Merge tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-2.6-block.git] / init / Kconfig
CommitLineData
ec8f24b7 1# SPDX-License-Identifier: GPL-2.0-only
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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
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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)
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21
22config GCC_VERSION
23 int
aec6c60a 24 default $(cc-version) if CC_IS_GCC
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25 default 0
26
469cb737 27config CC_IS_CLANG
aec6c60a 28 def_bool $(success,test "$(cc-name)" = Clang)
b744b43f 29
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30config CLANG_VERSION
31 int
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32 default $(cc-version) if CC_IS_CLANG
33 default 0
469cb737 34
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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
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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
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58config LLD_VERSION
59 int
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60 default $(ld-version) if LD_IS_LLD
61 default 0
d5750cd3 62
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63config RUST_IS_AVAILABLE
64 def_bool $(success,$(srctree)/scripts/rust_is_available.sh)
65 help
66 This shows whether a suitable Rust toolchain is available (found).
67
68 Please see Documentation/rust/quick-start.rst for instructions on how
eacf96d2 69 to satisfy the build requirements of Rust support.
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70
71 In particular, the Makefile target 'rustavailable' is useful to check
72 why the Rust toolchain is not being detected.
73
1a927fd3 74config CC_CAN_LINK
9371f86e 75 bool
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76 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
77 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
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78
79config CC_CAN_LINK_STATIC
80 bool
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81 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
82 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
1a927fd3 83
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84# Fixed in GCC 14, 13.3, 12.4 and 11.5
85# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
86config GCC_ASM_GOTO_OUTPUT_BROKEN
87 bool
88 depends on CC_IS_GCC
89 default y if GCC_VERSION < 110500
90 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
91 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
92
587f1701 93config CC_HAS_ASM_GOTO_OUTPUT
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94 def_bool y
95 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN
96 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 97
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98config CC_HAS_ASM_GOTO_TIED_OUTPUT
99 depends on CC_HAS_ASM_GOTO_OUTPUT
100 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
534bd703 101 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 102
5cf896fb 103config TOOLS_SUPPORT_RELR
2d122942 104 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
5cf896fb 105
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106config CC_HAS_ASM_INLINE
107 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
108
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109config CC_HAS_NO_PROFILE_FN_ATTR
110 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
111
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112config PAHOLE_VERSION
113 int
114 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
115
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116config CONSTRUCTORS
117 bool
b99b87f7 118
e360adbe 119config IRQ_WORK
fd0a68a2 120 def_bool y if SMP
e360adbe 121
10916706 122config BUILDTIME_TABLE_SORT
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123 bool
124
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125config THREAD_INFO_IN_TASK
126 bool
127 help
128 Select this to move thread_info off the stack into task_struct. To
129 make this work, an arch will need to remove all thread_info fields
130 except flags and fix any runtime bugs.
131
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132 One subtle change that will be needed is to use try_get_task_stack()
133 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
134
ff0cfc66 135menu "General setup"
1da177e4 136
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137config BROKEN
138 bool
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139
140config BROKEN_ON_SMP
141 bool
142 depends on BROKEN || !SMP
143 default y
144
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145config INIT_ENV_ARG_LIMIT
146 int
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147 default 32 if !UML
148 default 128 if UML
1da177e4 149 help
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150 Maximum of each of the number of arguments and environment
151 variables passed to init from the kernel command line.
1da177e4 152
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153config COMPILE_TEST
154 bool "Compile also drivers which will not load"
ea29b20a 155 depends on HAS_IOMEM
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156 help
157 Some drivers can be compiled on a different platform than they are
158 intended to be run on. Despite they cannot be loaded there (or even
159 when they load they cannot be used due to missing HW support),
160 developers still, opposing to distributors, might want to build such
161 drivers to compile-test them.
162
163 If you are a developer and want to build everything available, say Y
164 here. If you are a user/distributor, say N here to exclude useless
165 drivers to be distributed.
166
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167config WERROR
168 bool "Compile the kernel with warnings as errors"
b339ec9c 169 default COMPILE_TEST
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170 help
171 A kernel build should not cause any compiler warnings, and this
2f7ab126 172 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
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173 to enforce that rule by default. Certain warnings from other tools
174 such as the linker may be upgraded to errors with this option as
175 well.
3fe617cc 176
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177 However, if you have a new (or very old) compiler or linker with odd
178 and unusual warnings, or you have some architecture with problems,
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179 you may need to disable this config option in order to
180 successfully build the kernel.
181
182 If in doubt, say Y.
183
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184config UAPI_HEADER_TEST
185 bool "Compile test UAPI headers"
fcbb8461 186 depends on HEADERS_INSTALL && CC_CAN_LINK
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187 help
188 Compile test headers exported to user-space to ensure they are
189 self-contained, i.e. compilable as standalone units.
190
191 If you are a developer or tester and want to ensure the exported
192 headers are self-contained, say Y here. Otherwise, choose N.
193
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194config LOCALVERSION
195 string "Local version - append to kernel release"
196 help
197 Append an extra string to the end of your kernel version.
198 This will show up when you type uname, for example.
199 The string you set here will be appended after the contents of
200 any files with a filename matching localversion* in your
201 object and source tree, in that order. Your total string can
202 be a maximum of 64 characters.
203
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204config LOCALVERSION_AUTO
205 bool "Automatically append version information to the version string"
206 default y
ac3339ba 207 depends on !COMPILE_TEST
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208 help
209 This will try to automatically determine if the current tree is a
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210 release tree by looking for git tags that belong to the current
211 top of tree revision.
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212
213 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 214 if a git-based tree is found. The string generated by this will be
aaebf433 215 appended after any matching localversion* files, and after the value
6e5a5420 216 set in CONFIG_LOCALVERSION.
aaebf433 217
0f9c608d 218 (The actual string used here is the first 12 characters produced
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219 by running the command:
220
221 $ git rev-parse --verify HEAD
222
223 which is done within the script "scripts/setlocalversion".)
aaebf433 224
9afb719e 225config BUILD_SALT
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226 string "Build ID Salt"
227 default ""
228 help
229 The build ID is used to link binaries and their debug info. Setting
230 this option will use the value in the calculation of the build id.
231 This is mostly useful for distributions which want to ensure the
232 build is unique between builds. It's safe to leave the default.
9afb719e 233
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234config HAVE_KERNEL_GZIP
235 bool
236
237config HAVE_KERNEL_BZIP2
238 bool
239
240config HAVE_KERNEL_LZMA
241 bool
242
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243config HAVE_KERNEL_XZ
244 bool
245
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246config HAVE_KERNEL_LZO
247 bool
248
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249config HAVE_KERNEL_LZ4
250 bool
251
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252config HAVE_KERNEL_ZSTD
253 bool
254
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255config HAVE_KERNEL_UNCOMPRESSED
256 bool
257
30d65dbf 258choice
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259 prompt "Kernel compression mode"
260 default KERNEL_GZIP
48f7ddf7 261 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 262 help
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263 The linux kernel is a kind of self-extracting executable.
264 Several compression algorithms are available, which differ
265 in efficiency, compression and decompression speed.
266 Compression speed is only relevant when building a kernel.
267 Decompression speed is relevant at each boot.
268
269 If you have any problems with bzip2 or lzma compressed
270 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
271 version of this functionality (bzip2 only), for 2.4, was
272 supplied by Christian Ludwig)
273
274 High compression options are mostly useful for users, who
275 are low on disk space (embedded systems), but for whom ram
276 size matters less.
277
278 If in doubt, select 'gzip'
279
280config KERNEL_GZIP
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281 bool "Gzip"
282 depends on HAVE_KERNEL_GZIP
283 help
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284 The old and tried gzip compression. It provides a good balance
285 between compression ratio and decompression speed.
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286
287config KERNEL_BZIP2
288 bool "Bzip2"
2e9f3bdd 289 depends on HAVE_KERNEL_BZIP2
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290 help
291 Its compression ratio and speed is intermediate.
0a4dd35c 292 Decompression speed is slowest among the choices. The kernel
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293 size is about 10% smaller with bzip2, in comparison to gzip.
294 Bzip2 uses a large amount of memory. For modern kernels you
295 will need at least 8MB RAM or more for booting.
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296
297config KERNEL_LZMA
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298 bool "LZMA"
299 depends on HAVE_KERNEL_LZMA
300 help
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301 This compression algorithm's ratio is best. Decompression speed
302 is between gzip and bzip2. Compression is slowest.
303 The kernel size is about 33% smaller with LZMA in comparison to gzip.
30d65dbf 304
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305config KERNEL_XZ
306 bool "XZ"
307 depends on HAVE_KERNEL_XZ
308 help
309 XZ uses the LZMA2 algorithm and instruction set specific
310 BCJ filters which can improve compression ratio of executable
311 code. The size of the kernel is about 30% smaller with XZ in
312 comparison to gzip. On architectures for which there is a BCJ
313 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
314 will create a few percent smaller kernel than plain LZMA.
315
316 The speed is about the same as with LZMA: The decompression
317 speed of XZ is better than that of bzip2 but worse than gzip
318 and LZO. Compression is slow.
319
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320config KERNEL_LZO
321 bool "LZO"
322 depends on HAVE_KERNEL_LZO
323 help
0a4dd35c 324 Its compression ratio is the poorest among the choices. The kernel
681b3049 325 size is about 10% bigger than gzip; however its speed
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326 (both compression and decompression) is the fastest.
