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/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 498 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN 499 depends on GENERIC_CLOCKEVENTS 500 select VIRT_CPU_ACCOUNTING 501 select CONTEXT_TRACKING 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 MEMCG 949 bool "Memory controller" 950 select PAGE_COUNTER 951 select EVENTFD 952 help 953 Provides control over the memory footprint of tasks in a cgroup. 954 955config MEMCG_SWAP 956 bool 957 depends on MEMCG && SWAP 958 default y 959 960config MEMCG_KMEM 961 bool 962 depends on MEMCG && !SLOB 963 default y 964 965config BLK_CGROUP 966 bool "IO controller" 967 depends on BLOCK 968 default n 969 help 970 Generic block IO controller cgroup interface. This is the common 971 cgroup interface which should be used by various IO controlling 972 policies. 973 974 Currently, CFQ IO scheduler uses it to recognize task groups and 975 control disk bandwidth allocation (proportional time slice allocation) 976 to such task groups. It is also used by bio throttling logic in 977 block layer to implement upper limit in IO rates on a device. 978 979 This option only enables generic Block IO controller infrastructure. 980 One needs to also enable actual IO controlling logic/policy. For 981 enabling proportional weight division of disk bandwidth in CFQ, set 982 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 983 CONFIG_BLK_DEV_THROTTLING=y. 984 985 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. 986 987config CGROUP_WRITEBACK 988 bool 989 depends on MEMCG && BLK_CGROUP 990 default y 991 992menuconfig CGROUP_SCHED 993 bool "CPU controller" 994 default n 995 help 996 This feature lets CPU scheduler recognize task groups and control CPU 997 bandwidth allocation to such task groups. It uses cgroups to group 998 tasks. 999 1000if CGROUP_SCHED 1001config FAIR_GROUP_SCHED 1002 bool "Group scheduling for SCHED_OTHER" 1003 depends on CGROUP_SCHED 1004 default CGROUP_SCHED 1005 1006config CFS_BANDWIDTH 1007 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 1008 depends on FAIR_GROUP_SCHED 1009 default n 1010 help 1011 This option allows users to define CPU bandwidth rates (limits) for 1012 tasks running within the fair group scheduler. Groups with no limit 1013 set are considered to be unconstrained and will run with no 1014 restriction. 1015 See Documentation/scheduler/sched-bwc.rst for more information. 1016 1017config RT_GROUP_SCHED 1018 bool "Group scheduling for SCHED_RR/FIFO" 1019 depends on CGROUP_SCHED 1020 default n 1021 help 1022 This feature lets you explicitly allocate real CPU bandwidth 1023 to task groups. If enabled, it will also make it impossible to 1024 schedule realtime tasks for non-root users until you allocate 1025 realtime bandwidth for them. 1026 See Documentation/scheduler/sched-rt-group.rst for more information. 1027 1028endif #CGROUP_SCHED 1029 1030config UCLAMP_TASK_GROUP 1031 bool "Utilization clamping per group of tasks" 1032 depends on CGROUP_SCHED 1033 depends on UCLAMP_TASK 1034 default n 1035 help 1036 This feature enables the scheduler to track the clamped utilization 1037 of each CPU based on RUNNABLE tasks currently scheduled on that CPU. 1038 1039 When this option is enabled, the user can specify a min and max 1040 CPU bandwidth which is allowed for each single task in a group. 1041 The max bandwidth allows to clamp the maximum frequency a task 1042 can use, while the min bandwidth allows to define a minimum 1043 frequency a task will always use. 1044 1045 When task group based utilization clamping is enabled, an eventually 1046 specified task-specific clamp value is constrained by the cgroup 1047 specified clamp value. Both minimum and maximum task clamping cannot 1048 be bigger than the corresponding clamping defined at task group level. 1049 1050 If in doubt, say N. 1051 1052config CGROUP_PIDS 1053 bool "PIDs controller" 1054 help 1055 Provides enforcement of process number limits in the scope of a 1056 cgroup. Any attempt to fork more processes than is allowed in the 1057 cgroup will fail. PIDs are fundamentally a global resource because it 1058 is fairly trivial to reach PID exhaustion before you reach even a 1059 conservative kmemcg limit. As a result, it is possible to grind a 1060 system to halt without being limited by other cgroup policies. The 1061 PIDs controller is designed to stop this from happening. 1062 1063 It should be noted that organisational operations (such as attaching 1064 to a cgroup hierarchy) will *not* be blocked by the PIDs controller, 1065 since the PIDs limit only affects a process's ability to fork, not to 1066 attach to a cgroup. 1067 1068config CGROUP_RDMA 1069 bool "RDMA controller" 1070 help 1071 Provides enforcement of RDMA resources defined by IB stack. 1072 It is fairly easy for consumers to exhaust RDMA resources, which 1073 can result into resource unavailability to other consumers. 1074 RDMA controller is designed to stop this from happening. 1075 Attaching processes with active RDMA resources to the cgroup 1076 hierarchy is allowed even if can cross the hierarchy's limit. 1077 1078config CGROUP_FREEZER 1079 bool "Freezer controller" 1080 help 1081 Provides a way to freeze and unfreeze all tasks in a 1082 cgroup. 1083 1084 This option affects the ORIGINAL cgroup interface. The cgroup2 memory 1085 controller includes important in-kernel memory consumers per default. 1086 1087 If you're using cgroup2, say N. 1088 1089config CGROUP_HUGETLB 1090 bool "HugeTLB controller" 1091 depends on HUGETLB_PAGE 1092 select PAGE_COUNTER 1093 default n 1094 help 1095 Provides a cgroup controller for HugeTLB pages. 