZ 365 help 366 XZ uses the LZMA2 algorithm and instruction set specific 367 BCJ filters which can improve compression ratio of executable 368 code. The size of the kernel is about 30% smaller with XZ in 369 comparison to gzip. On architectures for which there is a BCJ 370 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC, 371 and SPARC), XZ will create a few percent smaller kernel than 372 plain LZMA. 373 374 The speed is about the same as with LZMA: The decompression 375 speed of XZ is better than that of bzip2 but worse than gzip 376 and LZO. Compression is slow. 377 378config KERNEL_LZO 379 bool "LZO" 380 depends on HAVE_KERNEL_LZO 381 help 382 Its compression ratio is the poorest among the choices. The kernel 383 size is about 10% bigger than gzip; however its speed 384 (both compression and decompression) is the fastest. 385 386config KERNEL_LZ4 387 bool "LZ4" 388 depends on HAVE_KERNEL_LZ4 389 help 390 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 391 A preliminary version of LZ4 de/compression tool is available at 392 <https://code.google.com/p/lz4/>. 393 394 Its compression ratio is worse than LZO. The size of the kernel 395 is about 8% bigger than LZO. But the decompression speed is 396 faster than LZO. 397 398config KERNEL_ZSTD 399 bool "ZSTD" 400 depends on HAVE_KERNEL_ZSTD 401 help 402 ZSTD is a compression algorithm targeting intermediate compression 403 with fast decompression speed. It will compress better than GZIP and 404 decompress around the same speed as LZO, but slower than LZ4. You 405 will need at least 192 KB RAM or more for booting. The zstd command 406 line tool is required for compression. 407 408config KERNEL_UNCOMPRESSED 409 bool "None" 410 depends on HAVE_KERNEL_UNCOMPRESSED 411 help 412 Produce uncompressed kernel image. This option is usually not what 413 you want. It is useful for debugging the kernel in slow simulation 414 environments, where decompressing and moving the kernel is awfully 415 slow. This option allows early boot code to skip the decompressor 416 and jump right at uncompressed kernel image. 417 418endchoice 419 420config DEFAULT_INIT 421 string "Default init path" 422 default "" 423 help 424 This option determines the default init for the system if no init= 425 option is passed on the kernel command line. If the requested path is 426 not present, we will still then move on to attempting further 427 locations (e.g. /sbin/init, etc). If this is empty, we will just use 428 the fallback list when init= is not passed. 429 430config DEFAULT_HOSTNAME 431 string "Default hostname" 432 default "(none)" 433 help 434 This option determines the default system hostname before userspace 435 calls sethostname(2). The kernel traditionally uses "(none)" here, 436 but you may wish to use a different default here to make a minimal 437 system more usable with less configuration. 438 439config SYSVIPC 440 bool "System V IPC" 441 help 442 Inter Process Communication is a suite of library functions and 443 system calls which let processes (running programs) synchronize and 444 exchange information. It is generally considered to be a good thing, 445 and some programs won't run unless you say Y here. In particular, if 446 you want to run the DOS emulator dosemu under Linux (read the 447 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 448 you'll need to say Y here. 449 450 You can find documentation about IPC with "info ipc" and also in 451 section 6.4 of the Linux Programmer's Guide, available from 452 <http://www.tldp.org/guides.html>. 453 454config SYSVIPC_SYSCTL 455 bool 456 depends on SYSVIPC 457 depends on SYSCTL 458 default y 459 460config SYSVIPC_COMPAT 461 def_bool y 462 depends on COMPAT && SYSVIPC 463 464config POSIX_MQUEUE 465 bool "POSIX Message Queues" 466 depends on NET 467 help 468 POSIX variant of message queues is a part of IPC. In POSIX message 469 queues every message has a priority which decides about succession 470 of receiving it by a process. If you want to compile and run 471 programs written e.g. for Solaris with use of its POSIX message 472 queues (functions mq_*) say Y here. 473 474 POSIX message queues are visible as a filesystem called 'mqueue' 475 and can be mounted somewhere if you want to do filesystem 476 operations on message queues. 477 478 If unsure, say Y. 479 480config POSIX_MQUEUE_SYSCTL 481 bool 482 depends on POSIX_MQUEUE 483 depends on SYSCTL 484 default y 485 486config WATCH_QUEUE 487 bool "General notification queue" 488 default n 489 help 490 491 This is a general notification queue for the kernel to pass events to 492 userspace by splicing them into pipes. It can be used in conjunction 493 with watches for key/keyring change notifications and device 494 notifications. 495 496 See Documentation/core-api/watch_queue.rst 497 498config CROSS_MEMORY_ATTACH 499 bool "Enable process_vm_readv/writev syscalls" 500 depends on MMU 501 default y 502 help 503 Enabling this option adds the system calls process_vm_readv and 504 process_vm_writev which allow a process with the correct privileges 505 to directly read from or write to another process' address space. 506 See the man page for more details. 507 508config AUDIT 509 bool "Auditing support" 510 depends on NET 511 help 512 Enable auditing infrastructure that can be used with another 513 kernel subsystem, such as SELinux (which requires this for 514 logging of avc messages output). System call auditing is included 515 on architectures which support it. 516 517config HAVE_ARCH_AUDITSYSCALL 518 bool 519 520config AUDITSYSCALL 521 def_bool y 522 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 523 select FSNOTIFY 524 525source "kernel/irq/Kconfig" 526source "kernel/time/Kconfig" 527source "kernel/bpf/Kconfig" 528source "kernel/Kconfig.preempt" 529 530menu "CPU/Task time and stats accounting" 531 532config VIRT_CPU_ACCOUNTING 533 bool 534 535choice 536 prompt "Cputime accounting" 537 default TICK_CPU_ACCOUNTING 538 539# Kind of a stub config for the pure tick based cputime accounting 540config TICK_CPU_ACCOUNTING 541 bool "Simple tick based cputime accounting" 542 depends on !S390 && !NO_HZ_FULL 543 help 544 This is the basic tick based cputime accounting that maintains 545 statistics about user, system and idle time spent on per jiffies 546 granularity. 547 548 If unsure, say Y. 549 550config VIRT_CPU_ACCOUNTING_NATIVE 551 bool "Deterministic task and CPU time accounting" 552 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 553 select VIRT_CPU_ACCOUNTING 554 help 555 Select this option to enable more accurate task and CPU time 556 accounting. This is done by reading a CPU counter on each 557 kernel entry and exit and on transitions within the kernel 558 between system, softirq and hardirq state, so there is a 559 small performance impact. In the case of s390 or IBM POWER > 5, 560 this also enables accounting of stolen time on logically-partitioned 561 systems. 562 563config VIRT_CPU_ACCOUNTING_GEN 564 bool "Full dynticks CPU time accounting" 565 depends on HAVE_CONTEXT_TRACKING_USER 566 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 567 depends on GENERIC_CLOCKEVENTS 568 select VIRT_CPU_ACCOUNTING 569 select CONTEXT_TRACKING_USER 570 help 571 Select this option to enable task and CPU time accounting on full 572 dynticks systems. This accounting is implemented by watching every 573 kernel-user boundaries using the context tracking subsystem. 574 The accounting is thus performed at the expense of some significant 575 overhead. 576 577 For now this is only useful if you are working on the full 578 dynticks subsystem development. 579 580 If unsure, say N. 581 582endchoice 583 584config IRQ_TIME_ACCOUNTING 585 bool "Fine granularity task level IRQ time accounting" 586 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 587 help 588 Select this option to enable fine granularity task irq time 589 accounting. This is done by reading a timestamp on each 590 transitions between softirq and hardirq state, so there can be a 591 small performance impact. 