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 CC_CAN_LINK 64 bool 65 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT 66 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag)) 67 68config CC_CAN_LINK_STATIC 69 bool 70 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT 71 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static) 72 73config CC_HAS_ASM_GOTO 74 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC)) 75 76config CC_HAS_ASM_GOTO_OUTPUT 77 depends on CC_HAS_ASM_GOTO 78 def_bool $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null) 79 80config CC_HAS_ASM_GOTO_TIED_OUTPUT 81 depends on CC_HAS_ASM_GOTO_OUTPUT 82 # Detect buggy gcc and clang, fixed in gcc-11 clang-14. 83 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .\n": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null) 84 85config TOOLS_SUPPORT_RELR 86 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) 87 88config CC_HAS_ASM_INLINE 89 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) 90 91config CC_HAS_NO_PROFILE_FN_ATTR 92 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) 93 94config PAHOLE_VERSION 95 int 96 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) 97 98config CONSTRUCTORS 99 bool 100 101config IRQ_WORK 102 bool 103 104config BUILDTIME_TABLE_SORT 105 bool 106 107config THREAD_INFO_IN_TASK 108 bool 109 help 110 Select this to move thread_info off the stack into task_struct. To 111 make this work, an arch will need to remove all thread_info fields 112 except flags and fix any runtime bugs. 113 114 One subtle change that will be needed is to use try_get_task_stack() 115 and put_task_stack() in save_thread_stack_tsk() and get_wchan(). 116 117menu "General setup" 118 119config BROKEN 120 bool 121 122config BROKEN_ON_SMP 123 bool 124 depends on BROKEN || !SMP 125 default y 126 127config INIT_ENV_ARG_LIMIT 128 int 129 default 32 if !UML 130 default 128 if UML 131 help 132 Maximum of each of the number of arguments and environment 133 variables passed to init from the kernel command line. 134 135config COMPILE_TEST 136 bool "Compile also drivers which will not load" 137 depends on HAS_IOMEM 138 help 139 Some drivers can be compiled on a different platform than they are 140 intended to be run on. Despite they cannot be loaded there (or even 141 when they load they cannot be used due to missing HW support), 142 developers still, opposing to distributors, might want to build such 143 drivers to compile-test them. 144 145 If you are a developer and want to build everything available, say Y 146 here. If you are a user/distributor, say N here to exclude useless 147 drivers to be distributed. 148 149config WERROR 150 bool "Compile the kernel with warnings as errors" 151 default COMPILE_TEST 152 help 153 A kernel build should not cause any compiler warnings, and this 154 enables the '-Werror' flag to enforce that rule by default. 155 156 However, if you have a new (or very old) compiler with odd and 157 unusual warnings, or you have some architecture with problems, 158 you may need to disable this config option in order to 159 successfully build the kernel. 160 161 If in doubt, say Y. 162 163config UAPI_HEADER_TEST 164 bool "Compile test UAPI headers" 165 depends on HEADERS_INSTALL && CC_CAN_LINK 166 help 167 Compile test headers exported to user-space to ensure they are 168 self-contained, i.e. compilable as standalone units. 169 170 If you are a developer or tester and want to ensure the exported 171 headers are self-contained, say Y here. Otherwise, choose N. 172 173config LOCALVERSION 174 string "Local version - append to kernel release" 175 help 176 Append an extra string to the end of your kernel version. 177 This will show up when you type uname, for example. 178 The string you set here will be appended after the contents of 179 any files with a filename matching localversion* in your 180 object and source tree, in that order. Your total string can 181 be a maximum of 64 characters. 182 183config LOCALVERSION_AUTO 184 bool "Automatically append version information to the version string" 185 default y 186 depends on !COMPILE_TEST 187 help 188 This will try to automatically determine if the current tree is a 189 release tree by looking for git tags that belong to the current 190 top of tree revision. 191 192 A string of the format -gxxxxxxxx will be added to the localversion 193 if a git-based tree is found. The string generated by this will be 194 appended after any matching localversion* files, and after the value 195 set in CONFIG_LOCALVERSION. 196 197 (The actual string used here is the first eight characters produced 198 by running the command: 199 200 $ git rev-parse --verify HEAD 201 202 which is done within the script "scripts/setlocalversion".) 203 204config BUILD_SALT 205 string "Build ID Salt" 206 default "" 207 help 208 The build ID is used to link binaries and their debug info. Setting 209 this option will use the value in the calculation of the build id. 210 This is mostly useful for distributions which want to ensure the 211 build is unique between builds. It's safe to leave the default. 212 213config HAVE_KERNEL_GZIP 214 bool 215 216config HAVE_KERNEL_BZIP2 217 bool 218 219config HAVE_KERNEL_LZMA 220 bool 221 222config HAVE_KERNEL_XZ 223 bool 224 225config HAVE_KERNEL_LZO 226 bool 227 228config HAVE_KERNEL_LZ4 229 bool 230 231config HAVE_KERNEL_ZSTD 232 bool 233 234config HAVE_KERNEL_UNCOMPRESSED 235 bool 236 237choice 238 prompt "Kernel compression mode" 239 default KERNEL_GZIP 240 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 241 help 242 The linux kernel is a kind of self-extracting executable. 243 Several compression algorithms are available, which differ 244 in efficiency, compression and decompression speed. 245 Compression speed is only relevant when building a kernel. 246 Decompression speed is relevant at each boot. 247 248 If you have any problems with bzip2 or lzma compressed 249 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 250 version of this functionality (bzip2 only), for 2.4, was 251 supplied by Christian Ludwig) 252 253 High compression options are mostly useful for users, who 254 are low on disk space (embedded systems), but for whom ram 255 size matters less. 256 257 If in doubt, select 'gzip' 258 259config KERNEL_GZIP 260 bool "Gzip" 261 depends on HAVE_KERNEL_GZIP 262 help 263 The old and tried gzip compression. It provides a good balance 264 between compression ratio and decompression speed. 265 266config KERNEL_BZIP2 267 bool "Bzip2" 268 depends on HAVE_KERNEL_BZIP2 269 help 270 Its compression ratio and speed is intermediate. 271 Decompression speed is slowest among the choices. The kernel 272 size is about 10% smaller with bzip2, in comparison to gzip. 273 Bzip2 uses a large amount of memory. For modern kernels you 274 will need at least 8MB RAM or more for booting. 275 276config KERNEL_LZMA 277 bool "LZMA" 278 depends on HAVE_KERNEL_LZMA 279 help 280 This compression algorithm's ratio is best. Decompression speed 281 is between gzip and bzip2. Compression is slowest. 282 The kernel size is about 33% smaller with LZMA in comparison to gzip. 283 284config KERNEL_XZ 285 bool "XZ" 286 depends on HAVE_KERNEL_XZ 287 help 288 XZ uses the LZMA2 algorithm and instruction set specific 289 BCJ filters which can improve compression ratio of executable 290 code. The size of the kernel is about 30% smaller with XZ in 291 comparison to gzip. On architectures for which there is a BCJ 292 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ 293 will create a few percent smaller kernel than plain LZMA. 294 295 The speed is about the same as with LZMA: The decompression 296 speed of XZ is better than that of bzip2 but worse than gzip 297 and LZO. Compression is slow. 298 299config KERNEL_LZO 300 bool "LZO" 301 depends on HAVE_KERNEL_LZO 302 help 303 Its compression ratio is the poorest among the choices. The kernel 304 size is about 10% bigger than gzip; however its speed 305 (both compression and decompression) is the fastest. 306 307config KERNEL_LZ4 308 bool "LZ4" 309 depends on HAVE_KERNEL_LZ4 310 help 311 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. 312 A preliminary version of LZ4 de/compression tool is available at 313 <https://code.google.com/p/lz4/>. 314 315 Its compression ratio is worse than LZO. The size of the kernel 316 is about 8% bigger than LZO. But the decompression speed is 317 faster than LZO. 318 319config KERNEL_ZSTD 320 bool "ZSTD" 321 depends on HAVE_KERNEL_ZSTD 322 help 323 ZSTD is a compression algorithm targeting intermediate compression 324 with fast decompression speed. It will compress better than GZIP and 325 decompress around the same speed as LZO, but slower than LZ4. You 326 will need at least 192 KB RAM or more for booting. The zstd command 327 line tool is required for compression. 328 329config KERNEL_UNCOMPRESSED 330 bool "None" 331 depends on HAVE_KERNEL_UNCOMPRESSED 332 help 333 Produce uncompressed kernel image. This option is usually not what 334 you want. It is useful for debugging the kernel in slow simulation 335 environments, where decompressing and moving the kernel is awfully 336 slow. This option allows early boot code to skip the decompressor 337 and jump right at uncompressed kernel image. 338 339endchoice 340 341config DEFAULT_INIT 342 string "Default init path" 343 default "" 344 help 345 This option determines the default init for the system if no init= 346 option is passed on the kernel command line. If the requested path is 347 not present, we will still then move on to attempting further 348 locations (e.g. /sbin/init, etc). If this is empty, we will just use 349 the fallback list when init= is not passed. 