1096 When you enable this, you can put a per cgroup limit on HugeTLB usage. 1097 The limit is enforced during page fault. Since HugeTLB doesn't 1098 support page reclaim, enforcing the limit at page fault time implies 1099 that, the application will get SIGBUS signal if it tries to access 1100 HugeTLB pages beyond its limit. This requires the application to know 1101 beforehand how much HugeTLB pages it would require for its use. The 1102 control group is tracked in the third page lru pointer. This means 1103 that we cannot use the controller with huge page less than 3 pages. 1104 1105config CPUSETS 1106 bool "Cpuset controller" 1107 depends on SMP 1108 help 1109 This option will let you create and manage CPUSETs which 1110 allow dynamically partitioning a system into sets of CPUs and 1111 Memory Nodes and assigning tasks to run only within those sets. 1112 This is primarily useful on large SMP or NUMA systems. 1113 1114 Say N if unsure. 1115 1116config PROC_PID_CPUSET 1117 bool "Include legacy /proc/<pid>/cpuset file" 1118 depends on CPUSETS 1119 default y 1120 1121config CGROUP_DEVICE 1122 bool "Device controller" 1123 help 1124 Provides a cgroup controller implementing whitelists for 1125 devices which a process in the cgroup can mknod or open. 1126 1127config CGROUP_CPUACCT 1128 bool "Simple CPU accounting controller" 1129 help 1130 Provides a simple controller for monitoring the 1131 total CPU consumed by the tasks in a cgroup. 1132 1133config CGROUP_PERF 1134 bool "Perf controller" 1135 depends on PERF_EVENTS 1136 help 1137 This option extends the perf per-cpu mode to restrict monitoring 1138 to threads which belong to the cgroup specified and run on the 1139 designated cpu. Or this can be used to have cgroup ID in samples 1140 so that it can monitor performance events among cgroups. 1141 1142 Say N if unsure. 1143 1144config CGROUP_BPF 1145 bool "Support for eBPF programs attached to cgroups" 1146 depends on BPF_SYSCALL 1147 select SOCK_CGROUP_DATA 1148 help 1149 Allow attaching eBPF programs to a cgroup using the bpf(2) 1150 syscall command BPF_PROG_ATTACH. 1151 1152 In which context these programs are accessed depends on the type 1153 of attachment. For instance, programs that are attached using 1154 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of 1155 inet sockets. 1156 1157config CGROUP_MISC 1158 bool "Misc resource controller" 1159 default n 1160 help 1161 Provides a controller for miscellaneous resources on a host. 1162 1163 Miscellaneous scalar resources are the resources on the host system 1164 which cannot be abstracted like the other cgroups. This controller 1165 tracks and limits the miscellaneous resources used by a process 1166 attached to a cgroup hierarchy. 1167 1168 For more information, please check misc cgroup section in 1169 /Documentation/admin-guide/cgroup-v2.rst. 1170 1171config CGROUP_DEBUG 1172 bool "Debug controller" 1173 default n 1174 depends on DEBUG_KERNEL 1175 help 1176 This option enables a simple controller that exports 1177 debugging information about the cgroups framework. This 1178 controller is for control cgroup debugging only. Its 1179 interfaces are not stable. 1180 1181 Say N. 1182 1183config SOCK_CGROUP_DATA 1184 bool 1185 default n 1186 1187endif # CGROUPS 1188 1189menuconfig NAMESPACES 1190 bool "Namespaces support" if EXPERT 1191 depends on MULTIUSER 1192 default !EXPERT 1193 help 1194 Provides the way to make tasks work with different objects using 1195 the same id. For example same IPC id may refer to different objects 1196 or same user id or pid may refer to different tasks when used in 1197 different namespaces. 1198 1199if NAMESPACES 1200 1201config UTS_NS 1202 bool "UTS namespace" 1203 default y 1204 help 1205 In this namespace tasks see different info provided with the 1206 uname() system call 1207 1208config TIME_NS 1209 bool "TIME namespace" 1210 depends on GENERIC_VDSO_TIME_NS 1211 default y 1212 help 1213 In this namespace boottime and monotonic clocks can be set. 1214 The time will keep going with the same pace. 1215 1216config IPC_NS 1217 bool "IPC namespace" 1218 depends on (SYSVIPC || POSIX_MQUEUE) 1219 default y 1220 help 1221 In this namespace tasks work with IPC ids which correspond to 1222 different IPC objects in different namespaces. 1223 1224config USER_NS 1225 bool "User namespace" 1226 default n 1227 help 1228 This allows containers, i.e. vservers, to use user namespaces 1229 to provide different user info for different servers. 1230 1231 When user namespaces are enabled in the kernel it is 1232 recommended that the MEMCG option also be enabled and that 1233 user-space use the memory control groups to limit the amount 1234 of memory a memory unprivileged users can use. 1235 1236 If unsure, say N. 1237 1238config PID_NS 1239 bool "PID Namespaces" 1240 default y 1241 help 1242 Support process id namespaces. This allows having multiple 1243 processes with the same pid as long as they are in different 1244 pid namespaces. This is a building block of containers. 1245 1246config NET_NS 1247 bool "Network namespace" 1248 depends on NET 1249 default y 1250 help 1251 Allow user space to create what appear to be multiple instances 1252 of the network stack. 1253 1254endif # NAMESPACES 1255 1256config CHECKPOINT_RESTORE 1257 bool "Checkpoint/restore support" 1258 select PROC_CHILDREN 1259 select KCMP 1260 default n 1261 help 1262 Enables additional kernel features in a sake of checkpoint/restore. 1263 In particular it adds auxiliary prctl codes to setup process text, 1264 data and heap segment sizes, and a few additional /proc filesystem 1265 entries. 