linux-6.8/init/Kconfig

1 # SPDX-License-Identifier: GPL-2.0-only
4 	default "$(CC_VERSION_TEXT)"
8 	  - Re-run Kconfig when the compiler is updated
9 	    The 'default' property references the environment variable,
13 	  - Ensure full rebuild when the compiler is updated
14 	    include/linux/compiler-version.h contains this option in the comment
16 	    auto-generated dependency. When the compiler is updated, syncconfig
20 	def_bool $(success,test "$(cc-name)" = GCC)
24 	default $(cc-version) if CC_IS_GCC
25 	default 0
28 	def_bool $(success,test "$(cc-name)" = Clang)
32 	default $(cc-version) if CC_IS_CLANG
33 	default 0
36 	def_bool $(success,test "$(as-name)" = GNU)
39 	def_bool $(success,test "$(as-name)" = LLVM)
44 	default CLANG_VERSION if AS_IS_LLVM
45 	default $(as-version)
48 	def_bool $(success,test "$(ld-name)" = BFD)
52 	default $(ld-version) if LD_IS_BFD
53 	default 0
56 	def_bool $(success,test "$(ld-name)" = LLD)
60 	default $(ld-version) if LD_IS_LLD
61 	default 0
68 	  Please see Documentation/rust/quick-start.rst for instructions on how
76 …default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLA…
77 …default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLA…
81 …default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLA…
82 …default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLA…
85 …nt x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
88 	depends on CC_HAS_ASM_GOTO_OUTPUT
89 	# Detect buggy gcc and clang, fixed in gcc-11 clang-14.
90 …foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $…
94 	depends on CC_IS_GCC && CC_HAS_ASM_GOTO_OUTPUT
97 	default y if GCC_VERSION < 110500
98 	default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
99 	default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
102 …env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
105 	def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
108 … '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
112 	default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
140 	depends on BROKEN || !SMP
141 	default y
145 	default 32 if !UML
146 	default 128 if UML
153 	depends on HAS_IOMEM
155 	  Some drivers can be compiled on a different platform than they are
156 	  intended to be run on. Despite they cannot be loaded there (or even
159 	  drivers to compile-test them.
167 	default COMPILE_TEST
170 	  enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
171 	  to enforce that rule by default. Certain warnings from other tools
184 	depends on HEADERS_INSTALL && CC_CAN_LINK
186 	  Compile test headers exported to user-space to ensure they are
187 	  self-contained, i.e. compilable as standalone units.
190 	  headers are self-contained, say Y here. Otherwise, choose N.
193 	string "Local version - append to kernel release"
204 	default y
205 	depends on !COMPILE_TEST
211 	  A string of the format -gxxxxxxxx will be added to the localversion
212 	  if a git-based tree is found.  The string generated by this will be
219 	    $ git rev-parse --verify HEAD
225 	default ""
230 	  build is unique between builds. It's safe to leave the default.
258 	default KERNEL_GZIP
259 …depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KER…
261 	  The linux kernel is a kind of self-extracting executable.
273 	  are low on disk space (embedded systems), but for whom ram
280 	depends on HAVE_KERNEL_GZIP
287 	depends on HAVE_KERNEL_BZIP2
297 	depends on HAVE_KERNEL_LZMA
305 	depends on HAVE_KERNEL_XZ
310 	  comparison to gzip. On architectures for which there is a BCJ
311 	  filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
320 	depends on HAVE_KERNEL_LZO
328 	depends on HAVE_KERNEL_LZ4
330 	  LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
340 	depends on HAVE_KERNEL_ZSTD
350 	depends on HAVE_KERNEL_UNCOMPRESSED
361 	string "Default init path"
362 	default ""
364 	  This option determines the default init for the system if no init=
365 	  option is passed on the kernel command line. If the requested path is
366 	  not present, we will still then move on to attempting further
371 	string "Default hostname"
372 	default "(none)"
374 	  This option determines the default system hostname before userspace
376 	  but you may wish to use a different default here to make a minimal
387 	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
396 	depends on SYSVIPC
397 	depends on SYSCTL
398 	default y
402 	depends on COMPAT && SYSVIPC
406 	depends on NET
416 	  operations on message queues.