350 351config DEFAULT_HOSTNAME 352 string "Default hostname" 353 default "(none)" 354 help 355 This option determines the default system hostname before userspace 356 calls sethostname(2). The kernel traditionally uses "(none)" here, 357 but you may wish to use a different default here to make a minimal 358 system more usable with less configuration. 359 360config SYSVIPC 361 bool "System V IPC" 362 help 363 Inter Process Communication is a suite of library functions and 364 system calls which let processes (running programs) synchronize and 365 exchange information. It is generally considered to be a good thing, 366 and some programs won't run unless you say Y here. In particular, if 367 you want to run the DOS emulator dosemu under Linux (read the 368 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 369 you'll need to say Y here. 370 371 You can find documentation about IPC with "info ipc" and also in 372 section 6.4 of the Linux Programmer's Guide, available from 373 <http://www.tldp.org/guides.html>. 374 375config SYSVIPC_SYSCTL 376 bool 377 depends on SYSVIPC 378 depends on SYSCTL 379 default y 380 381config SYSVIPC_COMPAT 382 def_bool y 383 depends on COMPAT && SYSVIPC 384 385config POSIX_MQUEUE 386 bool "POSIX Message Queues" 387 depends on NET 388 help 389 POSIX variant of message queues is a part of IPC. In POSIX message 390 queues every message has a priority which decides about succession 391 of receiving it by a process. If you want to compile and run 392 programs written e.g. for Solaris with use of its POSIX message 393 queues (functions mq_*) say Y here. 394 395 POSIX message queues are visible as a filesystem called 'mqueue' 396 and can be mounted somewhere if you want to do filesystem 397 operations on message queues. 398 399 If unsure, say Y. 400 401config POSIX_MQUEUE_SYSCTL 402 bool 403 depends on POSIX_MQUEUE 404 depends on SYSCTL 405 default y 406 407config WATCH_QUEUE 408 bool "General notification queue" 409 default n 410 help 411 412 This is a general notification queue for the kernel to pass events to 413 userspace by splicing them into pipes. It can be used in conjunction 414 with watches for key/keyring change notifications and device 415 notifications. 416 417 See Documentation/core-api/watch_queue.rst 418 419config CROSS_MEMORY_ATTACH 420 bool "Enable process_vm_readv/writev syscalls" 421 depends on MMU 422 default y 423 help 424 Enabling this option adds the system calls process_vm_readv and 425 process_vm_writev which allow a process with the correct privileges 426 to directly read from or write to another process' address space. 427 See the man page for more details. 428 429config USELIB 430 bool "uselib syscall (for libc5 and earlier)" 431 default ALPHA || M68K || SPARC 432 help 433 This option enables the uselib syscall, a system call used in the 434 dynamic linker from libc5 and earlier. glibc does not use this 435 system call. If you intend to run programs built on libc5 or 436 earlier, you may need to enable this syscall. Current systems 437 running glibc can safely disable this. 438 439config AUDIT 440 bool "Auditing support" 441 depends on NET 442 help 443 Enable auditing infrastructure that can be used with another 444 kernel subsystem, such as SELinux (which requires this for 445 logging of avc messages output). System call auditing is included 446 on architectures which support it. 447 448config HAVE_ARCH_AUDITSYSCALL 449 bool 450 451config AUDITSYSCALL 452 def_bool y 453 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL 454 select FSNOTIFY 455 456source "kernel/irq/Kconfig" 457source "kernel/time/Kconfig" 458source "kernel/bpf/Kconfig" 459source "kernel/Kconfig.preempt" 460 461menu "CPU/Task time and stats accounting" 462 463config VIRT_CPU_ACCOUNTING 464 bool 465 466choice 467 prompt "Cputime accounting" 468 default TICK_CPU_ACCOUNTING if !PPC64 469 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 470 471# Kind of a stub config for the pure tick based cputime accounting 472config TICK_CPU_ACCOUNTING 473 bool "Simple tick based cputime accounting" 474 depends on !S390 && !NO_HZ_FULL 475 help 476 This is the basic tick based cputime accounting that maintains 477 statistics about user, system and idle time spent on per jiffies 478 granularity. 479 480 If unsure, say Y. 481 482config VIRT_CPU_ACCOUNTING_NATIVE 483 bool "Deterministic task and CPU time accounting" 484 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL 485 select VIRT_CPU_ACCOUNTING 486 help 487 Select this option to enable more accurate task and CPU time 488 accounting. This is done by reading a CPU counter on each 489 kernel entry and exit and on transitions within the kernel 490 between system, softirq and hardirq state, so there is a 491 small performance impact. In the case of s390 or IBM POWER > 5, 492 this also enables accounting of stolen time on logically-partitioned 493 systems. 494 495config VIRT_CPU_ACCOUNTING_GEN 496 bool "Full dynticks CPU time accounting" 497 depends on HAVE_CONTEXT_TRACKING_USER 498 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 499 depends on GENERIC_CLOCKEVENTS 500 select VIRT_CPU_ACCOUNTING 501 select CONTEXT_TRACKING_USER 502 help 503 Select this option to enable task and CPU time accounting on full 504 dynticks systems. This accounting is implemented by watching every 505 kernel-user boundaries using the context tracking subsystem. 506 The accounting is thus performed at the expense of some significant 507 overhead. 508 509 For now this is only useful if you are working on the full 510 dynticks subsystem development. 511 512 If unsure, say N. 513 514endchoice 515 516config IRQ_TIME_ACCOUNTING 517 bool "Fine granularity task level IRQ time accounting" 518 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE 519 help 520 Select this option to enable fine granularity task irq time 521 accounting. This is done by reading a timestamp on each 522 transitions between softirq and hardirq state, so there can be a 523 small performance impact. 524 525 If in doubt, say N here. 526 527config HAVE_SCHED_AVG_IRQ 528 def_bool y 529 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING 530 depends on SMP 531 532config SCHED_THERMAL_PRESSURE 533 bool 534 default y if ARM && ARM_CPU_TOPOLOGY 535 default y if ARM64 536 depends on SMP 537 depends on CPU_FREQ_THERMAL 538 help 539 Select this option to enable thermal pressure accounting in the 540 scheduler. Thermal pressure is the value conveyed to the scheduler 541 that reflects the reduction in CPU compute capacity resulted from 542 thermal throttling. Thermal throttling occurs when the performance of 543 a CPU is capped due to high operating temperatures. 544 545 If selected, the scheduler will be able to balance tasks accordingly, 546 i.e. put less load on throttled CPUs than on non/less throttled ones. 547 548 This requires the architecture to implement 549 arch_update_thermal_pressure() and arch_scale_thermal_pressure(). 550 551config BSD_PROCESS_ACCT 552 bool "BSD Process Accounting" 553 depends on MULTIUSER 554 help 555 If you say Y here, a user level program will be able to instruct the 556 kernel (via a special system call) to write process accounting 557 information to a file: whenever a process exits, information about 558 that process will be appended to the file by the kernel. The 559 information includes things such as creation time, owning user, 560 command name, memory usage, controlling terminal etc. (the complete 561 list is in the struct acct in <file:include/linux/acct.h>). It is 562 up to the user level program to do useful things with this 563 information. This is generally a good idea, so say Y. 564 565config BSD_PROCESS_ACCT_V3 566 bool "BSD Process Accounting version 3 file format" 567 depends on BSD_PROCESS_ACCT 568 default n 569 help 570 If you say Y here, the process accounting information is written 571 in a new file format that also logs the process IDs of each 572 process and its parent. Note that this file format is incompatible 573 with previous v0/v1/v2 file formats, so you will need updated tools 574 for processing it. A preliminary version of these tools is available 575 at <http://www.gnu.org/software/acct/>. 576 577config TASKSTATS 578 bool "Export task/process statistics through netlink" 579 depends on NET 580 depends on MULTIUSER 581 default n 582 help 583 Export selected statistics for tasks/processes through the 584 generic netlink interface. Unlike BSD process accounting, the 585 statistics are available during the lifetime of tasks/processes as 586 responses to commands. Like BSD accounting, they are sent to user 587 space on task exit. 588 589 Say N if unsure. 590 591config TASK_DELAY_ACCT 592 bool "Enable per-task delay accounting" 593 depends on TASKSTATS 594 select SCHED_INFO 595 help 596 Collect information on time spent by a task waiting for system 597 resources like cpu, synchronous block I/O completion and swapping 598 in pages. Such statistics can help in setting a task's priorities 599 relative to other tasks for cpu, io, rss limits etc. 600 601 Say N if unsure. 602 603config TASK_XACCT 604 bool "Enable extended accounting over taskstats" 605 depends on TASKSTATS 606 help 607 Collect extended task accounting data and send the data 608 to userland for processing over the taskstats interface. 609 610 Say N if unsure. 611 612config TASK_IO_ACCOUNTING 613 bool "Enable per-task storage I/O accounting" 614 depends on TASK_XACCT 615 help 616 Collect information on the number of bytes of storage I/O which this 617 task has caused. 618 619 Say N if unsure. 