327
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328config KERNEL_LZ4
329 bool "LZ4"
330 depends on HAVE_KERNEL_LZ4
331 help
332 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
333 A preliminary version of LZ4 de/compression tool is available at
334 <https://code.google.com/p/lz4/>.
335
336 Its compression ratio is worse than LZO. The size of the kernel
337 is about 8% bigger than LZO. But the decompression speed is
338 faster than LZO.
339
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340config KERNEL_ZSTD
341 bool "ZSTD"
342 depends on HAVE_KERNEL_ZSTD
343 help
344 ZSTD is a compression algorithm targeting intermediate compression
345 with fast decompression speed. It will compress better than GZIP and
346 decompress around the same speed as LZO, but slower than LZ4. You
347 will need at least 192 KB RAM or more for booting. The zstd command
348 line tool is required for compression.
349
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350config KERNEL_UNCOMPRESSED
351 bool "None"
352 depends on HAVE_KERNEL_UNCOMPRESSED
353 help
354 Produce uncompressed kernel image. This option is usually not what
355 you want. It is useful for debugging the kernel in slow simulation
356 environments, where decompressing and moving the kernel is awfully
357 slow. This option allows early boot code to skip the decompressor
358 and jump right at uncompressed kernel image.
359
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360endchoice
361
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362config DEFAULT_INIT
363 string "Default init path"
364 default ""
365 help
366 This option determines the default init for the system if no init=
367 option is passed on the kernel command line. If the requested path is
368 not present, we will still then move on to attempting further
369 locations (e.g. /sbin/init, etc). If this is empty, we will just use
370 the fallback list when init= is not passed.
371
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372config DEFAULT_HOSTNAME
373 string "Default hostname"
374 default "(none)"
375 help
376 This option determines the default system hostname before userspace
377 calls sethostname(2). The kernel traditionally uses "(none)" here,
378 but you may wish to use a different default here to make a minimal
379 system more usable with less configuration.
380
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381config SYSVIPC
382 bool "System V IPC"
a7f7f624 383 help
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384 Inter Process Communication is a suite of library functions and
385 system calls which let processes (running programs) synchronize and
386 exchange information. It is generally considered to be a good thing,
387 and some programs won't run unless you say Y here. In particular, if
388 you want to run the DOS emulator dosemu under Linux (read the
389 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
390 you'll need to say Y here.
391
392 You can find documentation about IPC with "info ipc" and also in
393 section 6.4 of the Linux Programmer's Guide, available from
394 <http://www.tldp.org/guides.html>.
395
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396config SYSVIPC_SYSCTL
397 bool
398 depends on SYSVIPC
399 depends on SYSCTL
400 default y
401
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402config SYSVIPC_COMPAT
403 def_bool y
404 depends on COMPAT && SYSVIPC
405
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406config POSIX_MQUEUE
407 bool "POSIX Message Queues"
19c92399 408 depends on NET
a7f7f624 409 help
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410 POSIX variant of message queues is a part of IPC. In POSIX message
411 queues every message has a priority which decides about succession
412 of receiving it by a process. If you want to compile and run
413 programs written e.g. for Solaris with use of its POSIX message
b0e37650 414 queues (functions mq_*) say Y here.
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415
416 POSIX message queues are visible as a filesystem called 'mqueue'
417 and can be mounted somewhere if you want to do filesystem
418 operations on message queues.
419
420 If unsure, say Y.
421
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422config POSIX_MQUEUE_SYSCTL
423 bool
424 depends on POSIX_MQUEUE
425 depends on SYSCTL
426 default y
427
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428config WATCH_QUEUE
429 bool "General notification queue"
430 default n
431 help
432
433 This is a general notification queue for the kernel to pass events to
434 userspace by splicing them into pipes. It can be used in conjunction
435 with watches for key/keyring change notifications and device
436 notifications.
437
c02b872a 438 See Documentation/core-api/watch_queue.rst
c73be61c 439
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440config CROSS_MEMORY_ATTACH
441 bool "Enable process_vm_readv/writev syscalls"
442 depends on MMU
443 default y
444 help
445 Enabling this option adds the system calls process_vm_readv and
446 process_vm_writev which allow a process with the correct privileges
a2a368d9 447 to directly read from or write to another process' address space.
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448 See the man page for more details.
449
69369a70 450config USELIB
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451 bool "uselib syscall (for libc5 and earlier)"
452 default ALPHA || M68K || SPARC
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453 help
454 This option enables the uselib syscall, a system call used in the
455 dynamic linker from libc5 and earlier. glibc does not use this
456 system call. If you intend to run programs built on libc5 or
457 earlier, you may need to enable this syscall. Current systems
458 running glibc can safely disable this.
459
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460config AUDIT
461 bool "Auditing support"
462 depends on NET
463 help
464 Enable auditing infrastructure that can be used with another
465 kernel subsystem, such as SELinux (which requires this for
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466 logging of avc messages output). System call auditing is included
467 on architectures which support it.
391dc69c 468
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469config HAVE_ARCH_AUDITSYSCALL
470 bool
471
391dc69c 472config AUDITSYSCALL
cb74ed27 473 def_bool y
7a017721 474 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
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475 select FSNOTIFY
476
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477source "kernel/irq/Kconfig"
478source "kernel/time/Kconfig"
b24abcff 479source "kernel/bpf/Kconfig"
87a4c375 480source "kernel/Kconfig.preempt"
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481
482menu "CPU/Task time and stats accounting"
483
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484config VIRT_CPU_ACCOUNTING
485 bool
486
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487choice
488 prompt "Cputime accounting"
02382aff 489 default TICK_CPU_ACCOUNTING
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490
491# Kind of a stub config for the pure tick based cputime accounting
492config TICK_CPU_ACCOUNTING
493 bool "Simple tick based cputime accounting"
c58b0df1 494 depends on !S390 && !NO_HZ_FULL
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495 help
496 This is the basic tick based cputime accounting that maintains
497 statistics about user, system and idle time spent on per jiffies
498 granularity.
499
500 If unsure, say Y.
501
abf917cd 502config VIRT_CPU_ACCOUNTING_NATIVE
b952741c 503 bool "Deterministic task and CPU time accounting"
c58b0df1 504 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
abf917cd 505 select VIRT_CPU_ACCOUNTING
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506 help
507 Select this option to enable more accurate task and CPU time
508 accounting. This is done by reading a CPU counter on each
509 kernel entry and exit and on transitions within the kernel
510 between system, softirq and hardirq state, so there is a
511 small performance impact. In the case of s390 or IBM POWER > 5,
512 this also enables accounting of stolen time on logically-partitioned
513 systems.
514
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515config VIRT_CPU_ACCOUNTING_GEN
516 bool "Full dynticks CPU time accounting"
24a9c541 517 depends on HAVE_CONTEXT_TRACKING_USER
554b0004 518 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
041a1574 519 depends on GENERIC_CLOCKEVENTS
abf917cd 520 select VIRT_CPU_ACCOUNTING
24a9c541 521 select CONTEXT_TRACKING_USER
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522 help
523 Select this option to enable task and CPU time accounting on full
524 dynticks systems. This accounting is implemented by watching every
525 kernel-user boundaries using the context tracking subsystem.
526 The accounting is thus performed at the expense of some significant
527 overhead.
528
529 For now this is only useful if you are working on the full
530 dynticks subsystem development.
531
532 If unsure, say N.
533
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534endchoice
535
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536config IRQ_TIME_ACCOUNTING
537 bool "Fine granularity task level IRQ time accounting"
b58c3584 538 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
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539 help
540 Select this option to enable fine granularity task irq time
541 accounting. This is done by reading a timestamp on each
542 transitions between softirq and hardirq state, so there can be a
543 small performance impact.
544
545 If in doubt, say N here.
546
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547config HAVE_SCHED_AVG_IRQ
548 def_bool y
549 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
550 depends on SMP
551
d4dbc991 552config SCHED_HW_PRESSURE
98eb401d 553 bool
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554 default y if ARM && ARM_CPU_TOPOLOGY
555 default y if ARM64
76504793 556 depends on SMP
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557 depends on CPU_FREQ_THERMAL
558 help
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559 Select this option to enable HW pressure accounting in the
560 scheduler. HW pressure is the value conveyed to the scheduler
98eb401d 561 that reflects the reduction in CPU compute capacity resulted from
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562 HW throttling. HW throttling occurs when the performance of
563 a CPU is capped due to high operating temperatures as an example.
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564
565 If selected, the scheduler will be able to balance tasks accordingly,
566 i.e. put less load on throttled CPUs than on non/less throttled ones.
567
568 This requires the architecture to implement
d4dbc991 569 arch_update_hw_pressure() and arch_scale_thermal_pressure().
76504793 570
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571config BSD_PROCESS_ACCT
572 bool "BSD Process Accounting"
2813893f 573 depends on MULTIUSER
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574 help
575 If you say Y here, a user level program will be able to instruct the
576 kernel (via a special system call) to write process accounting
577 information to a file: whenever a process exits, information about
578 that process will be appended to the file by the kernel. The
579 information includes things such as creation time, owning user,
580 command name, memory usage, controlling terminal etc. (the complete
581 list is in the struct acct in <file:include/linux/acct.h>). It is
582 up to the user level program to do useful things with this
583 information. This is generally a good idea, so say Y.