592 593 If in doubt, say N here. 594 595config HAVE_SCHED_AVG_IRQ 596 def_bool y 597 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 598 depends on SMP 599 600config SCHED_HW_PRESSURE 601 bool 602 default y if ARM && ARM_CPU_TOPOLOGY 603 default y if ARM64 604 depends on SMP 605 depends on CPU_FREQ_THERMAL 606 help 607 Select this option to enable HW pressure accounting in the 608 scheduler. HW pressure is the value conveyed to the scheduler 609 that reflects the reduction in CPU compute capacity resulted from 610 HW throttling. HW throttling occurs when the performance of 611 a CPU is capped due to high operating temperatures as an example. 612 613 If selected, the scheduler will be able to balance tasks accordingly, 614 i.e. put less load on throttled CPUs than on non/less throttled ones. 615 616 This requires the architecture to implement 617 arch_update_hw_pressure() and arch_scale_thermal_pressure(). 618 619config BSD_PROCESS_ACCT 620 bool "BSD Process Accounting" 621 depends on MULTIUSER 622 help 623 If you say Y here, a user level program will be able to instruct the 624 kernel (via a special system call) to write process accounting 625 information to a file: whenever a process exits, information about 626 that process will be appended to the file by the kernel. The 627 information includes things such as creation time, owning user, 628 command name, memory usage, controlling terminal etc. (the complete 629 list is in the struct acct in <file:include/linux/acct.h>). It is 630 up to the user level program to do useful things with this 631 information. This is generally a good idea, so say Y. 632 633config BSD_PROCESS_ACCT_V3 634 bool "BSD Process Accounting version 3 file format" 635 depends on BSD_PROCESS_ACCT 636 default n 637 help 638 If you say Y here, the process accounting information is written 639 in a new file format that also logs the process IDs of each 640 process and its parent. Note that this file format is incompatible 641 with previous v0/v1/v2 file formats, so you will need updated tools 642 for processing it. A preliminary version of these tools is available 643 at <http://www.gnu.org/software/acct/>. 644 645config TASKSTATS 646 bool "Export task/process statistics through netlink" 647 depends on NET 648 depends on MULTIUSER 649 default n 650 help 651 Export selected statistics for tasks/processes through the 652 generic netlink interface. Unlike BSD process accounting, the 653 statistics are available during the lifetime of tasks/processes as 654 responses to commands. Like BSD accounting, they are sent to user 655 space on task exit. 656 657 Say N if unsure. 658 659config TASK_DELAY_ACCT 660 bool "Enable per-task delay accounting" 661 depends on TASKSTATS 662 select SCHED_INFO 663 help 664 Collect information on time spent by a task waiting for system 665 resources like cpu, synchronous block I/O completion and swapping 666 in pages. Such statistics can help in setting a task's priorities 667 relative to other tasks for cpu, io, rss limits etc. 668 669 Say N if unsure. 670 671config TASK_XACCT 672 bool "Enable extended accounting over taskstats" 673 depends on TASKSTATS 674 help 675 Collect extended task accounting data and send the data 676 to userland for processing over the taskstats interface. 677 678 Say N if unsure. 679 680config TASK_IO_ACCOUNTING 681 bool "Enable per-task storage I/O accounting" 682 depends on TASK_XACCT 683 help 684 Collect information on the number of bytes of storage I/O which this 685 task has caused. 686 687 Say N if unsure. 688 689config PSI 690 bool "Pressure stall information tracking" 691 select KERNFS 692 help 693 Collect metrics that indicate how overcommitted the CPU, memory, 694 and IO capacity are in the system. 695 696 If you say Y here, the kernel will create /proc/pressure/ with the 697 pressure statistics files cpu, memory, and io. These will indicate 698 the share of walltime in which some or all tasks in the system are 699 delayed due to contention of the respective resource. 700 701 In kernels with cgroup support, cgroups (cgroup2 only) will 702 have cpu.pressure, memory.pressure, and io.pressure files, 703 which aggregate pressure stalls for the grouped tasks only. 704 705 For more details see Documentation/accounting/psi.rst. 706 707 Say N if unsure. 708 709config PSI_DEFAULT_DISABLED 710 bool "Require boot parameter to enable pressure stall information tracking" 711 default n 712 depends on PSI 713 help 714 If set, pressure stall information tracking will be disabled 715 per default but can be enabled through passing psi=1 on the 716 kernel commandline during boot. 717 718 This feature adds some code to the task wakeup and sleep 719 paths of the scheduler. The overhead is too low to affect 720 common scheduling-intense workloads in practice (such as 721 webservers, memcache), but it does show up in artificial 722 scheduler stress tests, such as hackbench. 723 724 If you are paranoid and not sure what the kernel will be 725 used for, say Y. 726 727 Say N if unsure. 728 729endmenu # "CPU/Task time and stats accounting" 730 731config CPU_ISOLATION 732 bool "CPU isolation" 733 depends on SMP 734 default y 735 help 736 Make sure that CPUs running critical tasks are not disturbed by 737 any source of "noise" such as unbound workqueues, timers, kthreads... 738 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 739 the "isolcpus=" boot parameter. 740 741 Say Y if unsure. 742 743source "kernel/rcu/Kconfig" 744 745config IKCONFIG 746 tristate "Kernel .config support" 747 help 748 This option enables the complete Linux kernel ".config" file 749 contents to be saved in the kernel. It provides documentation 750 of which kernel options are used in a running kernel or in an 751 on-disk kernel. This information can be extracted from the kernel 752 image file with the script scripts/extract-ikconfig and used as 753 input to rebuild the current kernel or to build another kernel. 754 It can also be extracted from a running kernel by reading 755 /proc/config.gz if enabled (below). 756 757config IKCONFIG_PROC 758 bool "Enable access to .config through /proc/config.gz" 759 depends on IKCONFIG && PROC_FS 760 help 761 This option enables access to the kernel configuration file 762 through /proc/config.gz. 763 764config IKHEADERS 765 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 766 depends on SYSFS 767 help 768 This option enables access to the in-kernel headers that are generated during 769 the build process. These can be used to build eBPF tracing programs, 770 or similar programs. If you build the headers as a module, a module called 771 kheaders.ko is built which can be loaded on-demand to get access to headers. 772 773config LOG_BUF_SHIFT 774 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 775 range 12 25 776 default 17 777 depends on PRINTK 778 help 779 Select the minimal kernel log buffer size as a power of 2. 780 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 781 parameter, see below. Any higher size also might be forced 782 by "log_buf_len" boot parameter. 783 784 Examples: 785 17 => 128 KB 786 16 => 64 KB 787 15 => 32 KB 788 14 => 16 KB 789 13 => 8 KB 790 12 => 4 KB 791 792config LOG_CPU_MAX_BUF_SHIFT 793 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 794 depends on SMP 795 range 0 21 796 default 0 if BASE_SMALL 797 default 12 798 depends on PRINTK 799 help 800 This option allows to increase the default ring buffer size 801 according to the number of CPUs. The value defines the contribution 802 of each CPU as a power of 2. The used space is typically only few 803 lines however it might be much more when problems are reported, 804 e.g. backtraces. 805 806 The increased size means that a new buffer has to be allocated and 807 the original static one is unused. It makes sense only on systems 808 with more CPUs. Therefore this value is used only when the sum of 809 contributions is greater than the half of the default kernel ring 810 buffer as defined by LOG_BUF_SHIFT. The default values are set 811 so that more than 16 CPUs are needed to trigger the allocation. 