Merge tag 'io_uring-6.16-20250630' of git://git.kernel.dk/linux
[linux-2.6-block.git] / init / Kconfig
CommitLineData
ec8f24b7 1# SPDX-License-Identifier: GPL-2.0-only
8b59cd81
MY
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
f9c8bc46 13 - Ensure full rebuild when the compiler is updated
ce6ed1c4 14 include/linux/compiler-version.h contains this option in the comment
0e0345b7 15 line so fixdep adds include/config/CC_VERSION_TEXT into the
ce6ed1c4
MY
16 auto-generated dependency. When the compiler is updated, syncconfig
17 will touch it and then every file will be rebuilt.
8b59cd81 18
a4353898 19config CC_IS_GCC
aec6c60a 20 def_bool $(success,test "$(cc-name)" = GCC)
a4353898
MY
21
22config GCC_VERSION
23 int
aec6c60a 24 default $(cc-version) if CC_IS_GCC
a4353898
MY
25 default 0
26
469cb737 27config CC_IS_CLANG
aec6c60a 28 def_bool $(success,test "$(cc-name)" = Clang)
b744b43f 29
469cb737
MY
30config CLANG_VERSION
31 int
aec6c60a
MY
32 default $(cc-version) if CC_IS_CLANG
33 default 0
469cb737 34
ba64beb1
MY
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
02aff859
MY
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)
469cb737 57
d5750cd3
NC
58config LLD_VERSION
59 int
02aff859
MY
60 default $(ld-version) if LD_IS_LLD
61 default 0
d5750cd3 62
6e74c6b5
MO
63config RUSTC_VERSION
64 int
af0121c2 65 default $(rustc-version)
6e74c6b5
MO
66 help
67 It does not depend on `RUST` since that one may need to use the version
68 in a `depends on`.
69
2f7ab126
MO
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
eacf96d2 76 to satisfy the build requirements of Rust support.
2f7ab126
MO
77
78 In particular, the Makefile target 'rustavailable' is useful to check
79 why the Rust toolchain is not being detected.
80
af0121c2
GG
81config RUSTC_LLVM_VERSION
82 int
83 default $(rustc-llvm-version)
84
1a927fd3 85config CC_CAN_LINK
9371f86e 86 bool
f67695c9
EB
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))
b1183b6d 89
f2f6a8e8
MR
90# Fixed in GCC 14, 13.3, 12.4 and 11.5
91# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
92config GCC_ASM_GOTO_OUTPUT_BROKEN
93 bool
94 depends on CC_IS_GCC
95 default y if GCC_VERSION < 110500
96 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
97 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
98
587f1701 99config CC_HAS_ASM_GOTO_OUTPUT
f2f6a8e8
MR
100 def_bool y
101 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN
102 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)
587f1701 103
1aa0e8b1
SC
104config CC_HAS_ASM_GOTO_TIED_OUTPUT
105 depends on CC_HAS_ASM_GOTO_OUTPUT
106 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
534bd703 107 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)
1aa0e8b1 108
5cf896fb 109config TOOLS_SUPPORT_RELR
2d122942 110 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
5cf896fb 111
eb111869
RV
112config CC_HAS_ASM_INLINE
113 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
114
51c2ee6d
ND
115config CC_HAS_NO_PROFILE_FN_ATTR
116 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
117
f06e108a 118config CC_HAS_COUNTED_BY
5106c650 119 bool
f06e108a
JHF
120 # clang needs to be at least 19.1.3 to avoid __bdos miscalculations
121 # https://github.com/llvm/llvm-project/pull/110497
122 # https://github.com/llvm/llvm-project/pull/112636
5106c650
JHF
123 default y if CC_IS_CLANG && CLANG_VERSION >= 190103
124 # supported since gcc 15.1.0
125 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896
126 default y if CC_IS_GCC && GCC_VERSION >= 150100
f06e108a 127
b688f369
KC
128config CC_HAS_MULTIDIMENSIONAL_NONSTRING
129 def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror)
130
e7607f7d
NC
131config LD_CAN_USE_KEEP_IN_OVERLAY
132 # ld.lld prior to 21.0.0 did not support KEEP within an overlay description
133 # https://github.com/llvm/llvm-project/pull/130661
134 def_bool LD_IS_BFD || LLD_VERSION >= 210000
135
47cb6bf7
XD
136config RUSTC_HAS_COERCE_POINTEE
137 def_bool RUSTC_VERSION >= 108400
138
36174d16
MO
139config RUSTC_HAS_SPAN_FILE
140 def_bool RUSTC_VERSION >= 108800
141
7129ea6e
MO
142config RUSTC_HAS_UNNECESSARY_TRANSMUTES
143 def_bool RUSTC_VERSION >= 108800
144
613fe169
NC
145config PAHOLE_VERSION
146 int
147 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
148
b99b87f7
PO
149config CONSTRUCTORS
150 bool
b99b87f7 151
e360adbe 152config IRQ_WORK
fd0a68a2 153 def_bool y if SMP
e360adbe 154
10916706 155config BUILDTIME_TABLE_SORT
1dbdc6f1
DD
156 bool
157
c65eacbe
AL
158config THREAD_INFO_IN_TASK
159 bool
160 help
161 Select this to move thread_info off the stack into task_struct. To
162 make this work, an arch will need to remove all thread_info fields
163 except flags and fix any runtime bugs.
164
c6c314a6
AL
165 One subtle change that will be needed is to use try_get_task_stack()
166 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
167
ff0cfc66 168menu "General setup"
1da177e4 169
1da177e4
LT
170config BROKEN
171 bool
1da177e4
LT
172
173config BROKEN_ON_SMP
174 bool
175 depends on BROKEN || !SMP
176 default y
177
1da177e4
LT
178config INIT_ENV_ARG_LIMIT
179 int
dd673bca
AB
180 default 32 if !UML
181 default 128 if UML
1da177e4 182 help
34ad92c2
RD
183 Maximum of each of the number of arguments and environment
184 variables passed to init from the kernel command line.
1da177e4 185
4bb16672
JS
186config COMPILE_TEST
187 bool "Compile also drivers which will not load"
ea29b20a 188 depends on HAS_IOMEM
4bb16672
JS
189 help
190 Some drivers can be compiled on a different platform than they are
191 intended to be run on. Despite they cannot be loaded there (or even
192 when they load they cannot be used due to missing HW support),
193 developers still, opposing to distributors, might want to build such
194 drivers to compile-test them.
195
196 If you are a developer and want to build everything available, say Y
197 here. If you are a user/distributor, say N here to exclude useless
198 drivers to be distributed.
199
3fe617cc
LT
200config WERROR
201 bool "Compile the kernel with warnings as errors"
b339ec9c 202 default COMPILE_TEST
3fe617cc
LT
203 help
204 A kernel build should not cause any compiler warnings, and this
2f7ab126 205 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
e1789d7c
XL
206 to enforce that rule by default. Certain warnings from other tools
207 such as the linker may be upgraded to errors with this option as
208 well.
3fe617cc 209
e1789d7c
XL
210 However, if you have a new (or very old) compiler or linker with odd
211 and unusual warnings, or you have some architecture with problems,
3fe617cc
LT
212 you may need to disable this config option in order to
213 successfully build the kernel.
214
215 If in doubt, say Y.
216
d6fc9fcb
MY
217config UAPI_HEADER_TEST
218 bool "Compile test UAPI headers"
fcbb8461 219 depends on HEADERS_INSTALL && CC_CAN_LINK
d6fc9fcb
MY
220 help
221 Compile test headers exported to user-space to ensure they are
222 self-contained, i.e. compilable as standalone units.
223
224 If you are a developer or tester and want to ensure the exported
225 headers are self-contained, say Y here. Otherwise, choose N.
226
1da177e4
LT
227config LOCALVERSION
228 string "Local version - append to kernel release"
229 help
230 Append an extra string to the end of your kernel version.
231 This will show up when you type uname, for example.
232 The string you set here will be appended after the contents of
233 any files with a filename matching localversion* in your
234 object and source tree, in that order. Your total string can
235 be a maximum of 64 characters.
236
aaebf433
RA
237config LOCALVERSION_AUTO
238 bool "Automatically append version information to the version string"
239 default y
ac3339ba 240 depends on !COMPILE_TEST
aaebf433
RA
241 help
242 This will try to automatically determine if the current tree is a
6e5a5420
RD
243 release tree by looking for git tags that belong to the current
244 top of tree revision.
aaebf433
RA
245
246 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 247 if a git-based tree is found. The string generated by this will be
aaebf433 248 appended after any matching localversion* files, and after the value
6e5a5420 249 set in CONFIG_LOCALVERSION.
aaebf433 250
0f9c608d 251 (The actual string used here is the first 12 characters produced
6e5a5420
RD
252 by running the command:
253
254 $ git rev-parse --verify HEAD
255
256 which is done within the script "scripts/setlocalversion".)
aaebf433 257
9afb719e 258config BUILD_SALT
e8cf4e9c
KK
259 string "Build ID Salt"
260 default ""
261 help
262 The build ID is used to link binaries and their debug info. Setting
263 this option will use the value in the calculation of the build id.
264 This is mostly useful for distributions which want to ensure the
265 build is unique between builds. It's safe to leave the default.
9afb719e 266
2e9f3bdd
PA
267config HAVE_KERNEL_GZIP
268 bool
269
270config HAVE_KERNEL_BZIP2
271 bool
272
273config HAVE_KERNEL_LZMA
274 bool
275
3ebe1243
LC
276config HAVE_KERNEL_XZ
277 bool
278
7dd65feb
AT
279config HAVE_KERNEL_LZO
280 bool
281
e76e1fdf
KL
282config HAVE_KERNEL_LZ4
283 bool
284
48f7ddf7
NT
285config HAVE_KERNEL_ZSTD
286 bool
287
f16466af
VG
288config HAVE_KERNEL_UNCOMPRESSED
289 bool
290
30d65dbf 291choice
2e9f3bdd
PA
292 prompt "Kernel compression mode"
293 default KERNEL_GZIP
48f7ddf7 294 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
2e9f3bdd 295 help
30d65dbf
AK
296 The linux kernel is a kind of self-extracting executable.
297 Several compression algorithms are available, which differ
298 in efficiency, compression and decompression speed.