584
585config BSD_PROCESS_ACCT_V3
586 bool "BSD Process Accounting version 3 file format"
587 depends on BSD_PROCESS_ACCT
588 default n
589 help
590 If you say Y here, the process accounting information is written
591 in a new file format that also logs the process IDs of each
3903bf94 592 process and its parent. Note that this file format is incompatible
1da177e4
LT
593 with previous v0/v1/v2 file formats, so you will need updated tools
594 for processing it. A preliminary version of these tools is available
37a4c940 595 at <http://www.gnu.org/software/acct/>.
1da177e4 596
c757249a 597config TASKSTATS
19c92399 598 bool "Export task/process statistics through netlink"
c757249a 599 depends on NET
2813893f 600 depends on MULTIUSER
c757249a
SN
601 default n
602 help
603 Export selected statistics for tasks/processes through the
604 generic netlink interface. Unlike BSD process accounting, the
605 statistics are available during the lifetime of tasks/processes as
606 responses to commands. Like BSD accounting, they are sent to user
607 space on task exit.
608
609 Say N if unsure.
610
ca74e92b 611config TASK_DELAY_ACCT
19c92399 612 bool "Enable per-task delay accounting"
6f44993f 613 depends on TASKSTATS
f6db8347 614 select SCHED_INFO
ca74e92b
SN
615 help
616 Collect information on time spent by a task waiting for system
617 resources like cpu, synchronous block I/O completion and swapping
618 in pages. Such statistics can help in setting a task's priorities
619 relative to other tasks for cpu, io, rss limits etc.
620
621 Say N if unsure.
622
18f705f4 623config TASK_XACCT
19c92399 624 bool "Enable extended accounting over taskstats"
18f705f4
AD
625 depends on TASKSTATS
626 help
627 Collect extended task accounting data and send the data
628 to userland for processing over the taskstats interface.
629
630 Say N if unsure.
631
632config TASK_IO_ACCOUNTING
19c92399 633 bool "Enable per-task storage I/O accounting"
18f705f4
AD
634 depends on TASK_XACCT
635 help
636 Collect information on the number of bytes of storage I/O which this
637 task has caused.
638
639 Say N if unsure.
640
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JW
641config PSI
642 bool "Pressure stall information tracking"
98dfdd9e 643 select KERNFS
eb414681
JW
644 help
645 Collect metrics that indicate how overcommitted the CPU, memory,
646 and IO capacity are in the system.
647
648 If you say Y here, the kernel will create /proc/pressure/ with the
649 pressure statistics files cpu, memory, and io. These will indicate
650 the share of walltime in which some or all tasks in the system are
651 delayed due to contention of the respective resource.
652
2ce7135a
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653 In kernels with cgroup support, cgroups (cgroup2 only) will
654 have cpu.pressure, memory.pressure, and io.pressure files,
655 which aggregate pressure stalls for the grouped tasks only.
656
c3123552 657 For more details see Documentation/accounting/psi.rst.
eb414681
JW
658
659 Say N if unsure.
660
e0c27447
JW
661config PSI_DEFAULT_DISABLED
662 bool "Require boot parameter to enable pressure stall information tracking"
663 default n
664 depends on PSI
665 help
666 If set, pressure stall information tracking will be disabled
428a1cb4
BS
667 per default but can be enabled through passing psi=1 on the
668 kernel commandline during boot.
e0c27447 669
7b2489d3
JW
670 This feature adds some code to the task wakeup and sleep
671 paths of the scheduler. The overhead is too low to affect
672 common scheduling-intense workloads in practice (such as
673 webservers, memcache), but it does show up in artificial
674 scheduler stress tests, such as hackbench.
675
676 If you are paranoid and not sure what the kernel will be
677 used for, say Y.
678
679 Say N if unsure.
680
391dc69c 681endmenu # "CPU/Task time and stats accounting"
d9817ebe 682
5c4991e2
FW
683config CPU_ISOLATION
684 bool "CPU isolation"
414a2dc1 685 depends on SMP || COMPILE_TEST
2c43838c 686 default y
5c4991e2
FW
687 help
688 Make sure that CPUs running critical tasks are not disturbed by
689 any source of "noise" such as unbound workqueues, timers, kthreads...
2c43838c
FW
690 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
691 the "isolcpus=" boot parameter.
692
693 Say Y if unsure.
5c4991e2 694
0af92d46 695source "kernel/rcu/Kconfig"
c903ff83 696
1da177e4 697config IKCONFIG
f2443ab6 698 tristate "Kernel .config support"
a7f7f624 699 help
1da177e4
LT
700 This option enables the complete Linux kernel ".config" file
701 contents to be saved in the kernel. It provides documentation
702 of which kernel options are used in a running kernel or in an
703 on-disk kernel. This information can be extracted from the kernel
704 image file with the script scripts/extract-ikconfig and used as
705 input to rebuild the current kernel or to build another kernel.
706 It can also be extracted from a running kernel by reading
707 /proc/config.gz if enabled (below).
708
709config IKCONFIG_PROC
710 bool "Enable access to .config through /proc/config.gz"
711 depends on IKCONFIG && PROC_FS
a7f7f624 712 help
1da177e4
LT
713 This option enables access to the kernel configuration file
714 through /proc/config.gz.
715
f7b101d3
JFG
716config IKHEADERS
717 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
718 depends on SYSFS
719 help
720 This option enables access to the in-kernel headers that are generated during
721 the build process. These can be used to build eBPF tracing programs,
722 or similar programs. If you build the headers as a module, a module called
723 kheaders.ko is built which can be loaded on-demand to get access to headers.
43d8ce9d 724
794543a2
AJS
725config LOG_BUF_SHIFT
726 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
1c4b5ecb 727 range 12 25
f17a32e9 728 default 17
361e9dfb 729 depends on PRINTK
794543a2 730 help
23b2899f
LR
731 Select the minimal kernel log buffer size as a power of 2.
732 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
733 parameter, see below. Any higher size also might be forced
734 by "log_buf_len" boot parameter.
735
f17a32e9 736 Examples:
23b2899f 737 17 => 128 KB
f17a32e9 738 16 => 64 KB
23b2899f
LR
739 15 => 32 KB
740 14 => 16 KB
794543a2
AJS
741 13 => 8 KB
742 12 => 4 KB
743
23b2899f
LR
744config LOG_CPU_MAX_BUF_SHIFT
745 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
2240a31d 746 depends on SMP
23b2899f 747 range 0 21
23b2899f 748 default 0 if BASE_SMALL
320bf431 749 default 12
361e9dfb 750 depends on PRINTK
23b2899f
LR
751 help
752 This option allows to increase the default ring buffer size
753 according to the number of CPUs. The value defines the contribution
754 of each CPU as a power of 2. The used space is typically only few
755 lines however it might be much more when problems are reported,
756 e.g. backtraces.
757
758 The increased size means that a new buffer has to be allocated and
759 the original static one is unused. It makes sense only on systems
760 with more CPUs. Therefore this value is used only when the sum of
761 contributions is greater than the half of the default kernel ring
762 buffer as defined by LOG_BUF_SHIFT. The default values are set
0f7636e1 763 so that more than 16 CPUs are needed to trigger the allocation.
23b2899f
LR
764
765 Also this option is ignored when "log_buf_len" kernel parameter is
766 used as it forces an exact (power of two) size of the ring buffer.
767
768 The number of possible CPUs is used for this computation ignoring
5e0d8d59
GU
769 hotplugging making the computation optimal for the worst case
770 scenario while allowing a simple algorithm to be used from bootup.
23b2899f
LR
771
772 Examples shift values and their meaning:
773 17 => 128 KB for each CPU
774 16 => 64 KB for each CPU
775 15 => 32 KB for each CPU
776 14 => 16 KB for each CPU
777 13 => 8 KB for each CPU
778 12 => 4 KB for each CPU
779
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780config PRINTK_INDEX
781 bool "Printk indexing debugfs interface"
782 depends on PRINTK && DEBUG_FS
783 help
784 Add support for indexing of all printk formats known at compile time
785 at <debugfs>/printk/index/<module>.
786
787 This can be used as part of maintaining daemons which monitor
788 /dev/kmsg, as it permits auditing the printk formats present in a
789 kernel, allowing detection of cases where monitored printks are
790 changed or no longer present.
791
792 There is no additional runtime cost to printk with this enabled.
793
a5574cf6
IM
794#
795# Architectures with an unreliable sched_clock() should select this:
796#
797config HAVE_UNSTABLE_SCHED_CLOCK
798 bool
799
38ff87f7
SB
800config GENERIC_SCHED_CLOCK
801 bool
802
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803menu "Scheduler features"
804
805config UCLAMP_TASK
806 bool "Enable utilization clamping for RT/FAIR tasks"
807 depends on CPU_FREQ_GOV_SCHEDUTIL
808 help
809 This feature enables the scheduler to track the clamped utilization
810 of each CPU based on RUNNABLE tasks scheduled on that CPU.
811
812 With this option, the user can specify the min and max CPU
813 utilization allowed for RUNNABLE tasks. The max utilization defines
814 the maximum frequency a task should use while the min utilization
815 defines the minimum frequency it should use.
816
817 Both min and max utilization clamp values are hints to the scheduler,
818 aiming at improving its frequency selection policy, but they do not
819 enforce or grant any specific bandwidth for tasks.