812 813 Also this option is ignored when "log_buf_len" kernel parameter is 814 used as it forces an exact (power of two) size of the ring buffer. 815 816 The number of possible CPUs is used for this computation ignoring 817 hotplugging making the computation optimal for the worst case 818 scenario while allowing a simple algorithm to be used from bootup. 819 820 Examples shift values and their meaning: 821 17 => 128 KB for each CPU 822 16 => 64 KB for each CPU 823 15 => 32 KB for each CPU 824 14 => 16 KB for each CPU 825 13 => 8 KB for each CPU 826 12 => 4 KB for each CPU 827 828config PRINTK_INDEX 829 bool "Printk indexing debugfs interface" 830 depends on PRINTK && DEBUG_FS 831 help 832 Add support for indexing of all printk formats known at compile time 833 at <debugfs>/printk/index/<module>. 834 835 This can be used as part of maintaining daemons which monitor 836 /dev/kmsg, as it permits auditing the printk formats present in a 837 kernel, allowing detection of cases where monitored printks are 838 changed or no longer present. 839 840 There is no additional runtime cost to printk with this enabled. 841 842# 843# Architectures with an unreliable sched_clock() should select this: 844# 845config HAVE_UNSTABLE_SCHED_CLOCK 846 bool 847 848config GENERIC_SCHED_CLOCK 849 bool 850 851menu "Scheduler features" 852 853config UCLAMP_TASK 854 bool "Enable utilization clamping for RT/FAIR tasks" 855 depends on CPU_FREQ_GOV_SCHEDUTIL 856 help 857 This feature enables the scheduler to track the clamped utilization 858 of each CPU based on RUNNABLE tasks scheduled on that CPU. 859 860 With this option, the user can specify the min and max CPU 861 utilization allowed for RUNNABLE tasks. The max utilization defines 862 the maximum frequency a task should use while the min utilization 863 defines the minimum frequency it should use. 864 865 Both min and max utilization clamp values are hints to the scheduler, 866 aiming at improving its frequency selection policy, but they do not 867 enforce or grant any specific bandwidth for tasks. 868 869 If in doubt, say N. 870 871config UCLAMP_BUCKETS_COUNT 872 int "Number of supported utilization clamp buckets" 873 range 5 20 874 default 5 875 depends on UCLAMP_TASK 876 help 877 Defines the number of clamp buckets to use. The range of each bucket 878 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 879 number of clamp buckets the finer their granularity and the higher 880 the precision of clamping aggregation and tracking at run-time. 881 882 For example, with the minimum configuration value we will have 5 883 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 884 be refcounted in the [20..39]% bucket and will set the bucket clamp 885 effective value to 25%. 886 If a second 30% boosted task should be co-scheduled on the same CPU, 887 that task will be refcounted in the same bucket of the first task and 888 it will boost the bucket clamp effective value to 30%. 889 The clamp effective value of a bucket is reset to its nominal value 890 (20% in the example above) when there are no more tasks refcounted in 891 that bucket. 892 893 An additional boost/capping margin can be added to some tasks. In the 894 example above the 25% task will be boosted to 30% until it exits the 895 CPU. If that should be considered not acceptable on certain systems, 896 it's always possible to reduce the margin by increasing the number of 897 clamp buckets to trade off used memory for run-time tracking 898 precision. 899 900 If in doubt, use the default value. 901 902config SCHED_PROXY_EXEC 903 bool "Proxy Execution" 904 # Avoid some build failures w/ PREEMPT_RT until it can be fixed 905 depends on !PREEMPT_RT 906 # Need to investigate how to inform sched_ext of split contexts 907 depends on !SCHED_CLASS_EXT 908 # Not particularly useful until we get to multi-rq proxying 909 depends on EXPERT 910 help 911 This option enables proxy execution, a mechanism for mutex-owning 912 tasks to inherit the scheduling context of higher priority waiters. 913 914endmenu 915 916# 917# For architectures that want to enable the support for NUMA-affine scheduler 918# balancing logic: 919# 920config ARCH_SUPPORTS_NUMA_BALANCING 921 bool 922 923# 924# For architectures that prefer to flush all TLBs after a number of pages 925# are unmapped instead of sending one IPI per page to flush. The architecture 926# must provide guarantees on what happens if a clean TLB cache entry is 927# written after the unmap. Details are in mm/rmap.c near the check for 928# should_defer_flush. The architecture should also consider if the full flush 929# and the refill costs are offset by the savings of sending fewer IPIs. 930config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 931 bool 932 933config CC_HAS_INT128 934 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 935 936config CC_IMPLICIT_FALLTHROUGH 937 string 938 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 939 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 940 941# Currently, disable gcc-10+ array-bounds globally. 942# It's still broken in gcc-13, so no upper bound yet. 943config GCC10_NO_ARRAY_BOUNDS 944 def_bool y 945 946config CC_NO_ARRAY_BOUNDS 947 bool 948 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS 949 950# Currently, disable -Wstringop-overflow for GCC globally. 951config GCC_NO_STRINGOP_OVERFLOW 952 def_bool y 953 954config CC_NO_STRINGOP_OVERFLOW 955 bool 956 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW 957 958config CC_STRINGOP_OVERFLOW 959 bool 960 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW 961 962# 963# For architectures that know their GCC __int128 support is sound 964# 965config ARCH_SUPPORTS_INT128 966 bool 967 968# For architectures that (ab)use NUMA to represent different memory regions 969# all cpu-local but of different latencies, such as SuperH. 970# 971config ARCH_WANT_NUMA_VARIABLE_LOCALITY 972 bool 973 974config NUMA_BALANCING 975 bool "Memory placement aware NUMA scheduler" 976 depends on ARCH_SUPPORTS_NUMA_BALANCING 977 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 978 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 979 help 980 This option adds support for automatic NUMA aware memory/task placement. 981 The mechanism is quite primitive and is based on migrating memory when 982 it has references to the node the task is running on. 983 984 This system will be inactive on UMA systems. 985 986config NUMA_BALANCING_DEFAULT_ENABLED 987 bool "Automatically enable NUMA aware memory/task placement" 988 default y 989 depends on NUMA_BALANCING 990 help 991 If set, automatic NUMA balancing will be enabled if running on a NUMA 992 machine. 993 994config SLAB_OBJ_EXT 995 bool 996 997menuconfig CGROUPS 998 bool "Control Group support" 999 select KERNFS 1000 help 1001 This option adds support for grouping sets of processes together, for 1002 use with process control subsystems such as Cpusets, CFS, memory 1003 controls or device isolation. 1004 See 1005 - Documentation/scheduler/sched-design-CFS.rst (CFS) 1006 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 1007 and resource control) 1008 1009 Say N if unsure. 1010 1011if CGROUPS 1012 1013config PAGE_COUNTER 1014 bool 1015 1016config CGROUP_FAVOR_DYNMODS 1017 bool "Favor dynamic modification latency reduction by default" 1018 help 1019 This option enables the "favordynmods" mount option by default 1020 which reduces the latencies of dynamic cgroup modifications such 1021 as task migrations and controller on/offs at the cost of making 1022 hot path operations such as forks and exits more expensive. 1023 1024 Say N if unsure. 1025 1026config MEMCG 1027 bool "Memory controller" 1028 select PAGE_COUNTER 1029 select EVENTFD 1030 select SLAB_OBJ_EXT 1031 select VM_EVENT_COUNTERS 1032 help 1033 Provides control over the memory footprint of tasks in a cgroup. 