620 621config PSI 622 bool "Pressure stall information tracking" 623 help 624 Collect metrics that indicate how overcommitted the CPU, memory, 625 and IO capacity are in the system. 626 627 If you say Y here, the kernel will create /proc/pressure/ with the 628 pressure statistics files cpu, memory, and io. These will indicate 629 the share of walltime in which some or all tasks in the system are 630 delayed due to contention of the respective resource. 631 632 In kernels with cgroup support, cgroups (cgroup2 only) will 633 have cpu.pressure, memory.pressure, and io.pressure files, 634 which aggregate pressure stalls for the grouped tasks only. 635 636 For more details see Documentation/accounting/psi.rst. 637 638 Say N if unsure. 639 640config PSI_DEFAULT_DISABLED 641 bool "Require boot parameter to enable pressure stall information tracking" 642 default n 643 depends on PSI 644 help 645 If set, pressure stall information tracking will be disabled 646 per default but can be enabled through passing psi=1 on the 647 kernel commandline during boot. 648 649 This feature adds some code to the task wakeup and sleep 650 paths of the scheduler. The overhead is too low to affect 651 common scheduling-intense workloads in practice (such as 652 webservers, memcache), but it does show up in artificial 653 scheduler stress tests, such as hackbench. 654 655 If you are paranoid and not sure what the kernel will be 656 used for, say Y. 657 658 Say N if unsure. 659 660endmenu # "CPU/Task time and stats accounting" 661 662config CPU_ISOLATION 663 bool "CPU isolation" 664 depends on SMP || COMPILE_TEST 665 default y 666 help 667 Make sure that CPUs running critical tasks are not disturbed by 668 any source of "noise" such as unbound workqueues, timers, kthreads... 669 Unbound jobs get offloaded to housekeeping CPUs. This is driven by 670 the "isolcpus=" boot parameter. 671 672 Say Y if unsure. 673 674source "kernel/rcu/Kconfig" 675 676config BUILD_BIN2C 677 bool 678 default n 679 680config IKCONFIG 681 tristate "Kernel .config support" 682 help 683 This option enables the complete Linux kernel ".config" file 684 contents to be saved in the kernel. It provides documentation 685 of which kernel options are used in a running kernel or in an 686 on-disk kernel. This information can be extracted from the kernel 687 image file with the script scripts/extract-ikconfig and used as 688 input to rebuild the current kernel or to build another kernel. 689 It can also be extracted from a running kernel by reading 690 /proc/config.gz if enabled (below). 691 692config IKCONFIG_PROC 693 bool "Enable access to .config through /proc/config.gz" 694 depends on IKCONFIG && PROC_FS 695 help 696 This option enables access to the kernel configuration file 697 through /proc/config.gz. 698 699config IKHEADERS 700 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" 701 depends on SYSFS 702 help 703 This option enables access to the in-kernel headers that are generated during 704 the build process. These can be used to build eBPF tracing programs, 705 or similar programs. If you build the headers as a module, a module called 706 kheaders.ko is built which can be loaded on-demand to get access to headers. 707 708config LOG_BUF_SHIFT 709 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 710 range 12 25 711 default 17 712 depends on PRINTK 713 help 714 Select the minimal kernel log buffer size as a power of 2. 715 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config 716 parameter, see below. Any higher size also might be forced 717 by "log_buf_len" boot parameter. 718 719 Examples: 720 17 => 128 KB 721 16 => 64 KB 722 15 => 32 KB 723 14 => 16 KB 724 13 => 8 KB 725 12 => 4 KB 726 727config LOG_CPU_MAX_BUF_SHIFT 728 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" 729 depends on SMP 730 range 0 21 731 default 12 if !BASE_SMALL 732 default 0 if BASE_SMALL 733 depends on PRINTK 734 help 735 This option allows to increase the default ring buffer size 736 according to the number of CPUs. The value defines the contribution 737 of each CPU as a power of 2. The used space is typically only few 738 lines however it might be much more when problems are reported, 739 e.g. backtraces. 740 741 The increased size means that a new buffer has to be allocated and 742 the original static one is unused. It makes sense only on systems 743 with more CPUs. Therefore this value is used only when the sum of 744 contributions is greater than the half of the default kernel ring 745 buffer as defined by LOG_BUF_SHIFT. The default values are set 746 so that more than 16 CPUs are needed to trigger the allocation. 747 748 Also this option is ignored when "log_buf_len" kernel parameter is 749 used as it forces an exact (power of two) size of the ring buffer. 750 751 The number of possible CPUs is used for this computation ignoring 752 hotplugging making the computation optimal for the worst case 753 scenario while allowing a simple algorithm to be used from bootup. 754 755 Examples shift values and their meaning: 756 17 => 128 KB for each CPU 757 16 => 64 KB for each CPU 758 15 => 32 KB for each CPU 759 14 => 16 KB for each CPU 760 13 => 8 KB for each CPU 761 12 => 4 KB for each CPU 762 763config PRINTK_SAFE_LOG_BUF_SHIFT 764 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" 765 range 10 21 766 default 13 767 depends on PRINTK 768 help 769 Select the size of an alternate printk per-CPU buffer where messages 770 printed from usafe contexts are temporary stored. One example would 771 be NMI messages, another one - printk recursion. The messages are 772 copied to the main log buffer in a safe context to avoid a deadlock. 773 The value defines the size as a power of 2. 774 775 Those messages are rare and limited. The largest one is when 776 a backtrace is printed. It usually fits into 4KB. Select 777 8KB if you want to be on the safe side. 778 779 Examples: 780 17 => 128 KB for each CPU 781 16 => 64 KB for each CPU 782 15 => 32 KB for each CPU 783 14 => 16 KB for each CPU 784 13 => 8 KB for each CPU 785 12 => 4 KB for each CPU 786 787config PRINTK_INDEX 788 bool "Printk indexing debugfs interface" 789 depends on PRINTK && DEBUG_FS 790 help 791 Add support for indexing of all printk formats known at compile time 792 at <debugfs>/printk/index/<module>. 793 794 This can be used as part of maintaining daemons which monitor 795 /dev/kmsg, as it permits auditing the printk formats present in a 796 kernel, allowing detection of cases where monitored printks are 797 changed or no longer present. 798 799 There is no additional runtime cost to printk with this enabled. 800 801# 802# Architectures with an unreliable sched_clock() should select this: 803# 804config HAVE_UNSTABLE_SCHED_CLOCK 805 bool 806 807config GENERIC_SCHED_CLOCK 808 bool 809 810menu "Scheduler features" 811 812config UCLAMP_TASK 813 bool "Enable utilization clamping for RT/FAIR tasks" 814 depends on CPU_FREQ_GOV_SCHEDUTIL 815 help 816 This feature enables the scheduler to track the clamped utilization 817 of each CPU based on RUNNABLE tasks scheduled on that CPU. 818 819 With this option, the user can specify the min and max CPU 820 utilization allowed for RUNNABLE tasks. The max utilization defines 821 the maximum frequency a task should use while the min utilization 822 defines the minimum frequency it should use. 823 824 Both min and max utilization clamp values are hints to the scheduler, 825 aiming at improving its frequency selection policy, but they do not 826 enforce or grant any specific bandwidth for tasks. 827 828 If in doubt, say N. 829 830config UCLAMP_BUCKETS_COUNT 831 int "Number of supported utilization clamp buckets" 832 range 5 20 833 default 5 834 depends on UCLAMP_TASK 835 help 836 Defines the number of clamp buckets to use. The range of each bucket 837 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the 838 number of clamp buckets the finer their granularity and the higher 839 the precision of clamping aggregation and tracking at run-time. 840 841 For example, with the minimum configuration value we will have 5 842 clamp buckets tracking 20% utilization each. A 25% boosted tasks will 843 be refcounted in the [20..39]% bucket and will set the bucket clamp 844 effective value to 25%. 845 If a second 30% boosted task should be co-scheduled on the same CPU, 846 that task will be refcounted in the same bucket of the first task and 847 it will boost the bucket clamp effective value to 30%. 848 The clamp effective value of a bucket is reset to its nominal value 849 (20% in the example above) when there are no more tasks refcounted in 850 that bucket. 851 852 An additional boost/capping margin can be added to some tasks. In the 853 example above the 25% task will be boosted to 30% until it exits the 854 CPU. If that should be considered not acceptable on certain systems, 855 it's always possible to reduce the margin by increasing the number of 856 clamp buckets to trade off used memory for run-time tracking 857 precision. 858 859 If in doubt, use the default value. 860 861endmenu 862 863# 864# For architectures that want to enable the support for NUMA-affine scheduler 865# balancing logic: 866# 867config ARCH_SUPPORTS_NUMA_BALANCING 868 bool 869 870# 871# For architectures that prefer to flush all TLBs after a number of pages 872# are unmapped instead of sending one IPI per page to flush. The architecture 873# must provide guarantees on what happens if a clean TLB cache entry is 874# written after the unmap. Details are in mm/rmap.c near the check for 875# should_defer_flush. The architecture should also consider if the full flush 876# and the refill costs are offset by the savings of sending fewer IPIs. 877config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 878 bool 879 880config CC_HAS_INT128 881 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT 882 883config CC_IMPLICIT_FALLTHROUGH 884 string 885 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) 886 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) 887 888# Currently, disable gcc-12 array-bounds globally. 