1266 1267 If unsure, say N here. 1268 1269config SCHED_AUTOGROUP 1270 bool "Automatic process group scheduling" 1271 select CGROUPS 1272 select CGROUP_SCHED 1273 select FAIR_GROUP_SCHED 1274 help 1275 This option optimizes the scheduler for common desktop workloads by 1276 automatically creating and populating task groups. This separation 1277 of workloads isolates aggressive CPU burners (like build jobs) from 1278 desktop applications. Task group autogeneration is currently based 1279 upon task session. 1280 1281config SYSFS_DEPRECATED 1282 bool "Enable deprecated sysfs features to support old userspace tools" 1283 depends on SYSFS 1284 default n 1285 help 1286 This option adds code that switches the layout of the "block" class 1287 devices, to not show up in /sys/class/block/, but only in 1288 /sys/block/. 1289 1290 This switch is only active when the sysfs.deprecated=1 boot option is 1291 passed or the SYSFS_DEPRECATED_V2 option is set. 1292 1293 This option allows new kernels to run on old distributions and tools, 1294 which might get confused by /sys/class/block/. Since 2007/2008 all 1295 major distributions and tools handle this just fine. 1296 1297 Recent distributions and userspace tools after 2009/2010 depend on 1298 the existence of /sys/class/block/, and will not work with this 1299 option enabled. 1300 1301 Only if you are using a new kernel on an old distribution, you might 1302 need to say Y here. 1303 1304config SYSFS_DEPRECATED_V2 1305 bool "Enable deprecated sysfs features by default" 1306 default n 1307 depends on SYSFS 1308 depends on SYSFS_DEPRECATED 1309 help 1310 Enable deprecated sysfs by default. 1311 1312 See the CONFIG_SYSFS_DEPRECATED option for more details about this 1313 option. 1314 1315 Only if you are using a new kernel on an old distribution, you might 1316 need to say Y here. Even then, odds are you would not need it 1317 enabled, you can always pass the boot option if absolutely necessary. 1318 1319config RELAY 1320 bool "Kernel->user space relay support (formerly relayfs)" 1321 select IRQ_WORK 1322 help 1323 This option enables support for relay interface support in 1324 certain file systems (such as debugfs). 1325 It is designed to provide an efficient mechanism for tools and 1326 facilities to relay large amounts of data from kernel space to 1327 user space. 1328 1329 If unsure, say N. 1330 1331config BLK_DEV_INITRD 1332 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1333 help 1334 The initial RAM filesystem is a ramfs which is loaded by the 1335 boot loader (loadlin or lilo) and that is mounted as root 1336 before the normal boot procedure. It is typically used to 1337 load modules needed to mount the "real" root file system, 1338 etc. See <file:Documentation/admin-guide/initrd.rst> for details. 1339 1340 If RAM disk support (BLK_DEV_RAM) is also included, this 1341 also enables initial RAM disk (initrd) support and adds 1342 15 Kbytes (more on some other architectures) to the kernel size. 1343 1344 If unsure say Y. 1345 1346if BLK_DEV_INITRD 1347 1348source "usr/Kconfig" 1349 1350endif 1351 1352config BOOT_CONFIG 1353 bool "Boot config support" 1354 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED 1355 help 1356 Extra boot config allows system admin to pass a config file as 1357 complemental extension of kernel cmdline when booting. 1358 The boot config file must be attached at the end of initramfs 1359 with checksum, size and magic word. 1360 See <file:Documentation/admin-guide/bootconfig.rst> for details. 1361 1362 If unsure, say Y. 1363 1364config BOOT_CONFIG_EMBED 1365 bool "Embed bootconfig file in the kernel" 1366 depends on BOOT_CONFIG 1367 help 1368 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the 1369 kernel. Usually, the bootconfig file is loaded with the initrd 1370 image. But if the system doesn't support initrd, this option will 1371 help you by embedding a bootconfig file while building the kernel. 1372 1373 If unsure, say N. 1374 1375config BOOT_CONFIG_EMBED_FILE 1376 string "Embedded bootconfig file path" 1377 depends on BOOT_CONFIG_EMBED 1378 help 1379 Specify a bootconfig file which will be embedded to the kernel. 1380 This bootconfig will be used if there is no initrd or no other 1381 bootconfig in the initrd. 1382 1383config INITRAMFS_PRESERVE_MTIME 1384 bool "Preserve cpio archive mtimes in initramfs" 1385 default y 1386 help 1387 Each entry in an initramfs cpio archive carries an mtime value. When 1388 enabled, extracted cpio items take this mtime, with directory mtime 1389 setting deferred until after creation of any child entries. 1390 1391 If unsure, say Y. 1392 1393choice 1394 prompt "Compiler optimization level" 1395 default CC_OPTIMIZE_FOR_PERFORMANCE 1396 1397config CC_OPTIMIZE_FOR_PERFORMANCE 1398 bool "Optimize for performance (-O2)" 1399 help 1400 This is the default optimization level for the kernel, building 1401 with the "-O2" compiler flag for best performance and most 1402 helpful compile-time warnings. 1403 1404config CC_OPTIMIZE_FOR_SIZE 1405 bool "Optimize for size (-Os)" 1406 help 1407 Choosing this option will pass "-Os" to your compiler resulting 1408 in a smaller kernel. 1409 1410endchoice 1411 1412config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1413 bool 1414 help 1415 This requires that the arch annotates or otherwise protects 1416 its external entry points from being discarded. Linker scripts 1417 must also merge .text.*, .data.*, and .bss.* correctly into 1418 output sections. Care must be taken not to pull in unrelated 1419 sections (e.g., '.text.init'). Typically '.' in section names 1420 is used to distinguish them from label names / C identifiers. 