1034 1035config MEMCG_NMI_UNSAFE 1036 bool 1037 depends on MEMCG 1038 depends on HAVE_NMI 1039 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG 1040 default y 1041 1042config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC 1043 bool 1044 depends on MEMCG 1045 depends on HAVE_NMI 1046 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG 1047 default y 1048 1049config MEMCG_V1 1050 bool "Legacy cgroup v1 memory controller" 1051 depends on MEMCG 1052 default n 1053 help 1054 Legacy cgroup v1 memory controller which has been deprecated by 1055 cgroup v2 implementation. The v1 is there for legacy applications 1056 which haven't migrated to the new cgroup v2 interface yet. If you 1057 do not have any such application then you are completely fine leaving 1058 this option disabled. 1059 1060 Please note that feature set of the legacy memory controller is likely 1061 going to shrink due to deprecation process. New deployments with v1 1062 controller are highly discouraged. 1063 1064 Say N if unsure. 1065 1066config BLK_CGROUP 1067 bool "IO controller" 1068 depends on BLOCK 1069 default n 1070 help 1071 Generic block IO controller cgroup interface. This is the common 1072 cgroup interface which should be used by various IO controlling 1073 policies. 1074 1075 Currently, CFQ IO scheduler uses it to recognize task groups and 1076 control disk bandwidth allocation (proportional time slice allocation) 1077 to such task groups. It is also used by bio throttling logic in 1078 block layer to implement upper limit in IO rates on a device. 1079 1080 This option only enables generic Block IO controller infrastructure. 1081 One needs to also enable actual IO controlling logic/policy. For 1082 enabling proportional weight division of disk bandwidth in CFQ, set 1083 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 1084 CONFIG_BLK_DEV_THROTTLING=y. 1085 1086 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 1087 1088config CGROUP_WRITEBACK 1089 bool 1090 depends on MEMCG && BLK_CGROUP 1091 default y 1092 1093menuconfig CGROUP_SCHED 1094 bool "CPU controller" 1095 default n 1096 help 1097 This feature lets CPU scheduler recognize task groups and control CPU 1098 bandwidth allocation to such task groups. It uses cgroups to group 1099 tasks. 1100 1101if CGROUP_SCHED 1102config GROUP_SCHED_WEIGHT 1103 def_bool n 1104 1105config GROUP_SCHED_BANDWIDTH 1106 def_bool n 1107 1108config FAIR_GROUP_SCHED 1109 bool "Group scheduling for SCHED_OTHER" 1110 depends on CGROUP_SCHED 1111 select GROUP_SCHED_WEIGHT 1112 default CGROUP_SCHED 1113 1114config CFS_BANDWIDTH 1115 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1116 depends on FAIR_GROUP_SCHED 1117 select GROUP_SCHED_BANDWIDTH 1118 default n 1119 help 1120 This option allows users to define CPU bandwidth rates (limits) for 1121 tasks running within the fair group scheduler. Groups with no limit 1122 set are considered to be unconstrained and will run with no 1123 restriction. 1124 See Documentation/scheduler/sched-bwc.rst for more information. 1125 1126config RT_GROUP_SCHED 1127 bool "Group scheduling for SCHED_RR/FIFO" 1128 depends on CGROUP_SCHED 1129 default n 1130 help 1131 This feature lets you explicitly allocate real CPU bandwidth 1132 to task groups. If enabled, it will also make it impossible to 1133 schedule realtime tasks for non-root users until you allocate 1134 realtime bandwidth for them. 1135 See Documentation/scheduler/sched-rt-group.rst for more information. 1136 1137config RT_GROUP_SCHED_DEFAULT_DISABLED 1138 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO" 1139 depends on RT_GROUP_SCHED 1140 default n 1141 help 1142 When set, the RT group scheduling is disabled by default. The option 1143 is in inverted form so that mere RT_GROUP_SCHED enables the group 1144 scheduling. 1145 1146 Say N if unsure. 1147 1148config EXT_GROUP_SCHED 1149 bool 1150 depends on SCHED_CLASS_EXT && CGROUP_SCHED 1151 select GROUP_SCHED_WEIGHT 1152 select GROUP_SCHED_BANDWIDTH 1153 default y 1154 1155endif #CGROUP_SCHED 1156 1157config SCHED_MM_CID 1158 def_bool y 1159 depends on SMP && RSEQ 1160 1161config UCLAMP_TASK_GROUP 1162 bool "Utilization clamping per group of tasks" 1163 depends on CGROUP_SCHED 1164 depends on UCLAMP_TASK 1165 default n 1166 help 1167 This feature enables the scheduler to track the clamped utilization 1168 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1169 1170 When this option is enabled, the user can specify a min and max 1171 CPU bandwidth which is allowed for each single task in a group. 1172 The max bandwidth allows to clamp the maximum frequency a task 1173 can use, while the min bandwidth allows to define a minimum 1174 frequency a task will always use. 1175 1176 When task group based utilization clamping is enabled, an eventually 1177 specified task-specific clamp value is constrained by the cgroup 1178 specified clamp value. Both minimum and maximum task clamping cannot 1179 be bigger than the corresponding clamping defined at task group level. 1180 1181 If in doubt, say N. 1182 1183config CGROUP_PIDS 1184 bool "PIDs controller" 1185 help 1186 Provides enforcement of process number limits in the scope of a 1187 cgroup. Any attempt to fork more processes than is allowed in the 1188 cgroup will fail. PIDs are fundamentally a global resource because it 1189 is fairly trivial to reach PID exhaustion before you reach even a 1190 conservative kmemcg limit. As a result, it is possible to grind a 1191 system to halt without being limited by other cgroup policies. The 1192 PIDs controller is designed to stop this from happening. 1193 1194 It should be noted that organisational operations (such as attaching 1195 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1196 since the PIDs limit only affects a process's ability to fork, not to 1197 attach to a cgroup. 1198 1199config CGROUP_RDMA 1200 bool "RDMA controller" 1201 help 1202 Provides enforcement of RDMA resources defined by IB stack. 1203 It is fairly easy for consumers to exhaust RDMA resources, which 1204 can result into resource unavailability to other consumers. 1205 RDMA controller is designed to stop this from happening. 1206 Attaching processes with active RDMA resources to the cgroup 1207 hierarchy is allowed even if can cross the hierarchy's limit. 1208 1209config CGROUP_DMEM 1210 bool "Device memory controller (DMEM)" 1211 select PAGE_COUNTER 1212 help 1213 The DMEM controller allows compatible devices to restrict device 1214 memory usage based on the cgroup hierarchy. 1215 1216 As an example, it allows you to restrict VRAM usage for applications 1217 in the DRM subsystem. 1218 1219config CGROUP_FREEZER 1220 bool "Freezer controller" 1221 help 1222 Provides a way to freeze and unfreeze all tasks in a 1223 cgroup. 1224 1225 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1226 controller includes important in-kernel memory consumers per default. 1227 1228 If you're using cgroup2, say N. 1229 1230config CGROUP_HUGETLB 1231 bool "HugeTLB controller" 1232 depends on HUGETLB_PAGE 1233 select PAGE_COUNTER 1234 default n 1235 help 1236 Provides a cgroup controller for HugeTLB pages. 1237 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1238 The limit is enforced during page fault. Since HugeTLB doesn't 1239 support page reclaim, enforcing the limit at page fault time implies 1240 that, the application will get SIGBUS signal if it tries to access 1241 HugeTLB pages beyond its limit. This requires the application to know 1242 beforehand how much HugeTLB pages it would require for its use. The 1243 control group is tracked in the third page lru pointer. This means 1244 that we cannot use the controller with huge page less than 3 pages. 