1# SPDX-License-Identifier: GPL-2.0-only
   2config CC_VERSION_TEXT
   3	string
   4	default "$(CC_VERSION_TEXT)"
   5	help
   6	  This is used in unclear ways:
   7
   8	  - Re-run Kconfig when the compiler is updated
   9	    The 'default' property references the environment variable,
  10	    CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.
  11	    When the compiler is updated, Kconfig will be invoked.
  12
  13	  - Ensure full rebuild when the compiler is updated
  14	    include/linux/compiler-version.h contains this option in the comment
  15	    line so fixdep adds include/config/CC_VERSION_TEXT into the
  16	    auto-generated dependency. When the compiler is updated, syncconfig
  17	    will touch it and then every file will be rebuilt.
  18
  19config CC_IS_GCC
  20	def_bool $(success,test "$(cc-name)" = GCC)
  21
  22config GCC_VERSION
  23	int
  24	default $(cc-version) if CC_IS_GCC
  25	default 0
  26
  27config CC_IS_CLANG
  28	def_bool $(success,test "$(cc-name)" = Clang)
  29
  30config CLANG_VERSION
  31	int
  32	default $(cc-version) if CC_IS_CLANG
  33	default 0
  34
  35config AS_IS_GNU
  36	def_bool $(success,test "$(as-name)" = GNU)
  37
  38config AS_IS_LLVM
  39	def_bool $(success,test "$(as-name)" = LLVM)
  40
  41config AS_VERSION
  42	int
  43	# Use clang version if this is the integrated assembler
  44	default CLANG_VERSION if AS_IS_LLVM
  45	default $(as-version)
  46
  47config LD_IS_BFD
  48	def_bool $(success,test "$(ld-name)" = BFD)
  49
  50config LD_VERSION
  51	int
  52	default $(ld-version) if LD_IS_BFD
  53	default 0
  54
  55config LD_IS_LLD
  56	def_bool $(success,test "$(ld-name)" = LLD)
  57
  58config LLD_VERSION
  59	int
  60	default $(ld-version) if LD_IS_LLD
  61	default 0
  62
  63config RUSTC_VERSION
  64	int
  65	default $(rustc-version)
  66	help
  67	  It does not depend on `RUST` since that one may need to use the version
  68	  in a `depends on`.
  69
  70config RUST_IS_AVAILABLE
  71	def_bool $(success,$(srctree)/scripts/rust_is_available.sh)
  72	help
  73	  This shows whether a suitable Rust toolchain is available (found).
  74
  75	  Please see Documentation/rust/quick-start.rst for instructions on how
  76	  to satisfy the build requirements of Rust support.
  77
  78	  In particular, the Makefile target 'rustavailable' is useful to check
  79	  why the Rust toolchain is not being detected.
  80
  81config RUSTC_LLVM_VERSION
  82	int
  83	default $(rustc-llvm-version)
  84
  85config CC_CAN_LINK
  86	bool
  87	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
  88	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
  89
  90config CC_CAN_LINK_STATIC
  91	bool
  92	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
  93	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
  94
  95# Fixed in GCC 14, 13.3, 12.4 and 11.5
  96# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
  97config GCC_ASM_GOTO_OUTPUT_BROKEN
  98	bool
  99	depends on CC_IS_GCC
 100	default y if GCC_VERSION < 110500
 101	default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
 102	default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
 103
 104config CC_HAS_ASM_GOTO_OUTPUT
 105	def_bool y
 106	depends on !GCC_ASM_GOTO_OUTPUT_BROKEN
 107	depends on $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
 108
 109config CC_HAS_ASM_GOTO_TIED_OUTPUT
 110	depends on CC_HAS_ASM_GOTO_OUTPUT
 111	# Detect buggy gcc and clang, fixed in gcc-11 clang-14.
 112	def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
 113
 114config TOOLS_SUPPORT_RELR
 115	def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
 116
 117config CC_HAS_ASM_INLINE
 118	def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
 119
 120config CC_HAS_NO_PROFILE_FN_ATTR
 121	def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
 122
 123config CC_HAS_COUNTED_BY
 124	# TODO: when gcc 15 is released remove the build test and add
 125	# a gcc version check
 126	def_bool $(success,echo 'struct flex { int count; int array[] __attribute__((__counted_by__(count))); };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror)
 127	# clang needs to be at least 19.1.3 to avoid __bdos miscalculations
 128	# https://github.com/llvm/llvm-project/pull/110497
 129	# https://github.com/llvm/llvm-project/pull/112636
 130	depends on !(CC_IS_CLANG && CLANG_VERSION < 190103)
 131
 132config PAHOLE_VERSION
 133	int
 134	default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
 
 
 
 
 
 
 135
 136config CONSTRUCTORS
 137	bool
 
 138
 139config IRQ_WORK
 140	def_bool y if SMP
 141
 142config BUILDTIME_TABLE_SORT
 143	bool
 144
 145config THREAD_INFO_IN_TASK
 146	bool
 147	help
 148	  Select this to move thread_info off the stack into task_struct.  To
 149	  make this work, an arch will need to remove all thread_info fields
 150	  except flags and fix any runtime bugs.
 151
 152	  One subtle change that will be needed is to use try_get_task_stack()
 153	  and put_task_stack() in save_thread_stack_tsk() and get_wchan().
 154
 155menu "General setup"
 156
 157config BROKEN
 158	bool
 159
 160config BROKEN_ON_SMP
 161	bool
 162	depends on BROKEN || !SMP
 163	default y
 164
 165config INIT_ENV_ARG_LIMIT
 166	int
 167	default 32 if !UML
 168	default 128 if UML
 169	help
 170	  Maximum of each of the number of arguments and environment
 171	  variables passed to init from the kernel command line.
 172
 
 
 
 
 
 
 
 
 
