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Thomas Gleixnerec8f24b2019-05-19 13:07:45 +01001# SPDX-License-Identifier: GPL-2.0-only
Masahiro Yamada8b59cd82020-04-23 23:23:52 +09002config 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
Bhaskar Chowdhuryf9c8bc42021-02-25 17:22:18 -080013 - Ensure full rebuild when the compiler is updated
Masahiro Yamadace6ed1c2021-03-04 20:37:08 +090014 include/linux/compiler-version.h contains this option in the comment
Alexey Dobriyan0e0345b2021-04-15 20:36:07 +030015 line so fixdep adds include/config/CC_VERSION_TEXT into the
Masahiro Yamadace6ed1c2021-03-04 20:37:08 +090016 auto-generated dependency. When the compiler is updated, syncconfig
17 will touch it and then every file will be rebuilt.
Masahiro Yamada8b59cd82020-04-23 23:23:52 +090018
Masahiro Yamadaa4353892018-05-28 18:22:01 +090019config CC_IS_GCC
Masahiro Yamadaaec6c602021-01-16 08:35:42 +090020 def_bool $(success,test "$(cc-name)" = GCC)
Masahiro Yamadaa4353892018-05-28 18:22:01 +090021
22config GCC_VERSION
23 int
Masahiro Yamadaaec6c602021-01-16 08:35:42 +090024 default $(cc-version) if CC_IS_GCC
Masahiro Yamadaa4353892018-05-28 18:22:01 +090025 default 0
26
Masahiro Yamada469cb732018-05-28 18:22:02 +090027config CC_IS_CLANG
Masahiro Yamadaaec6c602021-01-16 08:35:42 +090028 def_bool $(success,test "$(cc-name)" = Clang)
Sami Tolvanenb744b432020-04-28 15:14:15 -070029
Masahiro Yamada469cb732018-05-28 18:22:02 +090030config CLANG_VERSION
31 int
Masahiro Yamadaaec6c602021-01-16 08:35:42 +090032 default $(cc-version) if CC_IS_CLANG
33 default 0
Masahiro Yamada469cb732018-05-28 18:22:02 +090034
Masahiro Yamadaba64beb2021-03-16 01:12:56 +090035config 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
Masahiro Yamada02aff852021-02-16 12:10:04 +090047config 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)
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070057
Nathan Chancellord5750cd2020-11-19 13:46:58 -070058config LLD_VERSION
59 int
Masahiro Yamada02aff852021-02-16 12:10:04 +090060 default $(ld-version) if LD_IS_LLD
61 default 0
Nathan Chancellord5750cd2020-11-19 13:46:58 -070062
Miguel Ojeda6e74c6b2024-09-02 18:55:28 +020063config RUSTC_VERSION
64 int
65 default $(shell,$(srctree)/scripts/rustc-version.sh $(RUSTC))
66 help
67 It does not depend on `RUST` since that one may need to use the version
68 in a `depends on`.
69
Miguel Ojeda2f7ab122021-07-03 16:42:57 +020070config 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
Colin Ian Kingeacf96d2022-10-07 21:43:39 +010076 to satisfy the build requirements of Rust support.
Miguel Ojeda2f7ab122021-07-03 16:42:57 +020077
78 In particular, the Makefile target 'rustavailable' is useful to check
79 why the Rust toolchain is not being detected.
80
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090081config CC_CAN_LINK
Masahiro Yamada9371f862020-04-29 12:45:13 +090082 bool
Elliot Bermanf67695c92022-02-01 13:35:42 -080083 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
84 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090085
Masahiro Yamadab1183b62020-05-09 16:39:15 +090086config CC_CAN_LINK_STATIC
87 bool
Elliot Bermanf67695c92022-02-01 13:35:42 -080088 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
89 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070090
Mark Rutlandf2f6a8e2024-07-18 13:06:47 +010091# Fixed in GCC 14, 13.3, 12.4 and 11.5
92# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
93config GCC_ASM_GOTO_OUTPUT_BROKEN
94 bool
95 depends on CC_IS_GCC
96 default y if GCC_VERSION < 110500
97 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
98 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
99
Nick Desaulniers587f1702020-02-14 14:18:11 -0800100config CC_HAS_ASM_GOTO_OUTPUT
Mark Rutlandf2f6a8e2024-07-18 13:06:47 +0100101 def_bool y
102 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN
103 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)
Nick Desaulniers587f1702020-02-14 14:18:11 -0800104
Sean Christopherson1aa0e8b2022-02-02 00:49:41 +0000105config CC_HAS_ASM_GOTO_TIED_OUTPUT
106 depends on CC_HAS_ASM_GOTO_OUTPUT
107 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
Alexandre Belloni534bd702022-11-15 12:01:58 +0100108 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)
Sean Christopherson1aa0e8b2022-02-02 00:49:41 +0000109
Peter Collingbourne5cf896fb62019-07-31 18:18:42 -0700110config TOOLS_SUPPORT_RELR
Will Deacon2d122942019-08-20 10:11:54 +0100111 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
Peter Collingbourne5cf896fb62019-07-31 18:18:42 -0700112
Rasmus Villemoeseb111862019-09-13 00:19:25 +0200113config CC_HAS_ASM_INLINE
114 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
115
Nick Desaulniers51c2ee62021-06-21 16:18:22 -0700116config CC_HAS_NO_PROFILE_FN_ATTR
117 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
118
Nathan Chancellor613fe162022-02-01 13:56:21 -0700119config PAHOLE_VERSION
120 int
121 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
122
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -0700123config CONSTRUCTORS
124 bool
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -0700125
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800126config IRQ_WORK
Tejun Heofd0a68a2024-02-15 19:10:01 -1000127 def_bool y if SMP
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800128
Shile Zhang10916702019-12-04 08:46:31 +0800129config BUILDTIME_TABLE_SORT
David Daney1dbdc6f2012-04-19 14:59:57 -0700130 bool
131
Andy Lutomirskic65eacb2016-09-13 14:29:24 -0700132config THREAD_INFO_IN_TASK
133 bool
134 help
135 Select this to move thread_info off the stack into task_struct. To
136 make this work, an arch will need to remove all thread_info fields
137 except flags and fix any runtime bugs.
138
Andy Lutomirskic6c314a2016-09-15 22:45:43 -0700139 One subtle change that will be needed is to use try_get_task_stack()
140 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
141
Al Boldiff0cfc62007-07-31 00:39:23 -0700142menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144config BROKEN
145 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146
147config BROKEN_ON_SMP
148 bool
149 depends on BROKEN || !SMP
150 default y
151
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152config INIT_ENV_ARG_LIMIT
153 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -0700154 default 32 if !UML
155 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 help
Randy Dunlap34ad92c22005-10-30 15:01:46 -0800157 Maximum of each of the number of arguments and environment
158 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159
Jiri Slaby4bb16672013-05-22 10:56:24 +0200160config COMPILE_TEST
161 bool "Compile also drivers which will not load"
Masahiro Yamadaea29b202021-03-12 21:07:08 -0800162 depends on HAS_IOMEM
Jiri Slaby4bb16672013-05-22 10:56:24 +0200163 help
164 Some drivers can be compiled on a different platform than they are
165 intended to be run on. Despite they cannot be loaded there (or even
166 when they load they cannot be used due to missing HW support),
167 developers still, opposing to distributors, might want to build such
168 drivers to compile-test them.
169
170 If you are a developer and want to build everything available, say Y
171 here. If you are a user/distributor, say N here to exclude useless
172 drivers to be distributed.
173
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700174config WERROR
175 bool "Compile the kernel with warnings as errors"
Marco Elverb339ec92021-09-07 23:12:08 +0200176 default COMPILE_TEST
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700177 help
178 A kernel build should not cause any compiler warnings, and this
Miguel Ojeda2f7ab122021-07-03 16:42:57 +0200179 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
Xin Lie1789d72022-10-25 00:30:23 -0700180 to enforce that rule by default. Certain warnings from other tools
181 such as the linker may be upgraded to errors with this option as
182 well.