889# We may want to target only particular configurations some day. 890config GCC12_NO_ARRAY_BOUNDS 891 def_bool y 892 893config CC_NO_ARRAY_BOUNDS 894 bool 895 default y if CC_IS_GCC && GCC_VERSION >= 120000 && GCC_VERSION < 130000 && GCC12_NO_ARRAY_BOUNDS 896 897# 898# For architectures that know their GCC __int128 support is sound 899# 900config ARCH_SUPPORTS_INT128 901 bool 902 903# For architectures that (ab)use NUMA to represent different memory regions 904# all cpu-local but of different latencies, such as SuperH. 905# 906config ARCH_WANT_NUMA_VARIABLE_LOCALITY 907 bool 908 909config NUMA_BALANCING 910 bool "Memory placement aware NUMA scheduler" 911 depends on ARCH_SUPPORTS_NUMA_BALANCING 912 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 913 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT 914 help 915 This option adds support for automatic NUMA aware memory/task placement. 916 The mechanism is quite primitive and is based on migrating memory when 917 it has references to the node the task is running on. 918 919 This system will be inactive on UMA systems. 920 921config NUMA_BALANCING_DEFAULT_ENABLED 922 bool "Automatically enable NUMA aware memory/task placement" 923 default y 924 depends on NUMA_BALANCING 925 help 926 If set, automatic NUMA balancing will be enabled if running on a NUMA 927 machine. 928 929menuconfig CGROUPS 930 bool "Control Group support" 931 select KERNFS 932 help 933 This option adds support for grouping sets of processes together, for 934 use with process control subsystems such as Cpusets, CFS, memory 935 controls or device isolation. 936 See 937 - Documentation/scheduler/sched-design-CFS.rst (CFS) 938 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation 939 and resource control) 940 941 Say N if unsure. 942 943if CGROUPS 944 945config PAGE_COUNTER 946 bool 947 948config CGROUP_FAVOR_DYNMODS 949 bool "Favor dynamic modification latency reduction by default" 950 help 951 This option enables the "favordynmods" mount option by default 952 which reduces the latencies of dynamic cgroup modifications such 953 as task migrations and controller on/offs at the cost of making 954 hot path operations such as forks and exits more expensive. 955 956 Say N if unsure. 957 958config MEMCG 959 bool "Memory controller" 960 select PAGE_COUNTER 961 select EVENTFD 962 help 963 Provides control over the memory footprint of tasks in a cgroup. 964 965config MEMCG_SWAP 966 bool 967 depends on MEMCG && SWAP 968 default y 969 970config MEMCG_KMEM 971 bool 972 depends on MEMCG && !SLOB 973 default y 974 975config BLK_CGROUP 976 bool "IO controller" 977 depends on BLOCK 978 default n 979 help 980 Generic block IO controller cgroup interface. This is the common 981 cgroup interface which should be used by various IO controlling 982 policies. 983 984 Currently, CFQ IO scheduler uses it to recognize task groups and 985 control disk bandwidth allocation (proportional time slice allocation) 986 to such task groups. It is also used by bio throttling logic in 987 block layer to implement upper limit in IO rates on a device. 988 989 This option only enables generic Block IO controller infrastructure. 990 One needs to also enable actual IO controlling logic/policy. For 991 enabling proportional weight division of disk bandwidth in CFQ, set 992 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 993 CONFIG_BLK_DEV_THROTTLING=y. 994 995 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 996 997config CGROUP_WRITEBACK 998 bool 999 depends on MEMCG && BLK_CGROUP 1000 default y 1001 1002menuconfig CGROUP_SCHED 1003 bool "CPU controller" 1004 default n 1005 help 1006 This feature lets CPU scheduler recognize task groups and control CPU 1007 bandwidth allocation to such task groups. It uses cgroups to group 1008 tasks. 1009 1010if CGROUP_SCHED 1011config FAIR_GROUP_SCHED 1012 bool "Group scheduling for SCHED_OTHER" 1013 depends on CGROUP_SCHED 1014 default CGROUP_SCHED 1015 1016config CFS_BANDWIDTH 1017 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1018 depends on FAIR_GROUP_SCHED 1019 default n 1020 help 1021 This option allows users to define CPU bandwidth rates (limits) for 1022 tasks running within the fair group scheduler. Groups with no limit 1023 set are considered to be unconstrained and will run with no 1024 restriction. 1025 See Documentation/scheduler/sched-bwc.rst for more information. 1026 1027config RT_GROUP_SCHED 1028 bool "Group scheduling for SCHED_RR/FIFO" 1029 depends on CGROUP_SCHED 1030 default n 1031 help 1032 This feature lets you explicitly allocate real CPU bandwidth 1033 to task groups. If enabled, it will also make it impossible to 1034 schedule realtime tasks for non-root users until you allocate 1035 realtime bandwidth for them. 1036 See Documentation/scheduler/sched-rt-group.rst for more information. 1037 1038endif #CGROUP_SCHED 1039 1040config UCLAMP_TASK_GROUP 1041 bool "Utilization clamping per group of tasks" 1042 depends on CGROUP_SCHED 1043 depends on UCLAMP_TASK 1044 default n 1045 help 1046 This feature enables the scheduler to track the clamped utilization 1047 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1048 1049 When this option is enabled, the user can specify a min and max 1050 CPU bandwidth which is allowed for each single task in a group. 1051 The max bandwidth allows to clamp the maximum frequency a task 1052 can use, while the min bandwidth allows to define a minimum 1053 frequency a task will always use. 1054 1055 When task group based utilization clamping is enabled, an eventually 1056 specified task-specific clamp value is constrained by the cgroup 1057 specified clamp value. Both minimum and maximum task clamping cannot 1058 be bigger than the corresponding clamping defined at task group level. 1059 1060 If in doubt, say N. 1061 1062config CGROUP_PIDS 1063 bool "PIDs controller" 1064 help 1065 Provides enforcement of process number limits in the scope of a 1066 cgroup. Any attempt to fork more processes than is allowed in the 1067 cgroup will fail. PIDs are fundamentally a global resource because it 1068 is fairly trivial to reach PID exhaustion before you reach even a 1069 conservative kmemcg limit. As a result, it is possible to grind a 1070 system to halt without being limited by other cgroup policies. The 1071 PIDs controller is designed to stop this from happening. 1072 1073 It should be noted that organisational operations (such as attaching 1074 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1075 since the PIDs limit only affects a process's ability to fork, not to 1076 attach to a cgroup. 1077 1078config CGROUP_RDMA 1079 bool "RDMA controller" 1080 help 1081 Provides enforcement of RDMA resources defined by IB stack. 1082 It is fairly easy for consumers to exhaust RDMA resources, which 1083 can result into resource unavailability to other consumers. 1084 RDMA controller is designed to stop this from happening. 1085 Attaching processes with active RDMA resources to the cgroup 1086 hierarchy is allowed even if can cross the hierarchy's limit. 1087 1088config CGROUP_FREEZER 1089 bool "Freezer controller" 1090 help 1091 Provides a way to freeze and unfreeze all tasks in a 1092 cgroup. 1093 1094 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1095 controller includes important in-kernel memory consumers per default. 1096 1097 If you're using cgroup2, say N. 1098 1099config CGROUP_HUGETLB 1100 bool "HugeTLB controller" 1101 depends on HUGETLB_PAGE 1102 select PAGE_COUNTER 1103 default n 1104 help 1105 Provides a cgroup controller for HugeTLB pages. 1106 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1107 The limit is enforced during page fault. Since HugeTLB doesn't 1108 support page reclaim, enforcing the limit at page fault time implies 1109 that, the application will get SIGBUS signal if it tries to access 1110 HugeTLB pages beyond its limit. This requires the application to know 1111 beforehand how much HugeTLB pages it would require for its use. The 1112 control group is tracked in the third page lru pointer. This means 1113 that we cannot use the controller with huge page less than 3 pages. 1114 1115config CPUSETS 1116 bool "Cpuset controller" 1117 depends on SMP 1118 help 1119 This option will let you create and manage CPUSETs which 1120 allow dynamically partitioning a system into sets of CPUs and 1121 Memory Nodes and assigning tasks to run only within those sets. 1122 This is primarily useful on large SMP or NUMA systems. 1123 1124 Say N if unsure. 1125 1126config PROC_PID_CPUSET 1127 bool "Include legacy /proc/<pid>/cpuset file" 1128 depends on CPUSETS 1129 default y 1130 1131config CGROUP_DEVICE 1132 bool "Device controller" 1133 help 1134 Provides a cgroup controller implementing whitelists for 1135 devices which a process in the cgroup can mknod or open. 1136 1137config CGROUP_CPUACCT 1138 bool "Simple CPU accounting controller" 1139 help 1140 Provides a simple controller for monitoring the 1141 total CPU consumed by the tasks in a cgroup. 1142 1143config CGROUP_PERF 1144 bool "Perf controller" 1145 depends on PERF_EVENTS 1146 help 1147 This option extends the perf per-cpu mode to restrict monitoring 1148 to threads which belong to the cgroup specified and run on the 1149 designated cpu. Or this can be used to have cgroup ID in samples 1150 so that it can monitor performance events among cgroups. 