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