 173config COMPILE_TEST
 174	bool "Compile also drivers which will not load"
 175	depends on HAS_IOMEM
 176	help
 177	  Some drivers can be compiled on a different platform than they are
 178	  intended to be run on. Despite they cannot be loaded there (or even
 179	  when they load they cannot be used due to missing HW support),
 180	  developers still, opposing to distributors, might want to build such
 181	  drivers to compile-test them.
 182
 183	  If you are a developer and want to build everything available, say Y
 184	  here. If you are a user/distributor, say N here to exclude useless
 185	  drivers to be distributed.
 186
 187config WERROR
 188	bool "Compile the kernel with warnings as errors"
 189	default COMPILE_TEST
 190	help
 191	  A kernel build should not cause any compiler warnings, and this
 192	  enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
 193	  to enforce that rule by default. Certain warnings from other tools
 194	  such as the linker may be upgraded to errors with this option as
 195	  well.
 196
 197	  However, if you have a new (or very old) compiler or linker with odd
 198	  and unusual warnings, or you have some architecture with problems,
 199	  you may need to disable this config option in order to
 200	  successfully build the kernel.
 201
 202	  If in doubt, say Y.
 203
 204config UAPI_HEADER_TEST
 205	bool "Compile test UAPI headers"
 206	depends on HEADERS_INSTALL && CC_CAN_LINK
 207	help
 208	  Compile test headers exported to user-space to ensure they are
 209	  self-contained, i.e. compilable as standalone units.
 210
 211	  If you are a developer or tester and want to ensure the exported
 212	  headers are self-contained, say Y here. Otherwise, choose N.
 213
 214config LOCALVERSION
 215	string "Local version - append to kernel release"
 216	help
 217	  Append an extra string to the end of your kernel version.
 218	  This will show up when you type uname, for example.
 219	  The string you set here will be appended after the contents of
 220	  any files with a filename matching localversion* in your
 221	  object and source tree, in that order.  Your total string can
 222	  be a maximum of 64 characters.
 223
 224config LOCALVERSION_AUTO
 225	bool "Automatically append version information to the version string"
 226	default y
 227	depends on !COMPILE_TEST
 228	help
 229	  This will try to automatically determine if the current tree is a
 230	  release tree by looking for git tags that belong to the current
 231	  top of tree revision.
 232
 233	  A string of the format -gxxxxxxxx will be added to the localversion
 234	  if a git-based tree is found.  The string generated by this will be
 235	  appended after any matching localversion* files, and after the value
 236	  set in CONFIG_LOCALVERSION.
 237
 238	  (The actual string used here is the first 12 characters produced
 239	  by running the command:
 240
 241	    $ git rev-parse --verify HEAD
 242
 243	  which is done within the script "scripts/setlocalversion".)
 244
 245config BUILD_SALT
 246	string "Build ID Salt"
 247	default ""
 248	help
 249	  The build ID is used to link binaries and their debug info. Setting
 250	  this option will use the value in the calculation of the build id.
 251	  This is mostly useful for distributions which want to ensure the
 252	  build is unique between builds. It's safe to leave the default.
 253
 254config HAVE_KERNEL_GZIP
 255	bool
 256
 257config HAVE_KERNEL_BZIP2
 258	bool
 259
 260config HAVE_KERNEL_LZMA
 261	bool
 262
 263config HAVE_KERNEL_XZ
 264	bool
 265
 266config HAVE_KERNEL_LZO
 267	bool
 268
 269config HAVE_KERNEL_LZ4
 270	bool
 271
 272config HAVE_KERNEL_ZSTD
 273	bool
 274
 275config HAVE_KERNEL_UNCOMPRESSED
 276	bool
 277
 278choice
 279	prompt "Kernel compression mode"
 280	default KERNEL_GZIP
 281	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
 282	help
 283	  The linux kernel is a kind of self-extracting executable.
 284	  Several compression algorithms are available, which differ
 285	  in efficiency, compression and decompression speed.
 286	  Compression speed is only relevant when building a kernel.
 287	  Decompression speed is relevant at each boot.
 288
 289	  If you have any problems with bzip2 or lzma compressed
 290	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 291	  version of this functionality (bzip2 only), for 2.4, was
 292	  supplied by Christian Ludwig)
 293
 294	  High compression options are mostly useful for users, who
 295	  are low on disk space (embedded systems), but for whom ram
 296	  size matters less.
 297
 298	  If in doubt, select 'gzip'
 299
 300config KERNEL_GZIP
 301	bool "Gzip"
 302	depends on HAVE_KERNEL_GZIP
 303	help
 304	  The old and tried gzip compression. It provides a good balance
 305	  between compression ratio and decompression speed.
 306
 307config KERNEL_BZIP2
 308	bool "Bzip2"
 309	depends on HAVE_KERNEL_BZIP2
 310	help
 311	  Its compression ratio and speed is intermediate.
 312	  Decompression speed is slowest among the choices.  The kernel
 313	  size is about 10% smaller with bzip2, in comparison to gzip.
 314	  Bzip2 uses a large amount of memory. For modern kernels you
 315	  will need at least 8MB RAM or more for booting.
 316
 317config KERNEL_LZMA
 318	bool "LZMA"
 319	depends on HAVE_KERNEL_LZMA
 320	help
 321	  This compression algorithm's ratio is best.  Decompression speed
 322	  is between gzip and bzip2.  Compression is slowest.
 323	  The kernel size is about 33% smaller with LZMA in comparison to gzip.
 324
 325config KERNEL_XZ
 326	bool "XZ"
 327	depends on HAVE_KERNEL_XZ
 328	help
 329	  XZ uses the LZMA2 algorithm and instruction set specific
 330	  BCJ filters which can improve compression ratio of executable
 331	  code. The size of the kernel is about 30% smaller with XZ in
 332	  comparison to gzip. On architectures for which there is a BCJ
 333	  filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC,
 334	  and SPARC), XZ will create a few percent smaller kernel than
 335	  plain LZMA.
 336
 337	  The speed is about the same as with LZMA: The decompression
 338	  speed of XZ is better than that of bzip2 but worse than gzip
 339	  and LZO. Compression is slow.
 340
 341config KERNEL_LZO
 342	bool "LZO"
 343	depends on HAVE_KERNEL_LZO
 344	help
 345	  Its compression ratio is the poorest among the choices. The kernel
 346	  size is about 10% bigger than gzip; however its speed
 347	  (both compression and decompression) is the fastest.
 348
 349config KERNEL_LZ4
 350	bool "LZ4"
 351	depends on HAVE_KERNEL_LZ4
 352	help
 353	  LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
 354	  A preliminary version of LZ4 de/compression tool is available at
 355	  <https://code.google.com/p/lz4/>.
 356
 357	  Its compression ratio is worse than LZO. The size of the kernel
 358	  is about 8% bigger than LZO. But the decompression speed is
 359	  faster than LZO.
 360
 361config KERNEL_ZSTD
 362	bool "ZSTD"
 363	depends on HAVE_KERNEL_ZSTD
 364	help
 365	  ZSTD is a compression algorithm targeting intermediate compression
 366	  with fast decompression speed. It will compress better than GZIP and
 367	  decompress around the same speed as LZO, but slower than LZ4. You
 368	  will need at least 192 KB RAM or more for booting. The zstd command
 369	  line tool is required for compression.
 370
 371config KERNEL_UNCOMPRESSED
 372	bool "None"
 373	depends on HAVE_KERNEL_UNCOMPRESSED
 374	help
 375	  Produce uncompressed kernel image. This option is usually not what
 376	  you want. It is useful for debugging the kernel in slow simulation
 377	  environments, where decompressing and moving the kernel is awfully
 378	  slow. This option allows early boot code to skip the decompressor
 379	  and jump right at uncompressed kernel image.
 380
 381endchoice
 382
 383config DEFAULT_INIT
 384	string "Default init path"
 385	default ""
 386	help
 387	  This option determines the default init for the system if no init=
 388	  option is passed on the kernel command line. If the requested path is
 389	  not present, we will still then move on to attempting further
 390	  locations (e.g. /sbin/init, etc). If this is empty, we will just use
 391	  the fallback list when init= is not passed.
 392
 393config DEFAULT_HOSTNAME
 394	string "Default hostname"
 395	default "(none)"
 396	help
 397	  This option determines the default system hostname before userspace
 398	  calls sethostname(2). The kernel traditionally uses "(none)" here,
 399	  but you may wish to use a different default here to make a minimal
 400	  system more usable with less configuration.
 401
 
 
 
 
 
 
 
 
 
 
 402config SYSVIPC
 403	bool "System V IPC"
 404	help
 405	  Inter Process Communication is a suite of library functions and
 406	  system calls which let processes (running programs) synchronize and
 407	  exchange information. It is generally considered to be a good thing,
 408	  and some programs won't run unless you say Y here. In particular, if
 409	  you want to run the DOS emulator dosemu under Linux (read the
 410	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 411	  you'll need to say Y here.
 412
 413	  You can find documentation about IPC with "info ipc" and also in
 414	  section 6.4 of the Linux Programmer's Guide, available from
 415	  <http://www.tldp.org/guides.html>.
 416
 417config SYSVIPC_SYSCTL
 418	bool
 419	depends on SYSVIPC
 420	depends on SYSCTL
 421	default y
 422
 423config SYSVIPC_COMPAT
 424	def_bool y
 425	depends on COMPAT && SYSVIPC
 426
 427config POSIX_MQUEUE
 428	bool "POSIX Message Queues"
 429	depends on NET
 430	help
 431	  POSIX variant of message queues is a part of IPC. In POSIX message
 432	  queues every message has a priority which decides about succession
 433	  of receiving it by a process. If you want to compile and run
 434	  programs written e.g. for Solaris with use of its POSIX message
 435	  queues (functions mq_*) say Y here.
 436
 437	  POSIX message queues are visible as a filesystem called 'mqueue'
 438	  and can be mounted somewhere if you want to do filesystem
 439	  operations on message queues.
 440
 441	  If unsure, say Y.
 442
 443config POSIX_MQUEUE_SYSCTL
 444	bool
 445	depends on POSIX_MQUEUE
 446	depends on SYSCTL
 447	default y
 448
 449config WATCH_QUEUE
 450	bool "General notification queue"
 451	default n
 452	help
 453
 454	  This is a general notification queue for the kernel to pass events to
 455	  userspace by splicing them into pipes.  It can be used in conjunction
 456	  with watches for key/keyring change notifications and device
 457	  notifications.
 458
 459	  See Documentation/core-api/watch_queue.rst
 460
 461config CROSS_MEMORY_ATTACH
 462	bool "Enable process_vm_readv/writev syscalls"
 463	depends on MMU
 464	default y
 465	help
 466	  Enabling this option adds the system calls process_vm_readv and
 467	  process_vm_writev which allow a process with the correct privileges
 468	  to directly read from or write to another process' address space.
 469	  See the man page for more details.
 470
 
 
 
 
 
 
 
 
 
 
 
 
 
 471config USELIB
 472	bool "uselib syscall (for libc5 and earlier)"
 473	default ALPHA || M68K || SPARC
 474	help
 475	  This option enables the uselib syscall, a system call used in the
 476	  dynamic linker from libc5 and earlier.  glibc does not use this
 477	  system call.  If you intend to run programs built on libc5 or
 478	  earlier, you may need to enable this syscall.  Current systems
 479	  running glibc can safely disable this.
 480
 481config AUDIT
 482	bool "Auditing support"
 483	depends on NET
 484	help
 485	  Enable auditing infrastructure that can be used with another
 486	  kernel subsystem, such as SELinux (which requires this for
 487	  logging of avc messages output).  System call auditing is included
 488	  on architectures which support it.
 489
 490config HAVE_ARCH_AUDITSYSCALL
 491	bool
 492
 493config AUDITSYSCALL
 494	def_bool y
 495	depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
 
 
 
 
 
 
 
 
 
 496	select FSNOTIFY
 497
 498source "kernel/irq/Kconfig"
 499source "kernel/time/Kconfig"
 500source "kernel/bpf/Kconfig"
 501source "kernel/Kconfig.preempt"
 502
 503menu "CPU/Task time and stats accounting"
 504
 505config VIRT_CPU_ACCOUNTING
 506	bool
 507
 508choice
 509	prompt "Cputime accounting"
 510	default TICK_CPU_ACCOUNTING
 