299 Compression speed is only relevant when building a kernel.
300 Decompression speed is relevant at each boot.
301
302 If you have any problems with bzip2 or lzma compressed
303 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
304 version of this functionality (bzip2 only), for 2.4, was
305 supplied by Christian Ludwig)
306
307 High compression options are mostly useful for users, who
308 are low on disk space (embedded systems), but for whom ram
309 size matters less.
310
311 If in doubt, select 'gzip'
312
313config KERNEL_GZIP
2e9f3bdd
PA
314 bool "Gzip"
315 depends on HAVE_KERNEL_GZIP
316 help
7dd65feb
AT
317 The old and tried gzip compression. It provides a good balance
318 between compression ratio and decompression speed.
30d65dbf
AK
319
320config KERNEL_BZIP2
321 bool "Bzip2"
2e9f3bdd 322 depends on HAVE_KERNEL_BZIP2
30d65dbf
AK
323 help
324 Its compression ratio and speed is intermediate.
0a4dd35c 325 Decompression speed is slowest among the choices. The kernel
2e9f3bdd
PA
326 size is about 10% smaller with bzip2, in comparison to gzip.
327 Bzip2 uses a large amount of memory. For modern kernels you
328 will need at least 8MB RAM or more for booting.
30d65dbf
AK
329
330config KERNEL_LZMA
2e9f3bdd
PA
331 bool "LZMA"
332 depends on HAVE_KERNEL_LZMA
333 help
0a4dd35c
RD
334 This compression algorithm's ratio is best. Decompression speed
335 is between gzip and bzip2. Compression is slowest.
336 The kernel size is about 33% smaller with LZMA in comparison to gzip.
30d65dbf 337
3ebe1243
LC
338config KERNEL_XZ
339 bool "XZ"
340 depends on HAVE_KERNEL_XZ
341 help
342 XZ uses the LZMA2 algorithm and instruction set specific
343 BCJ filters which can improve compression ratio of executable
344 code. The size of the kernel is about 30% smaller with XZ in
345 comparison to gzip. On architectures for which there is a BCJ
7472ff8a
LC
346 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC,
347 and SPARC), XZ will create a few percent smaller kernel than
348 plain LZMA.
3ebe1243
LC
349
350 The speed is about the same as with LZMA: The decompression
351 speed of XZ is better than that of bzip2 but worse than gzip
352 and LZO. Compression is slow.
353
7dd65feb
AT
354config KERNEL_LZO
355 bool "LZO"
356 depends on HAVE_KERNEL_LZO
357 help
0a4dd35c 358 Its compression ratio is the poorest among the choices. The kernel
681b3049 359 size is about 10% bigger than gzip; however its speed
7dd65feb
AT
360 (both compression and decompression) is the fastest.
361
e76e1fdf
KL
362config KERNEL_LZ4
363 bool "LZ4"
364 depends on HAVE_KERNEL_LZ4
365 help
366 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
367 A preliminary version of LZ4 de/compression tool is available at
368 <https://code.google.com/p/lz4/>.
369
370 Its compression ratio is worse than LZO. The size of the kernel
371 is about 8% bigger than LZO. But the decompression speed is
372 faster than LZO.
373
48f7ddf7
NT
374config KERNEL_ZSTD
375 bool "ZSTD"
376 depends on HAVE_KERNEL_ZSTD
377 help
378 ZSTD is a compression algorithm targeting intermediate compression
379 with fast decompression speed. It will compress better than GZIP and
380 decompress around the same speed as LZO, but slower than LZ4. You
381 will need at least 192 KB RAM or more for booting. The zstd command
382 line tool is required for compression.
383
f16466af
VG
384config KERNEL_UNCOMPRESSED
385 bool "None"
386 depends on HAVE_KERNEL_UNCOMPRESSED
387 help
388 Produce uncompressed kernel image. This option is usually not what
389 you want. It is useful for debugging the kernel in slow simulation
390 environments, where decompressing and moving the kernel is awfully
391 slow. This option allows early boot code to skip the decompressor
392 and jump right at uncompressed kernel image.
393
30d65dbf
AK
394endchoice
395
ada4ab7a
CD
396config DEFAULT_INIT
397 string "Default init path"
398 default ""
399 help
400 This option determines the default init for the system if no init=
401 option is passed on the kernel command line. If the requested path is
402 not present, we will still then move on to attempting further
403 locations (e.g. /sbin/init, etc). If this is empty, we will just use
404 the fallback list when init= is not passed.
405
bd5dc17b
JT
406config DEFAULT_HOSTNAME
407 string "Default hostname"
408 default "(none)"
409 help
410 This option determines the default system hostname before userspace
411 calls sethostname(2). The kernel traditionally uses "(none)" here,
412 but you may wish to use a different default here to make a minimal
413 system more usable with less configuration.
414
1da177e4
LT
415config SYSVIPC
416 bool "System V IPC"
a7f7f624 417 help
1da177e4
LT
418 Inter Process Communication is a suite of library functions and
419 system calls which let processes (running programs) synchronize and
420 exchange information. It is generally considered to be a good thing,
421 and some programs won't run unless you say Y here. In particular, if
422 you want to run the DOS emulator dosemu under Linux (read the
423 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
424 you'll need to say Y here.
425
426 You can find documentation about IPC with "info ipc" and also in
427 section 6.4 of the Linux Programmer's Guide, available from
428 <http://www.tldp.org/guides.html>.
429
a5494dcd
EB
430config SYSVIPC_SYSCTL
431 bool
432 depends on SYSVIPC
433 depends on SYSCTL
434 default y
435
0cbed0ee
GR
436config SYSVIPC_COMPAT
437 def_bool y
438 depends on COMPAT && SYSVIPC
439
1da177e4
LT
440config POSIX_MQUEUE
441 bool "POSIX Message Queues"
19c92399 442 depends on NET
a7f7f624 443 help
1da177e4
LT
444 POSIX variant of message queues is a part of IPC. In POSIX message
445 queues every message has a priority which decides about succession
446 of receiving it by a process. If you want to compile and run
447 programs written e.g. for Solaris with use of its POSIX message
b0e37650 448 queues (functions mq_*) say Y here.
1da177e4
LT
449
450 POSIX message queues are visible as a filesystem called 'mqueue'
451 and can be mounted somewhere if you want to do filesystem
452 operations on message queues.
453
454 If unsure, say Y.
455
bdc8e5f8
SH
456config POSIX_MQUEUE_SYSCTL
457 bool
458 depends on POSIX_MQUEUE
459 depends on SYSCTL
460 default y
461
c73be61c
DH
462config WATCH_QUEUE
463 bool "General notification queue"
464 default n
465 help
466
467 This is a general notification queue for the kernel to pass events to
468 userspace by splicing them into pipes. It can be used in conjunction
469 with watches for key/keyring change notifications and device
470 notifications.
471
c02b872a 472 See Documentation/core-api/watch_queue.rst
c73be61c 473
226b4ccd
KK
474config CROSS_MEMORY_ATTACH
475 bool "Enable process_vm_readv/writev syscalls"
476 depends on MMU
477 default y
478 help
479 Enabling this option adds the system calls process_vm_readv and
480 process_vm_writev which allow a process with the correct privileges
a2a368d9 481 to directly read from or write to another process' address space.
226b4ccd
KK
482 See the man page for more details.
483
391dc69c
FW
484config AUDIT
485 bool "Auditing support"
486 depends on NET
487 help
488 Enable auditing infrastructure that can be used with another
489 kernel subsystem, such as SELinux (which requires this for
cb74ed27
PM
490 logging of avc messages output). System call auditing is included
491 on architectures which support it.
391dc69c 492
7a017721
AT
493config HAVE_ARCH_AUDITSYSCALL
494 bool
495
391dc69c 496config AUDITSYSCALL
cb74ed27 497 def_bool y
7a017721 498 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
391dc69c
FW
499 select FSNOTIFY
500
391dc69c
FW
501source "kernel/irq/Kconfig"
502source "kernel/time/Kconfig"
b24abcff 503source "kernel/bpf/Kconfig"
87a4c375 504source "kernel/Kconfig.preempt"
391dc69c
FW
505
506menu "CPU/Task time and stats accounting"
507
abf917cd
FW
508config VIRT_CPU_ACCOUNTING
509 bool
510
fdf9c356
FW
511choice
512 prompt "Cputime accounting"
02382aff 513 default TICK_CPU_ACCOUNTING
fdf9c356
FW
514
515# Kind of a stub config for the pure tick based cputime accounting
516config TICK_CPU_ACCOUNTING
517 bool "Simple tick based cputime accounting"
c58b0df1 518 depends on !S390 && !NO_HZ_FULL
fdf9c356
FW
519 help
520 This is the basic tick based cputime accounting that maintains
521 statistics about user, system and idle time spent on per jiffies
522 granularity.
523
524 If unsure, say Y.
525
abf917cd 526config VIRT_CPU_ACCOUNTING_NATIVE
b952741c 527 bool "Deterministic task and CPU time accounting"
c58b0df1 528 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
abf917cd 529 select VIRT_CPU_ACCOUNTING
b952741c
FW
530 help
531 Select this option to enable more accurate task and CPU time
532 accounting. This is done by reading a CPU counter on each
533 kernel entry and exit and on transitions within the kernel
534 between system, softirq and hardirq state, so there is a
535 small performance impact. In the case of s390 or IBM POWER > 5,
536 this also enables accounting of stolen time on logically-partitioned
537 systems.
538
abf917cd
FW
539config VIRT_CPU_ACCOUNTING_GEN
540 bool "Full dynticks CPU time accounting"
24a9c541 541 depends on HAVE_CONTEXT_TRACKING_USER
554b0004 542 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
041a1574 543 depends on GENERIC_CLOCKEVENTS
abf917cd 544 select VIRT_CPU_ACCOUNTING
24a9c541 545 select CONTEXT_TRACKING_USER
abf917cd
FW
546 help
547 Select this option to enable task and CPU time accounting on full
548 dynticks systems. This accounting is implemented by watching every
549 kernel-user boundaries using the context tracking subsystem.
550 The accounting is thus performed at the expense of some significant
551 overhead.
552
553 For now this is only useful if you are working on the full
554 dynticks subsystem development.
555
556 If unsure, say N.
557
b58c3584
RR
558endchoice
559
fdf9c356
FW
560config IRQ_TIME_ACCOUNTING
561 bool "Fine granularity task level IRQ time accounting"
b58c3584 562 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
fdf9c356
FW
563 help
564 Select this option to enable fine granularity task irq time
565 accounting. This is done by reading a timestamp on each
566 transitions between softirq and hardirq state, so there can be a
567 small performance impact.