820
821 If in doubt, say N.
822
823config UCLAMP_BUCKETS_COUNT
824 int "Number of supported utilization clamp buckets"
825 range 5 20
826 default 5
827 depends on UCLAMP_TASK
828 help
829 Defines the number of clamp buckets to use. The range of each bucket
830 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
831 number of clamp buckets the finer their granularity and the higher
832 the precision of clamping aggregation and tracking at run-time.
833
834 For example, with the minimum configuration value we will have 5
835 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
836 be refcounted in the [20..39]% bucket and will set the bucket clamp
837 effective value to 25%.
838 If a second 30% boosted task should be co-scheduled on the same CPU,
839 that task will be refcounted in the same bucket of the first task and
840 it will boost the bucket clamp effective value to 30%.
841 The clamp effective value of a bucket is reset to its nominal value
842 (20% in the example above) when there are no more tasks refcounted in
843 that bucket.
844
845 An additional boost/capping margin can be added to some tasks. In the
846 example above the 25% task will be boosted to 30% until it exits the
847 CPU. If that should be considered not acceptable on certain systems,
848 it's always possible to reduce the margin by increasing the number of
849 clamp buckets to trade off used memory for run-time tracking
850 precision.
851
852 If in doubt, use the default value.
853
854endmenu
855
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AA
856#
857# For architectures that want to enable the support for NUMA-affine scheduler
858# balancing logic:
859#
860config ARCH_SUPPORTS_NUMA_BALANCING
861 bool
862
72b252ae
MG
863#
864# For architectures that prefer to flush all TLBs after a number of pages
865# are unmapped instead of sending one IPI per page to flush. The architecture
866# must provide guarantees on what happens if a clean TLB cache entry is
867# written after the unmap. Details are in mm/rmap.c near the check for
868# should_defer_flush. The architecture should also consider if the full flush
869# and the refill costs are offset by the savings of sending fewer IPIs.
870config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
871 bool
872
c12d3362 873config CC_HAS_INT128
3a7c7331 874 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
c12d3362 875
dee2b702
GS
876config CC_IMPLICIT_FALLTHROUGH
877 string
158ea2d2 878 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
dee2b702
GS
879 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
880
3e00f580 881# Currently, disable gcc-10+ array-bounds globally.
0da6e5fd 882# It's still broken in gcc-13, so no upper bound yet.
3e00f580 883config GCC10_NO_ARRAY_BOUNDS
5a41237a
LT
884 def_bool y
885
f0be87c4
LT
886config CC_NO_ARRAY_BOUNDS
887 bool
8e5bd4ea 888 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS
f0be87c4 889
02153319
LT
890# Currently, disable -Wstringop-overflow for GCC globally.
891config GCC_NO_STRINGOP_OVERFLOW
a5e0ace0
GS
892 def_bool y
893
894config CC_NO_STRINGOP_OVERFLOW
895 bool
02153319 896 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
a5e0ace0
GS
897
898config CC_STRINGOP_OVERFLOW
899 bool
900 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
901
be5e610c
PZ
902#
903# For architectures that know their GCC __int128 support is sound
904#
905config ARCH_SUPPORTS_INT128
906 bool
907
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AA
908# For architectures that (ab)use NUMA to represent different memory regions
909# all cpu-local but of different latencies, such as SuperH.
910#
911config ARCH_WANT_NUMA_VARIABLE_LOCALITY
912 bool
913
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AA
914config NUMA_BALANCING
915 bool "Memory placement aware NUMA scheduler"
be3a7284
AA
916 depends on ARCH_SUPPORTS_NUMA_BALANCING
917 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
554b0f3c 918 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
be3a7284
AA
919 help
920 This option adds support for automatic NUMA aware memory/task placement.
921 The mechanism is quite primitive and is based on migrating memory when
6d56a410 922 it has references to the node the task is running on.
be3a7284
AA
923
924 This system will be inactive on UMA systems.
925
6f7c97e8
AK
926config NUMA_BALANCING_DEFAULT_ENABLED
927 bool "Automatically enable NUMA aware memory/task placement"
928 default y
929 depends on NUMA_BALANCING
930 help
931 If set, automatic NUMA balancing will be enabled if running on a NUMA
932 machine.
933
21c690a3
SB
934config SLAB_OBJ_EXT
935 bool
936
23964d2d 937menuconfig CGROUPS
6341e62b 938 bool "Control Group support"
2bd59d48 939 select KERNFS
5cdc38f9 940 help
23964d2d 941 This option adds support for grouping sets of processes together, for
5cdc38f9
KH
942 use with process control subsystems such as Cpusets, CFS, memory
943 controls or device isolation.
944 See
d6a3b247 945 - Documentation/scheduler/sched-design-CFS.rst (CFS)
da82c92f 946 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
45ce80fb 947 and resource control)
5cdc38f9
KH
948
949 Say N if unsure.
950
23964d2d
LZ
951if CGROUPS
952
3e32cb2e 953config PAGE_COUNTER
e8cf4e9c 954 bool
3e32cb2e 955
6a010a49
TH
956config CGROUP_FAVOR_DYNMODS
957 bool "Favor dynamic modification latency reduction by default"
958 help
959 This option enables the "favordynmods" mount option by default
960 which reduces the latencies of dynamic cgroup modifications such
961 as task migrations and controller on/offs at the cost of making
962 hot path operations such as forks and exits more expensive.
963
964 Say N if unsure.
965
c255a458 966config MEMCG
a0166ec4 967 bool "Memory controller"
3e32cb2e 968 select PAGE_COUNTER
79bd9814 969 select EVENTFD
21c690a3 970 select SLAB_OBJ_EXT
00f0b825 971 help
a0166ec4 972 Provides control over the memory footprint of tasks in a cgroup.
00f0b825 973
e93d4166
RG
974config MEMCG_V1
975 bool "Legacy cgroup v1 memory controller"
c9929f0e 976 depends on MEMCG
e93d4166
RG
977 default n
978 help
979 Legacy cgroup v1 memory controller which has been deprecated by
980 cgroup v2 implementation. The v1 is there for legacy applications
981 which haven't migrated to the new cgroup v2 interface yet. If you
982 do not have any such application then you are completely fine leaving
983 this option disabled.
984
985 Please note that feature set of the legacy memory controller is likely
986 going to shrink due to deprecation process. New deployments with v1
987 controller are highly discouraged.
988
989 San N is unsure.
84c07d11 990
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JW
991config BLK_CGROUP
992 bool "IO controller"
993 depends on BLOCK
2bc64a20 994 default n
a7f7f624 995 help
6bf024e6
JW
996 Generic block IO controller cgroup interface. This is the common
997 cgroup interface which should be used by various IO controlling
998 policies.
2bc64a20 999
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JW
1000 Currently, CFQ IO scheduler uses it to recognize task groups and
1001 control disk bandwidth allocation (proportional time slice allocation)
1002 to such task groups. It is also used by bio throttling logic in
1003 block layer to implement upper limit in IO rates on a device.
e5d1367f 1004
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JW
1005 This option only enables generic Block IO controller infrastructure.
1006 One needs to also enable actual IO controlling logic/policy. For
1007 enabling proportional weight division of disk bandwidth in CFQ, set
7baf2199 1008 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
6bf024e6
JW
1009 CONFIG_BLK_DEV_THROTTLING=y.
1010
da82c92f 1011 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
6bf024e6 1012
6bf024e6
JW
1013config CGROUP_WRITEBACK
1014 bool
1015 depends on MEMCG && BLK_CGROUP
1016 default y
e5d1367f 1017
7c941438 1018menuconfig CGROUP_SCHED
a0166ec4 1019 bool "CPU controller"
7c941438
DG
1020 default n
1021 help
1022 This feature lets CPU scheduler recognize task groups and control CPU
1023 bandwidth allocation to such task groups. It uses cgroups to group
1024 tasks.
1025
1026if CGROUP_SCHED
1027config FAIR_GROUP_SCHED
1028 bool "Group scheduling for SCHED_OTHER"
1029 depends on CGROUP_SCHED
1030 default CGROUP_SCHED
1031
ab84d31e
PT
1032config CFS_BANDWIDTH
1033 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
ab84d31e
PT
1034 depends on FAIR_GROUP_SCHED
1035 default n
1036 help
1037 This option allows users to define CPU bandwidth rates (limits) for
1038 tasks running within the fair group scheduler. Groups with no limit
1039 set are considered to be unconstrained and will run with no
1040 restriction.
d6a3b247 1041 See Documentation/scheduler/sched-bwc.rst for more information.
ab84d31e 1042
7c941438
DG
1043config RT_GROUP_SCHED
1044 bool "Group scheduling for SCHED_RR/FIFO"
7c941438
DG
1045 depends on CGROUP_SCHED
1046 default n
1047 help
1048 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 1049 to task groups. If enabled, it will also make it impossible to
7c941438
DG
1050 schedule realtime tasks for non-root users until you allocate
1051 realtime bandwidth for them.
d6a3b247 1052 See Documentation/scheduler/sched-rt-group.rst for more information.