 511
 512# Kind of a stub config for the pure tick based cputime accounting
 513config TICK_CPU_ACCOUNTING
 514	bool "Simple tick based cputime accounting"
 515	depends on !S390 && !NO_HZ_FULL
 516	help
 517	  This is the basic tick based cputime accounting that maintains
 518	  statistics about user, system and idle time spent on per jiffies
 519	  granularity.
 520
 521	  If unsure, say Y.
 522
 523config VIRT_CPU_ACCOUNTING_NATIVE
 524	bool "Deterministic task and CPU time accounting"
 525	depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
 526	select VIRT_CPU_ACCOUNTING
 527	help
 528	  Select this option to enable more accurate task and CPU time
 529	  accounting.  This is done by reading a CPU counter on each
 530	  kernel entry and exit and on transitions within the kernel
 531	  between system, softirq and hardirq state, so there is a
 532	  small performance impact.  In the case of s390 or IBM POWER > 5,
 533	  this also enables accounting of stolen time on logically-partitioned
 534	  systems.
 535
 536config VIRT_CPU_ACCOUNTING_GEN
 537	bool "Full dynticks CPU time accounting"
 538	depends on HAVE_CONTEXT_TRACKING_USER
 539	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 540	depends on GENERIC_CLOCKEVENTS
 541	select VIRT_CPU_ACCOUNTING
 542	select CONTEXT_TRACKING_USER
 543	help
 544	  Select this option to enable task and CPU time accounting on full
 545	  dynticks systems. This accounting is implemented by watching every
 546	  kernel-user boundaries using the context tracking subsystem.
 547	  The accounting is thus performed at the expense of some significant
 548	  overhead.
 549
 550	  For now this is only useful if you are working on the full
 551	  dynticks subsystem development.
 552
 553	  If unsure, say N.
 554
 555endchoice
 556
 557config IRQ_TIME_ACCOUNTING
 558	bool "Fine granularity task level IRQ time accounting"
 559	depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
 560	help
 561	  Select this option to enable fine granularity task irq time
 562	  accounting. This is done by reading a timestamp on each
 563	  transitions between softirq and hardirq state, so there can be a
 564	  small performance impact.
 565
 566	  If in doubt, say N here.
 567
 568config HAVE_SCHED_AVG_IRQ
 569	def_bool y
 570	depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
 571	depends on SMP
 572
 573config SCHED_HW_PRESSURE
 574	bool
 575	default y if ARM && ARM_CPU_TOPOLOGY
 576	default y if ARM64
 577	depends on SMP
 578	depends on CPU_FREQ_THERMAL
 579	help
 580	  Select this option to enable HW pressure accounting in the
 581	  scheduler. HW pressure is the value conveyed to the scheduler
 582	  that reflects the reduction in CPU compute capacity resulted from
 583	  HW throttling. HW throttling occurs when the performance of
 584	  a CPU is capped due to high operating temperatures as an example.
 585
 586	  If selected, the scheduler will be able to balance tasks accordingly,
 587	  i.e. put less load on throttled CPUs than on non/less throttled ones.
 588
 589	  This requires the architecture to implement
 590	  arch_update_hw_pressure() and arch_scale_thermal_pressure().
 591
 592config BSD_PROCESS_ACCT
 593	bool "BSD Process Accounting"
 594	depends on MULTIUSER
 595	help
 596	  If you say Y here, a user level program will be able to instruct the
 597	  kernel (via a special system call) to write process accounting
 598	  information to a file: whenever a process exits, information about
 599	  that process will be appended to the file by the kernel.  The
 600	  information includes things such as creation time, owning user,
 601	  command name, memory usage, controlling terminal etc. (the complete
 602	  list is in the struct acct in <file:include/linux/acct.h>).  It is
 603	  up to the user level program to do useful things with this
 604	  information.  This is generally a good idea, so say Y.
 605
 606config BSD_PROCESS_ACCT_V3
 607	bool "BSD Process Accounting version 3 file format"
 608	depends on BSD_PROCESS_ACCT
 609	default n
 610	help
 611	  If you say Y here, the process accounting information is written
 612	  in a new file format that also logs the process IDs of each
 613	  process and its parent. Note that this file format is incompatible
 614	  with previous v0/v1/v2 file formats, so you will need updated tools
 615	  for processing it. A preliminary version of these tools is available
 616	  at <http://www.gnu.org/software/acct/>.
 617
 618config TASKSTATS
 619	bool "Export task/process statistics through netlink"
 620	depends on NET
 621	depends on MULTIUSER
 622	default n
 623	help
 624	  Export selected statistics for tasks/processes through the
 625	  generic netlink interface. Unlike BSD process accounting, the
 626	  statistics are available during the lifetime of tasks/processes as
 627	  responses to commands. Like BSD accounting, they are sent to user
 628	  space on task exit.
 629
 630	  Say N if unsure.
 631
 632config TASK_DELAY_ACCT
 633	bool "Enable per-task delay accounting"
 634	depends on TASKSTATS
 635	select SCHED_INFO
 636	help
 637	  Collect information on time spent by a task waiting for system
 638	  resources like cpu, synchronous block I/O completion and swapping
 639	  in pages. Such statistics can help in setting a task's priorities
 640	  relative to other tasks for cpu, io, rss limits etc.
 641
 642	  Say N if unsure.
 643
 644config TASK_XACCT
 645	bool "Enable extended accounting over taskstats"
 646	depends on TASKSTATS
 647	help
 648	  Collect extended task accounting data and send the data
 649	  to userland for processing over the taskstats interface.
 650
 651	  Say N if unsure.
 652
 653config TASK_IO_ACCOUNTING
 654	bool "Enable per-task storage I/O accounting"
 655	depends on TASK_XACCT
 656	help
 657	  Collect information on the number of bytes of storage I/O which this
 658	  task has caused.
 659
 660	  Say N if unsure.
 661
 662config PSI
 663	bool "Pressure stall information tracking"
 664	select KERNFS
 
 
 
 
 665	help
 666	  Collect metrics that indicate how overcommitted the CPU, memory,
 667	  and IO capacity are in the system.
 
 
 668
 669	  If you say Y here, the kernel will create /proc/pressure/ with the
 670	  pressure statistics files cpu, memory, and io. These will indicate
 671	  the share of walltime in which some or all tasks in the system are
 672	  delayed due to contention of the respective resource.
 673
 674	  In kernels with cgroup support, cgroups (cgroup2 only) will
 675	  have cpu.pressure, memory.pressure, and io.pressure files,
 676	  which aggregate pressure stalls for the grouped tasks only.
 
 677
 678	  For more details see Documentation/accounting/psi.rst.
 679
 680	  Say N if unsure.
 
 
 
 
 
 
 
 681
 682config PSI_DEFAULT_DISABLED
 683	bool "Require boot parameter to enable pressure stall information tracking"
 684	default n
 685	depends on PSI
 686	help
 687	  If set, pressure stall information tracking will be disabled
 688	  per default but can be enabled through passing psi=1 on the
 689	  kernel commandline during boot.
 690
 691	  This feature adds some code to the task wakeup and sleep
 692	  paths of the scheduler. The overhead is too low to affect
 693	  common scheduling-intense workloads in practice (such as
 694	  webservers, memcache), but it does show up in artificial
 695	  scheduler stress tests, such as hackbench.
 696
 697	  If you are paranoid and not sure what the kernel will be
 698	  used for, say Y.
 699
 700	  Say N if unsure.
 701
 702endmenu # "CPU/Task time and stats accounting"
 
 
 
 
 
 703
 704config CPU_ISOLATION
 705	bool "CPU isolation"
 706	depends on SMP || COMPILE_TEST
 707	default y
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 708	help
 709	  Make sure that CPUs running critical tasks are not disturbed by
 710	  any source of "noise" such as unbound workqueues, timers, kthreads...
 711	  Unbound jobs get offloaded to housekeeping CPUs. This is driven by
 712	  the "isolcpus=" boot parameter.
 
 
 
 
 
 
 
 
 
 
 713
 714	  Say Y if unsure.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 715
 716source "kernel/rcu/Kconfig"
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 717
 718config IKCONFIG
 719	tristate "Kernel .config support"
 720	help
 
 721	  This option enables the complete Linux kernel ".config" file
 722	  contents to be saved in the kernel. It provides documentation
 723	  of which kernel options are used in a running kernel or in an
 724	  on-disk kernel.  This information can be extracted from the kernel
 725	  image file with the script scripts/extract-ikconfig and used as
 726	  input to rebuild the current kernel or to build another kernel.
 727	  It can also be extracted from a running kernel by reading
 728	  /proc/config.gz if enabled (below).
 729
 730config IKCONFIG_PROC
 731	bool "Enable access to .config through /proc/config.gz"
 732	depends on IKCONFIG && PROC_FS
 733	help
 734	  This option enables access to the kernel configuration file
 735	  through /proc/config.gz.
 736
 737config IKHEADERS
 738	tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
 739	depends on SYSFS
 740	help
 741	  This option enables access to the in-kernel headers that are generated during
 742	  the build process. These can be used to build eBPF tracing programs,
 743	  or similar programs.  If you build the headers as a module, a module called
 744	  kheaders.ko is built which can be loaded on-demand to get access to headers.
 745
 746config LOG_BUF_SHIFT
 747	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 748	range 12 25
 749	default 17
 750	depends on PRINTK
 751	help
 752	  Select the minimal kernel log buffer size as a power of 2.
 753	  The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
 754	  parameter, see below. Any higher size also might be forced
 755	  by "log_buf_len" boot parameter.
 756
 757	  Examples:
 758		     17 => 128 KB
 759		     16 => 64 KB
 760		     15 => 32 KB
 761		     14 => 16 KB
 762		     13 =>  8 KB
 763		     12 =>  4 KB
 764
 765config LOG_CPU_MAX_BUF_SHIFT
 766	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
 767	depends on SMP
 768	range 0 21
 