568
569 If in doubt, say N here.
570
11d4afd4
VG
571config HAVE_SCHED_AVG_IRQ
572 def_bool y
573 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
574 depends on SMP
575
d4dbc991 576config SCHED_HW_PRESSURE
98eb401d 577 bool
fcd7c9c3
VS
578 default y if ARM && ARM_CPU_TOPOLOGY
579 default y if ARM64
76504793 580 depends on SMP
98eb401d
VS
581 depends on CPU_FREQ_THERMAL
582 help
d4dbc991
VG
583 Select this option to enable HW pressure accounting in the
584 scheduler. HW pressure is the value conveyed to the scheduler
98eb401d 585 that reflects the reduction in CPU compute capacity resulted from
d4dbc991
VG
586 HW throttling. HW throttling occurs when the performance of
587 a CPU is capped due to high operating temperatures as an example.
98eb401d
VS
588
589 If selected, the scheduler will be able to balance tasks accordingly,
590 i.e. put less load on throttled CPUs than on non/less throttled ones.
591
592 This requires the architecture to implement
d4dbc991 593 arch_update_hw_pressure() and arch_scale_thermal_pressure().
76504793 594
1da177e4
LT
595config BSD_PROCESS_ACCT
596 bool "BSD Process Accounting"
2813893f 597 depends on MULTIUSER
1da177e4
LT
598 help
599 If you say Y here, a user level program will be able to instruct the
600 kernel (via a special system call) to write process accounting
601 information to a file: whenever a process exits, information about
602 that process will be appended to the file by the kernel. The
603 information includes things such as creation time, owning user,
604 command name, memory usage, controlling terminal etc. (the complete
605 list is in the struct acct in <file:include/linux/acct.h>). It is
606 up to the user level program to do useful things with this
607 information. This is generally a good idea, so say Y.
608
609config BSD_PROCESS_ACCT_V3
610 bool "BSD Process Accounting version 3 file format"
611 depends on BSD_PROCESS_ACCT
612 default n
613 help
614 If you say Y here, the process accounting information is written
615 in a new file format that also logs the process IDs of each
3903bf94 616 process and its parent. Note that this file format is incompatible
1da177e4
LT
617 with previous v0/v1/v2 file formats, so you will need updated tools
618 for processing it. A preliminary version of these tools is available
37a4c940 619 at <http://www.gnu.org/software/acct/>.
1da177e4 620
c757249a 621config TASKSTATS
19c92399 622 bool "Export task/process statistics through netlink"
c757249a 623 depends on NET
2813893f 624 depends on MULTIUSER
c757249a
SN
625 default n
626 help
627 Export selected statistics for tasks/processes through the
628 generic netlink interface. Unlike BSD process accounting, the
629 statistics are available during the lifetime of tasks/processes as
630 responses to commands. Like BSD accounting, they are sent to user
631 space on task exit.
632
633 Say N if unsure.
634
ca74e92b 635config TASK_DELAY_ACCT
19c92399 636 bool "Enable per-task delay accounting"
6f44993f 637 depends on TASKSTATS
f6db8347 638 select SCHED_INFO
ca74e92b
SN
639 help
640 Collect information on time spent by a task waiting for system
641 resources like cpu, synchronous block I/O completion and swapping
642 in pages. Such statistics can help in setting a task's priorities
643 relative to other tasks for cpu, io, rss limits etc.
644
645 Say N if unsure.
646
18f705f4 647config TASK_XACCT
19c92399 648 bool "Enable extended accounting over taskstats"
18f705f4
AD
649 depends on TASKSTATS
650 help
651 Collect extended task accounting data and send the data
652 to userland for processing over the taskstats interface.
653
654 Say N if unsure.
655
656config TASK_IO_ACCOUNTING
19c92399 657 bool "Enable per-task storage I/O accounting"
18f705f4
AD
658 depends on TASK_XACCT
659 help
660 Collect information on the number of bytes of storage I/O which this
661 task has caused.
662
663 Say N if unsure.
664
eb414681
JW
665config PSI
666 bool "Pressure stall information tracking"
98dfdd9e 667 select KERNFS
eb414681
JW
668 help
669 Collect metrics that indicate how overcommitted the CPU, memory,
670 and IO capacity are in the system.
671
672 If you say Y here, the kernel will create /proc/pressure/ with the
673 pressure statistics files cpu, memory, and io. These will indicate
674 the share of walltime in which some or all tasks in the system are
675 delayed due to contention of the respective resource.
676
2ce7135a
JW
677 In kernels with cgroup support, cgroups (cgroup2 only) will
678 have cpu.pressure, memory.pressure, and io.pressure files,
679 which aggregate pressure stalls for the grouped tasks only.
680
c3123552 681 For more details see Documentation/accounting/psi.rst.
eb414681
JW
682
683 Say N if unsure.
684
e0c27447
JW
685config PSI_DEFAULT_DISABLED
686 bool "Require boot parameter to enable pressure stall information tracking"
687 default n
688 depends on PSI
689 help
690 If set, pressure stall information tracking will be disabled
428a1cb4
BS
691 per default but can be enabled through passing psi=1 on the
692 kernel commandline during boot.
e0c27447 693
7b2489d3
JW
694 This feature adds some code to the task wakeup and sleep
695 paths of the scheduler. The overhead is too low to affect
696 common scheduling-intense workloads in practice (such as
697 webservers, memcache), but it does show up in artificial
698 scheduler stress tests, such as hackbench.
699
700 If you are paranoid and not sure what the kernel will be
701 used for, say Y.
702
703 Say N if unsure.
704
391dc69c 705endmenu # "CPU/Task time and stats accounting"
d9817ebe 706
5c4991e2
FW
707config CPU_ISOLATION
708 bool "CPU isolation"
97577684 709 depends on SMP
2c43838c 710 default y
5c4991e2
FW
711 help
712 Make sure that CPUs running critical tasks are not disturbed by
713 any source of "noise" such as unbound workqueues, timers, kthreads...
2c43838c
FW
714 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
715 the "isolcpus=" boot parameter.
716
717 Say Y if unsure.
5c4991e2 718
0af92d46 719source "kernel/rcu/Kconfig"
c903ff83 720
1da177e4 721config IKCONFIG
f2443ab6 722 tristate "Kernel .config support"
a7f7f624 723 help
1da177e4
LT
724 This option enables the complete Linux kernel ".config" file
725 contents to be saved in the kernel. It provides documentation
726 of which kernel options are used in a running kernel or in an
727 on-disk kernel. This information can be extracted from the kernel
728 image file with the script scripts/extract-ikconfig and used as
729 input to rebuild the current kernel or to build another kernel.
730 It can also be extracted from a running kernel by reading
731 /proc/config.gz if enabled (below).
732
733config IKCONFIG_PROC
734 bool "Enable access to .config through /proc/config.gz"
735 depends on IKCONFIG && PROC_FS
a7f7f624 736 help
1da177e4
LT
737 This option enables access to the kernel configuration file
738 through /proc/config.gz.
739
f7b101d3
JFG
740config IKHEADERS
741 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
742 depends on SYSFS
743 help
744 This option enables access to the in-kernel headers that are generated during
745 the build process. These can be used to build eBPF tracing programs,
746 or similar programs. If you build the headers as a module, a module called
747 kheaders.ko is built which can be loaded on-demand to get access to headers.
43d8ce9d 748
794543a2
AJS
749config LOG_BUF_SHIFT
750 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
1c4b5ecb 751 range 12 25
f17a32e9 752 default 17
361e9dfb 753 depends on PRINTK
794543a2 754 help
23b2899f
LR
755 Select the minimal kernel log buffer size as a power of 2.
756 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
757 parameter, see below. Any higher size also might be forced
758 by "log_buf_len" boot parameter.
759
f17a32e9 760 Examples:
23b2899f 761 17 => 128 KB
f17a32e9 762 16 => 64 KB
23b2899f
LR
763 15 => 32 KB
764 14 => 16 KB
794543a2
AJS
765 13 => 8 KB
766 12 => 4 KB
767
23b2899f
LR
768config LOG_CPU_MAX_BUF_SHIFT
769 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
2240a31d 770 depends on SMP
23b2899f 771 range 0 21
23b2899f 772 default 0 if BASE_SMALL
320bf431 773 default 12
361e9dfb 774 depends on PRINTK
23b2899f
LR
775 help
776 This option allows to increase the default ring buffer size
777 according to the number of CPUs. The value defines the contribution
778 of each CPU as a power of 2. The used space is typically only few
779 lines however it might be much more when problems are reported,
780 e.g. backtraces.
781
782 The increased size means that a new buffer has to be allocated and
783 the original static one is unused. It makes sense only on systems
784 with more CPUs. Therefore this value is used only when the sum of
785 contributions is greater than the half of the default kernel ring
786 buffer as defined by LOG_BUF_SHIFT. The default values are set
0f7636e1 787 so that more than 16 CPUs are needed to trigger the allocation.
23b2899f
LR
788
789 Also this option is ignored when "log_buf_len" kernel parameter is
790 used as it forces an exact (power of two) size of the ring buffer.
791
792 The number of possible CPUs is used for this computation ignoring
5e0d8d59
GU
793 hotplugging making the computation optimal for the worst case
794 scenario while allowing a simple algorithm to be used from bootup.
23b2899f
LR
795
796 Examples shift values and their meaning:
797 17 => 128 KB for each CPU
798 16 => 64 KB for each CPU
799 15 => 32 KB for each CPU
800 14 => 16 KB for each CPU
801 13 => 8 KB for each CPU
802 12 => 4 KB for each CPU
803
33701557
CD
804config PRINTK_INDEX
805 bool "Printk indexing debugfs interface"
806 depends on PRINTK && DEBUG_FS
807 help
808 Add support for indexing of all printk formats known at compile time
809 at <debugfs>/printk/index/<module>.
810
811 This can be used as part of maintaining daemons which monitor
812 /dev/kmsg, as it permits auditing the printk formats present in a
813 kernel, allowing detection of cases where monitored printks are
814 changed or no longer present.
815
816 There is no additional runtime cost to printk with this enabled.
817
a5574cf6
IM
818#
819# Architectures with an unreliable sched_clock() should select this:
820#
821config HAVE_UNSTABLE_SCHED_CLOCK
822 bool
823
38ff87f7
SB
824config GENERIC_SCHED_CLOCK
825 bool
826
69842cba
PB
827menu "Scheduler features"
828
829config UCLAMP_TASK
830 bool "Enable utilization clamping for RT/FAIR tasks"
831 depends on CPU_FREQ_GOV_SCHEDUTIL
832 help
833 This feature enables the scheduler to track the clamped utilization
834 of each CPU based on RUNNABLE tasks scheduled on that CPU.