7c941438
DG
1053
1054endif #CGROUP_SCHED
1055
af7f588d
MD
1056config SCHED_MM_CID
1057 def_bool y
1058 depends on SMP && RSEQ
1059
2480c093
PB
1060config UCLAMP_TASK_GROUP
1061 bool "Utilization clamping per group of tasks"
1062 depends on CGROUP_SCHED
1063 depends on UCLAMP_TASK
1064 default n
1065 help
1066 This feature enables the scheduler to track the clamped utilization
1067 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1068
1069 When this option is enabled, the user can specify a min and max
1070 CPU bandwidth which is allowed for each single task in a group.
1071 The max bandwidth allows to clamp the maximum frequency a task
1072 can use, while the min bandwidth allows to define a minimum
1073 frequency a task will always use.
1074
1075 When task group based utilization clamping is enabled, an eventually
1076 specified task-specific clamp value is constrained by the cgroup
1077 specified clamp value. Both minimum and maximum task clamping cannot
1078 be bigger than the corresponding clamping defined at task group level.
1079
1080 If in doubt, say N.
1081
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JW
1082config CGROUP_PIDS
1083 bool "PIDs controller"
1084 help
1085 Provides enforcement of process number limits in the scope of a
1086 cgroup. Any attempt to fork more processes than is allowed in the
1087 cgroup will fail. PIDs are fundamentally a global resource because it
1088 is fairly trivial to reach PID exhaustion before you reach even a
1089 conservative kmemcg limit. As a result, it is possible to grind a
1090 system to halt without being limited by other cgroup policies. The
6cc578df 1091 PIDs controller is designed to stop this from happening.
6bf024e6
JW
1092
1093 It should be noted that organisational operations (such as attaching
98076833 1094 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
6bf024e6
JW
1095 since the PIDs limit only affects a process's ability to fork, not to
1096 attach to a cgroup.
1097
39d3e758
PP
1098config CGROUP_RDMA
1099 bool "RDMA controller"
1100 help
1101 Provides enforcement of RDMA resources defined by IB stack.
1102 It is fairly easy for consumers to exhaust RDMA resources, which
1103 can result into resource unavailability to other consumers.
1104 RDMA controller is designed to stop this from happening.
1105 Attaching processes with active RDMA resources to the cgroup
1106 hierarchy is allowed even if can cross the hierarchy's limit.
1107
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JW
1108config CGROUP_FREEZER
1109 bool "Freezer controller"
1110 help
1111 Provides a way to freeze and unfreeze all tasks in a
1112 cgroup.
1113
489c2a20
JW
1114 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1115 controller includes important in-kernel memory consumers per default.
1116
1117 If you're using cgroup2, say N.
1118
6bf024e6
JW
1119config CGROUP_HUGETLB
1120 bool "HugeTLB controller"
1121 depends on HUGETLB_PAGE
1122 select PAGE_COUNTER
afc24d49 1123 default n
6bf024e6
JW
1124 help
1125 Provides a cgroup controller for HugeTLB pages.
1126 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1127 The limit is enforced during page fault. Since HugeTLB doesn't
1128 support page reclaim, enforcing the limit at page fault time implies
1129 that, the application will get SIGBUS signal if it tries to access
1130 HugeTLB pages beyond its limit. This requires the application to know
1131 beforehand how much HugeTLB pages it would require for its use. The
1132 control group is tracked in the third page lru pointer. This means
1133 that we cannot use the controller with huge page less than 3 pages.
afc24d49 1134
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JW
1135config CPUSETS
1136 bool "Cpuset controller"
e1d4eeec 1137 depends on SMP
6bf024e6
JW
1138 help
1139 This option will let you create and manage CPUSETs which
1140 allow dynamically partitioning a system into sets of CPUs and
1141 Memory Nodes and assigning tasks to run only within those sets.
1142 This is primarily useful on large SMP or NUMA systems.
afc24d49 1143
6bf024e6 1144 Say N if unsure.
afc24d49 1145
1abab1ba
CR
1146config CPUSETS_V1
1147 bool "Legacy cgroup v1 cpusets controller"
1148 depends on CPUSETS
1149 default n
1150 help
1151 Legacy cgroup v1 cpusets controller which has been deprecated by
1152 cgroup v2 implementation. The v1 is there for legacy applications
1153 which haven't migrated to the new cgroup v2 interface yet. If you
1154 do not have any such application then you are completely fine leaving
1155 this option disabled.
1156
1157 Say N if unsure.
1158
6bf024e6
JW
1159config PROC_PID_CPUSET
1160 bool "Include legacy /proc/<pid>/cpuset file"
1161 depends on CPUSETS
1162 default y
afc24d49 1163
6bf024e6
JW
1164config CGROUP_DEVICE
1165 bool "Device controller"
1166 help
1167 Provides a cgroup controller implementing whitelists for
1168 devices which a process in the cgroup can mknod or open.
1169
1170config CGROUP_CPUACCT
1171 bool "Simple CPU accounting controller"
1172 help
1173 Provides a simple controller for monitoring the
1174 total CPU consumed by the tasks in a cgroup.
1175
1176config CGROUP_PERF
1177 bool "Perf controller"
1178 depends on PERF_EVENTS
1179 help
1180 This option extends the perf per-cpu mode to restrict monitoring
1181 to threads which belong to the cgroup specified and run on the
6546b19f
NK
1182 designated cpu. Or this can be used to have cgroup ID in samples
1183 so that it can monitor performance events among cgroups.
6bf024e6
JW
1184
1185 Say N if unsure.
1186
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1187config CGROUP_BPF
1188 bool "Support for eBPF programs attached to cgroups"
483c4933
AL
1189 depends on BPF_SYSCALL
1190 select SOCK_CGROUP_DATA
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DM
1191 help
1192 Allow attaching eBPF programs to a cgroup using the bpf(2)
1193 syscall command BPF_PROG_ATTACH.
1194
1195 In which context these programs are accessed depends on the type
1196 of attachment. For instance, programs that are attached using
1197 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1198 inet sockets.
1199
a72232ea
VS
1200config CGROUP_MISC
1201 bool "Misc resource controller"
1202 default n
1203 help
1204 Provides a controller for miscellaneous resources on a host.
1205
1206 Miscellaneous scalar resources are the resources on the host system
1207 which cannot be abstracted like the other cgroups. This controller
1208 tracks and limits the miscellaneous resources used by a process
1209 attached to a cgroup hierarchy.
1210
1211 For more information, please check misc cgroup section in
1212 /Documentation/admin-guide/cgroup-v2.rst.
1213
6bf024e6 1214config CGROUP_DEBUG
23b0be48 1215 bool "Debug controller"
afc24d49 1216 default n
23b0be48 1217 depends on DEBUG_KERNEL
6bf024e6
JW
1218 help
1219 This option enables a simple controller that exports
23b0be48
WL
1220 debugging information about the cgroups framework. This
1221 controller is for control cgroup debugging only. Its
1222 interfaces are not stable.
afc24d49 1223
6bf024e6 1224 Say N.
89e9b9e0 1225
73b35147
AB
1226config SOCK_CGROUP_DATA
1227 bool
1228 default n
1229
23964d2d 1230endif # CGROUPS
c077719b 1231
8dd2a82c 1232menuconfig NAMESPACES
6a108a14 1233 bool "Namespaces support" if EXPERT
2813893f 1234 depends on MULTIUSER
6a108a14 1235 default !EXPERT
c5289a69
PE
1236 help
1237 Provides the way to make tasks work with different objects using
1238 the same id. For example same IPC id may refer to different objects
1239 or same user id or pid may refer to different tasks when used in
1240 different namespaces.
1241
8dd2a82c
DL
1242if NAMESPACES
1243
58bfdd6d
PE
1244config UTS_NS
1245 bool "UTS namespace"
17a6d441 1246 default y
58bfdd6d
PE
1247 help
1248 In this namespace tasks see different info provided with the
1249 uname() system call
1250
769071ac
AV
1251config TIME_NS
1252 bool "TIME namespace"
660fd04f 1253 depends on GENERIC_VDSO_TIME_NS
769071ac
AV
1254 default y
1255 help
1256 In this namespace boottime and monotonic clocks can be set.
1257 The time will keep going with the same pace.
1258
ae5e1b22
PE
1259config IPC_NS
1260 bool "IPC namespace"
8dd2a82c 1261 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 1262 default y
ae5e1b22
PE
1263 help
1264 In this namespace tasks work with IPC ids which correspond to
614b84cf 1265 different IPC objects in different namespaces.
ae5e1b22 1266
aee16ce7 1267config USER_NS
19c92399 1268 bool "User namespace"
5673a94c 1269 default n
aee16ce7
PE
1270 help
1271 This allows containers, i.e. vservers, to use user namespaces
1272 to provide different user info for different servers.
e11f0ae3
EB
1273
1274 When user namespaces are enabled in the kernel it is
d886f4e4
JW
1275 recommended that the MEMCG option also be enabled and that
1276 user-space use the memory control groups to limit the amount
1277 of memory a memory unprivileged users can use.
e11f0ae3 1278
aee16ce7
PE
1279 If unsure, say N.
1280
74bd59bb 1281config PID_NS
9bd38c2c 1282 bool "PID Namespaces"
17a6d441 1283 default y
74bd59bb 1284 help
12d2b8f9 1285 Support process id namespaces. This allows having multiple
692105b8 1286 processes with the same pid as long as they are in different
74bd59bb
PE
1287 pid namespaces. This is a building block of containers.
1288
d6eb633f
MH
1289config NET_NS
1290 bool "Network namespace"
8dd2a82c 1291 depends on NET
17a6d441 1292 default y
d6eb633f
MH
1293 help
1294 Allow user space to create what appear to be multiple instances
1295 of the network stack.