 769	default 0 if BASE_SMALL
 770	default 12
 771	depends on PRINTK
 772	help
 773	  This option allows to increase the default ring buffer size
 774	  according to the number of CPUs. The value defines the contribution
 775	  of each CPU as a power of 2. The used space is typically only few
 776	  lines however it might be much more when problems are reported,
 777	  e.g. backtraces.
 778
 779	  The increased size means that a new buffer has to be allocated and
 780	  the original static one is unused. It makes sense only on systems
 781	  with more CPUs. Therefore this value is used only when the sum of
 782	  contributions is greater than the half of the default kernel ring
 783	  buffer as defined by LOG_BUF_SHIFT. The default values are set
 784	  so that more than 16 CPUs are needed to trigger the allocation.
 785
 786	  Also this option is ignored when "log_buf_len" kernel parameter is
 787	  used as it forces an exact (power of two) size of the ring buffer.
 788
 789	  The number of possible CPUs is used for this computation ignoring
 790	  hotplugging making the computation optimal for the worst case
 791	  scenario while allowing a simple algorithm to be used from bootup.
 792
 793	  Examples shift values and their meaning:
 794		     17 => 128 KB for each CPU
 795		     16 =>  64 KB for each CPU
 796		     15 =>  32 KB for each CPU
 797		     14 =>  16 KB for each CPU
 798		     13 =>   8 KB for each CPU
 799		     12 =>   4 KB for each CPU
 800
 801config PRINTK_INDEX
 802	bool "Printk indexing debugfs interface"
 803	depends on PRINTK && DEBUG_FS
 804	help
 805	  Add support for indexing of all printk formats known at compile time
 806	  at <debugfs>/printk/index/<module>.
 807
 808	  This can be used as part of maintaining daemons which monitor
 809	  /dev/kmsg, as it permits auditing the printk formats present in a
 810	  kernel, allowing detection of cases where monitored printks are
 811	  changed or no longer present.
 812
 813	  There is no additional runtime cost to printk with this enabled.
 814
 815#
 816# Architectures with an unreliable sched_clock() should select this:
 817#
 818config HAVE_UNSTABLE_SCHED_CLOCK
 819	bool
 820
 821config GENERIC_SCHED_CLOCK
 822	bool
 823
 824menu "Scheduler features"
 825
 826config UCLAMP_TASK
 827	bool "Enable utilization clamping for RT/FAIR tasks"
 828	depends on CPU_FREQ_GOV_SCHEDUTIL
 829	help
 830	  This feature enables the scheduler to track the clamped utilization
 831	  of each CPU based on RUNNABLE tasks scheduled on that CPU.
 832
 833	  With this option, the user can specify the min and max CPU
 834	  utilization allowed for RUNNABLE tasks. The max utilization defines
 835	  the maximum frequency a task should use while the min utilization
 836	  defines the minimum frequency it should use.
 837
 838	  Both min and max utilization clamp values are hints to the scheduler,
 839	  aiming at improving its frequency selection policy, but they do not
 840	  enforce or grant any specific bandwidth for tasks.
 841
 842	  If in doubt, say N.
 843
 844config UCLAMP_BUCKETS_COUNT
 845	int "Number of supported utilization clamp buckets"
 846	range 5 20
 847	default 5
 848	depends on UCLAMP_TASK
 849	help
 850	  Defines the number of clamp buckets to use. The range of each bucket
 851	  will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
 852	  number of clamp buckets the finer their granularity and the higher
 853	  the precision of clamping aggregation and tracking at run-time.
 854
 855	  For example, with the minimum configuration value we will have 5
 856	  clamp buckets tracking 20% utilization each. A 25% boosted tasks will
 857	  be refcounted in the [20..39]% bucket and will set the bucket clamp
 858	  effective value to 25%.
 859	  If a second 30% boosted task should be co-scheduled on the same CPU,
 860	  that task will be refcounted in the same bucket of the first task and
 861	  it will boost the bucket clamp effective value to 30%.
 862	  The clamp effective value of a bucket is reset to its nominal value
 863	  (20% in the example above) when there are no more tasks refcounted in
 864	  that bucket.
 865
 866	  An additional boost/capping margin can be added to some tasks. In the
 867	  example above the 25% task will be boosted to 30% until it exits the
 868	  CPU. If that should be considered not acceptable on certain systems,
 869	  it's always possible to reduce the margin by increasing the number of
 870	  clamp buckets to trade off used memory for run-time tracking
 871	  precision.
 872
 873	  If in doubt, use the default value.
 874
 875endmenu
 876
 877#
 878# For architectures that want to enable the support for NUMA-affine scheduler
 879# balancing logic:
 880#
 881config ARCH_SUPPORTS_NUMA_BALANCING
 882	bool
 883
 884#
 885# For architectures that prefer to flush all TLBs after a number of pages
 886# are unmapped instead of sending one IPI per page to flush. The architecture
 887# must provide guarantees on what happens if a clean TLB cache entry is
 888# written after the unmap. Details are in mm/rmap.c near the check for
 889# should_defer_flush. The architecture should also consider if the full flush
 890# and the refill costs are offset by the savings of sending fewer IPIs.
 891config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
 892	bool
 893
 894config CC_HAS_INT128
 895	def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
 896
 897config CC_IMPLICIT_FALLTHROUGH
 898	string
 899	default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
 900	default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
 901
 902# Currently, disable gcc-10+ array-bounds globally.
 903# It's still broken in gcc-13, so no upper bound yet.
 904config GCC10_NO_ARRAY_BOUNDS
 905	def_bool y
 906
 907config CC_NO_ARRAY_BOUNDS
 908	bool
 909	default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS
 910
 911# Currently, disable -Wstringop-overflow for GCC globally.
 912config GCC_NO_STRINGOP_OVERFLOW
 913	def_bool y
 914
 915config CC_NO_STRINGOP_OVERFLOW
 916	bool
 917	default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
 918
 919config CC_STRINGOP_OVERFLOW
 920	bool
 921	default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
 922
 923#
 924# For architectures that know their GCC __int128 support is sound
 925#
 926config ARCH_SUPPORTS_INT128
 927	bool
 928
 929# For architectures that (ab)use NUMA to represent different memory regions
 930# all cpu-local but of different latencies, such as SuperH.
 931#
 932config ARCH_WANT_NUMA_VARIABLE_LOCALITY
 933	bool
 934
 935config NUMA_BALANCING
 936	bool "Memory placement aware NUMA scheduler"
 937	depends on ARCH_SUPPORTS_NUMA_BALANCING
 938	depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
 939	depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
 940	help
 941	  This option adds support for automatic NUMA aware memory/task placement.
 942	  The mechanism is quite primitive and is based on migrating memory when
 943	  it has references to the node the task is running on.
 944
 945	  This system will be inactive on UMA systems.
 946
 947config NUMA_BALANCING_DEFAULT_ENABLED
 948	bool "Automatically enable NUMA aware memory/task placement"
 949	default y
 950	depends on NUMA_BALANCING
 951	help
 952	  If set, automatic NUMA balancing will be enabled if running on a NUMA
 953	  machine.
 954
 955config SLAB_OBJ_EXT
 956	bool
 957
 958menuconfig CGROUPS
 959	bool "Control Group support"
 960	select KERNFS
 961	help
 962	  This option adds support for grouping sets of processes together, for
 963	  use with process control subsystems such as Cpusets, CFS, memory
 964	  controls or device isolation.
 965	  See
 966		- Documentation/scheduler/sched-design-CFS.rst	(CFS)
 967		- Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
 968					  and resource control)
 969
 970	  Say N if unsure.
 971
 972if CGROUPS
 973
 974config PAGE_COUNTER
 975	bool
 976
 977config CGROUP_FAVOR_DYNMODS
 978        bool "Favor dynamic modification latency reduction by default"
 979        help
 980          This option enables the "favordynmods" mount option by default
 981          which reduces the latencies of dynamic cgroup modifications such
 982          as task migrations and controller on/offs at the cost of making
 983          hot path operations such as forks and exits more expensive.
 984
 985          Say N if unsure.
 986
 987config MEMCG
 988	bool "Memory controller"
 989	select PAGE_COUNTER
 990	select EVENTFD
 991	select SLAB_OBJ_EXT
 992	help
 993	  Provides control over the memory footprint of tasks in a cgroup.
 994
 995config MEMCG_V1
 996	bool "Legacy cgroup v1 memory controller"
 997	depends on MEMCG
 998	default n
 999	help
1000	  Legacy cgroup v1 memory controller which has been deprecated by
1001	  cgroup v2 implementation. The v1 is there for legacy applications
1002	  which haven't migrated to the new cgroup v2 interface yet. If you
1003	  do not have any such application then you are completely fine leaving
1004	  this option disabled.
1005
1006	  Please note that feature set of the legacy memory controller is likely
1007	  going to shrink due to deprecation process. New deployments with v1
1008	  controller are highly discouraged.
1009
1010	  Say N if unsure.
 