835
836 With this option, the user can specify the min and max CPU
837 utilization allowed for RUNNABLE tasks. The max utilization defines
838 the maximum frequency a task should use while the min utilization
839 defines the minimum frequency it should use.
840
841 Both min and max utilization clamp values are hints to the scheduler,
842 aiming at improving its frequency selection policy, but they do not
843 enforce or grant any specific bandwidth for tasks.
844
845 If in doubt, say N.
846
847config UCLAMP_BUCKETS_COUNT
848 int "Number of supported utilization clamp buckets"
849 range 5 20
850 default 5
851 depends on UCLAMP_TASK
852 help
853 Defines the number of clamp buckets to use. The range of each bucket
854 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
855 number of clamp buckets the finer their granularity and the higher
856 the precision of clamping aggregation and tracking at run-time.
857
858 For example, with the minimum configuration value we will have 5
859 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
860 be refcounted in the [20..39]% bucket and will set the bucket clamp
861 effective value to 25%.
862 If a second 30% boosted task should be co-scheduled on the same CPU,
863 that task will be refcounted in the same bucket of the first task and
864 it will boost the bucket clamp effective value to 30%.
865 The clamp effective value of a bucket is reset to its nominal value
866 (20% in the example above) when there are no more tasks refcounted in
867 that bucket.
868
869 An additional boost/capping margin can be added to some tasks. In the
870 example above the 25% task will be boosted to 30% until it exits the
871 CPU. If that should be considered not acceptable on certain systems,
872 it's always possible to reduce the margin by increasing the number of
873 clamp buckets to trade off used memory for run-time tracking
874 precision.
875
876 If in doubt, use the default value.
877
878endmenu
879
be3a7284
AA
880#
881# For architectures that want to enable the support for NUMA-affine scheduler
882# balancing logic:
883#
884config ARCH_SUPPORTS_NUMA_BALANCING
885 bool
886
72b252ae
MG
887#
888# For architectures that prefer to flush all TLBs after a number of pages
889# are unmapped instead of sending one IPI per page to flush. The architecture
890# must provide guarantees on what happens if a clean TLB cache entry is
891# written after the unmap. Details are in mm/rmap.c near the check for
892# should_defer_flush. The architecture should also consider if the full flush
893# and the refill costs are offset by the savings of sending fewer IPIs.
894config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
895 bool
896
c12d3362 897config CC_HAS_INT128
3a7c7331 898 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
c12d3362 899
dee2b702
GS
900config CC_IMPLICIT_FALLTHROUGH
901 string
158ea2d2 902 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
dee2b702
GS
903 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
904
3e00f580 905# Currently, disable gcc-10+ array-bounds globally.
0da6e5fd 906# It's still broken in gcc-13, so no upper bound yet.
3e00f580 907config GCC10_NO_ARRAY_BOUNDS
5a41237a
LT
908 def_bool y
909
f0be87c4
LT
910config CC_NO_ARRAY_BOUNDS
911 bool
8e5bd4ea 912 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS
f0be87c4 913
02153319
LT
914# Currently, disable -Wstringop-overflow for GCC globally.
915config GCC_NO_STRINGOP_OVERFLOW
a5e0ace0
GS
916 def_bool y
917
918config CC_NO_STRINGOP_OVERFLOW
919 bool
02153319 920 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
a5e0ace0
GS
921
922config CC_STRINGOP_OVERFLOW
923 bool
924 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
925
be5e610c
PZ
926#
927# For architectures that know their GCC __int128 support is sound
928#
929config ARCH_SUPPORTS_INT128
930 bool
931
be3a7284
AA
932# For architectures that (ab)use NUMA to represent different memory regions
933# all cpu-local but of different latencies, such as SuperH.
934#
935config ARCH_WANT_NUMA_VARIABLE_LOCALITY
936 bool
937
be3a7284
AA
938config NUMA_BALANCING
939 bool "Memory placement aware NUMA scheduler"
be3a7284
AA
940 depends on ARCH_SUPPORTS_NUMA_BALANCING
941 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
554b0f3c 942 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
be3a7284
AA
943 help
944 This option adds support for automatic NUMA aware memory/task placement.
945 The mechanism is quite primitive and is based on migrating memory when
6d56a410 946 it has references to the node the task is running on.
be3a7284
AA
947
948 This system will be inactive on UMA systems.
949
6f7c97e8
AK
950config NUMA_BALANCING_DEFAULT_ENABLED
951 bool "Automatically enable NUMA aware memory/task placement"
952 default y
953 depends on NUMA_BALANCING
954 help
955 If set, automatic NUMA balancing will be enabled if running on a NUMA
956 machine.
957
21c690a3
SB
958config SLAB_OBJ_EXT
959 bool
960
23964d2d 961menuconfig CGROUPS
6341e62b 962 bool "Control Group support"
2bd59d48 963 select KERNFS
5cdc38f9 964 help
23964d2d 965 This option adds support for grouping sets of processes together, for
5cdc38f9
KH
966 use with process control subsystems such as Cpusets, CFS, memory
967 controls or device isolation.
968 See
d6a3b247 969 - Documentation/scheduler/sched-design-CFS.rst (CFS)
da82c92f 970 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
45ce80fb 971 and resource control)
5cdc38f9
KH
972
973 Say N if unsure.
974
23964d2d
LZ
975if CGROUPS
976
3e32cb2e 977config PAGE_COUNTER
e8cf4e9c 978 bool
3e32cb2e 979
6a010a49
TH
980config CGROUP_FAVOR_DYNMODS
981 bool "Favor dynamic modification latency reduction by default"
982 help
983 This option enables the "favordynmods" mount option by default
984 which reduces the latencies of dynamic cgroup modifications such
985 as task migrations and controller on/offs at the cost of making
986 hot path operations such as forks and exits more expensive.
987
988 Say N if unsure.
989
c255a458 990config MEMCG
a0166ec4 991 bool "Memory controller"
3e32cb2e 992 select PAGE_COUNTER
79bd9814 993 select EVENTFD
21c690a3 994 select SLAB_OBJ_EXT
00f0b825 995 help
a0166ec4 996 Provides control over the memory footprint of tasks in a cgroup.
00f0b825 997
25352d2f
SB
998config MEMCG_NMI_UNSAFE
999 bool
1000 depends on MEMCG
1001 depends on HAVE_NMI
1002 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !ARCH_HAVE_NMI_SAFE_CMPXCHG
1003 default y
1004
940b01fc
SB
1005config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC
1006 bool
1007 depends on MEMCG
1008 depends on HAVE_NMI
1009 depends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && ARCH_HAVE_NMI_SAFE_CMPXCHG
1010 default y
1011
e93d4166
RG
1012config MEMCG_V1
1013 bool "Legacy cgroup v1 memory controller"
c9929f0e 1014 depends on MEMCG
e93d4166
RG
1015 default n
1016 help
1017 Legacy cgroup v1 memory controller which has been deprecated by
1018 cgroup v2 implementation. The v1 is there for legacy applications
1019 which haven't migrated to the new cgroup v2 interface yet. If you
1020 do not have any such application then you are completely fine leaving
1021 this option disabled.
1022
1023 Please note that feature set of the legacy memory controller is likely
1024 going to shrink due to deprecation process. New deployments with v1
1025 controller are highly discouraged.
1026
fcb4824b 1027 Say N if unsure.
84c07d11 1028
6bf024e6
JW
1029config BLK_CGROUP
1030 bool "IO controller"
1031 depends on BLOCK
2bc64a20 1032 default n
a7f7f624 1033 help
6bf024e6
JW
1034 Generic block IO controller cgroup interface. This is the common
1035 cgroup interface which should be used by various IO controlling
1036 policies.
2bc64a20 1037
6bf024e6
JW
1038 Currently, CFQ IO scheduler uses it to recognize task groups and
1039 control disk bandwidth allocation (proportional time slice allocation)
1040 to such task groups. It is also used by bio throttling logic in
1041 block layer to implement upper limit in IO rates on a device.
e5d1367f 1042
6bf024e6
JW
1043 This option only enables generic Block IO controller infrastructure.
1044 One needs to also enable actual IO controlling logic/policy. For
1045 enabling proportional weight division of disk bandwidth in CFQ, set
7baf2199 1046 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
6bf024e6
JW
1047 CONFIG_BLK_DEV_THROTTLING=y.
1048
da82c92f 1049 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
6bf024e6 1050
6bf024e6
JW
1051config CGROUP_WRITEBACK
1052 bool
1053 depends on MEMCG && BLK_CGROUP
1054 default y
e5d1367f 1055
7c941438 1056menuconfig CGROUP_SCHED
a0166ec4 1057 bool "CPU controller"
7c941438
DG
1058 default n
1059 help
1060 This feature lets CPU scheduler recognize task groups and control CPU
1061 bandwidth allocation to such task groups. It uses cgroups to group
1062 tasks.
1063
1064if CGROUP_SCHED
e179e80c
TH
1065config GROUP_SCHED_WEIGHT
1066 def_bool n
1067
7c941438
DG
1068config FAIR_GROUP_SCHED
1069 bool "Group scheduling for SCHED_OTHER"
1070 depends on CGROUP_SCHED
e179e80c 1071 select GROUP_SCHED_WEIGHT
7c941438
DG
1072 default CGROUP_SCHED
1073
ab84d31e
PT
1074config CFS_BANDWIDTH
1075 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
ab84d31e
PT
1076 depends on FAIR_GROUP_SCHED
1077 default n
1078 help
1079 This option allows users to define CPU bandwidth rates (limits) for
1080 tasks running within the fair group scheduler. Groups with no limit
1081 set are considered to be unconstrained and will run with no
1082 restriction.
d6a3b247 1083 See Documentation/scheduler/sched-bwc.rst for more information.
ab84d31e 1084
7c941438
DG
1085config RT_GROUP_SCHED
1086 bool "Group scheduling for SCHED_RR/FIFO"
7c941438
DG
1087 depends on CGROUP_SCHED
1088 default n
1089 help
1090 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 1091 to task groups. If enabled, it will also make it impossible to
7c941438
DG
1092 schedule realtime tasks for non-root users until you allocate
1093 realtime bandwidth for them.
d6a3b247 1094 See Documentation/scheduler/sched-rt-group.rst for more information.