422 	depends on POSIX_MQUEUE
423 	depends on SYSCTL
424 	default y
428 	default n
436 	  See Documentation/core-api/watch_queue.rst
440 	depends on MMU
441 	default y
450 	default ALPHA || M68K || SPARC
454 	  system call.  If you intend to run programs built on libc5 or
460 	depends on NET
465 	  on architectures which support it.
472 	depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 	default TICK_CPU_ACCOUNTING
492 	depends on !S390 && !NO_HZ_FULL
495 	  statistics about user, system and idle time spent on per jiffies
502 	depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
506 	  accounting.  This is done by reading a CPU counter on each
507 	  kernel entry and exit and on transitions within the kernel
510 	  this also enables accounting of stolen time on logically-partitioned
515 	depends on HAVE_CONTEXT_TRACKING_USER
516 	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
517 	depends on GENERIC_CLOCKEVENTS
521 	  Select this option to enable task and CPU time accounting on full
523 	  kernel-user boundaries using the context tracking subsystem.
527 	  For now this is only useful if you are working on the full
536 	depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
539 	  accounting. This is done by reading a timestamp on each
547 	depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
548 	depends on SMP
552 	default y if ARM && ARM_CPU_TOPOLOGY
553 	default y if ARM64
554 	depends on SMP
555 	depends on CPU_FREQ_THERMAL
564 	  i.e. put less load on throttled CPUs than on non/less throttled ones.
571 	depends on MULTIUSER
585 	depends on BSD_PROCESS_ACCT
586 	default n
597 	depends on NET
598 	depends on MULTIUSER
599 	default n
605 	  space on task exit.
610 	bool "Enable per-task delay accounting"
611 	depends on TASKSTATS
614 	  Collect information on time spent by a task waiting for system
623 	depends on TASKSTATS
631 	bool "Enable per-task storage I/O accounting"
632 	depends on TASK_XACCT
634 	  Collect information on the number of bytes of storage I/O which this
661 	default n
662 	depends on PSI
665 	  per default but can be enabled through passing psi=1 on the
670 	  common scheduling-intense workloads in practice (such as
683 	depends on SMP || COMPILE_TEST
684 	default y
701 	  on-disk kernel.  This information can be extracted from the kernel
702 	  image file with the script scripts/extract-ikconfig and used as
709 	depends on IKCONFIG && PROC_FS
716 	depends on SYSFS
718 	  This option enables access to the in-kernel headers that are generated during
721 	  kheaders.ko is built which can be loaded on-demand to get access to headers.
726 	default 17
727 	depends on PRINTK
744 	depends on SMP
746 	default 12 if !BASE_SMALL
747 	default 0 if BASE_SMALL
748 	depends on PRINTK
750 	  This option allows to increase the default ring buffer size
757 	  the original static one is unused. It makes sense only on systems
759 	  contributions is greater than the half of the default kernel ring
760 	  buffer as defined by LOG_BUF_SHIFT. The default values are set
780 	depends on PRINTK && DEBUG_FS
805 	depends on CPU_FREQ_GOV_SCHEDUTIL
808 	  of each CPU based on RUNNABLE tasks scheduled on that CPU.
824 	default 5
825 	depends on UCLAMP_TASK
830 	  the precision of clamping aggregation and tracking at run-time.
836 	  If a second 30% boosted task should be co-scheduled on the same CPU,
845 	  CPU. If that should be considered not acceptable on certain systems,
847 	  clamp buckets to trade off used memory for run-time tracking
850 	  If in doubt, use the default value.
855 # For architectures that want to enable the support for NUMA-affine scheduler
864 # must provide guarantees on what happens if a clean TLB cache entry is
872 	def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
876 	default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
877 	default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
879 # Currently, disable gcc-10+ array-bounds globally.
880 # It's still broken in gcc-13, so no upper bound yet.
886 	default y if CC_IS_GCC && GCC_VERSION >= 100000 && GCC10_NO_ARRAY_BOUNDS
888 # Currently, disable -Wstringop-overflow for GCC globally.
894 	default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
898 	default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
907 # all cpu-local but of different latencies, such as SuperH.
914 	depends on ARCH_SUPPORTS_NUMA_BALANCING
915 	depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
916 	depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
919 	  The mechanism is quite primitive and is based on migrating memory when
920 	  it has references to the node the task is running on.