1421 1422config LD_DEAD_CODE_DATA_ELIMINATION 1423 bool "Dead code and data elimination (EXPERIMENTAL)" 1424 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1425 depends on EXPERT 1426 depends on $(cc-option,-ffunction-sections -fdata-sections) 1427 depends on $(ld-option,--gc-sections) 1428 help 1429 Enable this if you want to do dead code and data elimination with 1430 the linker by compiling with -ffunction-sections -fdata-sections, 1431 and linking with --gc-sections. 1432 1433 This can reduce on disk and in-memory size of the kernel 1434 code and static data, particularly for small configs and 1435 on small systems. This has the possibility of introducing 1436 silently broken kernel if the required annotations are not 1437 present. This option is not well tested yet, so use at your 1438 own risk. 1439 1440config LD_ORPHAN_WARN 1441 def_bool y 1442 depends on ARCH_WANT_LD_ORPHAN_WARN 1443 depends on $(ld-option,--orphan-handling=warn) 1444 1445config SYSCTL 1446 bool 1447 1448config HAVE_UID16 1449 bool 1450 1451config SYSCTL_EXCEPTION_TRACE 1452 bool 1453 help 1454 Enable support for /proc/sys/debug/exception-trace. 1455 1456config SYSCTL_ARCH_UNALIGN_NO_WARN 1457 bool 1458 help 1459 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1460 Allows arch to define/use @no_unaligned_warning to possibly warn 1461 about unaligned access emulation going on under the hood. 1462 1463config SYSCTL_ARCH_UNALIGN_ALLOW 1464 bool 1465 help 1466 Enable support for /proc/sys/kernel/unaligned-trap 1467 Allows arches to define/use @unaligned_enabled to runtime toggle 1468 the unaligned access emulation. 1469 see arch/parisc/kernel/unaligned.c for reference 1470 1471config HAVE_PCSPKR_PLATFORM 1472 bool 1473 1474# interpreter that classic socket filters depend on 1475config BPF 1476 bool 1477 1478menuconfig EXPERT 1479 bool "Configure standard kernel features (expert users)" 1480 # Unhide debug options, to make the on-by-default options visible 1481 select DEBUG_KERNEL 1482 help 1483 This option allows certain base kernel options and settings 1484 to be disabled or tweaked. This is for specialized 1485 environments which can tolerate a "non-standard" kernel. 1486 Only use this if you really know what you are doing. 1487 1488config UID16 1489 bool "Enable 16-bit UID system calls" if EXPERT 1490 depends on HAVE_UID16 && MULTIUSER 1491 default y 1492 help 1493 This enables the legacy 16-bit UID syscall wrappers. 1494 1495config MULTIUSER 1496 bool "Multiple users, groups and capabilities support" if EXPERT 1497 default y 1498 help 1499 This option enables support for non-root users, groups and 1500 capabilities. 1501 1502 If you say N here, all processes will run with UID 0, GID 0, and all 1503 possible capabilities. Saying N here also compiles out support for 1504 system calls related to UIDs, GIDs, and capabilities, such as setuid, 1505 setgid, and capset. 1506 1507 If unsure, say Y here. 1508 1509config SGETMASK_SYSCALL 1510 bool "sgetmask/ssetmask syscalls support" if EXPERT 1511 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH 1512 help 1513 sys_sgetmask and sys_ssetmask are obsolete system calls 1514 no longer supported in libc but still enabled by default in some 1515 architectures. 1516 1517 If unsure, leave the default option here. 1518 1519config SYSFS_SYSCALL 1520 bool "Sysfs syscall support" if EXPERT 1521 default y 1522 help 1523 sys_sysfs is an obsolete system call no longer supported in libc. 1524 Note that disabling this option is more secure but might break 1525 compatibility with some systems. 1526 1527 If unsure say Y here. 1528 1529config FHANDLE 1530 bool "open by fhandle syscalls" if EXPERT 1531 select EXPORTFS 1532 default y 1533 help 1534 If you say Y here, a user level program will be able to map 1535 file names to handle and then later use the handle for 1536 different file system operations. This is useful in implementing 1537 userspace file servers, which now track files using handles instead 1538 of names. The handle would remain the same even if file names 1539 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 1540 syscalls. 1541 1542config POSIX_TIMERS 1543 bool "Posix Clocks & timers" if EXPERT 1544 default y 1545 help 1546 This includes native support for POSIX timers to the kernel. 1547 Some embedded systems have no use for them and therefore they 1548 can be configured out to reduce the size of the kernel image. 1549 1550 When this option is disabled, the following syscalls won't be 1551 available: timer_create, timer_gettime: timer_getoverrun, 1552 timer_settime, timer_delete, clock_adjtime, getitimer, 1553 setitimer, alarm. Furthermore, the clock_settime, clock_gettime, 1554 clock_getres and clock_nanosleep syscalls will be limited to 1555 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. 1556 1557 If unsure say y. 1558 1559config PRINTK 1560 default y 1561 bool "Enable support for printk" if EXPERT 1562 select IRQ_WORK 1563 help 1564 This option enables normal printk support. Removing it 1565 eliminates most of the message strings from the kernel image 1566 and makes the kernel more or less silent. As this makes it 1567 very difficult to diagnose system problems, saying N here is 1568 strongly discouraged. 1569 1570config BUG 1571 bool "BUG() support" if EXPERT 1572 default y 1573 help 1574 Disabling this option eliminates support for BUG and WARN, reducing 1575 the size of your kernel image and potentially quietly ignoring 1576 numerous fatal conditions. You should only consider disabling this 1577 option for embedded systems with no facilities for reporting errors. 