 
 
1011
1012config BLK_CGROUP
1013	bool "IO controller"
1014	depends on BLOCK
1015	default n
1016	help
1017	Generic block IO controller cgroup interface. This is the common
1018	cgroup interface which should be used by various IO controlling
1019	policies.
1020
1021	Currently, CFQ IO scheduler uses it to recognize task groups and
1022	control disk bandwidth allocation (proportional time slice allocation)
1023	to such task groups. It is also used by bio throttling logic in
1024	block layer to implement upper limit in IO rates on a device.
1025
1026	This option only enables generic Block IO controller infrastructure.
1027	One needs to also enable actual IO controlling logic/policy. For
1028	enabling proportional weight division of disk bandwidth in CFQ, set
1029	CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1030	CONFIG_BLK_DEV_THROTTLING=y.
1031
1032	See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
 
 
 
 
 
 
 
 
1033
1034config CGROUP_WRITEBACK
1035	bool
1036	depends on MEMCG && BLK_CGROUP
1037	default y
1038
1039menuconfig CGROUP_SCHED
1040	bool "CPU controller"
1041	default n
1042	help
1043	  This feature lets CPU scheduler recognize task groups and control CPU
1044	  bandwidth allocation to such task groups. It uses cgroups to group
1045	  tasks.
1046
1047if CGROUP_SCHED
1048config GROUP_SCHED_WEIGHT
1049	def_bool n
1050
1051config FAIR_GROUP_SCHED
1052	bool "Group scheduling for SCHED_OTHER"
1053	depends on CGROUP_SCHED
1054	select GROUP_SCHED_WEIGHT
1055	default CGROUP_SCHED
1056
1057config CFS_BANDWIDTH
1058	bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1059	depends on FAIR_GROUP_SCHED
1060	default n
1061	help
1062	  This option allows users to define CPU bandwidth rates (limits) for
1063	  tasks running within the fair group scheduler.  Groups with no limit
1064	  set are considered to be unconstrained and will run with no
1065	  restriction.
1066	  See Documentation/scheduler/sched-bwc.rst for more information.
1067
1068config RT_GROUP_SCHED
1069	bool "Group scheduling for SCHED_RR/FIFO"
1070	depends on CGROUP_SCHED
1071	default n
1072	help
1073	  This feature lets you explicitly allocate real CPU bandwidth
1074	  to task groups. If enabled, it will also make it impossible to
1075	  schedule realtime tasks for non-root users until you allocate
1076	  realtime bandwidth for them.
1077	  See Documentation/scheduler/sched-rt-group.rst for more information.
1078
1079config EXT_GROUP_SCHED
1080	bool
1081	depends on SCHED_CLASS_EXT && CGROUP_SCHED
1082	select GROUP_SCHED_WEIGHT
1083	default y
1084
1085endif #CGROUP_SCHED
1086
1087config SCHED_MM_CID
1088	def_bool y
1089	depends on SMP && RSEQ
1090
1091config UCLAMP_TASK_GROUP
1092	bool "Utilization clamping per group of tasks"
1093	depends on CGROUP_SCHED
1094	depends on UCLAMP_TASK
1095	default n
1096	help
1097	  This feature enables the scheduler to track the clamped utilization
1098	  of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1099
1100	  When this option is enabled, the user can specify a min and max
1101	  CPU bandwidth which is allowed for each single task in a group.
1102	  The max bandwidth allows to clamp the maximum frequency a task
1103	  can use, while the min bandwidth allows to define a minimum
1104	  frequency a task will always use.
1105
1106	  When task group based utilization clamping is enabled, an eventually
1107	  specified task-specific clamp value is constrained by the cgroup
1108	  specified clamp value. Both minimum and maximum task clamping cannot
1109	  be bigger than the corresponding clamping defined at task group level.
1110
1111	  If in doubt, say N.
1112
1113config CGROUP_PIDS
1114	bool "PIDs controller"
1115	help
1116	  Provides enforcement of process number limits in the scope of a
1117	  cgroup. Any attempt to fork more processes than is allowed in the
1118	  cgroup will fail. PIDs are fundamentally a global resource because it
1119	  is fairly trivial to reach PID exhaustion before you reach even a
1120	  conservative kmemcg limit. As a result, it is possible to grind a
1121	  system to halt without being limited by other cgroup policies. The
1122	  PIDs controller is designed to stop this from happening.
1123
1124	  It should be noted that organisational operations (such as attaching
1125	  to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1126	  since the PIDs limit only affects a process's ability to fork, not to
1127	  attach to a cgroup.
1128
1129config CGROUP_RDMA
1130	bool "RDMA controller"
1131	help
1132	  Provides enforcement of RDMA resources defined by IB stack.
1133	  It is fairly easy for consumers to exhaust RDMA resources, which
1134	  can result into resource unavailability to other consumers.
1135	  RDMA controller is designed to stop this from happening.
1136	  Attaching processes with active RDMA resources to the cgroup
1137	  hierarchy is allowed even if can cross the hierarchy's limit.
1138
1139config CGROUP_FREEZER
1140	bool "Freezer controller"
1141	help
1142	  Provides a way to freeze and unfreeze all tasks in a
1143	  cgroup.
1144
1145	  This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1146	  controller includes important in-kernel memory consumers per default.
1147
1148	  If you're using cgroup2, say N.
1149
1150config CGROUP_HUGETLB
1151	bool "HugeTLB controller"
1152	depends on HUGETLB_PAGE
1153	select PAGE_COUNTER
1154	default n
1155	help
1156	  Provides a cgroup controller for HugeTLB pages.
1157	  When you enable this, you can put a per cgroup limit on HugeTLB usage.
1158	  The limit is enforced during page fault. Since HugeTLB doesn't
1159	  support page reclaim, enforcing the limit at page fault time implies
1160	  that, the application will get SIGBUS signal if it tries to access
1161	  HugeTLB pages beyond its limit. This requires the application to know
1162	  beforehand how much HugeTLB pages it would require for its use. The
1163	  control group is tracked in the third page lru pointer. This means
1164	  that we cannot use the controller with huge page less than 3 pages.
1165
1166config CPUSETS
1167	bool "Cpuset controller"
1168	depends on SMP
1169	select UNION_FIND
1170	help
1171	  This option will let you create and manage CPUSETs which
1172	  allow dynamically partitioning a system into sets of CPUs and
1173	  Memory Nodes and assigning tasks to run only within those sets.
1174	  This is primarily useful on large SMP or NUMA systems.
1175
1176	  Say N if unsure.
1177
1178config CPUSETS_V1
1179	bool "Legacy cgroup v1 cpusets controller"
1180	depends on CPUSETS
1181	default n
1182	help
1183	  Legacy cgroup v1 cpusets controller which has been deprecated by
1184	  cgroup v2 implementation. The v1 is there for legacy applications
1185	  which haven't migrated to the new cgroup v2 interface yet. If you
1186	  do not have any such application then you are completely fine leaving
1187	  this option disabled.
1188
1189	  Say N if unsure.
1190
1191config PROC_PID_CPUSET
1192	bool "Include legacy /proc/<pid>/cpuset file"
1193	depends on CPUSETS
1194	default y
1195
1196config CGROUP_DEVICE
1197	bool "Device controller"
1198	help
1199	  Provides a cgroup controller implementing whitelists for
1200	  devices which a process in the cgroup can mknod or open.
1201
1202config CGROUP_CPUACCT
1203	bool "Simple CPU accounting controller"
1204	help
1205	  Provides a simple controller for monitoring the
1206	  total CPU consumed by the tasks in a cgroup.
1207
1208config CGROUP_PERF
1209	bool "Perf controller"
1210	depends on PERF_EVENTS
1211	help
1212	  This option extends the perf per-cpu mode to restrict monitoring
1213	  to threads which belong to the cgroup specified and run on the
1214	  designated cpu.  Or this can be used to have cgroup ID in samples
1215	  so that it can monitor performance events among cgroups.
1216
1217	  Say N if unsure.
1218
1219config CGROUP_BPF
1220	bool "Support for eBPF programs attached to cgroups"
1221	depends on BPF_SYSCALL
1222	select SOCK_CGROUP_DATA
1223	help
1224	  Allow attaching eBPF programs to a cgroup using the bpf(2)
1225	  syscall command BPF_PROG_ATTACH.
1226
1227	  In which context these programs are accessed depends on the type
1228	  of attachment. For instance, programs that are attached using
1229	  BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1230	  inet sockets.
1231
1232config CGROUP_MISC
1233	bool "Misc resource controller"
1234	default n
1235	help
1236	  Provides a controller for miscellaneous resources on a host.
1237
1238	  Miscellaneous scalar resources are the resources on the host system
1239	  which cannot be abstracted like the other cgroups. This controller
1240	  tracks and limits the miscellaneous resources used by a process
1241	  attached to a cgroup hierarchy.
1242
1243	  For more information, please check misc cgroup section in
1244	  /Documentation/admin-guide/cgroup-v2.rst.
1245
1246config CGROUP_DEBUG
1247	bool "Debug controller"
1248	default n
1249	depends on DEBUG_KERNEL
1250	help
1251	  This option enables a simple controller that exports
1252	  debugging information about the cgroups framework. This
1253	  controller is for control cgroup debugging only. Its
1254	  interfaces are not stable.
1255
1256	  Say N.
1257
1258config SOCK_CGROUP_DATA
1259	bool
 
 
 
1260	default n
 
 
 
 
 