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700183
Xin Lie1789d72022-10-25 00:30:23 -0700184 However, if you have a new (or very old) compiler or linker with odd
185 and unusual warnings, or you have some architecture with problems,
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700186 you may need to disable this config option in order to
187 successfully build the kernel.
188
189 If in doubt, say Y.
190
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900191config UAPI_HEADER_TEST
192 bool "Compile test UAPI headers"
Masahiro Yamadafcbb8462019-11-07 16:14:40 +0900193 depends on HEADERS_INSTALL && CC_CAN_LINK
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900194 help
195 Compile test headers exported to user-space to ensure they are
196 self-contained, i.e. compilable as standalone units.
197
198 If you are a developer or tester and want to ensure the exported
199 headers are self-contained, say Y here. Otherwise, choose N.
200
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201config LOCALVERSION
202 string "Local version - append to kernel release"
203 help
204 Append an extra string to the end of your kernel version.
205 This will show up when you type uname, for example.
206 The string you set here will be appended after the contents of
207 any files with a filename matching localversion* in your
208 object and source tree, in that order. Your total string can
209 be a maximum of 64 characters.
210
Ryan Andersonaaebf432005-07-31 04:57:49 -0400211config LOCALVERSION_AUTO
212 bool "Automatically append version information to the version string"
213 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -0700214 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -0400215 help
216 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200217 release tree by looking for git tags that belong to the current
218 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400219
220 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200221 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400222 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200223 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400224
Rasmus Villemoes0f9c6082023-01-11 10:38:22 +0100225 (The actual string used here is the first 12 characters produced
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200226 by running the command:
227
228 $ git rev-parse --verify HEAD
229
230 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400231
Laura Abbott9afb7192018-07-05 17:49:37 -0700232config BUILD_SALT
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800233 string "Build ID Salt"
234 default ""
235 help
236 The build ID is used to link binaries and their debug info. Setting
237 this option will use the value in the calculation of the build id.
238 This is mostly useful for distributions which want to ensure the
239 build is unique between builds. It's safe to leave the default.
Laura Abbott9afb7192018-07-05 17:49:37 -0700240
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800241config HAVE_KERNEL_GZIP
242 bool
243
244config HAVE_KERNEL_BZIP2
245 bool
246
247config HAVE_KERNEL_LZMA
248 bool
249
Lasse Collin3ebe1242011-01-12 17:01:23 -0800250config HAVE_KERNEL_XZ
251 bool
252
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800253config HAVE_KERNEL_LZO
254 bool
255
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700256config HAVE_KERNEL_LZ4
257 bool
258
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700259config HAVE_KERNEL_ZSTD
260 bool
261
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200262config HAVE_KERNEL_UNCOMPRESSED
263 bool
264
Alain Knaff30d65db2009-01-04 22:46:17 +0100265choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800266 prompt "Kernel compression mode"
267 default KERNEL_GZIP
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700268 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
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800269 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100270 The linux kernel is a kind of self-extracting executable.
271 Several compression algorithms are available, which differ
272 in efficiency, compression and decompression speed.
273 Compression speed is only relevant when building a kernel.
274 Decompression speed is relevant at each boot.
275
276 If you have any problems with bzip2 or lzma compressed
277 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
278 version of this functionality (bzip2 only), for 2.4, was
279 supplied by Christian Ludwig)
280
281 High compression options are mostly useful for users, who
282 are low on disk space (embedded systems), but for whom ram
283 size matters less.
284
285 If in doubt, select 'gzip'
286
287config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800288 bool "Gzip"
289 depends on HAVE_KERNEL_GZIP
290 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800291 The old and tried gzip compression. It provides a good balance
292 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100293
294config KERNEL_BZIP2
295 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800296 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100297 help
298 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700299 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800300 size is about 10% smaller with bzip2, in comparison to gzip.
301 Bzip2 uses a large amount of memory. For modern kernels you
302 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100303
304config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800305 bool "LZMA"
306 depends on HAVE_KERNEL_LZMA
307 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700308 This compression algorithm's ratio is best. Decompression speed
309 is between gzip and bzip2. Compression is slowest.
310 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100311
Lasse Collin3ebe1242011-01-12 17:01:23 -0800312config KERNEL_XZ
313 bool "XZ"
314 depends on HAVE_KERNEL_XZ
315 help
316 XZ uses the LZMA2 algorithm and instruction set specific
317 BCJ filters which can improve compression ratio of executable
318 code. The size of the kernel is about 30% smaller with XZ in
319 comparison to gzip. On architectures for which there is a BCJ
Lasse Collin7472ff8a2024-07-21 16:36:29 +0300320 filter (i386, x86_64, ARM, ARM64, RISC-V, big endian PowerPC,
321 and SPARC), XZ will create a few percent smaller kernel than
322 plain LZMA.
Lasse Collin3ebe1242011-01-12 17:01:23 -0800323
324 The speed is about the same as with LZMA: The decompression
325 speed of XZ is better than that of bzip2 but worse than gzip
326 and LZO. Compression is slow.
327
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800328config KERNEL_LZO
329 bool "LZO"
330 depends on HAVE_KERNEL_LZO
331 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700332 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200333 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800334 (both compression and decompression) is the fastest.
335
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700336config KERNEL_LZ4
337 bool "LZ4"
338 depends on HAVE_KERNEL_LZ4
339 help
340 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
341 A preliminary version of LZ4 de/compression tool is available at
342 <https://code.google.com/p/lz4/>.
343
344 Its compression ratio is worse than LZO. The size of the kernel
345 is about 8% bigger than LZO. But the decompression speed is
346 faster than LZO.
347
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700348config KERNEL_ZSTD
349 bool "ZSTD"
350 depends on HAVE_KERNEL_ZSTD
351 help
352 ZSTD is a compression algorithm targeting intermediate compression
353 with fast decompression speed. It will compress better than GZIP and
354 decompress around the same speed as LZO, but slower than LZ4. You
355 will need at least 192 KB RAM or more for booting. The zstd command
356 line tool is required for compression.
357
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200358config KERNEL_UNCOMPRESSED
359 bool "None"
360 depends on HAVE_KERNEL_UNCOMPRESSED
361 help
362 Produce uncompressed kernel image. This option is usually not what
363 you want. It is useful for debugging the kernel in slow simulation
364 environments, where decompressing and moving the kernel is awfully
365 slow. This option allows early boot code to skip the decompressor
366 and jump right at uncompressed kernel image.
367
Alain Knaff30d65db2009-01-04 22:46:17 +0100368endchoice
369
Chris Downada4ab72020-06-04 16:50:53 -0700370config DEFAULT_INIT
371 string "Default init path"
372 default ""
373 help
374 This option determines the default init for the system if no init=
375 option is passed on the kernel command line. If the requested path is
376 not present, we will still then move on to attempting further
377 locations (e.g. /sbin/init, etc). If this is empty, we will just use
378 the fallback list when init= is not passed.
379
Josh Triplettbd5dc172011-06-15 15:08:28 -0700380config DEFAULT_HOSTNAME
381 string "Default hostname"
382 default "(none)"
383 help
384 This option determines the default system hostname before userspace
385 calls sethostname(2). The kernel traditionally uses "(none)" here,
386 but you may wish to use a different default here to make a minimal
387 system more usable with less configuration.
388
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389config SYSVIPC
390 bool "System V IPC"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900391 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 Inter Process Communication is a suite of library functions and
393 system calls which let processes (running programs) synchronize and
394 exchange information. It is generally considered to be a good thing,
395 and some programs won't run unless you say Y here. In particular, if
396 you want to run the DOS emulator dosemu under Linux (read the
397 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
398 you'll need to say Y here.
399
400 You can find documentation about IPC with "info ipc" and also in
401 section 6.4 of the Linux Programmer's Guide, available from
402 <http://www.tldp.org/guides.html>.