7c941438 1095
e34e0131
MK
1096config RT_GROUP_SCHED_DEFAULT_DISABLED
1097 bool "Require boot parameter to enable group scheduling for SCHED_RR/FIFO"
1098 depends on RT_GROUP_SCHED
1099 default n
1100 help
1101 When set, the RT group scheduling is disabled by default. The option
1102 is in inverted form so that mere RT_GROUP_SCHED enables the group
1103 scheduling.
1104
1105 Say N if unsure.
1106
81951366
TH
1107config EXT_GROUP_SCHED
1108 bool
1109 depends on SCHED_CLASS_EXT && CGROUP_SCHED
1110 select GROUP_SCHED_WEIGHT
1111 default y
1112
7c941438
DG
1113endif #CGROUP_SCHED
1114
af7f588d
MD
1115config SCHED_MM_CID
1116 def_bool y
1117 depends on SMP && RSEQ
1118
2480c093
PB
1119config UCLAMP_TASK_GROUP
1120 bool "Utilization clamping per group of tasks"
1121 depends on CGROUP_SCHED
1122 depends on UCLAMP_TASK
1123 default n
1124 help
1125 This feature enables the scheduler to track the clamped utilization
1126 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1127
1128 When this option is enabled, the user can specify a min and max
1129 CPU bandwidth which is allowed for each single task in a group.
1130 The max bandwidth allows to clamp the maximum frequency a task
1131 can use, while the min bandwidth allows to define a minimum
1132 frequency a task will always use.
1133
1134 When task group based utilization clamping is enabled, an eventually
1135 specified task-specific clamp value is constrained by the cgroup
1136 specified clamp value. Both minimum and maximum task clamping cannot
1137 be bigger than the corresponding clamping defined at task group level.
1138
1139 If in doubt, say N.
1140
6bf024e6
JW
1141config CGROUP_PIDS
1142 bool "PIDs controller"
1143 help
1144 Provides enforcement of process number limits in the scope of a
1145 cgroup. Any attempt to fork more processes than is allowed in the
1146 cgroup will fail. PIDs are fundamentally a global resource because it
1147 is fairly trivial to reach PID exhaustion before you reach even a
1148 conservative kmemcg limit. As a result, it is possible to grind a
1149 system to halt without being limited by other cgroup policies. The
6cc578df 1150 PIDs controller is designed to stop this from happening.
6bf024e6
JW
1151
1152 It should be noted that organisational operations (such as attaching
98076833 1153 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
6bf024e6
JW
1154 since the PIDs limit only affects a process's ability to fork, not to
1155 attach to a cgroup.
1156
39d3e758
PP
1157config CGROUP_RDMA
1158 bool "RDMA controller"
1159 help
1160 Provides enforcement of RDMA resources defined by IB stack.
1161 It is fairly easy for consumers to exhaust RDMA resources, which
1162 can result into resource unavailability to other consumers.
1163 RDMA controller is designed to stop this from happening.
1164 Attaching processes with active RDMA resources to the cgroup
1165 hierarchy is allowed even if can cross the hierarchy's limit.
1166
b168ed45
ML
1167config CGROUP_DMEM
1168 bool "Device memory controller (DMEM)"
e33b5149 1169 select PAGE_COUNTER
b168ed45
ML
1170 help
1171 The DMEM controller allows compatible devices to restrict device
1172 memory usage based on the cgroup hierarchy.
1173
1174 As an example, it allows you to restrict VRAM usage for applications
1175 in the DRM subsystem.
1176
6bf024e6
JW
1177config CGROUP_FREEZER
1178 bool "Freezer controller"
1179 help
1180 Provides a way to freeze and unfreeze all tasks in a
1181 cgroup.
1182
489c2a20
JW
1183 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1184 controller includes important in-kernel memory consumers per default.
1185
1186 If you're using cgroup2, say N.
1187
6bf024e6
JW
1188config CGROUP_HUGETLB
1189 bool "HugeTLB controller"
1190 depends on HUGETLB_PAGE
1191 select PAGE_COUNTER
afc24d49 1192 default n
6bf024e6
JW
1193 help
1194 Provides a cgroup controller for HugeTLB pages.
1195 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1196 The limit is enforced during page fault. Since HugeTLB doesn't
1197 support page reclaim, enforcing the limit at page fault time implies
1198 that, the application will get SIGBUS signal if it tries to access
1199 HugeTLB pages beyond its limit. This requires the application to know
1200 beforehand how much HugeTLB pages it would require for its use. The
1201 control group is tracked in the third page lru pointer. This means
1202 that we cannot use the controller with huge page less than 3 pages.
afc24d49 1203
6bf024e6
JW
1204config CPUSETS
1205 bool "Cpuset controller"
e1d4eeec 1206 depends on SMP
bf9850f6 1207 select UNION_FIND
6bf024e6
JW
1208 help
1209 This option will let you create and manage CPUSETs which
1210 allow dynamically partitioning a system into sets of CPUs and
1211 Memory Nodes and assigning tasks to run only within those sets.
1212 This is primarily useful on large SMP or NUMA systems.
afc24d49 1213
6bf024e6 1214 Say N if unsure.
afc24d49 1215
1abab1ba
CR
1216config CPUSETS_V1
1217 bool "Legacy cgroup v1 cpusets controller"
1218 depends on CPUSETS
1219 default n
1220 help
1221 Legacy cgroup v1 cpusets controller which has been deprecated by
1222 cgroup v2 implementation. The v1 is there for legacy applications
dae68fba
MK
1223 which haven't migrated to the new cgroup v2 interface yet. Legacy
1224 interface includes cpuset filesystem and /proc/<pid>/cpuset. If you
1abab1ba
CR
1225 do not have any such application then you are completely fine leaving
1226 this option disabled.
1227
1228 Say N if unsure.
1229
6bf024e6
JW
1230config PROC_PID_CPUSET
1231 bool "Include legacy /proc/<pid>/cpuset file"
dae68fba 1232 depends on CPUSETS_V1
6bf024e6 1233 default y
afc24d49 1234
6bf024e6
JW
1235config CGROUP_DEVICE
1236 bool "Device controller"
1237 help
1238 Provides a cgroup controller implementing whitelists for
1239 devices which a process in the cgroup can mknod or open.
1240
1241config CGROUP_CPUACCT
1242 bool "Simple CPU accounting controller"
1243 help
1244 Provides a simple controller for monitoring the
1245 total CPU consumed by the tasks in a cgroup.
1246
1247config CGROUP_PERF
1248 bool "Perf controller"
1249 depends on PERF_EVENTS
1250 help
1251 This option extends the perf per-cpu mode to restrict monitoring
1252 to threads which belong to the cgroup specified and run on the
6546b19f
NK
1253 designated cpu. Or this can be used to have cgroup ID in samples
1254 so that it can monitor performance events among cgroups.
6bf024e6
JW
1255
1256 Say N if unsure.
1257
30070984
DM
1258config CGROUP_BPF
1259 bool "Support for eBPF programs attached to cgroups"
483c4933
AL
1260 depends on BPF_SYSCALL
1261 select SOCK_CGROUP_DATA
30070984
DM
1262 help
1263 Allow attaching eBPF programs to a cgroup using the bpf(2)
1264 syscall command BPF_PROG_ATTACH.
1265
1266 In which context these programs are accessed depends on the type
1267 of attachment. For instance, programs that are attached using
1268 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1269 inet sockets.
1270
a72232ea
VS
1271config CGROUP_MISC
1272 bool "Misc resource controller"
1273 default n
1274 help
1275 Provides a controller for miscellaneous resources on a host.
1276
1277 Miscellaneous scalar resources are the resources on the host system
1278 which cannot be abstracted like the other cgroups. This controller
1279 tracks and limits the miscellaneous resources used by a process
1280 attached to a cgroup hierarchy.
1281
1282 For more information, please check misc cgroup section in
1283 /Documentation/admin-guide/cgroup-v2.rst.
1284
6bf024e6 1285config CGROUP_DEBUG
23b0be48 1286 bool "Debug controller"
afc24d49 1287 default n
23b0be48 1288 depends on DEBUG_KERNEL
6bf024e6
JW
1289 help
1290 This option enables a simple controller that exports
23b0be48
WL
1291 debugging information about the cgroups framework. This
1292 controller is for control cgroup debugging only. Its
1293 interfaces are not stable.
afc24d49 1294
6bf024e6 1295 Say N.
89e9b9e0 1296
73b35147
AB
1297config SOCK_CGROUP_DATA
1298 bool
1299 default n
1300
23964d2d 1301endif # CGROUPS
c077719b 1302
8dd2a82c 1303menuconfig NAMESPACES
6a108a14 1304 bool "Namespaces support" if EXPERT
2813893f 1305 depends on MULTIUSER
6a108a14 1306 default !EXPERT
c5289a69
PE
1307 help
1308 Provides the way to make tasks work with different objects using
1309 the same id. For example same IPC id may refer to different objects
1310 or same user id or pid may refer to different tasks when used in
1311 different namespaces.
1312
8dd2a82c
DL
1313if NAMESPACES
1314
58bfdd6d
PE
1315config UTS_NS
1316 bool "UTS namespace"
17a6d441 1317 default y
58bfdd6d
PE
1318 help
1319 In this namespace tasks see different info provided with the
1320 uname() system call
1321
769071ac
AV
1322config TIME_NS
1323 bool "TIME namespace"
660fd04f 1324 depends on GENERIC_VDSO_TIME_NS
769071ac
AV
1325 default y
1326 help
1327 In this namespace boottime and monotonic clocks can be set.
1328 The time will keep going with the same pace.
1329
ae5e1b22
PE
1330config IPC_NS
1331 bool "IPC namespace"
8dd2a82c 1332 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 1333 default y
ae5e1b22
PE
1334 help
1335 In this namespace tasks work with IPC ids which correspond to
614b84cf 1336 different IPC objects in different namespaces.
ae5e1b22 1337
aee16ce7 1338config USER_NS
19c92399 1339 bool "User namespace"
5673a94c 1340 default n
aee16ce7
PE
1341 help
1342 This allows containers, i.e. vservers, to use user namespaces
1343 to provide different user info for different servers.
e11f0ae3
EB
1344
1345 When user namespaces are enabled in the kernel it is
d886f4e4
JW
1346 recommended that the MEMCG option also be enabled and that
1347 user-space use the memory control groups to limit the amount
1348 of memory a memory unprivileged users can use.
e11f0ae3 1349
aee16ce7
PE
1350 If unsure, say N.
1351
74bd59bb 1352config PID_NS
9bd38c2c 1353 bool "PID Namespaces"
17a6d441 1354 default y
74bd59bb 1355 help
12d2b8f9 1356 Support process id namespaces. This allows having multiple
692105b8 1357 processes with the same pid as long as they are in different
74bd59bb
PE
1358 pid namespaces. This is a building block of containers.