1578 Just say Y. 1579 1580config ELF_CORE 1581 depends on COREDUMP 1582 default y 1583 bool "Enable ELF core dumps" if EXPERT 1584 help 1585 Enable support for generating core dumps. Disabling saves about 4k. 1586 1587 1588config PCSPKR_PLATFORM 1589 bool "Enable PC-Speaker support" if EXPERT 1590 depends on HAVE_PCSPKR_PLATFORM 1591 select I8253_LOCK 1592 default y 1593 help 1594 This option allows to disable the internal PC-Speaker 1595 support, saving some memory. 1596 1597config BASE_FULL 1598 default y 1599 bool "Enable full-sized data structures for core" if EXPERT 1600 help 1601 Disabling this option reduces the size of miscellaneous core 1602 kernel data structures. This saves memory on small machines, 1603 but may reduce performance. 1604 1605config FUTEX 1606 bool "Enable futex support" if EXPERT 1607 depends on !(SPARC32 && SMP) 1608 default y 1609 imply RT_MUTEXES 1610 help 1611 Disabling this option will cause the kernel to be built without 1612 support for "fast userspace mutexes". The resulting kernel may not 1613 run glibc-based applications correctly. 1614 1615config FUTEX_PI 1616 bool 1617 depends on FUTEX && RT_MUTEXES 1618 default y 1619 1620config EPOLL 1621 bool "Enable eventpoll support" if EXPERT 1622 default y 1623 help 1624 Disabling this option will cause the kernel to be built without 1625 support for epoll family of system calls. 1626 1627config SIGNALFD 1628 bool "Enable signalfd() system call" if EXPERT 1629 default y 1630 help 1631 Enable the signalfd() system call that allows to receive signals 1632 on a file descriptor. 1633 1634 If unsure, say Y. 1635 1636config TIMERFD 1637 bool "Enable timerfd() system call" if EXPERT 1638 default y 1639 help 1640 Enable the timerfd() system call that allows to receive timer 1641 events on a file descriptor. 1642 1643 If unsure, say Y. 1644 1645config EVENTFD 1646 bool "Enable eventfd() system call" if EXPERT 1647 default y 1648 help 1649 Enable the eventfd() system call that allows to receive both 1650 kernel notification (ie. KAIO) or userspace notifications. 1651 1652 If unsure, say Y. 1653 1654config SHMEM 1655 bool "Use full shmem filesystem" if EXPERT 1656 default y 1657 depends on MMU 1658 help 1659 The shmem is an internal filesystem used to manage shared memory. 1660 It is backed by swap and manages resource limits. It is also exported 1661 to userspace as tmpfs if TMPFS is enabled. Disabling this 1662 option replaces shmem and tmpfs with the much simpler ramfs code, 1663 which may be appropriate on small systems without swap. 1664 1665config AIO 1666 bool "Enable AIO support" if EXPERT 1667 default y 1668 help 1669 This option enables POSIX asynchronous I/O which may by used 1670 by some high performance threaded applications. Disabling 1671 this option saves about 7k. 1672 1673config IO_URING 1674 bool "Enable IO uring support" if EXPERT 1675 select IO_WQ 1676 default y 1677 help 1678 This option enables support for the io_uring interface, enabling 1679 applications to submit and complete IO through submission and 1680 completion rings that are shared between the kernel and application. 1681 1682config ADVISE_SYSCALLS 1683 bool "Enable madvise/fadvise syscalls" if EXPERT 1684 default y 1685 help 1686 This option enables the madvise and fadvise syscalls, used by 1687 applications to advise the kernel about their future memory or file 1688 usage, improving performance. If building an embedded system where no 1689 applications use these syscalls, you can disable this option to save 1690 space. 1691 1692config MEMBARRIER 1693 bool "Enable membarrier() system call" if EXPERT 1694 default y 1695 help 1696 Enable the membarrier() system call that allows issuing memory 1697 barriers across all running threads, which can be used to distribute 1698 the cost of user-space memory barriers asymmetrically by transforming 1699 pairs of memory barriers into pairs consisting of membarrier() and a 1700 compiler barrier. 1701 1702 If unsure, say Y. 1703 1704config KALLSYMS 1705 bool "Load all symbols for debugging/ksymoops" if EXPERT 1706 default y 1707 help 1708 Say Y here to let the kernel print out symbolic crash information and 1709 symbolic stack backtraces. This increases the size of the kernel 1710 somewhat, as all symbols have to be loaded into the kernel image. 1711 1712config KALLSYMS_ALL 1713 bool "Include all symbols in kallsyms" 1714 depends on DEBUG_KERNEL && KALLSYMS 1715 help 1716 Normally kallsyms only contains the symbols of functions for nicer 1717 OOPS messages and backtraces (i.e., symbols from the text and inittext 1718 sections). This is sufficient for most cases. And only if you want to 1719 enable kernel live patching, or other less common use cases (e.g., 1720 when a debugger is used) all symbols are required (i.e., names of 1721 variables from the data sections, etc). 1722 1723 This option makes sure that all symbols are loaded into the kernel 1724 image (i.e., symbols from all sections) in cost of increased kernel 1725 size (depending on the kernel configuration, it may be 300KiB or 1726 something like this). 1727 1728 Say N unless you really need all symbols, or kernel live patching. 1729 1730config KALLSYMS_ABSOLUTE_PERCPU 1731 bool 1732 depends on KALLSYMS 1733 default X86_64 && SMP 1734 1735config KALLSYMS_BASE_RELATIVE 1736 bool 1737 depends on KALLSYMS 1738 default !IA64 1739 help 1740 Instead of emitting them as absolute values in the native word size, 1741 emit the symbol references in the kallsyms table as 32-bit entries, 1742 each containing a relative value in the range [base, base + U32_MAX] 1743 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either 1744 an absolute value in the range [0, S32_MAX] or a relative value in the 1745 range [base, base + S32_MAX], where base is the lowest relative symbol 1746 address encountered in the image. 