403
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800404config SYSVIPC_SYSCTL
405 bool
406 depends on SYSVIPC
407 depends on SYSCTL
408 default y
409
Guo Ren0cbed0e2022-04-05 15:12:58 +0800410config SYSVIPC_COMPAT
411 def_bool y
412 depends on COMPAT && SYSVIPC
413
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414config POSIX_MQUEUE
415 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700416 depends on NET
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900417 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 POSIX variant of message queues is a part of IPC. In POSIX message
419 queues every message has a priority which decides about succession
420 of receiving it by a process. If you want to compile and run
421 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e376502007-05-09 07:25:13 +0200422 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423
424 POSIX message queues are visible as a filesystem called 'mqueue'
425 and can be mounted somewhere if you want to do filesystem
426 operations on message queues.
427
428 If unsure, say Y.
429
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700430config POSIX_MQUEUE_SYSCTL
431 bool
432 depends on POSIX_MQUEUE
433 depends on SYSCTL
434 default y
435
David Howellsc73be612020-01-14 17:07:11 +0000436config WATCH_QUEUE
437 bool "General notification queue"
438 default n
439 help
440
441 This is a general notification queue for the kernel to pass events to
442 userspace by splicing them into pipes. It can be used in conjunction
443 with watches for key/keyring change notifications and device
444 notifications.
445
Mauro Carvalho Chehabc02b8722022-06-26 10:10:56 +0100446 See Documentation/core-api/watch_queue.rst
David Howellsc73be612020-01-14 17:07:11 +0000447
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700448config CROSS_MEMORY_ATTACH
449 bool "Enable process_vm_readv/writev syscalls"
450 depends on MMU
451 default y
452 help
453 Enabling this option adds the system calls process_vm_readv and
454 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700455 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700456 See the man page for more details.
457
Josh Triplett69369a72014-04-03 14:48:27 -0700458config USELIB
Kees Cook7374fa32022-04-29 14:38:01 -0700459 bool "uselib syscall (for libc5 and earlier)"
460 default ALPHA || M68K || SPARC
Josh Triplett69369a72014-04-03 14:48:27 -0700461 help
462 This option enables the uselib syscall, a system call used in the
463 dynamic linker from libc5 and earlier. glibc does not use this
464 system call. If you intend to run programs built on libc5 or
465 earlier, you may need to enable this syscall. Current systems
466 running glibc can safely disable this.
467
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468config AUDIT
469 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100470 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 help
472 Enable auditing infrastructure that can be used with another
473 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500474 logging of avc messages output). System call auditing is included
475 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900477config HAVE_ARCH_AUDITSYSCALL
478 bool
479
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500481 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900482 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500483 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400484
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000485source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200486source "kernel/time/Kconfig"
Daniel Borkmannb24abcf2021-05-11 22:35:16 +0200487source "kernel/bpf/Kconfig"
Christoph Hellwig87a4c372018-07-31 13:39:32 +0200488source "kernel/Kconfig.preempt"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000489
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200490menu "CPU/Task time and stats accounting"
491
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200492config VIRT_CPU_ACCOUNTING
493 bool
494
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200495choice
496 prompt "Cputime accounting"
Nicholas Piggin02382af2022-09-02 18:53:15 +1000497 default TICK_CPU_ACCOUNTING
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200498
499# Kind of a stub config for the pure tick based cputime accounting
500config TICK_CPU_ACCOUNTING
501 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200502 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200503 help
504 This is the basic tick based cputime accounting that maintains
505 statistics about user, system and idle time spent on per jiffies
506 granularity.
507
508 If unsure, say Y.
509
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200510config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200511 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200512 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200513 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200514 help
515 Select this option to enable more accurate task and CPU time
516 accounting. This is done by reading a CPU counter on each
517 kernel entry and exit and on transitions within the kernel
518 between system, softirq and hardirq state, so there is a
519 small performance impact. In the case of s390 or IBM POWER > 5,
520 this also enables accounting of stolen time on logically-partitioned
521 systems.
522
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200523config VIRT_CPU_ACCOUNTING_GEN
524 bool "Full dynticks CPU time accounting"
Frederic Weisbecker24a9c5412022-06-08 16:40:24 +0200525 depends on HAVE_CONTEXT_TRACKING_USER
Kevin Hilman554b0002013-09-16 15:28:21 -0700526 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Arnd Bergmann041a1572019-03-04 21:01:31 +0100527 depends on GENERIC_CLOCKEVENTS
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200528 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker24a9c5412022-06-08 16:40:24 +0200529 select CONTEXT_TRACKING_USER
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200530 help
531 Select this option to enable task and CPU time accounting on full
532 dynticks systems. This accounting is implemented by watching every
533 kernel-user boundaries using the context tracking subsystem.
534 The accounting is thus performed at the expense of some significant
535 overhead.
536
537 For now this is only useful if you are working on the full
538 dynticks subsystem development.
539
540 If unsure, say N.
541
Rik van Rielb58c3582016-07-13 16:50:02 +0200542endchoice
543
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200544config IRQ_TIME_ACCOUNTING
545 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200546 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200547 help
548 Select this option to enable fine granularity task irq time
549 accounting. This is done by reading a timestamp on each
550 transitions between softirq and hardirq state, so there can be a
551 small performance impact.
552
553 If in doubt, say N here.
554
Vincent Guittot11d4afd2018-09-25 11:17:42 +0200555config HAVE_SCHED_AVG_IRQ
556 def_bool y
557 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
558 depends on SMP
559
Vincent Guittotd4dbc992024-03-26 10:16:15 +0100560config SCHED_HW_PRESSURE
Valentin Schneider98eb4012020-07-12 17:59:16 +0100561 bool
Valentin Schneiderfcd7c9c2020-07-29 14:57:18 +0100562 default y if ARM && ARM_CPU_TOPOLOGY
563 default y if ARM64
Thara Gopinath76504792020-02-21 19:52:05 -0500564 depends on SMP
Valentin Schneider98eb4012020-07-12 17:59:16 +0100565 depends on CPU_FREQ_THERMAL
566 help
Vincent Guittotd4dbc992024-03-26 10:16:15 +0100567 Select this option to enable HW pressure accounting in the
568 scheduler. HW pressure is the value conveyed to the scheduler
Valentin Schneider98eb4012020-07-12 17:59:16 +0100569 that reflects the reduction in CPU compute capacity resulted from
Vincent Guittotd4dbc992024-03-26 10:16:15 +0100570 HW throttling. HW throttling occurs when the performance of
571 a CPU is capped due to high operating temperatures as an example.
Valentin Schneider98eb4012020-07-12 17:59:16 +0100572
573 If selected, the scheduler will be able to balance tasks accordingly,
574 i.e. put less load on throttled CPUs than on non/less throttled ones.
575
576 This requires the architecture to implement
Vincent Guittotd4dbc992024-03-26 10:16:15 +0100577 arch_update_hw_pressure() and arch_scale_thermal_pressure().
Thara Gopinath76504792020-02-21 19:52:05 -0500578
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200579config BSD_PROCESS_ACCT
580 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700581 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200582 help
583 If you say Y here, a user level program will be able to instruct the
584 kernel (via a special system call) to write process accounting
585 information to a file: whenever a process exits, information about
586 that process will be appended to the file by the kernel. The
587 information includes things such as creation time, owning user,
588 command name, memory usage, controlling terminal etc. (the complete
589 list is in the struct acct in <file:include/linux/acct.h>). It is
590 up to the user level program to do useful things with this
591 information. This is generally a good idea, so say Y.
592
593config BSD_PROCESS_ACCT_V3
594 bool "BSD Process Accounting version 3 file format"
595 depends on BSD_PROCESS_ACCT
596 default n
597 help
598 If you say Y here, the process accounting information is written
599 in a new file format that also logs the process IDs of each
Randy Dunlap3903bf92018-08-21 21:58:34 -0700600 process and its parent. Note that this file format is incompatible
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200601 with previous v0/v1/v2 file formats, so you will need updated tools
602 for processing it. A preliminary version of these tools is available
603 at <http://www.gnu.org/software/acct/>.
604
605config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700606 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200607 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700608 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200609 default n
610 help
611 Export selected statistics for tasks/processes through the
612 generic netlink interface. Unlike BSD process accounting, the
613 statistics are available during the lifetime of tasks/processes as
614 responses to commands. Like BSD accounting, they are sent to user
615 space on task exit.