1359
d6eb633f
MH
1360config NET_NS
1361 bool "Network namespace"
8dd2a82c 1362 depends on NET
17a6d441 1363 default y
d6eb633f
MH
1364 help
1365 Allow user space to create what appear to be multiple instances
1366 of the network stack.
1367
8dd2a82c
DL
1368endif # NAMESPACES
1369
5cb366bb
AR
1370config CHECKPOINT_RESTORE
1371 bool "Checkpoint/restore support"
30341ec9 1372 depends on PROC_FS
5cb366bb 1373 select PROC_CHILDREN
bfe3911a 1374 select KCMP
5cb366bb
AR
1375 default n
1376 help
1377 Enables additional kernel features in a sake of checkpoint/restore.
1378 In particular it adds auxiliary prctl codes to setup process text,
1379 data and heap segment sizes, and a few additional /proc filesystem
1380 entries.
1381
1382 If unsure, say N here.
1383
5091faa4
MG
1384config SCHED_AUTOGROUP
1385 bool "Automatic process group scheduling"
5091faa4
MG
1386 select CGROUPS
1387 select CGROUP_SCHED
1388 select FAIR_GROUP_SCHED
1389 help
1390 This option optimizes the scheduler for common desktop workloads by
1391 automatically creating and populating task groups. This separation
1392 of workloads isolates aggressive CPU burners (like build jobs) from
1393 desktop applications. Task group autogeneration is currently based
1394 upon task session.
1395
7af37bec
DL
1396config RELAY
1397 bool "Kernel->user space relay support (formerly relayfs)"
26b5679e 1398 select IRQ_WORK
7af37bec
DL
1399 help
1400 This option enables support for relay interface support in
1401 certain file systems (such as debugfs).
1402 It is designed to provide an efficient mechanism for tools and
1403 facilities to relay large amounts of data from kernel space to
1404 user space.
1405
1406 If unsure, say N.
1407
f991633d
DG
1408config BLK_DEV_INITRD
1409 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
f991633d
DG
1410 help
1411 The initial RAM filesystem is a ramfs which is loaded by the
1412 boot loader (loadlin or lilo) and that is mounted as root
1413 before the normal boot procedure. It is typically used to
1414 load modules needed to mount the "real" root file system,
8c27ceff 1415 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
f991633d
DG
1416
1417 If RAM disk support (BLK_DEV_RAM) is also included, this
1418 also enables initial RAM disk (initrd) support and adds
1419 15 Kbytes (more on some other architectures) to the kernel size.
1420
1421 If unsure say Y.
1422
c33df4ea
JPS
1423if BLK_DEV_INITRD
1424
dbec4866
SR
1425source "usr/Kconfig"
1426
c33df4ea
JPS
1427endif
1428
76db5a27
MH
1429config BOOT_CONFIG
1430 bool "Boot config support"
a2a9d67a 1431 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
76db5a27
MH
1432 help
1433 Extra boot config allows system admin to pass a config file as
1434 complemental extension of kernel cmdline when booting.
0947db01 1435 The boot config file must be attached at the end of initramfs
85c46b78 1436 with checksum, size and magic word.
0947db01 1437 See <file:Documentation/admin-guide/bootconfig.rst> for details.
76db5a27
MH
1438
1439 If unsure, say Y.
1440
b743852c
PM
1441config BOOT_CONFIG_FORCE
1442 bool "Force unconditional bootconfig processing"
1443 depends on BOOT_CONFIG
6ded8a28 1444 default y if BOOT_CONFIG_EMBED
b743852c
PM
1445 help
1446 With this Kconfig option set, BOOT_CONFIG processing is carried
1447 out even when the "bootconfig" kernel-boot parameter is omitted.
1448 In fact, with this Kconfig option set, there is no way to
1449 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
1450 parameters.
1451
1452 If unsure, say N.
1453
a2a9d67a
MH
1454config BOOT_CONFIG_EMBED
1455 bool "Embed bootconfig file in the kernel"
1456 depends on BOOT_CONFIG
1457 help
1458 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1459 kernel. Usually, the bootconfig file is loaded with the initrd
1460 image. But if the system doesn't support initrd, this option will
1461 help you by embedding a bootconfig file while building the kernel.
1462
1463 If unsure, say N.
1464
1465config BOOT_CONFIG_EMBED_FILE
1466 string "Embedded bootconfig file path"
1467 depends on BOOT_CONFIG_EMBED
1468 help
1469 Specify a bootconfig file which will be embedded to the kernel.
1470 This bootconfig will be used if there is no initrd or no other
1471 bootconfig in the initrd.
1472
1274aea1
DD
1473config INITRAMFS_PRESERVE_MTIME
1474 bool "Preserve cpio archive mtimes in initramfs"
1475 default y
1476 help
1477 Each entry in an initramfs cpio archive carries an mtime value. When
1478 enabled, extracted cpio items take this mtime, with directory mtime
1479 setting deferred until after creation of any child entries.
1480
1481 If unsure, say Y.
76db5a27 1482
83c0b272
DD
1483config INITRAMFS_TEST
1484 bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS
1485 depends on BLK_DEV_INITRD && KUNIT=y
1486 default KUNIT_ALL_TESTS
1487 help
1488 Build KUnit tests for initramfs. See Documentation/dev-tools/kunit
1489
877417e6
AB
1490choice
1491 prompt "Compiler optimization level"
2cc3ce24 1492 default CC_OPTIMIZE_FOR_PERFORMANCE
877417e6
AB
1493
1494config CC_OPTIMIZE_FOR_PERFORMANCE
15f5db60 1495 bool "Optimize for performance (-O2)"
877417e6
AB
1496 help
1497 This is the default optimization level for the kernel, building
1498 with the "-O2" compiler flag for best performance and most
1499 helpful compile-time warnings.
1500
c45b4f1f 1501config CC_OPTIMIZE_FOR_SIZE
15f5db60 1502 bool "Optimize for size (-Os)"
c45b4f1f 1503 help
ce3b487f
MY
1504 Choosing this option will pass "-Os" to your compiler resulting
1505 in a smaller kernel.
c45b4f1f 1506
877417e6
AB
1507endchoice
1508
5d20ee31
NP
1509config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1510 bool
1511 help
1512 This requires that the arch annotates or otherwise protects
1513 its external entry points from being discarded. Linker scripts
1514 must also merge .text.*, .data.*, and .bss.* correctly into
1515 output sections. Care must be taken not to pull in unrelated
1516 sections (e.g., '.text.init'). Typically '.' in section names
1517 is used to distinguish them from label names / C identifiers.
1518
1519config LD_DEAD_CODE_DATA_ELIMINATION
1520 bool "Dead code and data elimination (EXPERIMENTAL)"
1521 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1522 depends on EXPERT
e85d1d65
MY
1523 depends on $(cc-option,-ffunction-sections -fdata-sections)
1524 depends on $(ld-option,--gc-sections)
5d20ee31 1525 help
8b9d2712
MY
1526 Enable this if you want to do dead code and data elimination with
1527 the linker by compiling with -ffunction-sections -fdata-sections,
1528 and linking with --gc-sections.
5d20ee31
NP
1529
1530 This can reduce on disk and in-memory size of the kernel
1531 code and static data, particularly for small configs and
1532 on small systems. This has the possibility of introducing
1533 silently broken kernel if the required annotations are not
1534 present. This option is not well tested yet, so use at your
1535 own risk.
1536
59612b24
NC
1537config LD_ORPHAN_WARN
1538 def_bool y
1539 depends on ARCH_WANT_LD_ORPHAN_WARN
1540 depends on $(ld-option,--orphan-handling=warn)
e1789d7c
XL
1541 depends on $(ld-option,--orphan-handling=error)
1542
1543config LD_ORPHAN_WARN_LEVEL
1544 string
1545 depends on LD_ORPHAN_WARN
1546 default "error" if WERROR
1547 default "warn"
59612b24 1548
0847062a
RD
1549config SYSCTL
1550 bool
1551
657a5209
MF
1552config HAVE_UID16
1553 bool
1554
1555config SYSCTL_EXCEPTION_TRACE
1556 bool
1557 help
1558 Enable support for /proc/sys/debug/exception-trace.
1559
1560config SYSCTL_ARCH_UNALIGN_NO_WARN
1561 bool
1562 help
1563 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1564 Allows arch to define/use @no_unaligned_warning to possibly warn
1565 about unaligned access emulation going on under the hood.
1566
1567config SYSCTL_ARCH_UNALIGN_ALLOW
1568 bool
1569 help
1570 Enable support for /proc/sys/kernel/unaligned-trap
1571 Allows arches to define/use @unaligned_enabled to runtime toggle
1572 the unaligned access emulation.
1573 see arch/parisc/kernel/unaligned.c for reference
1574
c443279a
CB
1575config SYSFS_SYSCALL
1576 bool "Sysfs syscall support"
1577 default n
1578 help
1579 sys_sysfs is an obsolete system call no longer supported in libc.
1580 Note that disabling this option is more secure but might break
1581 compatibility with some systems.
1582
1583 If unsure say N here.
1584
657a5209
MF
1585config HAVE_PCSPKR_PLATFORM
1586 bool
1587
6a108a14
DR
1588menuconfig EXPERT
1589 bool "Configure standard kernel features (expert users)"
f505c553
JT
1590 # Unhide debug options, to make the on-by-default options visible
1591 select DEBUG_KERNEL
1da177e4
LT
1592 help
1593 This option allows certain base kernel options and settings
e8cf4e9c
KK
1594 to be disabled or tweaked. This is for specialized
1595 environments which can tolerate a "non-standard" kernel.