1245 1246config CPUSETS 1247 bool "Cpuset controller" 1248 depends on SMP 1249 select UNION_FIND 1250 help 1251 This option will let you create and manage CPUSETs which 1252 allow dynamically partitioning a system into sets of CPUs and 1253 Memory Nodes and assigning tasks to run only within those sets. 1254 This is primarily useful on large SMP or NUMA systems. 1255 1256 Say N if unsure. 1257 1258config CPUSETS_V1 1259 bool "Legacy cgroup v1 cpusets controller" 1260 depends on CPUSETS 1261 default n 1262 help 1263 Legacy cgroup v1 cpusets controller which has been deprecated by 1264 cgroup v2 implementation. The v1 is there for legacy applications 1265 which haven't migrated to the new cgroup v2 interface yet. Legacy 1266 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you 1267 do not have any such application then you are completely fine leaving 1268 this option disabled. 1269 1270 Say N if unsure. 1271 1272config PROC_PID_CPUSET 1273 bool "Include legacy /proc/<pid>/cpuset file" 1274 depends on CPUSETS_V1 1275 default y 1276 1277config CGROUP_DEVICE 1278 bool "Device controller" 1279 help 1280 Provides a cgroup controller implementing whitelists for 1281 devices which a process in the cgroup can mknod or open. 1282 1283config CGROUP_CPUACCT 1284 bool "Simple CPU accounting controller" 1285 help 1286 Provides a simple controller for monitoring the 1287 total CPU consumed by the tasks in a cgroup. 1288 1289config CGROUP_PERF 1290 bool "Perf controller" 1291 depends on PERF_EVENTS 1292 help 1293 This option extends the perf per-cpu mode to restrict monitoring 1294 to threads which belong to the cgroup specified and run on the 1295 designated cpu. Or this can be used to have cgroup ID in samples 1296 so that it can monitor performance events among cgroups. 1297 1298 Say N if unsure. 1299 1300config CGROUP_BPF 1301 bool "Support for eBPF programs attached to cgroups" 1302 depends on BPF_SYSCALL 1303 select SOCK_CGROUP_DATA 1304 help 1305 Allow attaching eBPF programs to a cgroup using the bpf(2) 1306 syscall command BPF_PROG_ATTACH. 1307 1308 In which context these programs are accessed depends on the type 1309 of attachment. For instance, programs that are attached using 1310 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1311 inet sockets. 1312 1313config CGROUP_MISC 1314 bool "Misc resource controller" 1315 default n 1316 help 1317 Provides a controller for miscellaneous resources on a host. 1318 1319 Miscellaneous scalar resources are the resources on the host system 1320 which cannot be abstracted like the other cgroups. This controller 1321 tracks and limits the miscellaneous resources used by a process 1322 attached to a cgroup hierarchy. 1323 1324 For more information, please check misc cgroup section in 1325 /Documentation/admin-guide/cgroup-v2.rst. 1326 1327config CGROUP_DEBUG 1328 bool "Debug controller" 1329 default n 1330 depends on DEBUG_KERNEL 1331 help 1332 This option enables a simple controller that exports 1333 debugging information about the cgroups framework. This 1334 controller is for control cgroup debugging only. Its 1335 interfaces are not stable. 1336 1337 Say N. 1338 1339config SOCK_CGROUP_DATA 1340 bool 1341 default n 1342 1343endif # CGROUPS 1344 1345menuconfig NAMESPACES 1346 bool "Namespaces support" if EXPERT 1347 depends on MULTIUSER 1348 default !EXPERT 1349 help 1350 Provides the way to make tasks work with different objects using 1351 the same id. For example same IPC id may refer to different objects 1352 or same user id or pid may refer to different tasks when used in 1353 different namespaces. 1354 1355if NAMESPACES 1356 1357config UTS_NS 1358 bool "UTS namespace" 1359 default y 1360 help 1361 In this namespace tasks see different info provided with the 1362 uname() system call 1363 1364config TIME_NS 1365 bool "TIME namespace" 1366 depends on GENERIC_GETTIMEOFDAY 1367 default y 1368 help 1369 In this namespace boottime and monotonic clocks can be set. 1370 The time will keep going with the same pace. 1371 1372config IPC_NS 1373 bool "IPC namespace" 1374 depends on (SYSVIPC || POSIX_MQUEUE) 1375 default y 1376 help 1377 In this namespace tasks work with IPC ids which correspond to 1378 different IPC objects in different namespaces. 1379 1380config USER_NS 1381 bool "User namespace" 1382 default n 1383 help 1384 This allows containers, i.e. vservers, to use user namespaces 1385 to provide different user info for different servers. 1386 1387 When user namespaces are enabled in the kernel it is 1388 recommended that the MEMCG option also be enabled and that 1389 user-space use the memory control groups to limit the amount 1390 of memory a memory unprivileged users can use. 1391 1392 If unsure, say N. 1393 1394config PID_NS 1395 bool "PID Namespaces" 1396 default y 1397 help 1398 Support process id namespaces. This allows having multiple 1399 processes with the same pid as long as they are in different 1400 pid namespaces. This is a building block of containers. 1401 1402config NET_NS 1403 bool "Network namespace" 1404 depends on NET 1405 default y 1406 help 1407 Allow user space to create what appear to be multiple instances 1408 of the network stack. 1409 1410endif # NAMESPACES 1411 1412config CHECKPOINT_RESTORE 1413 bool "Checkpoint/restore support" 1414 depends on PROC_FS 1415 select PROC_CHILDREN 1416 select KCMP 1417 default n 1418 help 1419 Enables additional kernel features in a sake of checkpoint/restore. 1420 In particular it adds auxiliary prctl codes to setup process text, 1421 data and heap segment sizes, and a few additional /proc filesystem 1422 entries. 1423 1424 If unsure, say N here. 1425 1426config SCHED_AUTOGROUP 1427 bool "Automatic process group scheduling" 1428 select CGROUPS 1429 select CGROUP_SCHED 1430 select FAIR_GROUP_SCHED 1431 help 1432 This option optimizes the scheduler for common desktop workloads by 1433 automatically creating and populating task groups. This separation 1434 of workloads isolates aggressive CPU burners (like build jobs) from 1435 desktop applications. Task group autogeneration is currently based 1436 upon task session. 1437 1438config RELAY 1439 bool "Kernel->user space relay support (formerly relayfs)" 1440 select IRQ_WORK 1441 help 1442 This option enables support for relay interface support in 1443 certain file systems (such as debugfs). 1444 It is designed to provide an efficient mechanism for tools and 1445 facilities to relay large amounts of data from kernel space to 1446 user space. 1447 1448 If unsure, say N. 1449 1450config BLK_DEV_INITRD 1451 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1452 help 1453 The initial RAM filesystem is a ramfs which is loaded by the 1454 boot loader (loadlin or lilo) and that is mounted as root 1455 before the normal boot procedure. It is typically used to 1456 load modules needed to mount the "real" root file system, 1457 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1458 1459 If RAM disk support (BLK_DEV_RAM) is also included, this 1460 also enables initial RAM disk (initrd) support and adds 1461 15 Kbytes (more on some other architectures) to the kernel size. 1462 1463 If unsure say Y. 1464 1465if BLK_DEV_INITRD 1466 1467source "usr/Kconfig" 1468 1469endif 1470 1471config BOOT_CONFIG 1472 bool "Boot config support" 1473 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1474 help 1475 Extra boot config allows system admin to pass a config file as 1476 complemental extension of kernel cmdline when booting. 1477 The boot config file must be attached at the end of initramfs 1478 with checksum, size and magic word. 1479 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1480 1481 If unsure, say Y. 1482 1483config BOOT_CONFIG_FORCE 1484 bool "Force unconditional bootconfig processing" 1485 depends on BOOT_CONFIG 1486 default y if BOOT_CONFIG_EMBED 1487 help 1488 With this Kconfig option set, BOOT_CONFIG processing is carried 1489 out even when the "bootconfig" kernel-boot parameter is omitted. 1490 In fact, with this Kconfig option set, there is no way to 1491 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot 1492 parameters. 