616
617 Say N if unsure.
618
619config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700620 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200621 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530622 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200623 help
624 Collect information on time spent by a task waiting for system
625 resources like cpu, synchronous block I/O completion and swapping
626 in pages. Such statistics can help in setting a task's priorities
627 relative to other tasks for cpu, io, rss limits etc.
628
629 Say N if unsure.
630
631config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700632 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200633 depends on TASKSTATS
634 help
635 Collect extended task accounting data and send the data
636 to userland for processing over the taskstats interface.
637
638 Say N if unsure.
639
640config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700641 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200642 depends on TASK_XACCT
643 help
644 Collect information on the number of bytes of storage I/O which this
645 task has caused.
646
647 Say N if unsure.
648
Johannes Weinereb414682018-10-26 15:06:27 -0700649config PSI
650 bool "Pressure stall information tracking"
Randy Dunlap98dfdd92023-07-30 20:07:40 -0700651 select KERNFS
Johannes Weinereb414682018-10-26 15:06:27 -0700652 help
653 Collect metrics that indicate how overcommitted the CPU, memory,
654 and IO capacity are in the system.
655
656 If you say Y here, the kernel will create /proc/pressure/ with the
657 pressure statistics files cpu, memory, and io. These will indicate
658 the share of walltime in which some or all tasks in the system are
659 delayed due to contention of the respective resource.
660
Johannes Weiner2ce71352018-10-26 15:06:31 -0700661 In kernels with cgroup support, cgroups (cgroup2 only) will
662 have cpu.pressure, memory.pressure, and io.pressure files,
663 which aggregate pressure stalls for the grouped tasks only.
664
Mauro Carvalho Chehabc3123552019-04-17 05:46:08 -0300665 For more details see Documentation/accounting/psi.rst.
Johannes Weinereb414682018-10-26 15:06:27 -0700666
667 Say N if unsure.
668
Johannes Weinere0c27442018-11-30 14:09:58 -0800669config PSI_DEFAULT_DISABLED
670 bool "Require boot parameter to enable pressure stall information tracking"
671 default n
672 depends on PSI
673 help
674 If set, pressure stall information tracking will be disabled
Baruch Siach428a1cb2018-12-14 14:17:03 -0800675 per default but can be enabled through passing psi=1 on the
676 kernel commandline during boot.
Johannes Weinere0c27442018-11-30 14:09:58 -0800677
Johannes Weiner7b2489d2019-02-01 14:21:15 -0800678 This feature adds some code to the task wakeup and sleep
679 paths of the scheduler. The overhead is too low to affect
680 common scheduling-intense workloads in practice (such as
681 webservers, memcache), but it does show up in artificial
682 scheduler stress tests, such as hackbench.
683
684 If you are paranoid and not sure what the kernel will be
685 used for, say Y.
686
687 Say N if unsure.
688
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200689endmenu # "CPU/Task time and stats accounting"
690
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200691config CPU_ISOLATION
692 bool "CPU isolation"
Geert Uytterhoeven414a2dc2018-01-02 12:13:10 +0100693 depends on SMP || COMPILE_TEST
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100694 default y
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200695 help
696 Make sure that CPUs running critical tasks are not disturbed by
697 any source of "noise" such as unbound workqueues, timers, kthreads...
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100698 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
699 the "isolcpus=" boot parameter.
700
701 Say Y if unsure.
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200702
Paul E. McKenney0af92d42017-05-17 08:43:40 -0700703source "kernel/rcu/Kconfig"
Mike Travisc903ff82009-01-15 12:28:29 -0800704
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700706 tristate "Kernel .config support"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900707 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 This option enables the complete Linux kernel ".config" file
709 contents to be saved in the kernel. It provides documentation
710 of which kernel options are used in a running kernel or in an
711 on-disk kernel. This information can be extracted from the kernel
712 image file with the script scripts/extract-ikconfig and used as
713 input to rebuild the current kernel or to build another kernel.
714 It can also be extracted from a running kernel by reading
715 /proc/config.gz if enabled (below).
716
717config IKCONFIG_PROC
718 bool "Enable access to .config through /proc/config.gz"
719 depends on IKCONFIG && PROC_FS
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900720 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 This option enables access to the kernel configuration file
722 through /proc/config.gz.
723
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400724config IKHEADERS
725 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
726 depends on SYSFS
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400727 help
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400728 This option enables access to the in-kernel headers that are generated during
729 the build process. These can be used to build eBPF tracing programs,
730 or similar programs. If you build the headers as a module, a module called
731 kheaders.ko is built which can be loaded on-demand to get access to headers.
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400732
Alistair John Strachan794543a2007-05-08 00:31:15 -0700733config LOG_BUF_SHIFT
734 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Christoph Hellwig1c4b5ec2022-02-23 08:47:20 +0100735 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700736 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700737 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700738 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700739 Select the minimal kernel log buffer size as a power of 2.
740 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
741 parameter, see below. Any higher size also might be forced
742 by "log_buf_len" boot parameter.
743
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700744 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700745 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700746 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700747 15 => 32 KB
748 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700749 13 => 8 KB
750 12 => 4 KB
751
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700752config LOG_CPU_MAX_BUF_SHIFT
753 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700754 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700755 range 0 21
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700756 default 0 if BASE_SMALL
Yoann Congal320bf432024-05-05 10:03:41 +0200757 default 12
Josh Triplett361e9df2014-10-03 16:00:54 -0700758 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700759 help
760 This option allows to increase the default ring buffer size
761 according to the number of CPUs. The value defines the contribution
762 of each CPU as a power of 2. The used space is typically only few
763 lines however it might be much more when problems are reported,
764 e.g. backtraces.
765
766 The increased size means that a new buffer has to be allocated and
767 the original static one is unused. It makes sense only on systems
768 with more CPUs. Therefore this value is used only when the sum of
769 contributions is greater than the half of the default kernel ring
770 buffer as defined by LOG_BUF_SHIFT. The default values are set
Paul Menzel0f7636e12020-08-11 11:29:23 +0200771 so that more than 16 CPUs are needed to trigger the allocation.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700772
773 Also this option is ignored when "log_buf_len" kernel parameter is
774 used as it forces an exact (power of two) size of the ring buffer.
775
776 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200777 hotplugging making the computation optimal for the worst case
778 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700779
780 Examples shift values and their meaning:
781 17 => 128 KB for each CPU
782 16 => 64 KB for each CPU
783 15 => 32 KB for each CPU
784 14 => 16 KB for each CPU
785 13 => 8 KB for each CPU
786 12 => 4 KB for each CPU
787
Chris Down33701552021-06-15 17:52:53 +0100788config PRINTK_INDEX
789 bool "Printk indexing debugfs interface"
790 depends on PRINTK && DEBUG_FS
791 help
792 Add support for indexing of all printk formats known at compile time
793 at <debugfs>/printk/index/<module>.
794
795 This can be used as part of maintaining daemons which monitor
796 /dev/kmsg, as it permits auditing the printk formats present in a
797 kernel, allowing detection of cases where monitored printks are
798 changed or no longer present.
799
800 There is no additional runtime cost to printk with this enabled.
801
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800802#
803# Architectures with an unreliable sched_clock() should select this:
804#
805config HAVE_UNSTABLE_SCHED_CLOCK
806 bool
807
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700808config GENERIC_SCHED_CLOCK
809 bool
810
Patrick Bellasi69842cb2019-06-21 09:42:02 +0100811menu "Scheduler features"
812
813config UCLAMP_TASK
814 bool "Enable utilization clamping for RT/FAIR tasks"
815 depends on CPU_FREQ_GOV_SCHEDUTIL
816 help
817 This feature enables the scheduler to track the clamped utilization
818 of each CPU based on RUNNABLE tasks scheduled on that CPU.
819
820 With this option, the user can specify the min and max CPU
821 utilization allowed for RUNNABLE tasks. The max utilization defines
822 the maximum frequency a task should use while the min utilization
823 defines the minimum frequency it should use.
824
825 Both min and max utilization clamp values are hints to the scheduler,
826 aiming at improving its frequency selection policy, but they do not
827 enforce or grant any specific bandwidth for tasks.