1261
1262endif # CGROUPS
1263
1264menuconfig NAMESPACES
1265	bool "Namespaces support" if EXPERT
1266	depends on MULTIUSER
1267	default !EXPERT
1268	help
1269	  Provides the way to make tasks work with different objects using
1270	  the same id. For example same IPC id may refer to different objects
1271	  or same user id or pid may refer to different tasks when used in
1272	  different namespaces.
1273
1274if NAMESPACES
1275
1276config UTS_NS
1277	bool "UTS namespace"
1278	default y
1279	help
1280	  In this namespace tasks see different info provided with the
1281	  uname() system call
1282
1283config TIME_NS
1284	bool "TIME namespace"
1285	depends on GENERIC_VDSO_TIME_NS
1286	default y
1287	help
1288	  In this namespace boottime and monotonic clocks can be set.
1289	  The time will keep going with the same pace.
1290
1291config IPC_NS
1292	bool "IPC namespace"
1293	depends on (SYSVIPC || POSIX_MQUEUE)
1294	default y
1295	help
1296	  In this namespace tasks work with IPC ids which correspond to
1297	  different IPC objects in different namespaces.
1298
1299config USER_NS
1300	bool "User namespace"
1301	default n
1302	help
1303	  This allows containers, i.e. vservers, to use user namespaces
1304	  to provide different user info for different servers.
1305
1306	  When user namespaces are enabled in the kernel it is
1307	  recommended that the MEMCG option also be enabled and that
1308	  user-space use the memory control groups to limit the amount
1309	  of memory a memory unprivileged users can use.
1310
1311	  If unsure, say N.
1312
1313config PID_NS
1314	bool "PID Namespaces"
1315	default y
1316	help
1317	  Support process id namespaces.  This allows having multiple
1318	  processes with the same pid as long as they are in different
1319	  pid namespaces.  This is a building block of containers.
1320
1321config NET_NS
1322	bool "Network namespace"
1323	depends on NET
1324	default y
1325	help
1326	  Allow user space to create what appear to be multiple instances
1327	  of the network stack.
1328
1329endif # NAMESPACES
1330
1331config CHECKPOINT_RESTORE
1332	bool "Checkpoint/restore support"
1333	depends on PROC_FS
1334	select PROC_CHILDREN
1335	select KCMP
1336	default n
1337	help
1338	  Enables additional kernel features in a sake of checkpoint/restore.
1339	  In particular it adds auxiliary prctl codes to setup process text,
1340	  data and heap segment sizes, and a few additional /proc filesystem
1341	  entries.
1342
1343	  If unsure, say N here.
1344
1345config SCHED_AUTOGROUP
1346	bool "Automatic process group scheduling"
1347	select CGROUPS
1348	select CGROUP_SCHED
1349	select FAIR_GROUP_SCHED
1350	help
1351	  This option optimizes the scheduler for common desktop workloads by
1352	  automatically creating and populating task groups.  This separation
1353	  of workloads isolates aggressive CPU burners (like build jobs) from
1354	  desktop applications.  Task group autogeneration is currently based
1355	  upon task session.
1356
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1357config RELAY
1358	bool "Kernel->user space relay support (formerly relayfs)"
1359	select IRQ_WORK
1360	help
1361	  This option enables support for relay interface support in
1362	  certain file systems (such as debugfs).
1363	  It is designed to provide an efficient mechanism for tools and
1364	  facilities to relay large amounts of data from kernel space to
1365	  user space.
1366
1367	  If unsure, say N.
1368
1369config BLK_DEV_INITRD
1370	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 
1371	help
1372	  The initial RAM filesystem is a ramfs which is loaded by the
1373	  boot loader (loadlin or lilo) and that is mounted as root
1374	  before the normal boot procedure. It is typically used to
1375	  load modules needed to mount the "real" root file system,
1376	  etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1377
1378	  If RAM disk support (BLK_DEV_RAM) is also included, this
1379	  also enables initial RAM disk (initrd) support and adds
1380	  15 Kbytes (more on some other architectures) to the kernel size.
1381
1382	  If unsure say Y.
1383
1384if BLK_DEV_INITRD
1385
1386source "usr/Kconfig"
1387
1388endif
1389
1390config BOOT_CONFIG
1391	bool "Boot config support"
1392	select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
1393	help
1394	  Extra boot config allows system admin to pass a config file as
1395	  complemental extension of kernel cmdline when booting.
1396	  The boot config file must be attached at the end of initramfs
1397	  with checksum, size and magic word.
1398	  See <file:Documentation/admin-guide/bootconfig.rst> for details.
1399
1400	  If unsure, say Y.
1401
1402config BOOT_CONFIG_FORCE
1403	bool "Force unconditional bootconfig processing"
1404	depends on BOOT_CONFIG
1405	default y if BOOT_CONFIG_EMBED
1406	help
1407	  With this Kconfig option set, BOOT_CONFIG processing is carried
1408	  out even when the "bootconfig" kernel-boot parameter is omitted.
1409	  In fact, with this Kconfig option set, there is no way to
1410	  make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
1411	  parameters.
1412
1413	  If unsure, say N.
1414
1415config BOOT_CONFIG_EMBED
1416	bool "Embed bootconfig file in the kernel"
1417	depends on BOOT_CONFIG
1418	help
1419	  Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1420	  kernel. Usually, the bootconfig file is loaded with the initrd
1421	  image. But if the system doesn't support initrd, this option will
1422	  help you by embedding a bootconfig file while building the kernel.
1423
1424	  If unsure, say N.
1425
1426config BOOT_CONFIG_EMBED_FILE
1427	string "Embedded bootconfig file path"
1428	depends on BOOT_CONFIG_EMBED
1429	help
1430	  Specify a bootconfig file which will be embedded to the kernel.
1431	  This bootconfig will be used if there is no initrd or no other
1432	  bootconfig in the initrd.
1433
1434config INITRAMFS_PRESERVE_MTIME
1435	bool "Preserve cpio archive mtimes in initramfs"
1436	default y
1437	help
1438	  Each entry in an initramfs cpio archive carries an mtime value. When
1439	  enabled, extracted cpio items take this mtime, with directory mtime
1440	  setting deferred until after creation of any child entries.
1441
1442	  If unsure, say Y.
1443
1444choice
1445	prompt "Compiler optimization level"
1446	default CC_OPTIMIZE_FOR_PERFORMANCE
1447
1448config CC_OPTIMIZE_FOR_PERFORMANCE
1449	bool "Optimize for performance (-O2)"
1450	help
1451	  This is the default optimization level for the kernel, building
1452	  with the "-O2" compiler flag for best performance and most
1453	  helpful compile-time warnings.
1454
1455config CC_OPTIMIZE_FOR_SIZE
1456	bool "Optimize for size (-Os)"
1457	help
1458	  Choosing this option will pass "-Os" to your compiler resulting
1459	  in a smaller kernel.
1460
1461endchoice
1462
1463config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1464	bool
1465	help
1466	  This requires that the arch annotates or otherwise protects
1467	  its external entry points from being discarded. Linker scripts
1468	  must also merge .text.*, .data.*, and .bss.* correctly into
1469	  output sections. Care must be taken not to pull in unrelated
1470	  sections (e.g., '.text.init'). Typically '.' in section names
1471	  is used to distinguish them from label names / C identifiers.
1472
1473config LD_DEAD_CODE_DATA_ELIMINATION
1474	bool "Dead code and data elimination (EXPERIMENTAL)"
1475	depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1476	depends on EXPERT
1477	depends on $(cc-option,-ffunction-sections -fdata-sections)
1478	depends on $(ld-option,--gc-sections)
1479	help
1480	  Enable this if you want to do dead code and data elimination with
1481	  the linker by compiling with -ffunction-sections -fdata-sections,
1482	  and linking with --gc-sections.
1483
1484	  This can reduce on disk and in-memory size of the kernel
1485	  code and static data, particularly for small configs and
1486	  on small systems. This has the possibility of introducing
1487	  silently broken kernel if the required annotations are not
1488	  present. This option is not well tested yet, so use at your
1489	  own risk.
1490
1491config LD_ORPHAN_WARN
1492	def_bool y
1493	depends on ARCH_WANT_LD_ORPHAN_WARN
1494	depends on $(ld-option,--orphan-handling=warn)
1495	depends on $(ld-option,--orphan-handling=error)
1496
1497config LD_ORPHAN_WARN_LEVEL
1498        string
1499        depends on LD_ORPHAN_WARN
1500        default "error" if WERROR
1501        default "warn"
1502
1503config SYSCTL
1504	bool
1505
1506config HAVE_UID16
1507	bool
1508
1509config SYSCTL_EXCEPTION_TRACE
1510	bool
1511	help
1512	  Enable support for /proc/sys/debug/exception-trace.
1513
1514config SYSCTL_ARCH_UNALIGN_NO_WARN
1515	bool
1516	help
1517	  Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1518	  Allows arch to define/use @no_unaligned_warning to possibly warn
1519	  about unaligned access emulation going on under the hood.
1520
1521config SYSCTL_ARCH_UNALIGN_ALLOW
1522	bool
1523	help
1524	  Enable support for /proc/sys/kernel/unaligned-trap
1525	  Allows arches to define/use @unaligned_enabled to runtime toggle
1526	  the unaligned access emulation.
1527	  see arch/parisc/kernel/unaligned.c for reference
1528
1529config HAVE_PCSPKR_PLATFORM
1530	bool
1531
 