1493 1494 If unsure, say N. 1495 1496config BOOT_CONFIG_EMBED 1497 bool "Embed bootconfig file in the kernel" 1498 depends on BOOT_CONFIG 1499 help 1500 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1501 kernel. Usually, the bootconfig file is loaded with the initrd 1502 image. But if the system doesn't support initrd, this option will 1503 help you by embedding a bootconfig file while building the kernel. 1504 1505 If unsure, say N. 1506 1507config BOOT_CONFIG_EMBED_FILE 1508 string "Embedded bootconfig file path" 1509 depends on BOOT_CONFIG_EMBED 1510 help 1511 Specify a bootconfig file which will be embedded to the kernel. 1512 This bootconfig will be used if there is no initrd or no other 1513 bootconfig in the initrd. 1514 1515config INITRAMFS_PRESERVE_MTIME 1516 bool "Preserve cpio archive mtimes in initramfs" 1517 depends on BLK_DEV_INITRD 1518 default y 1519 help 1520 Each entry in an initramfs cpio archive carries an mtime value. When 1521 enabled, extracted cpio items take this mtime, with directory mtime 1522 setting deferred until after creation of any child entries. 1523 1524 If unsure, say Y. 1525 1526config INITRAMFS_TEST 1527 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS 1528 depends on BLK_DEV_INITRD && KUNIT=y 1529 default KUNIT_ALL_TESTS 1530 help 1531 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit 1532 1533choice 1534 prompt "Compiler optimization level" 1535 default CC_OPTIMIZE_FOR_PERFORMANCE 1536 1537config CC_OPTIMIZE_FOR_PERFORMANCE 1538 bool "Optimize for performance (-O2)" 1539 help 1540 This is the default optimization level for the kernel, building 1541 with the "-O2" compiler flag for best performance and most 1542 helpful compile-time warnings. 1543 1544config CC_OPTIMIZE_FOR_SIZE 1545 bool "Optimize for size (-Os)" 1546 help 1547 Choosing this option will pass "-Os" to your compiler resulting 1548 in a smaller kernel. 1549 1550endchoice 1551 1552config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1553 bool 1554 help 1555 This requires that the arch annotates or otherwise protects 1556 its external entry points from being discarded. Linker scripts 1557 must also merge .text.*, .data.*, and .bss.* correctly into 1558 output sections. Care must be taken not to pull in unrelated 1559 sections (e.g., '.text.init'). Typically '.' in section names 1560 is used to distinguish them from label names / C identifiers. 1561 1562config LD_DEAD_CODE_DATA_ELIMINATION 1563 bool "Dead code and data elimination (EXPERIMENTAL)" 1564 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1565 depends on EXPERT 1566 depends on $(cc-option,-ffunction-sections -fdata-sections) 1567 depends on $(ld-option,--gc-sections) 1568 help 1569 Enable this if you want to do dead code and data elimination with 1570 the linker by compiling with -ffunction-sections -fdata-sections, 1571 and linking with --gc-sections. 1572 1573 This can reduce on disk and in-memory size of the kernel 1574 code and static data, particularly for small configs and 1575 on small systems. This has the possibility of introducing 1576 silently broken kernel if the required annotations are not 1577 present. This option is not well tested yet, so use at your 1578 own risk. 1579 1580config LD_ORPHAN_WARN 1581 def_bool y 1582 depends on ARCH_WANT_LD_ORPHAN_WARN 1583 depends on $(ld-option,--orphan-handling=warn) 1584 depends on $(ld-option,--orphan-handling=error) 1585 1586config LD_ORPHAN_WARN_LEVEL 1587 string 1588 depends on LD_ORPHAN_WARN 1589 default "error" if WERROR 1590 default "warn" 1591 1592config SYSCTL 1593 bool 1594 1595config HAVE_UID16 1596 bool 1597 1598config SYSCTL_EXCEPTION_TRACE 1599 bool 1600 help 1601 Enable support for /proc/sys/debug/exception-trace. 1602 1603config SYSCTL_ARCH_UNALIGN_NO_WARN 1604 bool 1605 help 1606 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1607 Allows arch to define/use @no_unaligned_warning to possibly warn 1608 about unaligned access emulation going on under the hood. 1609 1610config SYSCTL_ARCH_UNALIGN_ALLOW 1611 bool 1612 help 1613 Enable support for /proc/sys/kernel/unaligned-trap 1614 Allows arches to define/use @unaligned_enabled to runtime toggle 1615 the unaligned access emulation. 1616 see arch/parisc/kernel/unaligned.c for reference 1617 1618config SYSFS_SYSCALL 1619 bool "Sysfs syscall support" 1620 default n 1621 help 1622 sys_sysfs is an obsolete system call no longer supported in libc. 1623 Note that disabling this option is more secure but might break 1624 compatibility with some systems. 1625 1626 If unsure say N here. 1627 1628config HAVE_PCSPKR_PLATFORM 1629 bool 1630 1631menuconfig EXPERT 1632 bool "Configure standard kernel features (expert users)" 1633 # Unhide debug options, to make the on-by-default options visible 1634 select DEBUG_KERNEL 1635 help 1636 This option allows certain base kernel options and settings 1637 to be disabled or tweaked. This is for specialized 1638 environments which can tolerate a "non-standard" kernel. 1639 Only use this if you really know what you are doing. 1640 1641config UID16 1642 bool "Enable 16-bit UID system calls" if EXPERT 1643 depends on HAVE_UID16 && MULTIUSER 1644 default y 1645 help 1646 This enables the legacy 16-bit UID syscall wrappers. 1647 1648config MULTIUSER 1649 bool "Multiple users, groups and capabilities support" if EXPERT 1650 default y 1651 help 1652 This option enables support for non-root users, groups and 1653 capabilities. 1654 1655 If you say N here, all processes will run with UID 0, GID 0, and all 1656 possible capabilities. Saying N here also compiles out support for 1657 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1658 setgid, and capset. 1659 1660 If unsure, say Y here. 1661 1662config SGETMASK_SYSCALL 1663 bool "sgetmask/ssetmask syscalls support" if EXPERT 1664 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1665 help 1666 sys_sgetmask and sys_ssetmask are obsolete system calls 1667 no longer supported in libc but still enabled by default in some 1668 architectures. 1669 1670 If unsure, leave the default option here. 1671 1672config FHANDLE 1673 bool "open by fhandle syscalls" if EXPERT 1674 select EXPORTFS 1675 default y 1676 help 1677 If you say Y here, a user level program will be able to map 1678 file names to handle and then later use the handle for 1679 different file system operations. This is useful in implementing 1680 userspace file servers, which now track files using handles instead 1681 of names. The handle would remain the same even if file names 1682 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1683 syscalls. 1684 1685config POSIX_TIMERS 1686 bool "Posix Clocks & timers" if EXPERT 1687 default y 1688 help 1689 This includes native support for POSIX timers to the kernel. 1690 Some embedded systems have no use for them and therefore they 1691 can be configured out to reduce the size of the kernel image. 1692 1693 When this option is disabled, the following syscalls won't be 1694 available: timer_create, timer_gettime: timer_getoverrun, 1695 timer_settime, timer_delete, clock_adjtime, getitimer, 1696 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1697 clock_getres and clock_nanosleep syscalls will be limited to 1698 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1699 1700 If unsure say y. 1701 1702config PRINTK 1703 default y 1704 bool "Enable support for printk" if EXPERT 1705 select IRQ_WORK 1706 help 1707 This option enables normal printk support. Removing it 1708 eliminates most of the message strings from the kernel image 1709 and makes the kernel more or less silent. As this makes it 1710 very difficult to diagnose system problems, saying N here is 1711 strongly discouraged. 1712 1713config PRINTK_RINGBUFFER_KUNIT_TEST 1714 tristate "KUnit Test for the printk ringbuffer" if !KUNIT_ALL_TESTS 1715 depends on PRINTK && KUNIT 1716 default KUNIT_ALL_TESTS 1717 help 1718 This builds the printk ringbuffer KUnit test suite. 