1296
8dd2a82c
DL
1297endif # NAMESPACES
1298
5cb366bb
AR
1299config CHECKPOINT_RESTORE
1300 bool "Checkpoint/restore support"
30341ec9 1301 depends on PROC_FS
5cb366bb 1302 select PROC_CHILDREN
bfe3911a 1303 select KCMP
5cb366bb
AR
1304 default n
1305 help
1306 Enables additional kernel features in a sake of checkpoint/restore.
1307 In particular it adds auxiliary prctl codes to setup process text,
1308 data and heap segment sizes, and a few additional /proc filesystem
1309 entries.
1310
1311 If unsure, say N here.
1312
5091faa4
MG
1313config SCHED_AUTOGROUP
1314 bool "Automatic process group scheduling"
5091faa4
MG
1315 select CGROUPS
1316 select CGROUP_SCHED
1317 select FAIR_GROUP_SCHED
1318 help
1319 This option optimizes the scheduler for common desktop workloads by
1320 automatically creating and populating task groups. This separation
1321 of workloads isolates aggressive CPU burners (like build jobs) from
1322 desktop applications. Task group autogeneration is currently based
1323 upon task session.
1324
7af37bec
DL
1325config RELAY
1326 bool "Kernel->user space relay support (formerly relayfs)"
26b5679e 1327 select IRQ_WORK
7af37bec
DL
1328 help
1329 This option enables support for relay interface support in
1330 certain file systems (such as debugfs).
1331 It is designed to provide an efficient mechanism for tools and
1332 facilities to relay large amounts of data from kernel space to
1333 user space.
1334
1335 If unsure, say N.
1336
f991633d
DG
1337config BLK_DEV_INITRD
1338 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
f991633d
DG
1339 help
1340 The initial RAM filesystem is a ramfs which is loaded by the
1341 boot loader (loadlin or lilo) and that is mounted as root
1342 before the normal boot procedure. It is typically used to
1343 load modules needed to mount the "real" root file system,
8c27ceff 1344 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
f991633d
DG
1345
1346 If RAM disk support (BLK_DEV_RAM) is also included, this
1347 also enables initial RAM disk (initrd) support and adds
1348 15 Kbytes (more on some other architectures) to the kernel size.
1349
1350 If unsure say Y.
1351
c33df4ea
JPS
1352if BLK_DEV_INITRD
1353
dbec4866
SR
1354source "usr/Kconfig"
1355
c33df4ea
JPS
1356endif
1357
76db5a27
MH
1358config BOOT_CONFIG
1359 bool "Boot config support"
a2a9d67a 1360 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
76db5a27
MH
1361 help
1362 Extra boot config allows system admin to pass a config file as
1363 complemental extension of kernel cmdline when booting.
0947db01 1364 The boot config file must be attached at the end of initramfs
85c46b78 1365 with checksum, size and magic word.
0947db01 1366 See <file:Documentation/admin-guide/bootconfig.rst> for details.
76db5a27
MH
1367
1368 If unsure, say Y.
1369
b743852c
PM
1370config BOOT_CONFIG_FORCE
1371 bool "Force unconditional bootconfig processing"
1372 depends on BOOT_CONFIG
6ded8a28 1373 default y if BOOT_CONFIG_EMBED
b743852c
PM
1374 help
1375 With this Kconfig option set, BOOT_CONFIG processing is carried
1376 out even when the "bootconfig" kernel-boot parameter is omitted.
1377 In fact, with this Kconfig option set, there is no way to
1378 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
1379 parameters.
1380
1381 If unsure, say N.
1382
a2a9d67a
MH
1383config BOOT_CONFIG_EMBED
1384 bool "Embed bootconfig file in the kernel"
1385 depends on BOOT_CONFIG
1386 help
1387 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1388 kernel. Usually, the bootconfig file is loaded with the initrd
1389 image. But if the system doesn't support initrd, this option will
1390 help you by embedding a bootconfig file while building the kernel.
1391
1392 If unsure, say N.
1393
1394config BOOT_CONFIG_EMBED_FILE
1395 string "Embedded bootconfig file path"
1396 depends on BOOT_CONFIG_EMBED
1397 help
1398 Specify a bootconfig file which will be embedded to the kernel.
1399 This bootconfig will be used if there is no initrd or no other
1400 bootconfig in the initrd.
1401
1274aea1
DD
1402config INITRAMFS_PRESERVE_MTIME
1403 bool "Preserve cpio archive mtimes in initramfs"
1404 default y
1405 help
1406 Each entry in an initramfs cpio archive carries an mtime value. When
1407 enabled, extracted cpio items take this mtime, with directory mtime
1408 setting deferred until after creation of any child entries.
1409
1410 If unsure, say Y.
76db5a27 1411
877417e6
AB
1412choice
1413 prompt "Compiler optimization level"
2cc3ce24 1414 default CC_OPTIMIZE_FOR_PERFORMANCE
877417e6
AB
1415
1416config CC_OPTIMIZE_FOR_PERFORMANCE
15f5db60 1417 bool "Optimize for performance (-O2)"
877417e6
AB
1418 help
1419 This is the default optimization level for the kernel, building
1420 with the "-O2" compiler flag for best performance and most
1421 helpful compile-time warnings.
1422
c45b4f1f 1423config CC_OPTIMIZE_FOR_SIZE
15f5db60 1424 bool "Optimize for size (-Os)"
c45b4f1f 1425 help
ce3b487f
MY
1426 Choosing this option will pass "-Os" to your compiler resulting
1427 in a smaller kernel.
c45b4f1f 1428
877417e6
AB
1429endchoice
1430
5d20ee31
NP
1431config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1432 bool
1433 help
1434 This requires that the arch annotates or otherwise protects
1435 its external entry points from being discarded. Linker scripts
1436 must also merge .text.*, .data.*, and .bss.* correctly into
1437 output sections. Care must be taken not to pull in unrelated
1438 sections (e.g., '.text.init'). Typically '.' in section names
1439 is used to distinguish them from label names / C identifiers.
1440
1441config LD_DEAD_CODE_DATA_ELIMINATION
1442 bool "Dead code and data elimination (EXPERIMENTAL)"
1443 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1444 depends on EXPERT
e85d1d65
MY
1445 depends on $(cc-option,-ffunction-sections -fdata-sections)
1446 depends on $(ld-option,--gc-sections)
5d20ee31 1447 help
8b9d2712
MY
1448 Enable this if you want to do dead code and data elimination with
1449 the linker by compiling with -ffunction-sections -fdata-sections,
1450 and linking with --gc-sections.
5d20ee31
NP
1451
1452 This can reduce on disk and in-memory size of the kernel
1453 code and static data, particularly for small configs and
1454 on small systems. This has the possibility of introducing
1455 silently broken kernel if the required annotations are not
1456 present. This option is not well tested yet, so use at your
1457 own risk.
1458
59612b24
NC
1459config LD_ORPHAN_WARN
1460 def_bool y
1461 depends on ARCH_WANT_LD_ORPHAN_WARN
1462 depends on $(ld-option,--orphan-handling=warn)
e1789d7c
XL
1463 depends on $(ld-option,--orphan-handling=error)
1464
1465config LD_ORPHAN_WARN_LEVEL
1466 string
1467 depends on LD_ORPHAN_WARN
1468 default "error" if WERROR
1469 default "warn"
59612b24 1470
0847062a
RD
1471config SYSCTL
1472 bool
1473
657a5209
MF
1474config HAVE_UID16
1475 bool
1476
1477config SYSCTL_EXCEPTION_TRACE
1478 bool
1479 help
1480 Enable support for /proc/sys/debug/exception-trace.
1481
1482config SYSCTL_ARCH_UNALIGN_NO_WARN
1483 bool
1484 help
1485 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1486 Allows arch to define/use @no_unaligned_warning to possibly warn
1487 about unaligned access emulation going on under the hood.
1488
1489config SYSCTL_ARCH_UNALIGN_ALLOW
1490 bool
1491 help
1492 Enable support for /proc/sys/kernel/unaligned-trap
1493 Allows arches to define/use @unaligned_enabled to runtime toggle
1494 the unaligned access emulation.
1495 see arch/parisc/kernel/unaligned.c for reference
1496
657a5209
MF
1497config HAVE_PCSPKR_PLATFORM
1498 bool
1499
6a108a14
DR
1500menuconfig EXPERT
1501 bool "Configure standard kernel features (expert users)"
f505c553
JT
1502 # Unhide debug options, to make the on-by-default options visible
1503 select DEBUG_KERNEL
1da177e4
LT
1504 help
1505 This option allows certain base kernel options and settings
e8cf4e9c
KK
1506 to be disabled or tweaked. This is for specialized
1507 environments which can tolerate a "non-standard" kernel.
1508 Only use this if you really know what you are doing.
1da177e4 1509
ae81f9e3 1510config UID16
6a108a14 1511 bool "Enable 16-bit UID system calls" if EXPERT
2813893f 1512 depends on HAVE_UID16 && MULTIUSER
ae81f9e3
CE
1513 default y
1514 help
1515 This enables the legacy 16-bit UID syscall wrappers.
1516
2813893f
IM
1517config MULTIUSER
1518 bool "Multiple users, groups and capabilities support" if EXPERT
1519 default y
1520 help
1521 This option enables support for non-root users, groups and
1522 capabilities.