1747 1748 On 64-bit builds, this reduces the size of the address table by 50%, 1749 but more importantly, it results in entries whose values are build 1750 time constants, and no relocation pass is required at runtime to fix 1751 up the entries based on the runtime load address of the kernel. 1752 1753# end of the "standard kernel features (expert users)" menu 1754 1755# syscall, maps, verifier 1756 1757config ARCH_HAS_MEMBARRIER_CALLBACKS 1758 bool 1759 1760config ARCH_HAS_MEMBARRIER_SYNC_CORE 1761 bool 1762 1763config KCMP 1764 bool "Enable kcmp() system call" if EXPERT 1765 help 1766 Enable the kernel resource comparison system call. It provides 1767 user-space with the ability to compare two processes to see if they 1768 share a common resource, such as a file descriptor or even virtual 1769 memory space. 1770 1771 If unsure, say N. 1772 1773config RSEQ 1774 bool "Enable rseq() system call" if EXPERT 1775 default y 1776 depends on HAVE_RSEQ 1777 select MEMBARRIER 1778 help 1779 Enable the restartable sequences system call. It provides a 1780 user-space cache for the current CPU number value, which 1781 speeds up getting the current CPU number from user-space, 1782 as well as an ABI to speed up user-space operations on 1783 per-CPU data. 1784 1785 If unsure, say Y. 1786 1787config DEBUG_RSEQ 1788 default n 1789 bool "Enabled debugging of rseq() system call" if EXPERT 1790 depends on RSEQ && DEBUG_KERNEL 1791 help 1792 Enable extra debugging checks for the rseq system call. 1793 1794 If unsure, say N. 1795 1796config EMBEDDED 1797 bool "Embedded system" 1798 select EXPERT 1799 help 1800 This option should be enabled if compiling the kernel for 1801 an embedded system so certain expert options are available 1802 for configuration. 1803 1804config HAVE_PERF_EVENTS 1805 bool 1806 help 1807 See tools/perf/design.txt for details. 1808 1809config GUEST_PERF_EVENTS 1810 bool 1811 depends on HAVE_PERF_EVENTS 1812 1813config PERF_USE_VMALLOC 1814 bool 1815 help 1816 See tools/perf/design.txt for details 1817 1818config PC104 1819 bool "PC/104 support" if EXPERT 1820 help 1821 Expose PC/104 form factor device drivers and options available for 1822 selection and configuration. Enable this option if your target 1823 machine has a PC/104 bus. 1824 1825menu "Kernel Performance Events And Counters" 1826 1827config PERF_EVENTS 1828 bool "Kernel performance events and counters" 1829 default y if PROFILING 1830 depends on HAVE_PERF_EVENTS 1831 select IRQ_WORK 1832 select SRCU 1833 help 1834 Enable kernel support for various performance events provided 1835 by software and hardware. 1836 1837 Software events are supported either built-in or via the 1838 use of generic tracepoints. 1839 1840 Most modern CPUs support performance events via performance 1841 counter registers. These registers count the number of certain 1842 types of hw events: such as instructions executed, cachemisses 1843 suffered, or branches mis-predicted - without slowing down the 1844 kernel or applications. These registers can also trigger interrupts 1845 when a threshold number of events have passed - and can thus be 1846 used to profile the code that runs on that CPU. 1847 1848 The Linux Performance Event subsystem provides an abstraction of 1849 these software and hardware event capabilities, available via a 1850 system call and used by the "perf" utility in tools/perf/. It 1851 provides per task and per CPU counters, and it provides event 1852 capabilities on top of those. 1853 1854 Say Y if unsure. 1855 1856config DEBUG_PERF_USE_VMALLOC 1857 default n 1858 bool "Debug: use vmalloc to back perf mmap() buffers" 1859 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC 1860 select PERF_USE_VMALLOC 1861 help 1862 Use vmalloc memory to back perf mmap() buffers. 1863 1864 Mostly useful for debugging the vmalloc code on platforms 1865 that don't require it. 1866 1867 Say N if unsure. 1868 1869endmenu 1870 1871config SYSTEM_DATA_VERIFICATION 1872 def_bool n 1873 select SYSTEM_TRUSTED_KEYRING 1874 select KEYS 1875 select CRYPTO 1876 select CRYPTO_RSA 1877 select ASYMMETRIC_KEY_TYPE 1878 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1879 select ASN1 1880 select OID_REGISTRY 1881 select X509_CERTIFICATE_PARSER 1882 select PKCS7_MESSAGE_PARSER 1883 help 1884 Provide PKCS#7 message verification using the contents of the system 1885 trusted keyring to provide public keys. This then can be used for 1886 module verification, kexec image verification and firmware blob 1887 verification. 1888 1889config PROFILING 1890 bool "Profiling support" 1891 help 1892 Say Y here to enable the extended profiling support mechanisms used 1893 by profilers. 1894 1895# 1896# Place an empty function call at each tracepoint site. Can be 1897# dynamically changed for a probe function. 1898# 1899config TRACEPOINTS 1900 bool 1901 1902endmenu # General setup 1903 1904source "arch/Kconfig" 1905 1906config RT_MUTEXES 1907 bool 1908 default y if PREEMPT_RT 1909 1910config BASE_SMALL 1911 int 1912 default 0 if BASE_FULL 1913 default 1 if !BASE_FULL 1914 1915config MODULE_SIG_FORMAT 1916 def_bool n 1917 select SYSTEM_DATA_VERIFICATION 1918 1919menuconfig MODULES 1920 bool "Enable loadable module support" 1921 modules 1922 help 1923 Kernel modules are small pieces of compiled code which can 1924 be inserted in the running kernel, rather than being 1925 permanently built into the kernel. You use the "modprobe" 1926 tool to add (and sometimes remove) them. If you say Y here, 1927 many parts of the kernel can be built as modules (by 1928 answering M instead of Y where indicated): this is most 1929 useful for infrequently used options which are not required 1930 for booting. For more information, see the man pages for 1931 modprobe, lsmod, modinfo, insmod and rmmod. 