1719 1720 For more information on KUnit and unit tests in general, please refer 1721 to the KUnit documentation. 1722 1723 If unsure, say N. 1724 1725config BUG 1726 bool "BUG() support" if EXPERT 1727 default y 1728 help 1729 Disabling this option eliminates support for BUG and WARN, reducing 1730 the size of your kernel image and potentially quietly ignoring 1731 numerous fatal conditions. You should only consider disabling this 1732 option for embedded systems with no facilities for reporting errors. 1733 Just say Y. 1734 1735config ELF_CORE 1736 depends on COREDUMP 1737 default y 1738 bool "Enable ELF core dumps" if EXPERT 1739 help 1740 Enable support for generating core dumps. Disabling saves about 4k. 1741 1742 1743config PCSPKR_PLATFORM 1744 bool "Enable PC-Speaker support" if EXPERT 1745 depends on HAVE_PCSPKR_PLATFORM 1746 select I8253_LOCK 1747 default y 1748 help 1749 This option allows to disable the internal PC-Speaker 1750 support, saving some memory. 1751 1752config BASE_SMALL 1753 bool "Enable smaller-sized data structures for core" if EXPERT 1754 help 1755 Enabling this option reduces the size of miscellaneous core 1756 kernel data structures. This saves memory on small machines, 1757 but may reduce performance. 1758 1759config FUTEX 1760 bool "Enable futex support" if EXPERT 1761 depends on !(SPARC32 && SMP) 1762 default y 1763 imply RT_MUTEXES 1764 help 1765 Disabling this option will cause the kernel to be built without 1766 support for "fast userspace mutexes". The resulting kernel may not 1767 run glibc-based applications correctly. 1768 1769config FUTEX_PI 1770 bool 1771 depends on FUTEX && RT_MUTEXES 1772 default y 1773 1774config FUTEX_PRIVATE_HASH 1775 bool 1776 depends on FUTEX && !BASE_SMALL && MMU 1777 default y 1778 1779config FUTEX_MPOL 1780 bool 1781 depends on FUTEX && NUMA 1782 default y 1783 1784config EPOLL 1785 bool "Enable eventpoll support" if EXPERT 1786 default y 1787 help 1788 Disabling this option will cause the kernel to be built without 1789 support for epoll family of system calls. 1790 1791config SIGNALFD 1792 bool "Enable signalfd() system call" if EXPERT 1793 default y 1794 help 1795 Enable the signalfd() system call that allows to receive signals 1796 on a file descriptor. 1797 1798 If unsure, say Y. 1799 1800config TIMERFD 1801 bool "Enable timerfd() system call" if EXPERT 1802 default y 1803 help 1804 Enable the timerfd() system call that allows to receive timer 1805 events on a file descriptor. 1806 1807 If unsure, say Y. 1808 1809config EVENTFD 1810 bool "Enable eventfd() system call" if EXPERT 1811 default y 1812 help 1813 Enable the eventfd() system call that allows to receive both 1814 kernel notification (ie. KAIO) or userspace notifications. 1815 1816 If unsure, say Y. 1817 1818config SHMEM 1819 bool "Use full shmem filesystem" if EXPERT 1820 default y 1821 depends on MMU 1822 help 1823 The shmem is an internal filesystem used to manage shared memory. 1824 It is backed by swap and manages resource limits. It is also exported 1825 to userspace as tmpfs if TMPFS is enabled. Disabling this 1826 option replaces shmem and tmpfs with the much simpler ramfs code, 1827 which may be appropriate on small systems without swap. 1828 1829config AIO 1830 bool "Enable AIO support" if EXPERT 1831 default y 1832 help 1833 This option enables POSIX asynchronous I/O which may by used 1834 by some high performance threaded applications. Disabling 1835 this option saves about 7k. 1836 1837config IO_URING 1838 bool "Enable IO uring support" if EXPERT 1839 select IO_WQ 1840 default y 1841 help 1842 This option enables support for the io_uring interface, enabling 1843 applications to submit and complete IO through submission and 1844 completion rings that are shared between the kernel and application. 1845 1846config GCOV_PROFILE_URING 1847 bool "Enable GCOV profiling on the io_uring subsystem" 1848 depends on IO_URING && GCOV_KERNEL 1849 help 1850 Enable GCOV profiling on the io_uring subsystem, to facilitate 1851 code coverage testing. 1852 1853 If unsure, say N. 1854 1855 Note that this will have a negative impact on the performance of 1856 the io_uring subsystem, hence this should only be enabled for 1857 specific test purposes. 1858 1859config IO_URING_MOCK_FILE 1860 tristate "Enable io_uring mock files (Experimental)" if EXPERT 1861 default n 1862 depends on IO_URING 1863 help 1864 Enable mock files for io_uring subststem testing. The ABI might 1865 still change, so it's still experimental and should only be enabled 1866 for specific test purposes. 1867 1868 If unsure, say N. 1869 1870config ADVISE_SYSCALLS 1871 bool "Enable madvise/fadvise syscalls" if EXPERT 1872 default y 1873 help 1874 This option enables the madvise and fadvise syscalls, used by 1875 applications to advise the kernel about their future memory or file 1876 usage, improving performance. If building an embedded system where no 1877 applications use these syscalls, you can disable this option to save 1878 space. 1879 1880config MEMBARRIER 1881 bool "Enable membarrier() system call" if EXPERT 1882 default y 1883 help 1884 Enable the membarrier() system call that allows issuing memory 1885 barriers across all running threads, which can be used to distribute 1886 the cost of user-space memory barriers asymmetrically by transforming 1887 pairs of memory barriers into pairs consisting of membarrier() and a 1888 compiler barrier. 1889 1890 If unsure, say Y. 1891 1892config KCMP 1893 bool "Enable kcmp() system call" if EXPERT 1894 help 1895 Enable the kernel resource comparison system call. It provides 1896 user-space with the ability to compare two processes to see if they 1897 share a common resource, such as a file descriptor or even virtual 1898 memory space. 1899 1900 If unsure, say N. 1901 1902config RSEQ 1903 bool "Enable rseq() system call" if EXPERT 1904 default y 1905 depends on HAVE_RSEQ 1906 select MEMBARRIER 1907 help 1908 Enable the restartable sequences system call. It provides a 1909 user-space cache for the current CPU number value, which 1910 speeds up getting the current CPU number from user-space, 1911 as well as an ABI to speed up user-space operations on 1912 per-CPU data. 1913 1914 If unsure, say Y. 1915 1916config DEBUG_RSEQ 1917 default n 1918 bool "Enable debugging of rseq() system call" if EXPERT 1919 depends on RSEQ && DEBUG_KERNEL 1920 help 1921 Enable extra debugging checks for the rseq system call. 1922 1923 If unsure, say N. 1924 1925config CACHESTAT_SYSCALL 1926 bool "Enable cachestat() system call" if EXPERT 1927 default y 1928 help 1929 Enable the cachestat system call, which queries the page cache 1930 statistics of a file (number of cached pages, dirty pages, 1931 pages marked for writeback, (recently) evicted pages). 1932 1933 If unsure say Y here. 1934 1935config KALLSYMS 1936 bool "Load all symbols for debugging/ksymoops" if EXPERT 1937 default y 1938 help 1939 Say Y here to let the kernel print out symbolic crash information and 1940 symbolic stack backtraces. This increases the size of the kernel 1941 somewhat, as all symbols have to be loaded into the kernel image. 1942 1943config KALLSYMS_SELFTEST 1944 bool "Test the basic functions and performance of kallsyms" 1945 depends on KALLSYMS 1946 default n 1947 help 1948 Test the basic functions and performance of some interfaces, such as 1949 kallsyms_lookup_name. It also calculates the compression rate of the 1950 kallsyms compression algorithm for the current symbol set. 1951 1952 Start self-test automatically after system startup. Suggest executing 1953 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is 1954 displayed in the last line, indicating that the test is complete. 