1151 1152 Say N if unsure. 1153 1154config CGROUP_BPF 1155 bool "Support for eBPF programs attached to cgroups" 1156 depends on BPF_SYSCALL 1157 select SOCK_CGROUP_DATA 1158 help 1159 Allow attaching eBPF programs to a cgroup using the bpf(2) 1160 syscall command BPF_PROG_ATTACH. 1161 1162 In which context these programs are accessed depends on the type 1163 of attachment. For instance, programs that are attached using 1164 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1165 inet sockets. 1166 1167config CGROUP_MISC 1168 bool "Misc resource controller" 1169 default n 1170 help 1171 Provides a controller for miscellaneous resources on a host. 1172 1173 Miscellaneous scalar resources are the resources on the host system 1174 which cannot be abstracted like the other cgroups. This controller 1175 tracks and limits the miscellaneous resources used by a process 1176 attached to a cgroup hierarchy. 1177 1178 For more information, please check misc cgroup section in 1179 /Documentation/admin-guide/cgroup-v2.rst. 1180 1181config CGROUP_DEBUG 1182 bool "Debug controller" 1183 default n 1184 depends on DEBUG_KERNEL 1185 help 1186 This option enables a simple controller that exports 1187 debugging information about the cgroups framework. This 1188 controller is for control cgroup debugging only. Its 1189 interfaces are not stable. 1190 1191 Say N. 1192 1193config SOCK_CGROUP_DATA 1194 bool 1195 default n 1196 1197endif # CGROUPS 1198 1199menuconfig NAMESPACES 1200 bool "Namespaces support" if EXPERT 1201 depends on MULTIUSER 1202 default !EXPERT 1203 help 1204 Provides the way to make tasks work with different objects using 1205 the same id. For example same IPC id may refer to different objects 1206 or same user id or pid may refer to different tasks when used in 1207 different namespaces. 1208 1209if NAMESPACES 1210 1211config UTS_NS 1212 bool "UTS namespace" 1213 default y 1214 help 1215 In this namespace tasks see different info provided with the 1216 uname() system call 1217 1218config TIME_NS 1219 bool "TIME namespace" 1220 depends on GENERIC_VDSO_TIME_NS 1221 default y 1222 help 1223 In this namespace boottime and monotonic clocks can be set. 1224 The time will keep going with the same pace. 1225 1226config IPC_NS 1227 bool "IPC namespace" 1228 depends on (SYSVIPC || POSIX_MQUEUE) 1229 default y 1230 help 1231 In this namespace tasks work with IPC ids which correspond to 1232 different IPC objects in different namespaces. 1233 1234config USER_NS 1235 bool "User namespace" 1236 default n 1237 help 1238 This allows containers, i.e. vservers, to use user namespaces 1239 to provide different user info for different servers. 1240 1241 When user namespaces are enabled in the kernel it is 1242 recommended that the MEMCG option also be enabled and that 1243 user-space use the memory control groups to limit the amount 1244 of memory a memory unprivileged users can use. 1245 1246 If unsure, say N. 1247 1248config PID_NS 1249 bool "PID Namespaces" 1250 default y 1251 help 1252 Support process id namespaces. This allows having multiple 1253 processes with the same pid as long as they are in different 1254 pid namespaces. This is a building block of containers. 1255 1256config NET_NS 1257 bool "Network namespace" 1258 depends on NET 1259 default y 1260 help 1261 Allow user space to create what appear to be multiple instances 1262 of the network stack. 1263 1264endif # NAMESPACES 1265 1266config CHECKPOINT_RESTORE 1267 bool "Checkpoint/restore support" 1268 select PROC_CHILDREN 1269 select KCMP 1270 default n 1271 help 1272 Enables additional kernel features in a sake of checkpoint/restore. 1273 In particular it adds auxiliary prctl codes to setup process text, 1274 data and heap segment sizes, and a few additional /proc filesystem 1275 entries. 1276 1277 If unsure, say N here. 1278 1279config SCHED_AUTOGROUP 1280 bool "Automatic process group scheduling" 1281 select CGROUPS 1282 select CGROUP_SCHED 1283 select FAIR_GROUP_SCHED 1284 help 1285 This option optimizes the scheduler for common desktop workloads by 1286 automatically creating and populating task groups. This separation 1287 of workloads isolates aggressive CPU burners (like build jobs) from 1288 desktop applications. Task group autogeneration is currently based 1289 upon task session. 1290 1291config SYSFS_DEPRECATED 1292 bool "Enable deprecated sysfs features to support old userspace tools" 1293 depends on SYSFS 1294 default n 1295 help 1296 This option adds code that switches the layout of the "block" class 1297 devices, to not show up in /sys/class/block/, but only in 1298 /sys/block/. 1299 1300 This switch is only active when the sysfs.deprecated=1 boot option is 1301 passed or the SYSFS_DEPRECATED_V2 option is set. 1302 1303 This option allows new kernels to run on old distributions and tools, 1304 which might get confused by /sys/class/block/. Since 2007/2008 all 1305 major distributions and tools handle this just fine. 1306 1307 Recent distributions and userspace tools after 2009/2010 depend on 1308 the existence of /sys/class/block/, and will not work with this 1309 option enabled. 1310 1311 Only if you are using a new kernel on an old distribution, you might 1312 need to say Y here. 1313 1314config SYSFS_DEPRECATED_V2 1315 bool "Enable deprecated sysfs features by default" 1316 default n 1317 depends on SYSFS 1318 depends on SYSFS_DEPRECATED 1319 help 1320 Enable deprecated sysfs by default. 1321 1322 See the CONFIG_SYSFS_DEPRECATED option for more details about this 1323 option. 1324 1325 Only if you are using a new kernel on an old distribution, you might 1326 need to say Y here. Even then, odds are you would not need it 1327 enabled, you can always pass the boot option if absolutely necessary. 1328 1329config RELAY 1330 bool "Kernel->user space relay support (formerly relayfs)" 1331 select IRQ_WORK 1332 help 1333 This option enables support for relay interface support in 1334 certain file systems (such as debugfs). 1335 It is designed to provide an efficient mechanism for tools and 1336 facilities to relay large amounts of data from kernel space to 1337 user space. 1338 1339 If unsure, say N. 1340 1341config BLK_DEV_INITRD 1342 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1343 help 1344 The initial RAM filesystem is a ramfs which is loaded by the 1345 boot loader (loadlin or lilo) and that is mounted as root 1346 before the normal boot procedure. It is typically used to 1347 load modules needed to mount the "real" root file system, 1348 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1349 1350 If RAM disk support (BLK_DEV_RAM) is also included, this 1351 also enables initial RAM disk (initrd) support and adds 1352 15 Kbytes (more on some other architectures) to the kernel size. 1353 1354 If unsure say Y. 1355 1356if BLK_DEV_INITRD 1357 1358source "usr/Kconfig" 1359 1360endif 1361 1362config BOOT_CONFIG 1363 bool "Boot config support" 1364 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1365 help 1366 Extra boot config allows system admin to pass a config file as 1367 complemental extension of kernel cmdline when booting. 1368 The boot config file must be attached at the end of initramfs 1369 with checksum, size and magic word. 1370 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1371 1372 If unsure, say Y. 1373 1374config BOOT_CONFIG_EMBED 1375 bool "Embed bootconfig file in the kernel" 1376 depends on BOOT_CONFIG 1377 help 1378 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1379 kernel. Usually, the bootconfig file is loaded with the initrd 1380 image. But if the system doesn't support initrd, this option will 1381 help you by embedding a bootconfig file while building the kernel. 1382 1383 If unsure, say N. 1384 1385config BOOT_CONFIG_EMBED_FILE 1386 string "Embedded bootconfig file path" 1387 depends on BOOT_CONFIG_EMBED 1388 help 1389 Specify a bootconfig file which will be embedded to the kernel. 1390 This bootconfig will be used if there is no initrd or no other 1391 bootconfig in the initrd. 1392 1393config INITRAMFS_PRESERVE_MTIME 1394 bool "Preserve cpio archive mtimes in initramfs" 1395 default y 1396 help 1397 Each entry in an initramfs cpio archive carries an mtime value. When 1398 enabled, extracted cpio items take this mtime, with directory mtime 1399 setting deferred until after creation of any child entries. 1400 1401 If unsure, say Y. 1402 1403choice 1404 prompt "Compiler optimization level" 1405 default CC_OPTIMIZE_FOR_PERFORMANCE 1406 1407config CC_OPTIMIZE_FOR_PERFORMANCE 1408 bool "Optimize for performance (-O2)" 1409 help 1410 This is the default optimization level for the kernel, building 1411 with the "-O2" compiler flag for best performance and most 1412 helpful compile-time warnings. 1413 1414config CC_OPTIMIZE_FOR_PERFORMANCE_O3 1415 bool "Optimize more for performance (-O3)" 1416 depends on ARC 1417 help 1418 Choosing this option will pass "-O3" to your compiler to optimize 1419 the kernel yet more for performance. 1420 1421config CC_OPTIMIZE_FOR_SIZE 1422 bool "Optimize for size (-Os)" 1423 help 1424 Choosing this option will pass "-Os" to your compiler resulting 1425 in a smaller kernel. 1426 1427endchoice 1428 1429config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1430 bool 1431 help 1432 This requires that the arch annotates or otherwise protects 1433 its external entry points from being discarded. Linker scripts 1434 must also merge .text.*, .data.*, and .bss.* correctly into 1435 output sections. Care must be taken not to pull in unrelated 1436 sections (e.g., '.text.init'). Typically '.' in section names 1437 is used to distinguish them from label names / C identifiers. 