1523
1524 If you say N here, all processes will run with UID 0, GID 0, and all
1525 possible capabilities. Saying N here also compiles out support for
1526 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1527 setgid, and capset.
1528
1529 If unsure, say Y here.
1530
f6187769
FF
1531config SGETMASK_SYSCALL
1532 bool "sgetmask/ssetmask syscalls support" if EXPERT
cd14b018 1533 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
a7f7f624 1534 help
f6187769
FF
1535 sys_sgetmask and sys_ssetmask are obsolete system calls
1536 no longer supported in libc but still enabled by default in some
1537 architectures.
1538
1539 If unsure, leave the default option here.
1540
6af9f7bf
FF
1541config SYSFS_SYSCALL
1542 bool "Sysfs syscall support" if EXPERT
1543 default y
a7f7f624 1544 help
6af9f7bf
FF
1545 sys_sysfs is an obsolete system call no longer supported in libc.
1546 Note that disabling this option is more secure but might break
1547 compatibility with some systems.
1548
1549 If unsure say Y here.
1550
d1b069f5
RD
1551config FHANDLE
1552 bool "open by fhandle syscalls" if EXPERT
1553 select EXPORTFS
1554 default y
1555 help
1556 If you say Y here, a user level program will be able to map
1557 file names to handle and then later use the handle for
1558 different file system operations. This is useful in implementing
1559 userspace file servers, which now track files using handles instead
1560 of names. The handle would remain the same even if file names
1561 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1562 syscalls.
1563
baa73d9e
NP
1564config POSIX_TIMERS
1565 bool "Posix Clocks & timers" if EXPERT
1566 default y
1567 help
1568 This includes native support for POSIX timers to the kernel.
1569 Some embedded systems have no use for them and therefore they
1570 can be configured out to reduce the size of the kernel image.
1571
1572 When this option is disabled, the following syscalls won't be
1573 available: timer_create, timer_gettime: timer_getoverrun,
1574 timer_settime, timer_delete, clock_adjtime, getitimer,
1575 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1576 clock_getres and clock_nanosleep syscalls will be limited to
1577 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1578
1579 If unsure say y.
1580
d59745ce
MM
1581config PRINTK
1582 default y
6a108a14 1583 bool "Enable support for printk" if EXPERT
74876a98 1584 select IRQ_WORK
d59745ce
MM
1585 help
1586 This option enables normal printk support. Removing it
1587 eliminates most of the message strings from the kernel image
1588 and makes the kernel more or less silent. As this makes it
1589 very difficult to diagnose system problems, saying N here is
1590 strongly discouraged.
1591
c8538a7a 1592config BUG
6a108a14 1593 bool "BUG() support" if EXPERT
c8538a7a
MM
1594 default y
1595 help
e8cf4e9c
KK
1596 Disabling this option eliminates support for BUG and WARN, reducing
1597 the size of your kernel image and potentially quietly ignoring
1598 numerous fatal conditions. You should only consider disabling this
1599 option for embedded systems with no facilities for reporting errors.
1600 Just say Y.
c8538a7a 1601
708e9a79 1602config ELF_CORE
046d662f 1603 depends on COREDUMP
708e9a79 1604 default y
6a108a14 1605 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1606 help
1607 Enable support for generating core dumps. Disabling saves about 4k.
1608
8761f1ab 1609
e5e1d3cb 1610config PCSPKR_PLATFORM
6a108a14 1611 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1612 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1613 select I8253_LOCK
e5e1d3cb
SS
1614 default y
1615 help
e8cf4e9c
KK
1616 This option allows to disable the internal PC-Speaker
1617 support, saving some memory.
e5e1d3cb 1618
27021649
YC
1619config BASE_SMALL
1620 bool "Enable smaller-sized data structures for core" if EXPERT
1da177e4 1621 help
27021649 1622 Enabling this option reduces the size of miscellaneous core
1da177e4
LT
1623 kernel data structures. This saves memory on small machines,
1624 but may reduce performance.
1625
1626config FUTEX
6a108a14 1627 bool "Enable futex support" if EXPERT
3f2bedab 1628 depends on !(SPARC32 && SMP)
1da177e4 1629 default y
bc2eecd7 1630 imply RT_MUTEXES
1da177e4
LT
1631 help
1632 Disabling this option will cause the kernel to be built without
1633 support for "fast userspace mutexes". The resulting kernel may not
1634 run glibc-based applications correctly.
1635
bc2eecd7
NP
1636config FUTEX_PI
1637 bool
1638 depends on FUTEX && RT_MUTEXES
1639 default y
1640
1da177e4 1641config EPOLL
6a108a14 1642 bool "Enable eventpoll support" if EXPERT
1da177e4
LT
1643 default y
1644 help
1645 Disabling this option will cause the kernel to be built without
1646 support for epoll family of system calls.
1647
fba2afaa 1648config SIGNALFD
6a108a14 1649 bool "Enable signalfd() system call" if EXPERT
fba2afaa
DL
1650 default y
1651 help
1652 Enable the signalfd() system call that allows to receive signals
1653 on a file descriptor.
1654
1655 If unsure, say Y.
1656
b215e283 1657config TIMERFD
6a108a14 1658 bool "Enable timerfd() system call" if EXPERT
b215e283
DL
1659 default y
1660 help
1661 Enable the timerfd() system call that allows to receive timer
1662 events on a file descriptor.
1663
1664 If unsure, say Y.
1665
e1ad7468 1666config EVENTFD
6a108a14 1667 bool "Enable eventfd() system call" if EXPERT
e1ad7468
DL
1668 default y
1669 help
1670 Enable the eventfd() system call that allows to receive both
1671 kernel notification (ie. KAIO) or userspace notifications.
1672
1673 If unsure, say Y.
1674
1da177e4 1675config SHMEM
6a108a14 1676 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1677 default y
1678 depends on MMU
1679 help
1680 The shmem is an internal filesystem used to manage shared memory.
1681 It is backed by swap and manages resource limits. It is also exported
1682 to userspace as tmpfs if TMPFS is enabled. Disabling this
1683 option replaces shmem and tmpfs with the much simpler ramfs code,
1684 which may be appropriate on small systems without swap.
1685
ebf3f09c 1686config AIO
6a108a14 1687 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1688 default y
1689 help
1690 This option enables POSIX asynchronous I/O which may by used
657a5209
MF
1691 by some high performance threaded applications. Disabling
1692 this option saves about 7k.
1693
2b188cc1
JA
1694config IO_URING
1695 bool "Enable IO uring support" if EXPERT
561fb04a 1696 select IO_WQ
2b188cc1
JA
1697 default y
1698 help
1699 This option enables support for the io_uring interface, enabling
1700 applications to submit and complete IO through submission and
1701 completion rings that are shared between the kernel and application.
1702
1802656e
JA
1703config GCOV_PROFILE_URING
1704 bool "Enable GCOV profiling on the io_uring subsystem"
1705 depends on GCOV_KERNEL
1706 help
1707 Enable GCOV profiling on the io_uring subsystem, to facilitate
1708 code coverage testing.
1709
1710 If unsure, say N.
1711
1712 Note that this will have a negative impact on the performance of
1713 the io_uring subsystem, hence this should only be enabled for
1714 specific test purposes.
1715
d3ac21ca
JT
1716config ADVISE_SYSCALLS
1717 bool "Enable madvise/fadvise syscalls" if EXPERT
1718 default y
1719 help
1720 This option enables the madvise and fadvise syscalls, used by
1721 applications to advise the kernel about their future memory or file
1722 usage, improving performance. If building an embedded system where no
1723 applications use these syscalls, you can disable this option to save
1724 space.
1725
5b25b13a
MD
1726config MEMBARRIER
1727 bool "Enable membarrier() system call" if EXPERT
1728 default y
1729 help
1730 Enable the membarrier() system call that allows issuing memory
1731 barriers across all running threads, which can be used to distribute
1732 the cost of user-space memory barriers asymmetrically by transforming
1733 pairs of memory barriers into pairs consisting of membarrier() and a
1734 compiler barrier.
1735
1736 If unsure, say Y.
1737
a751ea34
RD
1738config KCMP
1739 bool "Enable kcmp() system call" if EXPERT
1740 help
1741 Enable the kernel resource comparison system call. It provides
1742 user-space with the ability to compare two processes to see if they
1743 share a common resource, such as a file descriptor or even virtual
1744 memory space.
1745
1746 If unsure, say N.
1747
1748config RSEQ
1749 bool "Enable rseq() system call" if EXPERT
1750 default y
1751 depends on HAVE_RSEQ
1752 select MEMBARRIER
1753 help
1754 Enable the restartable sequences system call. It provides a
1755 user-space cache for the current CPU number value, which
1756 speeds up getting the current CPU number from user-space,
1757 as well as an ABI to speed up user-space operations on
1758 per-CPU data.
1759
1760 If unsure, say Y.
1761
1762config DEBUG_RSEQ
1763 default n
1764 bool "Enable debugging of rseq() system call" if EXPERT
1765 depends on RSEQ && DEBUG_KERNEL
1766 help
1767 Enable extra debugging checks for the rseq system call.
1768
1769 If unsure, say N.
1770
1771config CACHESTAT_SYSCALL
1772 bool "Enable cachestat() system call" if EXPERT
1773 default y
1774 help
1775 Enable the cachestat system call, which queries the page cache
1776 statistics of a file (number of cached pages, dirty pages,
1777 pages marked for writeback, (recently) evicted pages).