 
 
 
1532menuconfig EXPERT
1533	bool "Configure standard kernel features (expert users)"
1534	# Unhide debug options, to make the on-by-default options visible
1535	select DEBUG_KERNEL
1536	help
1537	  This option allows certain base kernel options and settings
1538	  to be disabled or tweaked. This is for specialized
1539	  environments which can tolerate a "non-standard" kernel.
1540	  Only use this if you really know what you are doing.
1541
1542config UID16
1543	bool "Enable 16-bit UID system calls" if EXPERT
1544	depends on HAVE_UID16 && MULTIUSER
1545	default y
1546	help
1547	  This enables the legacy 16-bit UID syscall wrappers.
1548
1549config MULTIUSER
1550	bool "Multiple users, groups and capabilities support" if EXPERT
1551	default y
1552	help
1553	  This option enables support for non-root users, groups and
1554	  capabilities.
1555
1556	  If you say N here, all processes will run with UID 0, GID 0, and all
1557	  possible capabilities.  Saying N here also compiles out support for
1558	  system calls related to UIDs, GIDs, and capabilities, such as setuid,
1559	  setgid, and capset.
1560
1561	  If unsure, say Y here.
1562
1563config SGETMASK_SYSCALL
1564	bool "sgetmask/ssetmask syscalls support" if EXPERT
1565	default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1566	help
1567	  sys_sgetmask and sys_ssetmask are obsolete system calls
1568	  no longer supported in libc but still enabled by default in some
1569	  architectures.
1570
1571	  If unsure, leave the default option here.
1572
1573config SYSFS_SYSCALL
1574	bool "Sysfs syscall support" if EXPERT
1575	default y
1576	help
1577	  sys_sysfs is an obsolete system call no longer supported in libc.
1578	  Note that disabling this option is more secure but might break
1579	  compatibility with some systems.
1580
1581	  If unsure say Y here.
1582
1583config FHANDLE
1584	bool "open by fhandle syscalls" if EXPERT
1585	select EXPORTFS
1586	default y
1587	help
1588	  If you say Y here, a user level program will be able to map
1589	  file names to handle and then later use the handle for
1590	  different file system operations. This is useful in implementing
1591	  userspace file servers, which now track files using handles instead
1592	  of names. The handle would remain the same even if file names
1593	  get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1594	  syscalls.
 
 
1595
1596config POSIX_TIMERS
1597	bool "Posix Clocks & timers" if EXPERT
1598	default y
 
 
 
 
 
 
 
 
 
 
1599	help
1600	  This includes native support for POSIX timers to the kernel.
1601	  Some embedded systems have no use for them and therefore they
1602	  can be configured out to reduce the size of the kernel image.
1603
1604	  When this option is disabled, the following syscalls won't be
1605	  available: timer_create, timer_gettime: timer_getoverrun,
1606	  timer_settime, timer_delete, clock_adjtime, getitimer,
1607	  setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1608	  clock_getres and clock_nanosleep syscalls will be limited to
1609	  CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
 
 
 
 
 
 
1610
1611	  If unsure say y.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1612
1613config PRINTK
1614	default y
1615	bool "Enable support for printk" if EXPERT
1616	select IRQ_WORK
1617	help
1618	  This option enables normal printk support. Removing it
1619	  eliminates most of the message strings from the kernel image
1620	  and makes the kernel more or less silent. As this makes it
1621	  very difficult to diagnose system problems, saying N here is
1622	  strongly discouraged.
1623
1624config BUG
1625	bool "BUG() support" if EXPERT
1626	default y
1627	help
1628	  Disabling this option eliminates support for BUG and WARN, reducing
1629	  the size of your kernel image and potentially quietly ignoring
1630	  numerous fatal conditions. You should only consider disabling this
1631	  option for embedded systems with no facilities for reporting errors.
1632	  Just say Y.
1633
1634config ELF_CORE
1635	depends on COREDUMP
1636	default y
1637	bool "Enable ELF core dumps" if EXPERT
1638	help
1639	  Enable support for generating core dumps. Disabling saves about 4k.
1640
1641
1642config PCSPKR_PLATFORM
1643	bool "Enable PC-Speaker support" if EXPERT
1644	depends on HAVE_PCSPKR_PLATFORM
1645	select I8253_LOCK
1646	default y
1647	help
1648	  This option allows to disable the internal PC-Speaker
1649	  support, saving some memory.
1650
1651config BASE_SMALL
1652	bool "Enable smaller-sized data structures for core" if EXPERT
 
1653	help
1654	  Enabling this option reduces the size of miscellaneous core
1655	  kernel data structures. This saves memory on small machines,
1656	  but may reduce performance.
1657
1658config FUTEX
1659	bool "Enable futex support" if EXPERT
1660	depends on !(SPARC32 && SMP)
1661	default y
1662	imply RT_MUTEXES
1663	help
1664	  Disabling this option will cause the kernel to be built without
1665	  support for "fast userspace mutexes".  The resulting kernel may not
1666	  run glibc-based applications correctly.
1667
1668config FUTEX_PI
1669	bool
1670	depends on FUTEX && RT_MUTEXES
1671	default y
 
 
 
1672
1673config EPOLL
1674	bool "Enable eventpoll support" if EXPERT
1675	default y
 
1676	help
1677	  Disabling this option will cause the kernel to be built without
1678	  support for epoll family of system calls.
1679
1680config SIGNALFD
1681	bool "Enable signalfd() system call" if EXPERT
 
1682	default y
1683	help
1684	  Enable the signalfd() system call that allows to receive signals
1685	  on a file descriptor.
1686
1687	  If unsure, say Y.
1688
1689config TIMERFD
1690	bool "Enable timerfd() system call" if EXPERT
 
1691	default y
1692	help
1693	  Enable the timerfd() system call that allows to receive timer
1694	  events on a file descriptor.
1695
1696	  If unsure, say Y.
1697
1698config EVENTFD
1699	bool "Enable eventfd() system call" if EXPERT
 
1700	default y
1701	help
1702	  Enable the eventfd() system call that allows to receive both
1703	  kernel notification (ie. KAIO) or userspace notifications.
1704
1705	  If unsure, say Y.
1706
 
 
 
 
 
 
 
 
 