1438 1439config LD_DEAD_CODE_DATA_ELIMINATION 1440 bool "Dead code and data elimination (EXPERIMENTAL)" 1441 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1442 depends on EXPERT 1443 depends on $(cc-option,-ffunction-sections -fdata-sections) 1444 depends on $(ld-option,--gc-sections) 1445 help 1446 Enable this if you want to do dead code and data elimination with 1447 the linker by compiling with -ffunction-sections -fdata-sections, 1448 and linking with --gc-sections. 1449 1450 This can reduce on disk and in-memory size of the kernel 1451 code and static data, particularly for small configs and 1452 on small systems. This has the possibility of introducing 1453 silently broken kernel if the required annotations are not 1454 present. This option is not well tested yet, so use at your 1455 own risk. 1456 1457config LD_ORPHAN_WARN 1458 def_bool y 1459 depends on ARCH_WANT_LD_ORPHAN_WARN 1460 depends on $(ld-option,--orphan-handling=warn) 1461 1462config SYSCTL 1463 bool 1464 1465config HAVE_UID16 1466 bool 1467 1468config SYSCTL_EXCEPTION_TRACE 1469 bool 1470 help 1471 Enable support for /proc/sys/debug/exception-trace. 1472 1473config SYSCTL_ARCH_UNALIGN_NO_WARN 1474 bool 1475 help 1476 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1477 Allows arch to define/use @no_unaligned_warning to possibly warn 1478 about unaligned access emulation going on under the hood. 1479 1480config SYSCTL_ARCH_UNALIGN_ALLOW 1481 bool 1482 help 1483 Enable support for /proc/sys/kernel/unaligned-trap 1484 Allows arches to define/use @unaligned_enabled to runtime toggle 1485 the unaligned access emulation. 1486 see arch/parisc/kernel/unaligned.c for reference 1487 1488config HAVE_PCSPKR_PLATFORM 1489 bool 1490 1491# interpreter that classic socket filters depend on 1492config BPF 1493 bool 1494 select CRYPTO_LIB_SHA1 1495 1496menuconfig EXPERT 1497 bool "Configure standard kernel features (expert users)" 1498 # Unhide debug options, to make the on-by-default options visible 1499 select DEBUG_KERNEL 1500 help 1501 This option allows certain base kernel options and settings 1502 to be disabled or tweaked. This is for specialized 1503 environments which can tolerate a "non-standard" kernel. 1504 Only use this if you really know what you are doing. 1505 1506config UID16 1507 bool "Enable 16-bit UID system calls" if EXPERT 1508 depends on HAVE_UID16 && MULTIUSER 1509 default y 1510 help 1511 This enables the legacy 16-bit UID syscall wrappers. 1512 1513config MULTIUSER 1514 bool "Multiple users, groups and capabilities support" if EXPERT 1515 default y 1516 help 1517 This option enables support for non-root users, groups and 1518 capabilities. 1519 1520 If you say N here, all processes will run with UID 0, GID 0, and all 1521 possible capabilities. Saying N here also compiles out support for 1522 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1523 setgid, and capset. 1524 1525 If unsure, say Y here. 1526 1527config SGETMASK_SYSCALL 1528 bool "sgetmask/ssetmask syscalls support" if EXPERT 1529 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1530 help 1531 sys_sgetmask and sys_ssetmask are obsolete system calls 1532 no longer supported in libc but still enabled by default in some 1533 architectures. 1534 1535 If unsure, leave the default option here. 1536 1537config SYSFS_SYSCALL 1538 bool "Sysfs syscall support" if EXPERT 1539 default y 1540 help 1541 sys_sysfs is an obsolete system call no longer supported in libc. 1542 Note that disabling this option is more secure but might break 1543 compatibility with some systems. 1544 1545 If unsure say Y here. 1546 1547config FHANDLE 1548 bool "open by fhandle syscalls" if EXPERT 1549 select EXPORTFS 1550 default y 1551 help 1552 If you say Y here, a user level program will be able to map 1553 file names to handle and then later use the handle for 1554 different file system operations. This is useful in implementing 1555 userspace file servers, which now track files using handles instead 1556 of names. The handle would remain the same even if file names 1557 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1558 syscalls. 1559 1560config POSIX_TIMERS 1561 bool "Posix Clocks & timers" if EXPERT 1562 default y 1563 help 1564 This includes native support for POSIX timers to the kernel. 1565 Some embedded systems have no use for them and therefore they 1566 can be configured out to reduce the size of the kernel image. 1567 1568 When this option is disabled, the following syscalls won't be 1569 available: timer_create, timer_gettime: timer_getoverrun, 1570 timer_settime, timer_delete, clock_adjtime, getitimer, 1571 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1572 clock_getres and clock_nanosleep syscalls will be limited to 1573 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1574 1575 If unsure say y. 1576 1577config PRINTK 1578 default y 1579 bool "Enable support for printk" if EXPERT 1580 select IRQ_WORK 1581 help 1582 This option enables normal printk support. Removing it 1583 eliminates most of the message strings from the kernel image 1584 and makes the kernel more or less silent. As this makes it 1585 very difficult to diagnose system problems, saying N here is 1586 strongly discouraged. 1587 1588config BUG 1589 bool "BUG() support" if EXPERT 1590 default y 1591 help 1592 Disabling this option eliminates support for BUG and WARN, reducing 1593 the size of your kernel image and potentially quietly ignoring 1594 numerous fatal conditions. You should only consider disabling this 1595 option for embedded systems with no facilities for reporting errors. 1596 Just say Y. 1597 1598config ELF_CORE 1599 depends on COREDUMP 1600 default y 1601 bool "Enable ELF core dumps" if EXPERT 1602 help 1603 Enable support for generating core dumps. Disabling saves about 4k. 1604 1605 1606config PCSPKR_PLATFORM 1607 bool "Enable PC-Speaker support" if EXPERT 1608 depends on HAVE_PCSPKR_PLATFORM 1609 select I8253_LOCK 1610 default y 1611 help 1612 This option allows to disable the internal PC-Speaker 1613 support, saving some memory. 1614 1615config BASE_FULL 1616 default y 1617 bool "Enable full-sized data structures for core" if EXPERT 1618 help 1619 Disabling this option reduces the size of miscellaneous core 1620 kernel data structures. This saves memory on small machines, 1621 but may reduce performance. 1622 1623config FUTEX 1624 bool "Enable futex support" if EXPERT 1625 depends on !(SPARC32 && SMP) 1626 default y 1627 imply RT_MUTEXES 1628 help 1629 Disabling this option will cause the kernel to be built without 1630 support for "fast userspace mutexes". The resulting kernel may not 1631 run glibc-based applications correctly. 1632 1633config FUTEX_PI 1634 bool 1635 depends on FUTEX && RT_MUTEXES 1636 default y 1637 1638config EPOLL 1639 bool "Enable eventpoll support" if EXPERT 1640 default y 1641 help 1642 Disabling this option will cause the kernel to be built without 1643 support for epoll family of system calls. 1644 1645config SIGNALFD 1646 bool "Enable signalfd() system call" if EXPERT 1647 default y 1648 help 1649 Enable the signalfd() system call that allows to receive signals 1650 on a file descriptor. 1651 1652 If unsure, say Y. 1653 1654config TIMERFD 1655 bool "Enable timerfd() system call" if EXPERT 1656 default y 1657 help 1658 Enable the timerfd() system call that allows to receive timer 1659 events on a file descriptor. 1660 1661 If unsure, say Y. 1662 1663config EVENTFD 1664 bool "Enable eventfd() system call" if EXPERT 1665 default y 1666 help 1667 Enable the eventfd() system call that allows to receive both 1668 kernel notification (ie. KAIO) or userspace notifications. 1669 1670 If unsure, say Y. 1671 1672config SHMEM 1673 bool "Use full shmem filesystem" if EXPERT 1674 default y 1675 depends on MMU 1676 help 1677 The shmem is an internal filesystem used to manage shared memory. 1678 It is backed by swap and manages resource limits. It is also exported 1679 to userspace as tmpfs if TMPFS is enabled. Disabling this 1680 option replaces shmem and tmpfs with the much simpler ramfs code, 1681 which may be appropriate on small systems without swap. 1682 1683config AIO 1684 bool "Enable AIO support" if EXPERT 1685 default y 1686 help 1687 This option enables POSIX asynchronous I/O which may by used 1688 by some high performance threaded applications. Disabling 1689 this option saves about 7k. 1690 1691config IO_URING 1692 bool "Enable IO uring support" if EXPERT 1693 select IO_WQ 1694 default y 1695 help 1696 This option enables support for the io_uring interface, enabling 1697 applications to submit and complete IO through submission and 1698 completion rings that are shared between the kernel and application. 1699 1700config ADVISE_SYSCALLS 1701 bool "Enable madvise/fadvise syscalls" if EXPERT 1702 default y 1703 help 1704 This option enables the madvise and fadvise syscalls, used by 1705 applications to advise the kernel about their future memory or file 1706 usage, improving performance. If building an embedded system where no 1707 applications use these syscalls, you can disable this option to save 1708 space. 1709 1710config MEMBARRIER 1711 bool "Enable membarrier() system call" if EXPERT 1712 default y 1713 help 1714 Enable the membarrier() system call that allows issuing memory 1715 barriers across all running threads, which can be used to distribute 1716 the cost of user-space memory barriers asymmetrically by transforming 1717 pairs of memory barriers into pairs consisting of membarrier() and a 1718 compiler barrier. 