1955 1956config KALLSYMS_ALL 1957 bool "Include all symbols in kallsyms" 1958 depends on DEBUG_KERNEL && KALLSYMS 1959 help 1960 Normally kallsyms only contains the symbols of functions for nicer 1961 OOPS messages and backtraces (i.e., symbols from the text and inittext 1962 sections). This is sufficient for most cases. And only if you want to 1963 enable kernel live patching, or other less common use cases (e.g., 1964 when a debugger is used) all symbols are required (i.e., names of 1965 variables from the data sections, etc). 1966 1967 This option makes sure that all symbols are loaded into the kernel 1968 image (i.e., symbols from all sections) in cost of increased kernel 1969 size (depending on the kernel configuration, it may be 300KiB or 1970 something like this). 1971 1972 Say N unless you really need all symbols, or kernel live patching. 1973 1974# end of the "standard kernel features (expert users)" menu 1975 1976config ARCH_HAS_MEMBARRIER_CALLBACKS 1977 bool 1978 1979config ARCH_HAS_MEMBARRIER_SYNC_CORE 1980 bool 1981 1982config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS 1983 bool 1984 help 1985 Control MSEAL_SYSTEM_MAPPINGS access based on architecture. 1986 1987 A 64-bit kernel is required for the memory sealing feature. 1988 No specific hardware features from the CPU are needed. 1989 1990 To enable this feature, the architecture needs to update their 1991 special mappings calls to include the sealing flag and confirm 1992 that it doesn't unmap/remap system mappings during the life 1993 time of the process. The existence of this flag for an architecture 1994 implies that it does not require the remapping of the system 1995 mappings during process lifetime, so sealing these mappings is safe 1996 from a kernel perspective. 1997 1998 After the architecture enables this, a distribution can set 1999 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. 2000 2001 For complete descriptions of memory sealing, please see 2002 Documentation/userspace-api/mseal.rst 2003 2004config HAVE_PERF_EVENTS 2005 bool 2006 help 2007 See tools/perf/design.txt for details. 2008 2009config GUEST_PERF_EVENTS 2010 bool 2011 depends on HAVE_PERF_EVENTS 2012 2013config PERF_USE_VMALLOC 2014 bool 2015 help 2016 See tools/perf/design.txt for details 2017 2018menu "Kernel Performance Events And Counters" 2019 2020config PERF_EVENTS 2021 bool "Kernel performance events and counters" 2022 default y if PROFILING 2023 depends on HAVE_PERF_EVENTS 2024 select IRQ_WORK 2025 help 2026 Enable kernel support for various performance events provided 2027 by software and hardware. 2028 2029 Software events are supported either built-in or via the 2030 use of generic tracepoints. 2031 2032 Most modern CPUs support performance events via performance 2033 counter registers. These registers count the number of certain 2034 types of hw events: such as instructions executed, cachemisses 2035 suffered, or branches mis-predicted - without slowing down the 2036 kernel or applications. These registers can also trigger interrupts 2037 when a threshold number of events have passed - and can thus be 2038 used to profile the code that runs on that CPU. 2039 2040 The Linux Performance Event subsystem provides an abstraction of 2041 these software and hardware event capabilities, available via a 2042 system call and used by the "perf" utility in tools/perf/. It 2043 provides per task and per CPU counters, and it provides event 2044 capabilities on top of those. 2045 2046 Say Y if unsure. 2047 2048config DEBUG_PERF_USE_VMALLOC 2049 default n 2050 bool "Debug: use vmalloc to back perf mmap() buffers" 2051 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 2052 select PERF_USE_VMALLOC 2053 help 2054 Use vmalloc memory to back perf mmap() buffers. 2055 2056 Mostly useful for debugging the vmalloc code on platforms 2057 that don't require it. 2058 2059 Say N if unsure. 2060 2061endmenu 2062 2063config SYSTEM_DATA_VERIFICATION 2064 def_bool n 2065 select SYSTEM_TRUSTED_KEYRING 2066 select KEYS 2067 select CRYPTO 2068 select CRYPTO_RSA 2069 select ASYMMETRIC_KEY_TYPE 2070 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2071 select ASN1 2072 select OID_REGISTRY 2073 select X509_CERTIFICATE_PARSER 2074 select PKCS7_MESSAGE_PARSER 2075 help 2076 Provide PKCS#7 message verification using the contents of the system 2077 trusted keyring to provide public keys. This then can be used for 2078 module verification, kexec image verification and firmware blob 2079 verification. 2080 2081config PROFILING 2082 bool "Profiling support" 2083 help 2084 Say Y here to enable the extended profiling support mechanisms used 2085 by profilers. 2086 2087config RUST 2088 bool "Rust support" 2089 depends on HAVE_RUST 2090 depends on RUST_IS_AVAILABLE 2091 select EXTENDED_MODVERSIONS if MODVERSIONS 2092 depends on !MODVERSIONS || GENDWARFKSYMS 2093 depends on !GCC_PLUGIN_RANDSTRUCT 2094 depends on !RANDSTRUCT 2095 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO) 2096 depends on !CFI || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC 2097 select CFI_ICALL_NORMALIZE_INTEGERS if CFI 2098 depends on !CALL_PADDING || RUSTC_VERSION >= 108100 2099 depends on !KASAN_SW_TAGS 2100 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300 2101 help 2102 Enables Rust support in the kernel. 2103 2104 This allows other Rust-related options, like drivers written in Rust, 2105 to be selected. 2106 2107 It is also required to be able to load external kernel modules 2108 written in Rust. 2109 2110 See Documentation/rust/ for more information. 2111 2112 If unsure, say N. 2113 2114config RUSTC_VERSION_TEXT 2115 string 2116 depends on RUST 2117 default "$(RUSTC_VERSION_TEXT)" 2118 help 2119 See `CC_VERSION_TEXT`. 2120 2121config BINDGEN_VERSION_TEXT 2122 string 2123 depends on RUST 2124 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0 2125 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0 2126 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed 2127 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1 2128 # both fixed the issue). 2129 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)" 2130 2131# 2132# Place an empty function call at each tracepoint site. Can be 2133# dynamically changed for a probe function. 2134# 2135config TRACEPOINTS 2136 bool 2137 select TASKS_TRACE_RCU 2138 2139source "kernel/Kconfig.kexec" 2140 2141endmenu # General setup 2142 2143source "arch/Kconfig" 2144 2145config RT_MUTEXES 2146 bool 2147 default y if PREEMPT_RT 2148 2149config MODULE_SIG_FORMAT 2150 def_bool n 2151 select SYSTEM_DATA_VERIFICATION 2152 2153source "kernel/module/Kconfig" 2154 2155config INIT_ALL_POSSIBLE 2156 bool 2157 help 2158 Back when each arch used to define their own cpu_online_mask and 2159 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2160 with all 1s, and others with all 0s. When they were centralised, 2161 it was better to provide this option than to break all the archs 2162 and have several arch maintainers pursuing me down dark alleys. 2163 2164source "block/Kconfig" 2165 2166config PREEMPT_NOTIFIERS 2167 bool 2168 2169config PADATA 2170 depends on SMP 2171 bool 2172 2173config ASN1 2174 tristate 2175 help 2176 Build a simple ASN.1 grammar compiler that produces a bytecode output 2177 that can be interpreted by the ASN.1 stream decoder and used to 2178 inform it as to what tags are to be expected in a stream and what 2179 functions to call on what tags. 2180 2181source "kernel/Kconfig.locks" 2182 2183config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2184 bool 2185 2186config ARCH_HAS_PREPARE_SYNC_CORE_CMD 2187 bool 2188 2189config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2190 bool 2191 2192# It may be useful for an architecture to override the definitions of the 2193# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2194# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2195# different calling convention for syscalls. They can also override the 2196# macros for not-implemented syscalls in kernel/sys_ni.c and 2197# kernel/time/posix-stubs.c. All these overrides need to be available in 2198# <asm/syscall_wrapper.h>. 2199config ARCH_HAS_SYSCALL_WRAPPER 2200 def_bool n 2201