922 	  This system will be inactive on UMA systems.
926 	default y
927 	depends on NUMA_BALANCING
929 	  If set, automatic NUMA balancing will be enabled if running on a NUMA
940 		- Documentation/scheduler/sched-design-CFS.rst	(CFS)
941 		- Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
952         bool "Favor dynamic modification latency reduction by default"
954           This option enables the "favordynmods" mount option by default
956           as task migrations and controller on/offs at the cost of making
970 	depends on MEMCG
971 	default y
975 	depends on BLOCK
976 	default n
985 	block layer to implement upper limit in IO rates on a device.
993 	See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
997 	depends on MEMCG && BLK_CGROUP
998 	default y
1002 	default n
1011 	depends on CGROUP_SCHED
1012 	default CGROUP_SCHED
1016 	depends on FAIR_GROUP_SCHED
1017 	default n
1023 	  See Documentation/scheduler/sched-bwc.rst for more information.
1027 	depends on CGROUP_SCHED
1028 	default n
1032 	  schedule realtime tasks for non-root users until you allocate
1034 	  See Documentation/scheduler/sched-rt-group.rst for more information.
1040 	depends on SMP && RSEQ
1044 	depends on CGROUP_SCHED
1045 	depends on UCLAMP_TASK
1046 	default n
1049 	  of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1058 	  specified task-specific clamp value is constrained by the cgroup
1097 	  controller includes important in-kernel memory consumers per default.
1103 	depends on HUGETLB_PAGE
1105 	default n
1108 	  When you enable this, you can put a per cgroup limit on HugeTLB usage.
1119 	depends on SMP
1124 	  This is primarily useful on large SMP or NUMA systems.
1130 	depends on CPUSETS
1131 	default y
1147 	depends on PERF_EVENTS
1149 	  This option extends the perf per-cpu mode to restrict monitoring
1150 	  to threads which belong to the cgroup specified and run on the
1158 	depends on BPF_SYSCALL
1164 	  In which context these programs are accessed depends on the type
1166 	  BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1171 	default n
1173 	  Provides a controller for miscellaneous resources on a host.
1175 	  Miscellaneous scalar resources are the resources on the host system
1181 	  /Documentation/admin-guide/cgroup-v2.rst.
1185 	default n
1186 	depends on DEBUG_KERNEL
1197 	default n
1203 	depends on MULTIUSER
1204 	default !EXPERT
1215 	default y
1222 	depends on GENERIC_VDSO_TIME_NS
1223 	default y
1230 	depends on (SYSVIPC || POSIX_MQUEUE)
1231 	default y
1238 	default n
1245 	  user-space use the memory control groups to limit the amount
1252 	default y
1260 	depends on NET
1261 	default y
1270 	depends on PROC_FS
1273 	default n
1295 	bool "Kernel->user space relay support (formerly relayfs)"
1313 	  etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1317 	  15 Kbytes (more on some other architectures) to the kernel size.
1335 	  See <file:Documentation/admin-guide/bootconfig.rst> for details.
1341 	depends on BOOT_CONFIG
1342 	default y if BOOT_CONFIG_EMBED
1345 	  out even when the "bootconfig" kernel-boot parameter is omitted.
1347 	  make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
1354 	depends on BOOT_CONFIG
1365 	depends on BOOT_CONFIG_EMBED
1373 	default y
1383 	default CC_OPTIMIZE_FOR_PERFORMANCE
1386 	bool "Optimize for performance (-O2)"
1388 	  This is the default optimization level for the kernel, building
1389 	  with the "-O2" compiler flag for best performance and most
1390 	  helpful compile-time warnings.
1393 	bool "Optimize for size (-Os)"
1395 	  Choosing this option will pass "-Os" to your compiler resulting
1412 	depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1413 	depends on EXPERT
1414 	depends on $(cc-option,-ffunction-sections -fdata-sections)
1415 	depends on $(ld-option,--gc-sections)
1418 	  the linker by compiling with -ffunction-sections -fdata-sections,
1419 	  and linking with --gc-sections.
1421 	  This can reduce on disk and in-memory size of the kernel
1423 	  on small systems. This has the possibility of introducing
1430 	depends on ARCH_WANT_LD_ORPHAN_WARN
1431 	depends on $(ld-option,--orphan-handling=warn)
1432 	depends on $(ld-option,--orphan-handling=error)
1436         depends on LD_ORPHAN_WARN
1437         default "error" if WERROR
1438         default "warn"
1449 	  Enable support for /proc/sys/debug/exception-trace.
1454 	  Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1456 	  about unaligned access emulation going on under the hood.