1719 1720 If unsure, say Y. 1721 1722config KALLSYMS 1723 bool "Load all symbols for debugging/ksymoops" if EXPERT 1724 default y 1725 help 1726 Say Y here to let the kernel print out symbolic crash information and 1727 symbolic stack backtraces. This increases the size of the kernel 1728 somewhat, as all symbols have to be loaded into the kernel image. 1729 1730config KALLSYMS_ALL 1731 bool "Include all symbols in kallsyms" 1732 depends on DEBUG_KERNEL && KALLSYMS 1733 help 1734 Normally kallsyms only contains the symbols of functions for nicer 1735 OOPS messages and backtraces (i.e., symbols from the text and inittext 1736 sections). This is sufficient for most cases. And only in very rare 1737 cases (e.g., when a debugger is used) all symbols are required (e.g., 1738 names of variables from the data sections, etc). 1739 1740 This option makes sure that all symbols are loaded into the kernel 1741 image (i.e., symbols from all sections) in cost of increased kernel 1742 size (depending on the kernel configuration, it may be 300KiB or 1743 something like this). 1744 1745 Say N unless you really need all symbols. 1746 1747config KALLSYMS_ABSOLUTE_PERCPU 1748 bool 1749 depends on KALLSYMS 1750 default X86_64 && SMP 1751 1752config KALLSYMS_BASE_RELATIVE 1753 bool 1754 depends on KALLSYMS 1755 default !IA64 1756 help 1757 Instead of emitting them as absolute values in the native word size, 1758 emit the symbol references in the kallsyms table as 32-bit entries, 1759 each containing a relative value in the range [base, base + U32_MAX] 1760 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either 1761 an absolute value in the range [0, S32_MAX] or a relative value in the 1762 range [base, base + S32_MAX], where base is the lowest relative symbol 1763 address encountered in the image. 1764 1765 On 64-bit builds, this reduces the size of the address table by 50%, 1766 but more importantly, it results in entries whose values are build 1767 time constants, and no relocation pass is required at runtime to fix 1768 up the entries based on the runtime load address of the kernel. 1769 1770# end of the "standard kernel features (expert users)" menu 1771 1772# syscall, maps, verifier 1773 1774config ARCH_HAS_MEMBARRIER_CALLBACKS 1775 bool 1776 1777config ARCH_HAS_MEMBARRIER_SYNC_CORE 1778 bool 1779 1780config KCMP 1781 bool "Enable kcmp() system call" if EXPERT 1782 help 1783 Enable the kernel resource comparison system call. It provides 1784 user-space with the ability to compare two processes to see if they 1785 share a common resource, such as a file descriptor or even virtual 1786 memory space. 1787 1788 If unsure, say N. 1789 1790config RSEQ 1791 bool "Enable rseq() system call" if EXPERT 1792 default y 1793 depends on HAVE_RSEQ 1794 select MEMBARRIER 1795 help 1796 Enable the restartable sequences system call. It provides a 1797 user-space cache for the current CPU number value, which 1798 speeds up getting the current CPU number from user-space, 1799 as well as an ABI to speed up user-space operations on 1800 per-CPU data. 1801 1802 If unsure, say Y. 1803 1804config DEBUG_RSEQ 1805 default n 1806 bool "Enabled debugging of rseq() system call" if EXPERT 1807 depends on RSEQ && DEBUG_KERNEL 1808 help 1809 Enable extra debugging checks for the rseq system call. 1810 1811 If unsure, say N. 1812 1813config EMBEDDED 1814 bool "Embedded system" 1815 select EXPERT 1816 help 1817 This option should be enabled if compiling the kernel for 1818 an embedded system so certain expert options are available 1819 for configuration. 1820 1821config HAVE_PERF_EVENTS 1822 bool 1823 help 1824 See tools/perf/design.txt for details. 1825 1826config GUEST_PERF_EVENTS 1827 bool 1828 depends on HAVE_PERF_EVENTS 1829 1830config PERF_USE_VMALLOC 1831 bool 1832 help 1833 See tools/perf/design.txt for details 1834 1835config PC104 1836 bool "PC/104 support" if EXPERT 1837 help 1838 Expose PC/104 form factor device drivers and options available for 1839 selection and configuration. Enable this option if your target 1840 machine has a PC/104 bus. 1841 1842menu "Kernel Performance Events And Counters" 1843 1844config PERF_EVENTS 1845 bool "Kernel performance events and counters" 1846 default y if PROFILING 1847 depends on HAVE_PERF_EVENTS 1848 select IRQ_WORK 1849 select SRCU 1850 help 1851 Enable kernel support for various performance events provided 1852 by software and hardware. 1853 1854 Software events are supported either built-in or via the 1855 use of generic tracepoints. 1856 1857 Most modern CPUs support performance events via performance 1858 counter registers. These registers count the number of certain 1859 types of hw events: such as instructions executed, cachemisses 1860 suffered, or branches mis-predicted - without slowing down the 1861 kernel or applications. These registers can also trigger interrupts 1862 when a threshold number of events have passed - and can thus be 1863 used to profile the code that runs on that CPU. 1864 1865 The Linux Performance Event subsystem provides an abstraction of 1866 these software and hardware event capabilities, available via a 1867 system call and used by the "perf" utility in tools/perf/. It 1868 provides per task and per CPU counters, and it provides event 1869 capabilities on top of those. 1870 1871 Say Y if unsure. 1872 1873config DEBUG_PERF_USE_VMALLOC 1874 default n 1875 bool "Debug: use vmalloc to back perf mmap() buffers" 1876 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 1877 select PERF_USE_VMALLOC 1878 help 1879 Use vmalloc memory to back perf mmap() buffers. 1880 1881 Mostly useful for debugging the vmalloc code on platforms 1882 that don't require it. 1883 1884 Say N if unsure. 1885 1886endmenu 1887 1888config SYSTEM_DATA_VERIFICATION 1889 def_bool n 1890 select SYSTEM_TRUSTED_KEYRING 1891 select KEYS 1892 select CRYPTO 1893 select CRYPTO_RSA 1894 select ASYMMETRIC_KEY_TYPE 1895 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1896 select ASN1 1897 select OID_REGISTRY 1898 select X509_CERTIFICATE_PARSER 1899 select PKCS7_MESSAGE_PARSER 1900 help 1901 Provide PKCS#7 message verification using the contents of the system 1902 trusted keyring to provide public keys. This then can be used for 1903 module verification, kexec image verification and firmware blob 1904 verification. 1905 1906config PROFILING 1907 bool "Profiling support" 1908 help 1909 Say Y here to enable the extended profiling support mechanisms used 1910 by profilers. 1911 1912# 1913# Place an empty function call at each tracepoint site. Can be 1914# dynamically changed for a probe function. 1915# 1916config TRACEPOINTS 1917 bool 1918 1919endmenu # General setup 1920 1921source "arch/Kconfig" 1922 1923config RT_MUTEXES 1924 bool 1925 default y if PREEMPT_RT 1926 1927config BASE_SMALL 1928 int 1929 default 0 if BASE_FULL 1930 default 1 if !BASE_FULL 1931 1932config MODULE_SIG_FORMAT 1933 def_bool n 1934 select SYSTEM_DATA_VERIFICATION 1935 1936menuconfig MODULES 1937 bool "Enable loadable module support" 1938 modules 1939 help 1940 Kernel modules are small pieces of compiled code which can 1941 be inserted in the running kernel, rather than being 1942 permanently built into the kernel. You use the "modprobe" 1943 tool to add (and sometimes remove) them. If you say Y here, 1944 many parts of the kernel can be built as modules (by 1945 answering M instead of Y where indicated): this is most 1946 useful for infrequently used options which are not required 1947 for booting. For more information, see the man pages for 1948 modprobe, lsmod, modinfo, insmod and rmmod. 1949 1950 If you say Y here, you will need to run "make 1951 modules_install" to put the modules under /lib/modules/ 1952 where modprobe can find them (you may need to be root to do 1953 this). 1954 1955 If unsure, say Y. 1956 1957if MODULES 1958 1959config MODULE_FORCE_LOAD 1960 bool "Forced module loading" 1961 default n 1962 help 1963 Allow loading of modules without version information (ie. modprobe 1964 --force). Forced module loading sets the 'F' (forced) taint flag and 1965 is usually a really bad idea. 1966 1967config MODULE_UNLOAD 1968 bool "Module unloading" 1969 help 1970 Without this option you will not be able to unload any 1971 modules (note that some modules may not be unloadable 1972 anyway), which makes your kernel smaller, faster 1973 and simpler. If unsure, say Y. 1974 1975config MODULE_FORCE_UNLOAD 1976 bool "Forced module unloading" 1977 depends on MODULE_UNLOAD 1978 help 1979 This option allows you to force a module to unload, even if the 1980 kernel believes it is unsafe: the kernel will remove the module 1981 without waiting for anyone to stop using it (using the -f option to 1982 rmmod). This is mainly for kernel developers and desperate users. 1983 If unsure, say N. 1984 1985config MODULE_UNLOAD_TAINT_TRACKING 1986 bool "Tainted module unload tracking" 1987 depends on MODULE_UNLOAD 1988 default n 1989 help 1990 This option allows you to maintain a record of each unloaded 1991 module that tainted the kernel. In addition to displaying a 1992 list of linked (or loaded) modules e.g. on detection of a bad 1993 page (see bad_page()), the aforementioned details are also 1994 shown. If unsure, say N. 1995 1996config MODVERSIONS 1997 bool "Module versioning support" 1998 help 1999 Usually, you have to use modules compiled with your kernel. 