1932 1933 If you say Y here, you will need to run "make 1934 modules_install" to put the modules under /lib/modules/ 1935 where modprobe can find them (you may need to be root to do 1936 this). 1937 1938 If unsure, say Y. 1939 1940if MODULES 1941 1942config MODULE_FORCE_LOAD 1943 bool "Forced module loading" 1944 default n 1945 help 1946 Allow loading of modules without version information (ie. modprobe 1947 --force). Forced module loading sets the 'F' (forced) taint flag and 1948 is usually a really bad idea. 1949 1950config MODULE_UNLOAD 1951 bool "Module unloading" 1952 help 1953 Without this option you will not be able to unload any 1954 modules (note that some modules may not be unloadable 1955 anyway), which makes your kernel smaller, faster 1956 and simpler. If unsure, say Y. 1957 1958config MODULE_FORCE_UNLOAD 1959 bool "Forced module unloading" 1960 depends on MODULE_UNLOAD 1961 help 1962 This option allows you to force a module to unload, even if the 1963 kernel believes it is unsafe: the kernel will remove the module 1964 without waiting for anyone to stop using it (using the -f option to 1965 rmmod). This is mainly for kernel developers and desperate users. 1966 If unsure, say N. 1967 1968config MODULE_UNLOAD_TAINT_TRACKING 1969 bool "Tainted module unload tracking" 1970 depends on MODULE_UNLOAD 1971 default n 1972 help 1973 This option allows you to maintain a record of each unloaded 1974 module that tainted the kernel. In addition to displaying a 1975 list of linked (or loaded) modules e.g. on detection of a bad 1976 page (see bad_page()), the aforementioned details are also 1977 shown. If unsure, say N. 1978 1979config MODVERSIONS 1980 bool "Module versioning support" 1981 help 1982 Usually, you have to use modules compiled with your kernel. 1983 Saying Y here makes it sometimes possible to use modules 1984 compiled for different kernels, by adding enough information 1985 to the modules to (hopefully) spot any changes which would 1986 make them incompatible with the kernel you are running. If 1987 unsure, say N. 1988 1989config ASM_MODVERSIONS 1990 bool 1991 default HAVE_ASM_MODVERSIONS && MODVERSIONS 1992 help 1993 This enables module versioning for exported symbols also from 1994 assembly. This can be enabled only when the target architecture 1995 supports it. 1996 1997config MODULE_SRCVERSION_ALL 1998 bool "Source checksum for all modules" 1999 help 2000 Modules which contain a MODULE_VERSION get an extra "srcversion" 2001 field inserted into their modinfo section, which contains a 2002 sum of the source files which made it. This helps maintainers 2003 see exactly which source was used to build a module (since 2004 others sometimes change the module source without updating 2005 the version). With this option, such a "srcversion" field 2006 will be created for all modules. If unsure, say N. 2007 2008config MODULE_SIG 2009 bool "Module signature verification" 2010 select MODULE_SIG_FORMAT 2011 help 2012 Check modules for valid signatures upon load: the signature 2013 is simply appended to the module. For more information see 2014 <file:Documentation/admin-guide/module-signing.rst>. 2015 2016 Note that this option adds the OpenSSL development packages as a 2017 kernel build dependency so that the signing tool can use its crypto 2018 library. 2019 2020 You should enable this option if you wish to use either 2021 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via 2022 another LSM - otherwise unsigned modules will be loadable regardless 2023 of the lockdown policy. 2024 2025 !!!WARNING!!! If you enable this option, you MUST make sure that the 2026 module DOES NOT get stripped after being signed. This includes the 2027 debuginfo strip done by some packagers (such as rpmbuild) and 2028 inclusion into an initramfs that wants the module size reduced. 2029 2030config MODULE_SIG_FORCE 2031 bool "Require modules to be validly signed" 2032 depends on MODULE_SIG 2033 help 2034 Reject unsigned modules or signed modules for which we don't have a 2035 key. Without this, such modules will simply taint the kernel. 2036 2037config MODULE_SIG_ALL 2038 bool "Automatically sign all modules" 2039 default y 2040 depends on MODULE_SIG || IMA_APPRAISE_MODSIG 2041 help 2042 Sign all modules during make modules_install. Without this option, 2043 modules must be signed manually, using the scripts/sign-file tool. 2044 2045comment "Do not forget to sign required modules with scripts/sign-file" 2046 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL 2047 2048choice 2049 prompt "Which hash algorithm should modules be signed with?" 2050 depends on MODULE_SIG || IMA_APPRAISE_MODSIG 2051 help 2052 This determines which sort of hashing algorithm will be used during 2053 signature generation. This algorithm _must_ be built into the kernel 2054 directly so that signature verification can take place. It is not 2055 possible to load a signed module containing the algorithm to check 2056 the signature on that module. 