1778
1779 If unsure say Y here.
1780
1781config PC104
1782 bool "PC/104 support" if EXPERT
1783 help
1784 Expose PC/104 form factor device drivers and options available for
1785 selection and configuration. Enable this option if your target
1786 machine has a PC/104 bus.
1787
d1b069f5 1788config KALLSYMS
e8cf4e9c
KK
1789 bool "Load all symbols for debugging/ksymoops" if EXPERT
1790 default y
1791 help
1792 Say Y here to let the kernel print out symbolic crash information and
1793 symbolic stack backtraces. This increases the size of the kernel
1794 somewhat, as all symbols have to be loaded into the kernel image.
d1b069f5 1795
30f3bb09
ZL
1796config KALLSYMS_SELFTEST
1797 bool "Test the basic functions and performance of kallsyms"
1798 depends on KALLSYMS
1799 default n
1800 help
1801 Test the basic functions and performance of some interfaces, such as
1802 kallsyms_lookup_name. It also calculates the compression rate of the
1803 kallsyms compression algorithm for the current symbol set.
1804
1805 Start self-test automatically after system startup. Suggest executing
1806 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
1807 displayed in the last line, indicating that the test is complete.
1808
d1b069f5
RD
1809config KALLSYMS_ALL
1810 bool "Include all symbols in kallsyms"
1811 depends on DEBUG_KERNEL && KALLSYMS
1812 help
e8cf4e9c
KK
1813 Normally kallsyms only contains the symbols of functions for nicer
1814 OOPS messages and backtraces (i.e., symbols from the text and inittext
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BS
1815 sections). This is sufficient for most cases. And only if you want to
1816 enable kernel live patching, or other less common use cases (e.g.,
1817 when a debugger is used) all symbols are required (i.e., names of
1818 variables from the data sections, etc).
d1b069f5 1819
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1820 This option makes sure that all symbols are loaded into the kernel
1821 image (i.e., symbols from all sections) in cost of increased kernel
1822 size (depending on the kernel configuration, it may be 300KiB or
1823 something like this).
d1b069f5 1824
bdf0fe33 1825 Say N unless you really need all symbols, or kernel live patching.
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RD
1826
1827config KALLSYMS_ABSOLUTE_PERCPU
1828 bool
1829 depends on KALLSYMS
1830 default X86_64 && SMP
1831
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1832# end of the "standard kernel features (expert users)" menu
1833
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1834config ARCH_HAS_MEMBARRIER_CALLBACKS
1835 bool
1836
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1837config ARCH_HAS_MEMBARRIER_SYNC_CORE
1838 bool
1839
cdd6c482 1840config HAVE_PERF_EVENTS
0793a61d 1841 bool
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1842 help
1843 See tools/perf/design.txt for details.
0793a61d 1844
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1845config GUEST_PERF_EVENTS
1846 bool
1847 depends on HAVE_PERF_EVENTS
1848
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1849config PERF_USE_VMALLOC
1850 bool
1851 help
1852 See tools/perf/design.txt for details
1853
57c0c15b 1854menu "Kernel Performance Events And Counters"
0793a61d 1855
cdd6c482 1856config PERF_EVENTS
57c0c15b 1857 bool "Kernel performance events and counters"
392d65a9 1858 default y if PROFILING
cdd6c482 1859 depends on HAVE_PERF_EVENTS
e360adbe 1860 select IRQ_WORK
0793a61d 1861 help
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1862 Enable kernel support for various performance events provided
1863 by software and hardware.
0793a61d 1864
dd77038d 1865 Software events are supported either built-in or via the
57c0c15b 1866 use of generic tracepoints.
0793a61d 1867
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1868 Most modern CPUs support performance events via performance
1869 counter registers. These registers count the number of certain
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1870 types of hw events: such as instructions executed, cachemisses
1871 suffered, or branches mis-predicted - without slowing down the
1872 kernel or applications. These registers can also trigger interrupts
1873 when a threshold number of events have passed - and can thus be
1874 used to profile the code that runs on that CPU.
1875
57c0c15b 1876 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1877 these software and hardware event capabilities, available via a
57c0c15b 1878 system call and used by the "perf" utility in tools/perf/. It
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1879 provides per task and per CPU counters, and it provides event
1880 capabilities on top of those.
1881
1882 Say Y if unsure.
1883
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1884config DEBUG_PERF_USE_VMALLOC
1885 default n
1886 bool "Debug: use vmalloc to back perf mmap() buffers"
cb307113 1887 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
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1888 select PERF_USE_VMALLOC
1889 help
e8cf4e9c 1890 Use vmalloc memory to back perf mmap() buffers.
906010b2 1891
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1892 Mostly useful for debugging the vmalloc code on platforms
1893 that don't require it.
906010b2 1894
e8cf4e9c 1895 Say N if unsure.
906010b2 1896
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1897endmenu
1898
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1899config SYSTEM_DATA_VERIFICATION
1900 def_bool n
1901 select SYSTEM_TRUSTED_KEYRING
1902 select KEYS
1903 select CRYPTO
d43de6c7 1904 select CRYPTO_RSA
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1905 select ASYMMETRIC_KEY_TYPE
1906 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
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1907 select ASN1
1908 select OID_REGISTRY
1909 select X509_CERTIFICATE_PARSER
1910 select PKCS7_MESSAGE_PARSER
82c04ff8 1911 help
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1912 Provide PKCS#7 message verification using the contents of the system
1913 trusted keyring to provide public keys. This then can be used for
1914 module verification, kexec image verification and firmware blob
1915 verification.
82c04ff8 1916
125e5645 1917config PROFILING
b309a294 1918 bool "Profiling support"
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1919 help
1920 Say Y here to enable the extended profiling support mechanisms used
f8408264 1921 by profilers.
125e5645 1922
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1923config RUST
1924 bool "Rust support"
1925 depends on HAVE_RUST
1926 depends on RUST_IS_AVAILABLE
8933cf46 1927 depends on !CFI_CLANG
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1928 depends on !MODVERSIONS
1929 depends on !GCC_PLUGINS
1930 depends on !RANDSTRUCT
f126745d 1931 depends on !SHADOW_CALL_STACK
c1177979 1932 depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
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1933 help
1934 Enables Rust support in the kernel.
1935
1936 This allows other Rust-related options, like drivers written in Rust,
1937 to be selected.
1938
1939 It is also required to be able to load external kernel modules
1940 written in Rust.
1941
1942 See Documentation/rust/ for more information.
1943
1944 If unsure, say N.
1945
1946config RUSTC_VERSION_TEXT
1947 string
1948 depends on RUST
aacf93e8 1949 default "$(shell,$(RUSTC) --version 2>/dev/null)"
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1950
1951config BINDGEN_VERSION_TEXT
1952 string
1953 depends on RUST
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1954 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
1955 # (https://github.com/rust-lang/rust-bindgen/pull/2678). It can be removed when
1956 # the minimum version is upgraded past that (0.69.1 already fixed the issue).
aacf93e8 1957 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
2f7ab126 1958
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1959#
1960# Place an empty function call at each tracepoint site. Can be
1961# dynamically changed for a probe function.
1962#
97e1c18e 1963config TRACEPOINTS
5f87f112 1964 bool
97e1c18e 1965
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1966source "kernel/Kconfig.kexec"
1967
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1968endmenu # General setup
1969
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1970source "arch/Kconfig"
1971
ae81f9e3 1972config RT_MUTEXES
6341e62b 1973 bool
1c6f9ec0 1974 default y if PREEMPT_RT
ae81f9e3 1975
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1976config MODULE_SIG_FORMAT
1977 def_bool n
1978 select SYSTEM_DATA_VERIFICATION
1979
73b4fc92 1980source "kernel/module/Kconfig"
6c9692e2 1981
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1982config INIT_ALL_POSSIBLE
1983 bool
1984 help
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RR
1985 Back when each arch used to define their own cpu_online_mask and
1986 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1987 with all 1s, and others with all 0s. When they were centralised,
1988 it was better to provide this option than to break all the archs
692105b8 1989 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1990
3a65dfe8 1991source "block/Kconfig"
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1992
1993config PREEMPT_NOTIFIERS
1994 bool
e260be67 1995
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SK
1996config PADATA
1997 depends on SMP
1998 bool
1999
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2000config ASN1
2001 tristate
2002 help
2003 Build a simple ASN.1 grammar compiler that produces a bytecode output
2004 that can be interpreted by the ASN.1 stream decoder and used to
2005 inform it as to what tags are to be expected in a stream and what
2006 functions to call on what tags.
2007
6beb0009 2008source "kernel/Kconfig.locks"
e61938a9 2009
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2010config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2011 bool
2012
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AP
2013config ARCH_HAS_PREPARE_SYNC_CORE_CMD
2014 bool
2015
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MD
2016config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2017 bool
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DB
2018
2019# It may be useful for an architecture to override the definitions of the
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DB
2020# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2021# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2022# different calling convention for syscalls. They can also override the
2023# macros for not-implemented syscalls in kernel/sys_ni.c and
2024# kernel/time/posix-stubs.c. All these overrides need to be available in
2025# <asm/syscall_wrapper.h>.
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DB
2026config ARCH_HAS_SYSCALL_WRAPPER
2027 def_bool n