828
829 If in doubt, say N.
830
831config UCLAMP_BUCKETS_COUNT
832 int "Number of supported utilization clamp buckets"
833 range 5 20
834 default 5
835 depends on UCLAMP_TASK
836 help
837 Defines the number of clamp buckets to use. The range of each bucket
838 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
839 number of clamp buckets the finer their granularity and the higher
840 the precision of clamping aggregation and tracking at run-time.
841
842 For example, with the minimum configuration value we will have 5
843 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
844 be refcounted in the [20..39]% bucket and will set the bucket clamp
845 effective value to 25%.
846 If a second 30% boosted task should be co-scheduled on the same CPU,
847 that task will be refcounted in the same bucket of the first task and
848 it will boost the bucket clamp effective value to 30%.
849 The clamp effective value of a bucket is reset to its nominal value
850 (20% in the example above) when there are no more tasks refcounted in
851 that bucket.
852
853 An additional boost/capping margin can be added to some tasks. In the
854 example above the 25% task will be boosted to 30% until it exits the
855 CPU. If that should be considered not acceptable on certain systems,
856 it's always possible to reduce the margin by increasing the number of
857 clamp buckets to trade off used memory for run-time tracking
858 precision.
859
860 If in doubt, use the default value.
861
862endmenu
863
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200864#
865# For architectures that want to enable the support for NUMA-affine scheduler
866# balancing logic:
867#
868config ARCH_SUPPORTS_NUMA_BALANCING
869 bool
870
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100871#
Mel Gorman72b252a2015-09-04 15:47:32 -0700872# For architectures that prefer to flush all TLBs after a number of pages
873# are unmapped instead of sending one IPI per page to flush. The architecture
874# must provide guarantees on what happens if a clean TLB cache entry is
875# written after the unmap. Details are in mm/rmap.c near the check for
876# should_defer_flush. The architecture should also consider if the full flush
877# and the refill costs are offset by the savings of sending fewer IPIs.
878config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
879 bool
880
Ard Biesheuvelc12d3362019-11-08 13:22:27 +0100881config CC_HAS_INT128
Masahiro Yamada3a7c7332020-03-10 19:12:50 +0900882 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
Ard Biesheuvelc12d3362019-11-08 13:22:27 +0100883
Gustavo A. R. Silvadee2b7022021-11-13 18:57:25 -0600884config CC_IMPLICIT_FALLTHROUGH
885 string
Gustavo A. R. Silva158ea2d2021-11-14 20:48:44 -0600886 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
Gustavo A. R. Silvadee2b7022021-11-13 18:57:25 -0600887 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
888
Kees Cook3e00f582024-02-23 09:08:27 -0800889# Currently, disable gcc-10+ array-bounds globally.
Linus Torvalds0da6e5f2023-04-23 09:56:20 -0700890# It's still broken in gcc-13, so no upper bound yet.
Kees Cook3e00f582024-02-23 09:08:27 -0800891config GCC10_NO_ARRAY_BOUNDS
Linus Torvalds5a412372023-01-09 17:04:49 -0600892 def_bool y
893
Linus Torvaldsf0be87c2022-06-09 10:11:12 -0700894config CC_NO_ARRAY_BOUNDS
895 bool
Yury Norov8e5bd4e2024-05-22 15:58:30 -0700896 default y if CC_IS_GCC && GCC_VERSION >= 90000 && GCC10_NO_ARRAY_BOUNDS
Linus Torvaldsf0be87c2022-06-09 10:11:12 -0700897
Linus Torvalds02153312024-02-01 14:57:17 -0800898# Currently, disable -Wstringop-overflow for GCC globally.
899config GCC_NO_STRINGOP_OVERFLOW
Gustavo A. R. Silvaa5e0ace02023-11-30 14:29:34 -0600900 def_bool y
901
902config CC_NO_STRINGOP_OVERFLOW
903 bool
Linus Torvalds02153312024-02-01 14:57:17 -0800904 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
Gustavo A. R. Silvaa5e0ace02023-11-30 14:29:34 -0600905
906config CC_STRINGOP_OVERFLOW
907 bool
908 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
909
Mel Gorman72b252a2015-09-04 15:47:32 -0700910#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100911# For architectures that know their GCC __int128 support is sound
912#
913config ARCH_SUPPORTS_INT128
914 bool
915
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200916# For architectures that (ab)use NUMA to represent different memory regions
917# all cpu-local but of different latencies, such as SuperH.
918#
919config ARCH_WANT_NUMA_VARIABLE_LOCALITY
920 bool
921
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200922config NUMA_BALANCING
923 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200924 depends on ARCH_SUPPORTS_NUMA_BALANCING
925 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
Sebastian Andrzej Siewior554b0f32021-11-05 13:35:27 -0700926 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200927 help
928 This option adds support for automatic NUMA aware memory/task placement.
929 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400930 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200931
932 This system will be inactive on UMA systems.
933
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800934config NUMA_BALANCING_DEFAULT_ENABLED
935 bool "Automatically enable NUMA aware memory/task placement"
936 default y
937 depends on NUMA_BALANCING
938 help
939 If set, automatic NUMA balancing will be enabled if running on a NUMA
940 machine.
941
Suren Baghdasaryan21c690a2024-03-21 09:36:28 -0700942config SLAB_OBJ_EXT
943 bool
944
Li Zefan23964d22009-01-15 13:50:58 -0800945menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500946 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500947 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700948 help
Li Zefan23964d22009-01-15 13:50:58 -0800949 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800950 use with process control subsystems such as Cpusets, CFS, memory
951 controls or device isolation.
952 See
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300953 - Documentation/scheduler/sched-design-CFS.rst (CFS)
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300954 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800955 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700956
957 Say N if unsure.
958
Li Zefan23964d22009-01-15 13:50:58 -0800959if CGROUPS
960
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800961config PAGE_COUNTER
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800962 bool
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800963
Tejun Heo6a010a42022-07-23 04:28:28 -1000964config CGROUP_FAVOR_DYNMODS
965 bool "Favor dynamic modification latency reduction by default"
966 help
967 This option enables the "favordynmods" mount option by default
968 which reduces the latencies of dynamic cgroup modifications such
969 as task migrations and controller on/offs at the cost of making
970 hot path operations such as forks and exits more expensive.
971
972 Say N if unsure.
973
Andrew Mortonc255a452012-07-31 16:43:02 -0700974config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500975 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800976 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500977 select EVENTFD
Suren Baghdasaryan21c690a2024-03-21 09:36:28 -0700978 select SLAB_OBJ_EXT
Balbir Singh00f0b822008-03-04 14:28:39 -0800979 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500980 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800981
Roman Gushchine93d4162024-06-24 17:59:05 -0700982config MEMCG_V1
983 bool "Legacy cgroup v1 memory controller"
Vlastimil Babkac9929f02023-02-27 17:46:13 +0100984 depends on MEMCG
Roman Gushchine93d4162024-06-24 17:59:05 -0700985 default n
986 help
987 Legacy cgroup v1 memory controller which has been deprecated by
988 cgroup v2 implementation. The v1 is there for legacy applications
989 which haven't migrated to the new cgroup v2 interface yet. If you
990 do not have any such application then you are completely fine leaving
991 this option disabled.
992
993 Please note that feature set of the legacy memory controller is likely
994 going to shrink due to deprecation process. New deployments with v1
995 controller are highly discouraged.
996
Valdis Kletnieksfcb48242024-07-13 02:59:50 -0400997 Say N if unsure.
Kirill Tkhai84c07d12018-08-17 15:47:25 -0700998
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500999config BLK_CGROUP
1000 bool "IO controller"
1001 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -07001002 default n
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09001003 help
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001004 Generic block IO controller cgroup interface. This is the common
1005 cgroup interface which should be used by various IO controlling
1006 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -07001007
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001008 Currently, CFQ IO scheduler uses it to recognize task groups and
1009 control disk bandwidth allocation (proportional time slice allocation)
1010 to such task groups. It is also used by bio throttling logic in
1011 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +02001012
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001013 This option only enables generic Block IO controller infrastructure.