2057 2058config MODULE_SIG_SHA1 2059 bool "Sign modules with SHA-1" 2060 select CRYPTO_SHA1 2061 2062config MODULE_SIG_SHA224 2063 bool "Sign modules with SHA-224" 2064 select CRYPTO_SHA256 2065 2066config MODULE_SIG_SHA256 2067 bool "Sign modules with SHA-256" 2068 select CRYPTO_SHA256 2069 2070config MODULE_SIG_SHA384 2071 bool "Sign modules with SHA-384" 2072 select CRYPTO_SHA512 2073 2074config MODULE_SIG_SHA512 2075 bool "Sign modules with SHA-512" 2076 select CRYPTO_SHA512 2077 2078endchoice 2079 2080config MODULE_SIG_HASH 2081 string 2082 depends on MODULE_SIG || IMA_APPRAISE_MODSIG 2083 default "sha1" if MODULE_SIG_SHA1 2084 default "sha224" if MODULE_SIG_SHA224 2085 default "sha256" if MODULE_SIG_SHA256 2086 default "sha384" if MODULE_SIG_SHA384 2087 default "sha512" if MODULE_SIG_SHA512 2088 2089choice 2090 prompt "Module compression mode" 2091 help 2092 This option allows you to choose the algorithm which will be used to 2093 compress modules when 'make modules_install' is run. (or, you can 2094 choose to not compress modules at all.) 2095 2096 External modules will also be compressed in the same way during the 2097 installation. 2098 2099 For modules inside an initrd or initramfs, it's more efficient to 2100 compress the whole initrd or initramfs instead. 2101 2102 This is fully compatible with signed modules. 2103 2104 Please note that the tool used to load modules needs to support the 2105 corresponding algorithm. module-init-tools MAY support gzip, and kmod 2106 MAY support gzip, xz and zstd. 2107 2108 Your build system needs to provide the appropriate compression tool 2109 to compress the modules. 2110 2111 If in doubt, select 'None'. 2112 2113config MODULE_COMPRESS_NONE 2114 bool "None" 2115 help 2116 Do not compress modules. The installed modules are suffixed 2117 with .ko. 2118 2119config MODULE_COMPRESS_GZIP 2120 bool "GZIP" 2121 help 2122 Compress modules with GZIP. The installed modules are suffixed 2123 with .ko.gz. 2124 2125config MODULE_COMPRESS_XZ 2126 bool "XZ" 2127 help 2128 Compress modules with XZ. The installed modules are suffixed 2129 with .ko.xz. 2130 2131config MODULE_COMPRESS_ZSTD 2132 bool "ZSTD" 2133 help 2134 Compress modules with ZSTD. The installed modules are suffixed 2135 with .ko.zst. 2136 2137endchoice 2138 2139config MODULE_DECOMPRESS 2140 bool "Support in-kernel module decompression" 2141 depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ 2142 select ZLIB_INFLATE if MODULE_COMPRESS_GZIP 2143 select XZ_DEC if MODULE_COMPRESS_XZ 2144 help 2145 2146 Support for decompressing kernel modules by the kernel itself 2147 instead of relying on userspace to perform this task. Useful when 2148 load pinning security policy is enabled. 2149 2150 If unsure, say N. 2151 2152config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS 2153 bool "Allow loading of modules with missing namespace imports" 2154 help 2155 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in 2156 a namespace. A module that makes use of a symbol exported with such a 2157 namespace is required to import the namespace via MODULE_IMPORT_NS(). 2158 There is no technical reason to enforce correct namespace imports, 2159 but it creates consistency between symbols defining namespaces and 2160 users importing namespaces they make use of. This option relaxes this 2161 requirement and lifts the enforcement when loading a module. 2162 2163 If unsure, say N. 2164 2165config MODPROBE_PATH 2166 string "Path to modprobe binary" 2167 default "/sbin/modprobe" 2168 help 2169 When kernel code requests a module, it does so by calling 2170 the "modprobe" userspace utility. This option allows you to 2171 set the path where that binary is found. This can be changed 2172 at runtime via the sysctl file 2173 /proc/sys/kernel/modprobe. Setting this to the empty string 2174 removes the kernel's ability to request modules (but 2175 userspace can still load modules explicitly). 2176 2177config TRIM_UNUSED_KSYMS 2178 bool "Trim unused exported kernel symbols" if EXPERT 2179 depends on !COMPILE_TEST 2180 help 2181 The kernel and some modules make many symbols available for 2182 other modules to use via EXPORT_SYMBOL() and variants. Depending 2183 on the set of modules being selected in your kernel configuration, 2184 many of those exported symbols might never be used. 2185 2186 This option allows for unused exported symbols to be dropped from 2187 the build. In turn, this provides the compiler more opportunities 2188 (especially when using LTO) for optimizing the code and reducing 2189 binary size. This might have some security advantages as well. 2190 2191 If unsure, or if you need to build out-of-tree modules, say N. 2192 2193config UNUSED_KSYMS_WHITELIST 2194 string "Whitelist of symbols to keep in ksymtab" 2195 depends on TRIM_UNUSED_KSYMS 2196 help 2197 By default, all unused exported symbols will be un-exported from the 2198 build when TRIM_UNUSED_KSYMS is selected. 2199 2200 UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept 2201 exported at all times, even in absence of in-tree users. The value to 2202 set here is the path to a text file containing the list of symbols, 2203 one per line. The path can be absolute, or relative to the kernel 2204 source tree. 2205 2206endif # MODULES 2207 2208config MODULES_TREE_LOOKUP 2209 def_bool y 2210 depends on PERF_EVENTS || TRACING || CFI_CLANG 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_SYNC_CORE_BEFORE_USERMODE 2244 bool 2245 2246# It may be useful for an architecture to override the definitions of the 2247# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> 2248# and the COMPAT_ variants in <linux/compat.h>, in particular to use a 2249# different calling convention for syscalls. They can also override the 2250# macros for not-implemented syscalls in kernel/sys_ni.c and 2251# kernel/time/posix-stubs.c. All these overrides need to be available in 2252# <asm/syscall_wrapper.h>. 2253config ARCH_HAS_SYSCALL_WRAPPER 2254 def_bool n 2255