1596 Only use this if you really know what you are doing.
1da177e4 1597
ae81f9e3 1598config UID16
6a108a14 1599 bool "Enable 16-bit UID system calls" if EXPERT
2813893f 1600 depends on HAVE_UID16 && MULTIUSER
ae81f9e3
CE
1601 default y
1602 help
1603 This enables the legacy 16-bit UID syscall wrappers.
1604
2813893f
IM
1605config MULTIUSER
1606 bool "Multiple users, groups and capabilities support" if EXPERT
1607 default y
1608 help
1609 This option enables support for non-root users, groups and
1610 capabilities.
1611
1612 If you say N here, all processes will run with UID 0, GID 0, and all
1613 possible capabilities. Saying N here also compiles out support for
1614 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1615 setgid, and capset.
1616
1617 If unsure, say Y here.
1618
f6187769
FF
1619config SGETMASK_SYSCALL
1620 bool "sgetmask/ssetmask syscalls support" if EXPERT
cd14b018 1621 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
a7f7f624 1622 help
f6187769
FF
1623 sys_sgetmask and sys_ssetmask are obsolete system calls
1624 no longer supported in libc but still enabled by default in some
1625 architectures.
1626
1627 If unsure, leave the default option here.
1628
d1b069f5
RD
1629config FHANDLE
1630 bool "open by fhandle syscalls" if EXPERT
1631 select EXPORTFS
1632 default y
1633 help
1634 If you say Y here, a user level program will be able to map
1635 file names to handle and then later use the handle for
1636 different file system operations. This is useful in implementing
1637 userspace file servers, which now track files using handles instead
1638 of names. The handle would remain the same even if file names
1639 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1640 syscalls.
1641
baa73d9e
NP
1642config POSIX_TIMERS
1643 bool "Posix Clocks & timers" if EXPERT
1644 default y
1645 help
1646 This includes native support for POSIX timers to the kernel.
1647 Some embedded systems have no use for them and therefore they
1648 can be configured out to reduce the size of the kernel image.
1649
1650 When this option is disabled, the following syscalls won't be
1651 available: timer_create, timer_gettime: timer_getoverrun,
1652 timer_settime, timer_delete, clock_adjtime, getitimer,
1653 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1654 clock_getres and clock_nanosleep syscalls will be limited to
1655 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1656
1657 If unsure say y.
1658
d59745ce
MM
1659config PRINTK
1660 default y
6a108a14 1661 bool "Enable support for printk" if EXPERT
74876a98 1662 select IRQ_WORK
d59745ce
MM
1663 help
1664 This option enables normal printk support. Removing it
1665 eliminates most of the message strings from the kernel image
1666 and makes the kernel more or less silent. As this makes it
1667 very difficult to diagnose system problems, saying N here is
1668 strongly discouraged.
1669
c8538a7a 1670config BUG
6a108a14 1671 bool "BUG() support" if EXPERT
c8538a7a
MM
1672 default y
1673 help
e8cf4e9c
KK
1674 Disabling this option eliminates support for BUG and WARN, reducing
1675 the size of your kernel image and potentially quietly ignoring
1676 numerous fatal conditions. You should only consider disabling this
1677 option for embedded systems with no facilities for reporting errors.
1678 Just say Y.
c8538a7a 1679
708e9a79 1680config ELF_CORE
046d662f 1681 depends on COREDUMP
708e9a79 1682 default y
6a108a14 1683 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1684 help
1685 Enable support for generating core dumps. Disabling saves about 4k.
1686
8761f1ab 1687
e5e1d3cb 1688config PCSPKR_PLATFORM
6a108a14 1689 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1690 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1691 select I8253_LOCK
e5e1d3cb
SS
1692 default y
1693 help
e8cf4e9c
KK
1694 This option allows to disable the internal PC-Speaker
1695 support, saving some memory.
e5e1d3cb 1696
27021649
YC
1697config BASE_SMALL
1698 bool "Enable smaller-sized data structures for core" if EXPERT
1da177e4 1699 help
27021649 1700 Enabling this option reduces the size of miscellaneous core
1da177e4
LT
1701 kernel data structures. This saves memory on small machines,
1702 but may reduce performance.
1703
1704config FUTEX
6a108a14 1705 bool "Enable futex support" if EXPERT
3f2bedab 1706 depends on !(SPARC32 && SMP)
1da177e4 1707 default y
bc2eecd7 1708 imply RT_MUTEXES
1da177e4
LT
1709 help
1710 Disabling this option will cause the kernel to be built without
1711 support for "fast userspace mutexes". The resulting kernel may not
1712 run glibc-based applications correctly.
1713
bc2eecd7
NP
1714config FUTEX_PI
1715 bool
1716 depends on FUTEX && RT_MUTEXES
1717 default y
1718
80367ad0
SAS
1719config FUTEX_PRIVATE_HASH
1720 bool
1721 depends on FUTEX && !BASE_SMALL && MMU
1722 default y
1723
c042c505
PZ
1724config FUTEX_MPOL
1725 bool
1726 depends on FUTEX && NUMA
1727 default y
1728
1da177e4 1729config EPOLL
6a108a14 1730 bool "Enable eventpoll support" if EXPERT
1da177e4
LT
1731 default y
1732 help
1733 Disabling this option will cause the kernel to be built without
1734 support for epoll family of system calls.
1735
fba2afaa 1736config SIGNALFD
6a108a14 1737 bool "Enable signalfd() system call" if EXPERT
fba2afaa
DL
1738 default y
1739 help
1740 Enable the signalfd() system call that allows to receive signals
1741 on a file descriptor.
1742
1743 If unsure, say Y.
1744
b215e283 1745config TIMERFD
6a108a14 1746 bool "Enable timerfd() system call" if EXPERT
b215e283
DL
1747 default y
1748 help
1749 Enable the timerfd() system call that allows to receive timer
1750 events on a file descriptor.
1751
1752 If unsure, say Y.
1753
e1ad7468 1754config EVENTFD
6a108a14 1755 bool "Enable eventfd() system call" if EXPERT
e1ad7468
DL
1756 default y
1757 help
1758 Enable the eventfd() system call that allows to receive both
1759 kernel notification (ie. KAIO) or userspace notifications.
1760
1761 If unsure, say Y.
1762
1da177e4 1763config SHMEM
6a108a14 1764 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1765 default y
1766 depends on MMU
1767 help
1768 The shmem is an internal filesystem used to manage shared memory.
1769 It is backed by swap and manages resource limits. It is also exported
1770 to userspace as tmpfs if TMPFS is enabled. Disabling this
1771 option replaces shmem and tmpfs with the much simpler ramfs code,
1772 which may be appropriate on small systems without swap.
1773
ebf3f09c 1774config AIO
6a108a14 1775 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1776 default y
1777 help
1778 This option enables POSIX asynchronous I/O which may by used
657a5209
MF
1779 by some high performance threaded applications. Disabling
1780 this option saves about 7k.
1781
2b188cc1
JA
1782config IO_URING
1783 bool "Enable IO uring support" if EXPERT
561fb04a 1784 select IO_WQ
2b188cc1
JA
1785 default y
1786 help
1787 This option enables support for the io_uring interface, enabling
1788 applications to submit and complete IO through submission and
1789 completion rings that are shared between the kernel and application.
1790
1802656e
JA
1791config GCOV_PROFILE_URING
1792 bool "Enable GCOV profiling on the io_uring subsystem"
1793 depends on GCOV_KERNEL
1794 help
1795 Enable GCOV profiling on the io_uring subsystem, to facilitate
1796 code coverage testing.
1797
1798 If unsure, say N.
1799
1800 Note that this will have a negative impact on the performance of
1801 the io_uring subsystem, hence this should only be enabled for
1802 specific test purposes.
1803
d3ac21ca
JT
1804config ADVISE_SYSCALLS
1805 bool "Enable madvise/fadvise syscalls" if EXPERT
1806 default y
1807 help
1808 This option enables the madvise and fadvise syscalls, used by
1809 applications to advise the kernel about their future memory or file
1810 usage, improving performance. If building an embedded system where no
1811 applications use these syscalls, you can disable this option to save
1812 space.
1813
5b25b13a
MD
1814config MEMBARRIER
1815 bool "Enable membarrier() system call" if EXPERT
1816 default y
1817 help
1818 Enable the membarrier() system call that allows issuing memory
1819 barriers across all running threads, which can be used to distribute
1820 the cost of user-space memory barriers asymmetrically by transforming
1821 pairs of memory barriers into pairs consisting of membarrier() and a
1822 compiler barrier.
1823
1824 If unsure, say Y.
1825
a751ea34
RD
1826config KCMP
1827 bool "Enable kcmp() system call" if EXPERT
1828 help
1829 Enable the kernel resource comparison system call. It provides
1830 user-space with the ability to compare two processes to see if they
1831 share a common resource, such as a file descriptor or even virtual
1832 memory space.
1833
1834 If unsure, say N.
1835
1836config RSEQ
1837 bool "Enable rseq() system call" if EXPERT
1838 default y
1839 depends on HAVE_RSEQ
1840 select MEMBARRIER
1841 help
1842 Enable the restartable sequences system call. It provides a
1843 user-space cache for the current CPU number value, which
1844 speeds up getting the current CPU number from user-space,
1845 as well as an ABI to speed up user-space operations on
1846 per-CPU data.
1847
1848 If unsure, say Y.
1849
1850config DEBUG_RSEQ
1851 default n
1852 bool "Enable debugging of rseq() system call" if EXPERT
1853 depends on RSEQ && DEBUG_KERNEL
1854 help
1855 Enable extra debugging checks for the rseq system call.
1856
1857 If unsure, say N.
1858
1859config CACHESTAT_SYSCALL
1860 bool "Enable cachestat() system call" if EXPERT
1861 default y
1862 help
1863 Enable the cachestat system call, which queries the page cache
1864 statistics of a file (number of cached pages, dirty pages,
1865 pages marked for writeback, (recently) evicted pages).
1866
1867 If unsure say Y here.
1868
1869config PC104
1870 bool "PC/104 support" if EXPERT
1871 help
1872 Expose PC/104 form factor device drivers and options available for
1873 selection and configuration. Enable this option if your target
1874 machine has a PC/104 bus.
1875
d1b069f5 1876config KALLSYMS
e8cf4e9c
KK
1877 bool "Load all symbols for debugging/ksymoops" if EXPERT
1878 default y
1879 help
1880 Say Y here to let the kernel print out symbolic crash information and
1881 symbolic stack backtraces. This increases the size of the kernel
1882 somewhat, as all symbols have to be loaded into the kernel image.
d1b069f5 1883
30f3bb09
ZL
1884config KALLSYMS_SELFTEST
1885 bool "Test the basic functions and performance of kallsyms"
1886 depends on KALLSYMS
1887 default n
1888 help
1889 Test the basic functions and performance of some interfaces, such as
1890 kallsyms_lookup_name. It also calculates the compression rate of the
1891 kallsyms compression algorithm for the current symbol set.