1014 One needs to also enable actual IO controlling logic/policy. For
1015 enabling proportional weight division of disk bandwidth in CFQ, set
Krzysztof Kozlowski7baf2192020-04-06 20:12:02 -07001016 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001017 CONFIG_BLK_DEV_THROTTLING=y.
1018
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -03001019 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001020
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001021config CGROUP_WRITEBACK
1022 bool
1023 depends on MEMCG && BLK_CGROUP
1024 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +02001025
Dhaval Giani7c941432010-01-20 13:26:18 +01001026menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -05001027 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +01001028 default n
1029 help
1030 This feature lets CPU scheduler recognize task groups and control CPU
1031 bandwidth allocation to such task groups. It uses cgroups to group
1032 tasks.
1033
1034if CGROUP_SCHED
Tejun Heoe179e80c2024-09-04 10:24:59 -10001035config GROUP_SCHED_WEIGHT
1036 def_bool n
1037
Dhaval Giani7c941432010-01-20 13:26:18 +01001038config FAIR_GROUP_SCHED
1039 bool "Group scheduling for SCHED_OTHER"
1040 depends on CGROUP_SCHED
Tejun Heoe179e80c2024-09-04 10:24:59 -10001041 select GROUP_SCHED_WEIGHT
Dhaval Giani7c941432010-01-20 13:26:18 +01001042 default CGROUP_SCHED
1043
Paul Turnerab84d312011-07-21 09:43:28 -07001044config CFS_BANDWIDTH
1045 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -07001046 depends on FAIR_GROUP_SCHED
1047 default n
1048 help
1049 This option allows users to define CPU bandwidth rates (limits) for
1050 tasks running within the fair group scheduler. Groups with no limit
1051 set are considered to be unconstrained and will run with no
1052 restriction.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -03001053 See Documentation/scheduler/sched-bwc.rst for more information.
Paul Turnerab84d312011-07-21 09:43:28 -07001054
Dhaval Giani7c941432010-01-20 13:26:18 +01001055config RT_GROUP_SCHED
1056 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +01001057 depends on CGROUP_SCHED
1058 default n
1059 help
1060 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +08001061 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +01001062 schedule realtime tasks for non-root users until you allocate
1063 realtime bandwidth for them.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -03001064 See Documentation/scheduler/sched-rt-group.rst for more information.
Dhaval Giani7c941432010-01-20 13:26:18 +01001065
Tejun Heo81951362024-09-04 10:24:59 -10001066config EXT_GROUP_SCHED
1067 bool
1068 depends on SCHED_CLASS_EXT && CGROUP_SCHED
1069 select GROUP_SCHED_WEIGHT
1070 default y
1071
Dhaval Giani7c941432010-01-20 13:26:18 +01001072endif #CGROUP_SCHED
1073
Mathieu Desnoyersaf7f5882022-11-22 15:39:09 -05001074config SCHED_MM_CID
1075 def_bool y
1076 depends on SMP && RSEQ
1077
Patrick Bellasi2480c092019-08-22 14:28:06 +01001078config UCLAMP_TASK_GROUP
1079 bool "Utilization clamping per group of tasks"
1080 depends on CGROUP_SCHED
1081 depends on UCLAMP_TASK
1082 default n
1083 help
1084 This feature enables the scheduler to track the clamped utilization
1085 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1086
1087 When this option is enabled, the user can specify a min and max
1088 CPU bandwidth which is allowed for each single task in a group.
1089 The max bandwidth allows to clamp the maximum frequency a task
1090 can use, while the min bandwidth allows to define a minimum
1091 frequency a task will always use.
1092
1093 When task group based utilization clamping is enabled, an eventually
1094 specified task-specific clamp value is constrained by the cgroup
1095 specified clamp value. Both minimum and maximum task clamping cannot
1096 be bigger than the corresponding clamping defined at task group level.
1097
1098 If in doubt, say N.
1099
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001100config CGROUP_PIDS
1101 bool "PIDs controller"
1102 help
1103 Provides enforcement of process number limits in the scope of a
1104 cgroup. Any attempt to fork more processes than is allowed in the
1105 cgroup will fail. PIDs are fundamentally a global resource because it
1106 is fairly trivial to reach PID exhaustion before you reach even a
1107 conservative kmemcg limit. As a result, it is possible to grind a
1108 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +05301109 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001110
1111 It should be noted that organisational operations (such as attaching
Jonathan Neuschäfer98076832019-02-01 14:21:01 -08001112 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001113 since the PIDs limit only affects a process's ability to fork, not to
1114 attach to a cgroup.
1115
Parav Pandit39d3e752017-01-10 00:02:13 +00001116config CGROUP_RDMA
1117 bool "RDMA controller"
1118 help
1119 Provides enforcement of RDMA resources defined by IB stack.
1120 It is fairly easy for consumers to exhaust RDMA resources, which
1121 can result into resource unavailability to other consumers.
1122 RDMA controller is designed to stop this from happening.
1123 Attaching processes with active RDMA resources to the cgroup
1124 hierarchy is allowed even if can cross the hierarchy's limit.
1125
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001126config CGROUP_FREEZER
1127 bool "Freezer controller"
1128 help
1129 Provides a way to freeze and unfreeze all tasks in a
1130 cgroup.
1131
Johannes Weiner489c2a22016-01-20 15:02:41 -08001132 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1133 controller includes important in-kernel memory consumers per default.
1134
1135 If you're using cgroup2, say N.
1136
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001137config CGROUP_HUGETLB
1138 bool "HugeTLB controller"
1139 depends on HUGETLB_PAGE
1140 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +02001141 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001142 help
1143 Provides a cgroup controller for HugeTLB pages.
1144 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1145 The limit is enforced during page fault. Since HugeTLB doesn't
1146 support page reclaim, enforcing the limit at page fault time implies
1147 that, the application will get SIGBUS signal if it tries to access
1148 HugeTLB pages beyond its limit. This requires the application to know
1149 beforehand how much HugeTLB pages it would require for its use. The
1150 control group is tracked in the third page lru pointer. This means
1151 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001152
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001153config CPUSETS
1154 bool "Cpuset controller"
Nicolas Pitree1d4eee2017-06-14 13:19:23 -04001155 depends on SMP
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001156 help
1157 This option will let you create and manage CPUSETs which
1158 allow dynamically partitioning a system into sets of CPUs and
1159 Memory Nodes and assigning tasks to run only within those sets.
1160 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001161
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001162 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001163
Chen Ridong1abab1ba2024-08-30 10:02:28 +00001164config CPUSETS_V1
1165 bool "Legacy cgroup v1 cpusets controller"
1166 depends on CPUSETS
1167 default n
1168 help
1169 Legacy cgroup v1 cpusets controller which has been deprecated by
1170 cgroup v2 implementation. The v1 is there for legacy applications
1171 which haven't migrated to the new cgroup v2 interface yet. If you
1172 do not have any such application then you are completely fine leaving
1173 this option disabled.
1174
1175 Say N if unsure.
1176
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001177config PROC_PID_CPUSET
1178 bool "Include legacy /proc/<pid>/cpuset file"
1179 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001180 default y
1181
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001182config CGROUP_DEVICE
1183 bool "Device controller"
1184 help
1185 Provides a cgroup controller implementing whitelists for
1186 devices which a process in the cgroup can mknod or open.
1187
1188config CGROUP_CPUACCT
1189 bool "Simple CPU accounting controller"
1190 help
1191 Provides a simple controller for monitoring the
1192 total CPU consumed by the tasks in a cgroup.
1193
1194config CGROUP_PERF
1195 bool "Perf controller"
1196 depends on PERF_EVENTS
1197 help
1198 This option extends the perf per-cpu mode to restrict monitoring
1199 to threads which belong to the cgroup specified and run on the
Namhyung Kim6546b192020-03-25 21:45:29 +09001200 designated cpu. Or this can be used to have cgroup ID in samples
1201 so that it can monitor performance events among cgroups.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001202
1203 Say N if unsure.
1204
Daniel Mack30070982016-11-23 16:52:26 +01001205config CGROUP_BPF
1206 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirski483c4932016-12-16 08:33:45 -08001207 depends on BPF_SYSCALL
1208 select SOCK_CGROUP_DATA
Daniel Mack30070982016-11-23 16:52:26 +01001209 help
1210 Allow attaching eBPF programs to a cgroup using the bpf(2)
1211 syscall command BPF_PROG_ATTACH.