 
1707config SHMEM
1708	bool "Use full shmem filesystem" if EXPERT
1709	default y
1710	depends on MMU
1711	help
1712	  The shmem is an internal filesystem used to manage shared memory.
1713	  It is backed by swap and manages resource limits. It is also exported
1714	  to userspace as tmpfs if TMPFS is enabled. Disabling this
1715	  option replaces shmem and tmpfs with the much simpler ramfs code,
1716	  which may be appropriate on small systems without swap.
1717
1718config AIO
1719	bool "Enable AIO support" if EXPERT
1720	default y
1721	help
1722	  This option enables POSIX asynchronous I/O which may by used
1723	  by some high performance threaded applications. Disabling
1724	  this option saves about 7k.
1725
1726config IO_URING
1727	bool "Enable IO uring support" if EXPERT
1728	select IO_WQ
1729	default y
1730	help
1731	  This option enables support for the io_uring interface, enabling
1732	  applications to submit and complete IO through submission and
1733	  completion rings that are shared between the kernel and application.
1734
1735config GCOV_PROFILE_URING
1736	bool "Enable GCOV profiling on the io_uring subsystem"
1737	depends on GCOV_KERNEL
1738	help
1739	  Enable GCOV profiling on the io_uring subsystem, to facilitate
1740	  code coverage testing.
1741
1742	  If unsure, say N.
1743
1744	  Note that this will have a negative impact on the performance of
1745	  the io_uring subsystem, hence this should only be enabled for
1746	  specific test purposes.
1747
1748config ADVISE_SYSCALLS
1749	bool "Enable madvise/fadvise syscalls" if EXPERT
1750	default y
1751	help
1752	  This option enables the madvise and fadvise syscalls, used by
1753	  applications to advise the kernel about their future memory or file
1754	  usage, improving performance. If building an embedded system where no
1755	  applications use these syscalls, you can disable this option to save
1756	  space.
1757
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1758config MEMBARRIER
1759	bool "Enable membarrier() system call" if EXPERT
1760	default y
1761	help
1762	  Enable the membarrier() system call that allows issuing memory
1763	  barriers across all running threads, which can be used to distribute
1764	  the cost of user-space memory barriers asymmetrically by transforming
1765	  pairs of memory barriers into pairs consisting of membarrier() and a
1766	  compiler barrier.
1767
1768	  If unsure, say Y.
1769
1770config KCMP
1771	bool "Enable kcmp() system call" if EXPERT
1772	help
1773	  Enable the kernel resource comparison system call. It provides
1774	  user-space with the ability to compare two processes to see if they
1775	  share a common resource, such as a file descriptor or even virtual
1776	  memory space.
1777
1778	  If unsure, say N.
1779
1780config RSEQ
1781	bool "Enable rseq() system call" if EXPERT
1782	default y
1783	depends on HAVE_RSEQ
1784	select MEMBARRIER
1785	help
1786	  Enable the restartable sequences system call. It provides a
1787	  user-space cache for the current CPU number value, which
1788	  speeds up getting the current CPU number from user-space,
1789	  as well as an ABI to speed up user-space operations on
1790	  per-CPU data.
1791
1792	  If unsure, say Y.
1793
1794config DEBUG_RSEQ
1795	default n
1796	bool "Enable debugging of rseq() system call" if EXPERT
1797	depends on RSEQ && DEBUG_KERNEL
1798	help
1799	  Enable extra debugging checks for the rseq system call.
1800
1801	  If unsure, say N.
1802
1803config CACHESTAT_SYSCALL
1804	bool "Enable cachestat() system call" if EXPERT
1805	default y
1806	help
1807	  Enable the cachestat system call, which queries the page cache
1808	  statistics of a file (number of cached pages, dirty pages,
1809	  pages marked for writeback, (recently) evicted pages).
1810
1811	  If unsure say Y here.
1812
1813config PC104
1814	bool "PC/104 support" if EXPERT
1815	help
1816	  Expose PC/104 form factor device drivers and options available for
1817	  selection and configuration. Enable this option if your target
1818	  machine has a PC/104 bus.
1819
1820config KALLSYMS
1821	bool "Load all symbols for debugging/ksymoops" if EXPERT
1822	default y
1823	help
1824	  Say Y here to let the kernel print out symbolic crash information and
1825	  symbolic stack backtraces. This increases the size of the kernel
1826	  somewhat, as all symbols have to be loaded into the kernel image.
1827
1828config KALLSYMS_SELFTEST
1829	bool "Test the basic functions and performance of kallsyms"
1830	depends on KALLSYMS
1831	default n
1832	help
1833	  Test the basic functions and performance of some interfaces, such as
1834	  kallsyms_lookup_name. It also calculates the compression rate of the
1835	  kallsyms compression algorithm for the current symbol set.
1836
1837	  Start self-test automatically after system startup. Suggest executing
1838	  "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
1839	  displayed in the last line, indicating that the test is complete.
1840
1841config KALLSYMS_ALL
1842	bool "Include all symbols in kallsyms"
1843	depends on DEBUG_KERNEL && KALLSYMS
1844	help
1845	  Normally kallsyms only contains the symbols of functions for nicer
1846	  OOPS messages and backtraces (i.e., symbols from the text and inittext
1847	  sections). This is sufficient for most cases. And only if you want to
1848	  enable kernel live patching, or other less common use cases (e.g.,
1849	  when a debugger is used) all symbols are required (i.e., names of
1850	  variables from the data sections, etc).
1851
1852	  This option makes sure that all symbols are loaded into the kernel
1853	  image (i.e., symbols from all sections) in cost of increased kernel
1854	  size (depending on the kernel configuration, it may be 300KiB or
1855	  something like this).
1856
1857	  Say N unless you really need all symbols, or kernel live patching.
1858
1859config KALLSYMS_ABSOLUTE_PERCPU
1860	bool
1861	depends on KALLSYMS
1862	default X86_64 && SMP
1863
1864# end of the "standard kernel features (expert users)" menu
1865
1866config ARCH_HAS_MEMBARRIER_CALLBACKS
1867	bool
1868
1869config ARCH_HAS_MEMBARRIER_SYNC_CORE
1870	bool
1871
1872config HAVE_PERF_EVENTS
1873	bool
1874	help
1875	  See tools/perf/design.txt for details.
1876
1877config GUEST_PERF_EVENTS
1878	bool
1879	depends on HAVE_PERF_EVENTS
1880
1881config PERF_USE_VMALLOC
1882	bool
1883	help
1884	  See tools/perf/design.txt for details
1885
1886menu "Kernel Performance Events And Counters"
1887
1888config PERF_EVENTS
1889	bool "Kernel performance events and counters"
1890	default y if PROFILING
1891	depends on HAVE_PERF_EVENTS
 
1892	select IRQ_WORK
 
1893	help
1894	  Enable kernel support for various performance events provided
1895	  by software and hardware.
1896
1897	  Software events are supported either built-in or via the
1898	  use of generic tracepoints.
1899
1900	  Most modern CPUs support performance events via performance
1901	  counter registers. These registers count the number of certain
1902	  types of hw events: such as instructions executed, cachemisses
1903	  suffered, or branches mis-predicted - without slowing down the
1904	  kernel or applications. These registers can also trigger interrupts
1905	  when a threshold number of events have passed - and can thus be
1906	  used to profile the code that runs on that CPU.
1907
1908	  The Linux Performance Event subsystem provides an abstraction of
1909	  these software and hardware event capabilities, available via a
1910	  system call and used by the "perf" utility in tools/perf/. It
1911	  provides per task and per CPU counters, and it provides event
1912	  capabilities on top of those.
1913
1914	  Say Y if unsure.
1915
1916config DEBUG_PERF_USE_VMALLOC
1917	default n
1918	bool "Debug: use vmalloc to back perf mmap() buffers"
1919	depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1920	select PERF_USE_VMALLOC
1921	help
1922	  Use vmalloc memory to back perf mmap() buffers.
1923
1924	  Mostly useful for debugging the vmalloc code on platforms
1925	  that don't require it.
1926
1927	  Say N if unsure.
1928
1929endmenu
1930
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1931config SYSTEM_DATA_VERIFICATION
1932	def_bool n
1933	select SYSTEM_TRUSTED_KEYRING
1934	select KEYS
1935	select CRYPTO
1936	select CRYPTO_RSA
1937	select ASYMMETRIC_KEY_TYPE
1938	select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1939	select ASN1
1940	select OID_REGISTRY
1941	select X509_CERTIFICATE_PARSER
1942	select PKCS7_MESSAGE_PARSER
1943	help
1944	  Provide PKCS#7 message verification using the contents of the system
1945	  trusted keyring to provide public keys.  This then can be used for
1946	  module verification, kexec image verification and firmware blob
1947	  verification.
1948
1949config PROFILING
1950	bool "Profiling support"
1951	help
1952	  Say Y here to enable the extended profiling support mechanisms used
1953	  by profilers.
1954
1955config RUST
1956	bool "Rust support"
1957	depends on HAVE_RUST
1958	depends on RUST_IS_AVAILABLE
1959	depends on !MODVERSIONS
1960	depends on !GCC_PLUGIN_RANDSTRUCT
1961	depends on !RANDSTRUCT
1962	depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
1963	depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
1964	select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG
1965	depends on !CALL_PADDING || RUSTC_VERSION >= 108100
1966	depends on !KASAN_SW_TAGS
1967	depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300
1968	help
1969	  Enables Rust support in the kernel.
1970
1971	  This allows other Rust-related options, like drivers written in Rust,
1972	  to be selected.
1973
1974	  It is also required to be able to load external kernel modules
1975	  written in Rust.
1976
1977	  See Documentation/rust/ for more information.
1978
1979	  If unsure, say N.
1980
1981config RUSTC_VERSION_TEXT
1982	string
1983	depends on RUST
1984	default "$(RUSTC_VERSION_TEXT)"
1985	help
1986	  See `CC_VERSION_TEXT`.
1987
1988config BINDGEN_VERSION_TEXT
1989	string
1990	depends on RUST
1991	# The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
1992	# (https://github.com/rust-lang/rust-bindgen/pull/2678). It can be removed when
1993	# the minimum version is upgraded past that (0.69.1 already fixed the issue).
1994	default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
1995
1996#
1997# Place an empty function call at each tracepoint site. Can be
1998# dynamically changed for a probe function.
1999#
2000config TRACEPOINTS
2001	bool
2002	select TASKS_TRACE_RCU
2003
2004source "kernel/Kconfig.kexec"
2005
2006endmenu		# General setup
2007
2008source "arch/Kconfig"
 
 
 
 
 
 
 
 
2009
2010config RT_MUTEXES
2011	bool
2012	default y if PREEMPT_RT
2013
2014config MODULE_SIG_FORMAT
2015	def_bool n
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2016	select SYSTEM_DATA_VERIFICATION
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2017
2018source "kernel/module/Kconfig"
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2019
2020config INIT_ALL_POSSIBLE
2021	bool
2022	help
2023	  Back when each arch used to define their own cpu_online_mask and
2024	  cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2025	  with all 1s, and others with all 0s.  When they were centralised,
2026	  it was better to provide this option than to break all the archs
2027	  and have several arch maintainers pursuing me down dark alleys.
2028
2029source "block/Kconfig"
2030
2031config PREEMPT_NOTIFIERS
2032	bool
2033
2034config PADATA
2035	depends on SMP
2036	bool
2037
 
 
 
 
 
 
2038config ASN1
2039	tristate
2040	help
2041	  Build a simple ASN.1 grammar compiler that produces a bytecode output
2042	  that can be interpreted by the ASN.1 stream decoder and used to
2043	  inform it as to what tags are to be expected in a stream and what
2044	  functions to call on what tags.
2045
2046source "kernel/Kconfig.locks"
2047
2048config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2049	bool
2050
2051config ARCH_HAS_PREPARE_SYNC_CORE_CMD
2052	bool
2053
2054config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2055	bool
2056
2057# It may be useful for an architecture to override the definitions of the
2058# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2059# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2060# different calling convention for syscalls. They can also override the
2061# macros for not-implemented syscalls in kernel/sys_ni.c and
2062# kernel/time/posix-stubs.c. All these overrides need to be available in
2063# <asm/syscall_wrapper.h>.
2064config ARCH_HAS_SYSCALL_WRAPPER
2065	def_bool n