1892
1893 Start self-test automatically after system startup. Suggest executing
1894 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
1895 displayed in the last line, indicating that the test is complete.
1896
d1b069f5
RD
1897config KALLSYMS_ALL
1898 bool "Include all symbols in kallsyms"
1899 depends on DEBUG_KERNEL && KALLSYMS
1900 help
e8cf4e9c
KK
1901 Normally kallsyms only contains the symbols of functions for nicer
1902 OOPS messages and backtraces (i.e., symbols from the text and inittext
bdf0fe33
BS
1903 sections). This is sufficient for most cases. And only if you want to
1904 enable kernel live patching, or other less common use cases (e.g.,
1905 when a debugger is used) all symbols are required (i.e., names of
1906 variables from the data sections, etc).
d1b069f5 1907
e8cf4e9c
KK
1908 This option makes sure that all symbols are loaded into the kernel
1909 image (i.e., symbols from all sections) in cost of increased kernel
1910 size (depending on the kernel configuration, it may be 300KiB or
1911 something like this).
d1b069f5 1912
bdf0fe33 1913 Say N unless you really need all symbols, or kernel live patching.
d1b069f5 1914
d1b069f5
RD
1915# end of the "standard kernel features (expert users)" menu
1916
3ccfebed
MD
1917config ARCH_HAS_MEMBARRIER_CALLBACKS
1918 bool
1919
70216e18
MD
1920config ARCH_HAS_MEMBARRIER_SYNC_CORE
1921 bool
1922
5796d396
JX
1923config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
1924 bool
1925 help
1926 Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
1927
1928 A 64-bit kernel is required for the memory sealing feature.
1929 No specific hardware features from the CPU are needed.
1930
1931 To enable this feature, the architecture needs to update their
1932 special mappings calls to include the sealing flag and confirm
1933 that it doesn't unmap/remap system mappings during the life
1934 time of the process. The existence of this flag for an architecture
1935 implies that it does not require the remapping of the system
1936 mappings during process lifetime, so sealing these mappings is safe
1937 from a kernel perspective.
1938
1939 After the architecture enables this, a distribution can set
1940 CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
1941
1942 For complete descriptions of memory sealing, please see
1943 Documentation/userspace-api/mseal.rst
1944
cdd6c482 1945config HAVE_PERF_EVENTS
0793a61d 1946 bool
018df72d
MF
1947 help
1948 See tools/perf/design.txt for details.
0793a61d 1949
2aef6f30
SC
1950config GUEST_PERF_EVENTS
1951 bool
1952 depends on HAVE_PERF_EVENTS
1953
906010b2
PZ
1954config PERF_USE_VMALLOC
1955 bool
1956 help
1957 See tools/perf/design.txt for details
1958
57c0c15b 1959menu "Kernel Performance Events And Counters"
0793a61d 1960
cdd6c482 1961config PERF_EVENTS
57c0c15b 1962 bool "Kernel performance events and counters"
392d65a9 1963 default y if PROFILING
cdd6c482 1964 depends on HAVE_PERF_EVENTS
e360adbe 1965 select IRQ_WORK
0793a61d 1966 help
57c0c15b
IM
1967 Enable kernel support for various performance events provided
1968 by software and hardware.
0793a61d 1969
dd77038d 1970 Software events are supported either built-in or via the
57c0c15b 1971 use of generic tracepoints.
0793a61d 1972
57c0c15b
IM
1973 Most modern CPUs support performance events via performance
1974 counter registers. These registers count the number of certain
0793a61d
TG
1975 types of hw events: such as instructions executed, cachemisses
1976 suffered, or branches mis-predicted - without slowing down the
1977 kernel or applications. These registers can also trigger interrupts
1978 when a threshold number of events have passed - and can thus be
1979 used to profile the code that runs on that CPU.
1980
57c0c15b 1981 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1982 these software and hardware event capabilities, available via a
57c0c15b 1983 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1984 provides per task and per CPU counters, and it provides event
1985 capabilities on top of those.
1986
1987 Say Y if unsure.
1988
906010b2
PZ
1989config DEBUG_PERF_USE_VMALLOC
1990 default n
1991 bool "Debug: use vmalloc to back perf mmap() buffers"
cb307113 1992 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
906010b2
PZ
1993 select PERF_USE_VMALLOC
1994 help
e8cf4e9c 1995 Use vmalloc memory to back perf mmap() buffers.
906010b2 1996
e8cf4e9c
KK
1997 Mostly useful for debugging the vmalloc code on platforms
1998 that don't require it.
906010b2 1999
e8cf4e9c 2000 Say N if unsure.
906010b2 2001
0793a61d
TG
2002endmenu
2003
091f6e26
DH
2004config SYSTEM_DATA_VERIFICATION
2005 def_bool n
2006 select SYSTEM_TRUSTED_KEYRING
2007 select KEYS
2008 select CRYPTO
d43de6c7 2009 select CRYPTO_RSA
091f6e26
DH
2010 select ASYMMETRIC_KEY_TYPE
2011 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
091f6e26
DH
2012 select ASN1
2013 select OID_REGISTRY
2014 select X509_CERTIFICATE_PARSER
2015 select PKCS7_MESSAGE_PARSER
82c04ff8 2016 help
091f6e26
DH
2017 Provide PKCS#7 message verification using the contents of the system
2018 trusted keyring to provide public keys. This then can be used for
2019 module verification, kexec image verification and firmware blob
2020 verification.
82c04ff8 2021
125e5645 2022config PROFILING
b309a294 2023 bool "Profiling support"
125e5645
MD
2024 help
2025 Say Y here to enable the extended profiling support mechanisms used
f8408264 2026 by profilers.
125e5645 2027
2f7ab126
MO
2028config RUST
2029 bool "Rust support"
2030 depends on HAVE_RUST
2031 depends on RUST_IS_AVAILABLE
ac61506b
ST
2032 select EXTENDED_MODVERSIONS if MODVERSIONS
2033 depends on !MODVERSIONS || GENDWARFKSYMS
f1385dc6 2034 depends on !GCC_PLUGIN_RANDSTRUCT
2f7ab126 2035 depends on !RANDSTRUCT
5daa0c35 2036 depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
8b8ca9c2 2037 depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
ca627e63 2038 select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG
af6017b6 2039 depends on !CALL_PADDING || RUSTC_VERSION >= 108100
f64e2f3a 2040 depends on !KASAN_SW_TAGS
93e34a0b 2041 depends on !(MITIGATION_RETHUNK && KASAN) || RUSTC_VERSION >= 108300
2f7ab126
MO
2042 help
2043 Enables Rust support in the kernel.
2044
2045 This allows other Rust-related options, like drivers written in Rust,
2046 to be selected.
2047
2048 It is also required to be able to load external kernel modules
2049 written in Rust.
2050
2051 See Documentation/rust/ for more information.
2052
2053 If unsure, say N.
2054
2055config RUSTC_VERSION_TEXT
2056 string
2057 depends on RUST
5134a335
MO
2058 default "$(RUSTC_VERSION_TEXT)"
2059 help
2060 See `CC_VERSION_TEXT`.
2f7ab126
MO
2061
2062config BINDGEN_VERSION_TEXT
2063 string
2064 depends on RUST
9e98db17 2065 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
c23d1f7e
MO
2066 # (https://github.com/rust-lang/rust-bindgen/pull/2678) and 0.71.0
2067 # (https://github.com/rust-lang/rust-bindgen/pull/3040). It can be removed
2068 # when the minimum version is upgraded past the latter (0.69.1 and 0.71.1
2069 # both fixed the issue).
aacf93e8 2070 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
2f7ab126 2071
5f87f112
IM
2072#
2073# Place an empty function call at each tracepoint site. Can be
2074# dynamically changed for a probe function.
2075#
97e1c18e 2076config TRACEPOINTS
5f87f112 2077 bool
a363d27c 2078 select TASKS_TRACE_RCU
97e1c18e 2079
89cde455
ED
2080source "kernel/Kconfig.kexec"
2081
1da177e4
LT
2082endmenu # General setup
2083
1572497c
CH
2084source "arch/Kconfig"
2085
ae81f9e3 2086config RT_MUTEXES
6341e62b 2087 bool
1c6f9ec0 2088 default y if PREEMPT_RT
ae81f9e3 2089
c8424e77
TJB
2090config MODULE_SIG_FORMAT
2091 def_bool n
2092 select SYSTEM_DATA_VERIFICATION
2093
73b4fc92 2094source "kernel/module/Kconfig"
6c9692e2 2095
98a79d6a
RR
2096config INIT_ALL_POSSIBLE
2097 bool
2098 help
5f054e31
RR
2099 Back when each arch used to define their own cpu_online_mask and
2100 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
2101 with all 1s, and others with all 0s. When they were centralised,
2102 it was better to provide this option than to break all the archs
692105b8 2103 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 2104
3a65dfe8 2105source "block/Kconfig"
e98c3202
AK
2106
2107config PREEMPT_NOTIFIERS
2108 bool
e260be67 2109
16295bec
SK
2110config PADATA
2111 depends on SMP
2112 bool
2113
4520c6a4
DH
2114config ASN1
2115 tristate
2116 help
2117 Build a simple ASN.1 grammar compiler that produces a bytecode output
2118 that can be interpreted by the ASN.1 stream decoder and used to
2119 inform it as to what tags are to be expected in a stream and what
2120 functions to call on what tags.
2121
6beb0009 2122source "kernel/Kconfig.locks"
e61938a9 2123
0ebeea8c
DB
2124config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2125 bool
2126
4ff4c745
AP
2127config ARCH_HAS_PREPARE_SYNC_CORE_CMD
2128 bool
2129
e61938a9
MD
2130config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2131 bool
1bd21c6c
DB
2132
2133# It may be useful for an architecture to override the definitions of the
7303e30e
DB
2134# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2135# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2136# different calling convention for syscalls. They can also override the
2137# macros for not-implemented syscalls in kernel/sys_ni.c and
2138# kernel/time/posix-stubs.c. All these overrides need to be available in
2139# <asm/syscall_wrapper.h>.
1bd21c6c
DB
2140config ARCH_HAS_SYSCALL_WRAPPER
2141 def_bool n