1212
1213 In which context these programs are accessed depends on the type
1214 of attachment. For instance, programs that are attached using
1215 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1216 inet sockets.
1217
Vipin Sharmaa72232e2021-03-29 21:42:04 -07001218config CGROUP_MISC
1219 bool "Misc resource controller"
1220 default n
1221 help
1222 Provides a controller for miscellaneous resources on a host.
1223
1224 Miscellaneous scalar resources are the resources on the host system
1225 which cannot be abstracted like the other cgroups. This controller
1226 tracks and limits the miscellaneous resources used by a process
1227 attached to a cgroup hierarchy.
1228
1229 For more information, please check misc cgroup section in
1230 /Documentation/admin-guide/cgroup-v2.rst.
1231
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001232config CGROUP_DEBUG
Waiman Long23b0be42017-06-13 17:18:03 -04001233 bool "Debug controller"
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001234 default n
Waiman Long23b0be42017-06-13 17:18:03 -04001235 depends on DEBUG_KERNEL
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001236 help
1237 This option enables a simple controller that exports
Waiman Long23b0be42017-06-13 17:18:03 -04001238 debugging information about the cgroups framework. This
1239 controller is for control cgroup debugging only. Its
1240 interfaces are not stable.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001241
1242 Say N.
1243
Arnd Bergmann73b35142017-01-10 13:08:06 +01001244config SOCK_CGROUP_DATA
1245 bool
1246 default n
1247
Li Zefan23964d22009-01-15 13:50:58 -08001248endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001249
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001250menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001251 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001252 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001253 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001254 help
1255 Provides the way to make tasks work with different objects using
1256 the same id. For example same IPC id may refer to different objects
1257 or same user id or pid may refer to different tasks when used in
1258 different namespaces.
1259
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001260if NAMESPACES
1261
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001262config UTS_NS
1263 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001264 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001265 help
1266 In this namespace tasks see different info provided with the
1267 uname() system call
1268
Andrei Vagin769071a2019-11-12 01:26:52 +00001269config TIME_NS
1270 bool "TIME namespace"
Thomas Gleixner660fd042019-11-12 01:27:09 +00001271 depends on GENERIC_VDSO_TIME_NS
Andrei Vagin769071a2019-11-12 01:26:52 +00001272 default y
1273 help
1274 In this namespace boottime and monotonic clocks can be set.
1275 The time will keep going with the same pace.
1276
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001277config IPC_NS
1278 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001279 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001280 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001281 help
1282 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001283 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001284
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001285config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001286 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001287 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001288 help
1289 This allows containers, i.e. vservers, to use user namespaces
1290 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001291
1292 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001293 recommended that the MEMCG option also be enabled and that
1294 user-space use the memory control groups to limit the amount
1295 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001296
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001297 If unsure, say N.
1298
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001299config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001300 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001301 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001302 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001303 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001304 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001305 pid namespaces. This is a building block of containers.
1306
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001307config NET_NS
1308 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001309 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001310 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001311 help
1312 Allow user space to create what appear to be multiple instances
1313 of the network stack.
1314
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001315endif # NAMESPACES
1316
Adrian Reber5cb366b2018-08-21 22:01:17 -07001317config CHECKPOINT_RESTORE
1318 bool "Checkpoint/restore support"
Ren Zhijie30341ec2022-09-29 07:00:57 +00001319 depends on PROC_FS
Adrian Reber5cb366b2018-08-21 22:01:17 -07001320 select PROC_CHILDREN
Chris Wilsonbfe39112021-02-05 22:00:12 +00001321 select KCMP
Adrian Reber5cb366b2018-08-21 22:01:17 -07001322 default n
1323 help
1324 Enables additional kernel features in a sake of checkpoint/restore.
1325 In particular it adds auxiliary prctl codes to setup process text,
1326 data and heap segment sizes, and a few additional /proc filesystem
1327 entries.
1328
1329 If unsure, say N here.
1330
Mike Galbraith5091faa2010-11-30 14:18:03 +01001331config SCHED_AUTOGROUP
1332 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001333 select CGROUPS
1334 select CGROUP_SCHED
1335 select FAIR_GROUP_SCHED
1336 help
1337 This option optimizes the scheduler for common desktop workloads by
1338 automatically creating and populating task groups. This separation
1339 of workloads isolates aggressive CPU burners (like build jobs) from
1340 desktop applications. Task group autogeneration is currently based
1341 upon task session.
1342
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001343config RELAY
1344 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001345 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001346 help
1347 This option enables support for relay interface support in
1348 certain file systems (such as debugfs).
1349 It is designed to provide an efficient mechanism for tools and
1350 facilities to relay large amounts of data from kernel space to
1351 user space.
1352
1353 If unsure, say N.
1354
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001355config BLK_DEV_INITRD
1356 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001357 help
1358 The initial RAM filesystem is a ramfs which is loaded by the
1359 boot loader (loadlin or lilo) and that is mounted as root
1360 before the normal boot procedure. It is typically used to
1361 load modules needed to mount the "real" root file system,
Mauro Carvalho Chehab8c27ceff32016-10-18 10:12:27 -02001362 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001363
1364 If RAM disk support (BLK_DEV_RAM) is also included, this
1365 also enables initial RAM disk (initrd) support and adds
1366 15 Kbytes (more on some other architectures) to the kernel size.
1367
1368 If unsure say Y.
1369
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001370if BLK_DEV_INITRD
1371
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001372source "usr/Kconfig"
1373
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001374endif
1375
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001376config BOOT_CONFIG
1377 bool "Boot config support"
Masami Hiramatsua2a9d672022-04-06 11:31:19 +09001378 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001379 help
1380 Extra boot config allows system admin to pass a config file as
1381 complemental extension of kernel cmdline when booting.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001382 The boot config file must be attached at the end of initramfs
Masami Hiramatsu85c46b72020-02-20 21:18:42 +09001383 with checksum, size and magic word.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001384 See <file:Documentation/admin-guide/bootconfig.rst> for details.
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001385
1386 If unsure, say Y.
1387
Paul E. McKenneyb7438522023-02-22 08:27:48 +09001388config BOOT_CONFIG_FORCE
1389 bool "Force unconditional bootconfig processing"
1390 depends on BOOT_CONFIG
Paul E. McKenney6ded8a22023-02-22 08:27:49 +09001391 default y if BOOT_CONFIG_EMBED
Paul E. McKenneyb7438522023-02-22 08:27:48 +09001392 help
1393 With this Kconfig option set, BOOT_CONFIG processing is carried
1394 out even when the "bootconfig" kernel-boot parameter is omitted.
1395 In fact, with this Kconfig option set, there is no way to
1396 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
1397 parameters.
1398
1399 If unsure, say N.
1400
Masami Hiramatsua2a9d672022-04-06 11:31:19 +09001401config BOOT_CONFIG_EMBED
1402 bool "Embed bootconfig file in the kernel"
1403 depends on BOOT_CONFIG
1404 help
1405 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1406 kernel. Usually, the bootconfig file is loaded with the initrd
1407 image. But if the system doesn't support initrd, this option will
1408 help you by embedding a bootconfig file while building the kernel.
1409
1410 If unsure, say N.
1411
1412config BOOT_CONFIG_EMBED_FILE
1413 string "Embedded bootconfig file path"
1414 depends on BOOT_CONFIG_EMBED
1415 help
1416 Specify a bootconfig file which will be embedded to the kernel.
1417 This bootconfig will be used if there is no initrd or no other
1418 bootconfig in the initrd.
1419
David Disseldorp1274aea12022-05-09 18:29:19 -07001420config INITRAMFS_PRESERVE_MTIME
1421 bool "Preserve cpio archive mtimes in initramfs"
1422 default y
1423 help
1424 Each entry in an initramfs cpio archive carries an mtime value. When
1425 enabled, extracted cpio items take this mtime, with directory mtime
1426 setting deferred until after creation of any child entries.