1461 	  Enable support for /proc/sys/kernel/unaligned-trap
1469 # interpreter that classic socket filters depend on
1476 	# Unhide debug options, to make the on-by-default options visible
1481 	  environments which can tolerate a "non-standard" kernel.
1485 	bool "Enable 16-bit UID system calls" if EXPERT
1486 	depends on HAVE_UID16 && MULTIUSER
1487 	default y
1489 	  This enables the legacy 16-bit UID syscall wrappers.
1493 	default y
1495 	  This option enables support for non-root users, groups and
1510 	  no longer supported in libc but still enabled by default in some
1513 	  If unsure, leave the default option here.
1517 	default y
1528 	default y
1540 	default y
1556 	default y
1568 	default y
1577 	depends on COREDUMP
1578 	default y
1585 	bool "Enable PC-Speaker support" if EXPERT
1586 	depends on HAVE_PCSPKR_PLATFORM
1588 	default y
1590 	  This option allows to disable the internal PC-Speaker
1594 	default y
1595 	bool "Enable full-sized data structures for core" if EXPERT
1598 	  kernel data structures. This saves memory on small machines,
1603 	depends on !(SPARC32 && SMP)
1604 	default y
1609 	  run glibc-based applications correctly.
1613 	depends on FUTEX && RT_MUTEXES
1614 	default y
1618 	default y
1625 	default y
1628 	  on a file descriptor.
1634 	default y
1637 	  events on a file descriptor.
1643 	default y
1652 	default y
1653 	depends on MMU
1659 	  which may be appropriate on small systems without swap.
1663 	default y
1672 	default y
1680 	default y
1690 	default y
1694 	  the cost of user-space memory barriers asymmetrically by transforming
1704 	  user-space with the ability to compare two processes to see if they
1712 	default y
1713 	depends on HAVE_RSEQ
1717 	  user-space cache for the current CPU number value, which
1718 	  speeds up getting the current CPU number from user-space,
1719 	  as well as an ABI to speed up user-space operations on
1720 	  per-CPU data.
1725 	default n
1727 	depends on RSEQ && DEBUG_KERNEL
1735 	default y
1752 	default y
1760 	depends on KALLSYMS
1761 	default n
1767 	  Start self-test automatically after system startup. Suggest executing
1773 	depends on DEBUG_KERNEL && KALLSYMS
1784 	  size (depending on the kernel configuration, it may be 300KiB or
1791 	depends on KALLSYMS
1792 	default X86_64 && SMP
1796 	depends on KALLSYMS
1797 	default y
1800 	  emit the symbol references in the kallsyms table as 32-bit entries,
1807 	  On 64-bit builds, this reduces the size of the address table by 50%,
1810 	  up the entries based on the runtime load address of the kernel.
1827 	depends on HAVE_PERF_EVENTS
1838 	default y if PROFILING
1839 	depends on HAVE_PERF_EVENTS
1845 	  Software events are supported either built-in or via the
1851 	  suffered, or branches mis-predicted - without slowing down the
1853 	  when a threshold number of events have passed - and can thus be
1854 	  used to profile the code that runs on that CPU.
1860 	  capabilities on top of those.
1865 	default n
1867 	depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1872 	  Mostly useful for debugging the vmalloc code on platforms
1905 	depends on HAVE_RUST
1906 	depends on RUST_IS_AVAILABLE
1907 	depends on !MODVERSIONS
1908 	depends on !GCC_PLUGINS
1909 	depends on !RANDSTRUCT
1910 	depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
1915 	  This allows other Rust-related options, like drivers written in Rust,
1927 	depends on RUST
1928 	default $(shell,command -v $(RUSTC) >/dev/null 2>&1 && $(RUSTC) --version || echo n)
1932 	depends on RUST
1933 	default $(shell,command -v $(BINDGEN) >/dev/null 2>&1 && $(BINDGEN) --version || echo n)
1950 	default y if PREEMPT_RT
1954 	default 0 if BASE_FULL
1955 	default 1 if !BASE_FULL
1978 	depends on SMP
1987 	  functions to call on what tags.
2001 # macros for not-implemented syscalls in kernel/sys_ni.c and
2002 # kernel/time/posix-stubs.c. All these overrides need to be available in