2000 Saying Y here makes it sometimes possible to use modules 2001 compiled for different kernels, by adding enough information 2002 to the modules to (hopefully) spot any changes which would 2003 make them incompatible with the kernel you are running. If 2004 unsure, say N. 2005 2006config ASM_MODVERSIONS 2007 bool 2008 default HAVE_ASM_MODVERSIONS && MODVERSIONS 2009 help 2010 This enables module versioning for exported symbols also from 2011 assembly. This can be enabled only when the target architecture 2012 supports it. 2013 2014config MODULE_SRCVERSION_ALL 2015 bool "Source checksum for all modules" 2016 help 2017 Modules which contain a MODULE_VERSION get an extra "srcversion" 2018 field inserted into their modinfo section, which contains a 2019 sum of the source files which made it. This helps maintainers 2020 see exactly which source was used to build a module (since 2021 others sometimes change the module source without updating 2022 the version). With this option, such a "srcversion" field 2023 will be created for all modules. If unsure, say N. 2024 2025config MODULE_SIG 2026 bool "Module signature verification" 2027 select MODULE_SIG_FORMAT 2028 help 2029 Check modules for valid signatures upon load: the signature 2030 is simply appended to the module. For more information see 2031 <file:Documentation/admin-guide/module-signing.rst>. 2032 2033 Note that this option adds the OpenSSL development packages as a 2034 kernel build dependency so that the signing tool can use its crypto 2035 library. 2036 2037 You should enable this option if you wish to use either 2038 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via 2039 another LSM - otherwise unsigned modules will be loadable regardless 2040 of the lockdown policy. 2041 2042 !!!WARNING!!! If you enable this option, you MUST make sure that the 2043 module DOES NOT get stripped after being signed. This includes the 2044 debuginfo strip done by some packagers (such as rpmbuild) and 2045 inclusion into an initramfs that wants the module size reduced. 2046 2047config MODULE_SIG_FORCE 2048 bool "Require modules to be validly signed" 2049 depends on MODULE_SIG 2050 help 2051 Reject unsigned modules or signed modules for which we don't have a 2052 key. Without this, such modules will simply taint the kernel. 2053 2054config MODULE_SIG_ALL 2055 bool "Automatically sign all modules" 2056 default y 2057 depends on MODULE_SIG || IMA_APPRAISE_MODSIG 2058 help 2059 Sign all modules during make modules_install. Without this option, 2060 modules must be signed manually, using the scripts/sign-file tool. 2061 2062comment "Do not forget to sign required modules with scripts/sign-file" 2063 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL 2064 2065choice 2066 prompt "Which hash algorithm should modules be signed with?" 2067 depends on MODULE_SIG || IMA_APPRAISE_MODSIG 2068 help 2069 This determines which sort of hashing algorithm will be used during 2070 signature generation. This algorithm _must_ be built into the kernel 2071 directly so that signature verification can take place. It is not 2072 possible to load a signed module containing the algorithm to check 2073 the signature on that module. 2074 2075config MODULE_SIG_SHA1 2076 bool "Sign modules with SHA-1" 2077 select CRYPTO_SHA1 2078 2079config MODULE_SIG_SHA224 2080 bool "Sign modules with SHA-224" 2081 select CRYPTO_SHA256 2082 2083config MODULE_SIG_SHA256 2084 bool "Sign modules with SHA-256" 2085 select CRYPTO_SHA256 2086 2087config MODULE_SIG_SHA384 2088 bool "Sign modules with SHA-384" 2089 select CRYPTO_SHA512 2090 2091config MODULE_SIG_SHA512 2092 bool "Sign modules with SHA-512" 2093 select CRYPTO_SHA512 2094 2095endchoice 2096 2097config MODULE_SIG_HASH 2098 string 2099 depends on MODULE_SIG || IMA_APPRAISE_MODSIG 2100 default "sha1" if MODULE_SIG_SHA1 2101 default "sha224" if MODULE_SIG_SHA224 2102 default "sha256" if MODULE_SIG_SHA256 2103 default "sha384" if MODULE_SIG_SHA384 2104 default "sha512" if MODULE_SIG_SHA512 2105 2106choice 2107 prompt "Module compression mode" 2108 help 2109 This option allows you to choose the algorithm which will be used to 2110 compress modules when 'make modules_install' is run. (or, you can 2111 choose to not compress modules at all.) 2112 2113 External modules will also be compressed in the same way during the 2114 installation. 2115 2116 For modules inside an initrd or initramfs, it's more efficient to 2117 compress the whole initrd or initramfs instead. 2118 2119 This is fully compatible with signed modules. 2120 2121 Please note that the tool used to load modules needs to support the 2122 corresponding algorithm. module-init-tools MAY support gzip, and kmod 2123 MAY support gzip, xz and zstd. 2124 2125 Your build system needs to provide the appropriate compression tool 2126 to compress the modules. 2127 2128 If in doubt, select 'None'. 2129 2130config MODULE_COMPRESS_NONE 2131 bool "None" 2132 help 2133 Do not compress modules. The installed modules are suffixed 2134 with .ko. 2135 2136config MODULE_COMPRESS_GZIP 2137 bool "GZIP" 2138 help 2139 Compress modules with GZIP. The installed modules are suffixed 2140 with .ko.gz. 2141 2142config MODULE_COMPRESS_XZ 2143 bool "XZ" 2144 help 2145 Compress modules with XZ. The installed modules are suffixed 2146 with .ko.xz. 2147 2148config MODULE_COMPRESS_ZSTD 2149 bool "ZSTD" 2150 help 2151 Compress modules with ZSTD. The installed modules are suffixed 2152 with .ko.zst. 2153 2154endchoice 2155 2156config MODULE_DECOMPRESS 2157 bool "Support in-kernel module decompression" 2158 depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ 2159 select ZLIB_INFLATE if MODULE_COMPRESS_GZIP 2160 select XZ_DEC if MODULE_COMPRESS_XZ 2161 help 2162 2163 Support for decompressing kernel modules by the kernel itself 2164 instead of relying on userspace to perform this task. Useful when 2165 load pinning security policy is enabled. 2166 2167 If unsure, say N. 2168 2169config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS 2170 bool "Allow loading of modules with missing namespace imports" 2171 help 2172 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in 2173 a namespace. A module that makes use of a symbol exported with such a 2174 namespace is required to import the namespace via MODULE_IMPORT_NS(). 2175 There is no technical reason to enforce correct namespace imports, 2176 but it creates consistency between symbols defining namespaces and 2177 users importing namespaces they make use of. This option relaxes this 2178 requirement and lifts the enforcement when loading a module. 2179 2180 If unsure, say N. 2181 2182config MODPROBE_PATH 2183 string "Path to modprobe binary" 2184 default "/sbin/modprobe" 2185 help 2186 When kernel code requests a module, it does so by calling 2187 the "modprobe" userspace utility. This option allows you to 2188 set the path where that binary is found. This can be changed 2189 at runtime via the sysctl file 2190 /proc/sys/kernel/modprobe. Setting this to the empty string 2191 removes the kernel's ability to request modules (but 2192 userspace can still load modules explicitly). 2193 2194config TRIM_UNUSED_KSYMS 2195 bool "Trim unused exported kernel symbols" if EXPERT 2196 depends on !COMPILE_TEST 2197 help 2198 The kernel and some modules make many symbols available for 2199 other modules to use via EXPORT_SYMBOL() and variants. Depending 2200 on the set of modules being selected in your kernel configuration, 2201 many of those exported symbols might never be used. 2202 2203 This option allows for unused exported symbols to be dropped from 2204 the build. In turn, this provides the compiler more opportunities 2205 (especially when using LTO) for optimizing the code and reducing 2206 binary size. This might have some security advantages as well. 2207 2208 If unsure, or if you need to build out-of-tree modules, say N. 2209 2210config UNUSED_KSYMS_WHITELIST 2211 string "Whitelist of symbols to keep in ksymtab" 2212 depends on TRIM_UNUSED_KSYMS 2213 help 2214 By default, all unused exported symbols will be un-exported from the 2215 build when TRIM_UNUSED_KSYMS is selected. 2216 2217 UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept 2218 exported at all times, even in absence of in-tree users. The value to 2219 set here is the path to a text file containing the list of symbols, 2220 one per line. The path can be absolute, or relative to the kernel 2221 source tree. 2222 2223endif # MODULES 2224 2225config MODULES_TREE_LOOKUP 2226 def_bool y 2227 depends on PERF_EVENTS || TRACING || CFI_CLANG 2228 2229config INIT_ALL_POSSIBLE 2230 bool 2231 help 2232 Back when each arch used to define their own cpu_online_mask and 2233 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 2234 with all 1s, and others with all 0s. When they were centralised, 2235 it was better to provide this option than to break all the archs 2236 and have several arch maintainers pursuing me down dark alleys. 2237 2238source "block/Kconfig" 2239 2240config PREEMPT_NOTIFIERS 2241 bool 2242 2243config PADATA 2244 depends on SMP 2245 bool 2246 2247config ASN1 2248 tristate 2249 help 2250 Build a simple ASN.1 grammar compiler that produces a bytecode output 2251 that can be interpreted by the ASN.1 stream decoder and used to 2252 inform it as to what tags are to be expected in a stream and what 2253 functions to call on what tags. 2254 2255source "kernel/Kconfig.locks" 2256 2257config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2258 bool 2259 2260config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2261 bool 2262 2263# It may be useful for an architecture to override the definitions of the 2264# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2265# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2266# different calling convention for syscalls. They can also override the 2267# macros for not-implemented syscalls in kernel/sys_ni.c and 2268# kernel/time/posix-stubs.c. All these overrides need to be available in 2269# <asm/syscall_wrapper.h>. 2270config ARCH_HAS_SYSCALL_WRAPPER 2271 def_bool n 2272