1427
1428 If unsure, say Y.
1429
Arnd Bergmann877417e2016-04-25 17:35:27 +02001430choice
1431 prompt "Compiler optimization level"
Ulf Magnusson2cc3ce22017-10-04 01:53:26 +02001432 default CC_OPTIMIZE_FOR_PERFORMANCE
Arnd Bergmann877417e2016-04-25 17:35:27 +02001433
1434config CC_OPTIMIZE_FOR_PERFORMANCE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001435 bool "Optimize for performance (-O2)"
Arnd Bergmann877417e2016-04-25 17:35:27 +02001436 help
1437 This is the default optimization level for the kernel, building
1438 with the "-O2" compiler flag for best performance and most
1439 helpful compile-time warnings.
1440
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001441config CC_OPTIMIZE_FOR_SIZE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001442 bool "Optimize for size (-Os)"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001443 help
Masahiro Yamadace3b4872019-08-21 02:09:39 +09001444 Choosing this option will pass "-Os" to your compiler resulting
1445 in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001446
Arnd Bergmann877417e2016-04-25 17:35:27 +02001447endchoice
1448
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001449config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1450 bool
1451 help
1452 This requires that the arch annotates or otherwise protects
1453 its external entry points from being discarded. Linker scripts
1454 must also merge .text.*, .data.*, and .bss.* correctly into
1455 output sections. Care must be taken not to pull in unrelated
1456 sections (e.g., '.text.init'). Typically '.' in section names
1457 is used to distinguish them from label names / C identifiers.
1458
1459config LD_DEAD_CODE_DATA_ELIMINATION
1460 bool "Dead code and data elimination (EXPERIMENTAL)"
1461 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1462 depends on EXPERT
Masahiro Yamadae85d1d62018-08-22 22:51:09 +09001463 depends on $(cc-option,-ffunction-sections -fdata-sections)
1464 depends on $(ld-option,--gc-sections)
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001465 help
Masahiro Yamada8b9d2712018-06-24 01:41:51 +09001466 Enable this if you want to do dead code and data elimination with
1467 the linker by compiling with -ffunction-sections -fdata-sections,
1468 and linking with --gc-sections.
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001469
1470 This can reduce on disk and in-memory size of the kernel
1471 code and static data, particularly for small configs and
1472 on small systems. This has the possibility of introducing
1473 silently broken kernel if the required annotations are not
1474 present. This option is not well tested yet, so use at your
1475 own risk.
1476
Nathan Chancellor59612b22020-11-19 13:46:56 -07001477config LD_ORPHAN_WARN
1478 def_bool y
1479 depends on ARCH_WANT_LD_ORPHAN_WARN
1480 depends on $(ld-option,--orphan-handling=warn)
Xin Lie1789d72022-10-25 00:30:23 -07001481 depends on $(ld-option,--orphan-handling=error)
1482
1483config LD_ORPHAN_WARN_LEVEL
1484 string
1485 depends on LD_ORPHAN_WARN
1486 default "error" if WERROR
1487 default "warn"
Nathan Chancellor59612b22020-11-19 13:46:56 -07001488
Randy Dunlap08470622006-09-30 23:28:13 -07001489config SYSCTL
1490 bool
1491
Mike Frysinger657a5202013-04-30 15:28:45 -07001492config HAVE_UID16
1493 bool
1494
1495config SYSCTL_EXCEPTION_TRACE
1496 bool
1497 help
1498 Enable support for /proc/sys/debug/exception-trace.
1499
1500config SYSCTL_ARCH_UNALIGN_NO_WARN
1501 bool
1502 help
1503 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1504 Allows arch to define/use @no_unaligned_warning to possibly warn
1505 about unaligned access emulation going on under the hood.
1506
1507config SYSCTL_ARCH_UNALIGN_ALLOW
1508 bool
1509 help
1510 Enable support for /proc/sys/kernel/unaligned-trap
1511 Allows arches to define/use @unaligned_enabled to runtime toggle
1512 the unaligned access emulation.
1513 see arch/parisc/kernel/unaligned.c for reference
1514
Mike Frysinger657a5202013-04-30 15:28:45 -07001515config HAVE_PCSPKR_PLATFORM
1516 bool
1517
David Rientjes6a108a12011-01-20 14:44:16 -08001518menuconfig EXPERT
1519 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001520 # Unhide debug options, to make the on-by-default options visible
1521 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522 help
1523 This option allows certain base kernel options and settings
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001524 to be disabled or tweaked. This is for specialized
1525 environments which can tolerate a "non-standard" kernel.
1526 Only use this if you really know what you are doing.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001528config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001529 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001530 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001531 default y
1532 help
1533 This enables the legacy 16-bit UID syscall wrappers.
1534
Iulia Manda28138932015-04-15 16:16:41 -07001535config MULTIUSER
1536 bool "Multiple users, groups and capabilities support" if EXPERT
1537 default y
1538 help
1539 This option enables support for non-root users, groups and
1540 capabilities.
1541
1542 If you say N here, all processes will run with UID 0, GID 0, and all
1543 possible capabilities. Saying N here also compiles out support for
1544 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1545 setgid, and capset.
1546
1547 If unsure, say Y here.
1548
Fabian Frederickf6187762014-06-04 16:11:12 -07001549config SGETMASK_SYSCALL
1550 bool "sgetmask/ssetmask syscalls support" if EXPERT
Masahiro Yamadacd14b012024-02-11 21:48:08 +09001551 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09001552 help
Fabian Frederickf6187762014-06-04 16:11:12 -07001553 sys_sgetmask and sys_ssetmask are obsolete system calls
1554 no longer supported in libc but still enabled by default in some
1555 architectures.
1556
1557 If unsure, leave the default option here.
1558
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001559config SYSFS_SYSCALL
1560 bool "Sysfs syscall support" if EXPERT
1561 default y
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09001562 help
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001563 sys_sysfs is an obsolete system call no longer supported in libc.
1564 Note that disabling this option is more secure but might break
1565 compatibility with some systems.
1566
1567 If unsure say Y here.
1568
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001569config FHANDLE
1570 bool "open by fhandle syscalls" if EXPERT
1571 select EXPORTFS
1572 default y
1573 help
1574 If you say Y here, a user level program will be able to map
1575 file names to handle and then later use the handle for
1576 different file system operations. This is useful in implementing
1577 userspace file servers, which now track files using handles instead
1578 of names. The handle would remain the same even if file names
1579 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1580 syscalls.
1581
Nicolas Pitrebaa73d92016-11-11 00:10:10 -05001582config POSIX_TIMERS
1583 bool "Posix Clocks & timers" if EXPERT
1584 default y
1585 help
1586 This includes native support for POSIX timers to the kernel.
1587 Some embedded systems have no use for them and therefore they
1588 can be configured out to reduce the size of the kernel image.
1589
1590 When this option is disabled, the following syscalls won't be
1591 available: timer_create, timer_gettime: timer_getoverrun,
1592 timer_settime, timer_delete, clock_adjtime, getitimer,
1593 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1594 clock_getres and clock_nanosleep syscalls will be limited to
1595 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1596
1597 If unsure say y.
1598
Matt Mackalld59745c2005-05-01 08:59:02 -07001599config PRINTK
1600 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001601 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001602 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001603 help
1604 This option enables normal printk support. Removing it
1605 eliminates most of the message strings from the kernel image
1606 and makes the kernel more or less silent. As this makes it
1607 very difficult to diagnose system problems, saying N here is
1608 strongly discouraged.
1609
Matt Mackallc8538a72005-05-01 08:59:01 -07001610config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001611 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001612 default y
1613 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001614 Disabling this option eliminates support for BUG and WARN, reducing
1615 the size of your kernel image and potentially quietly ignoring
1616 numerous fatal conditions. You should only consider disabling this
1617 option for embedded systems with no facilities for reporting errors.
1618 Just say Y.
Matt Mackallc8538a72005-05-01 08:59:01 -07001619
Matt Mackall708e9a72006-01-08 01:05:25 -08001620config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001621 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001622 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001623 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001624 help
1625 Enable support for generating core dumps. Disabling saves about 4k.
1626
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001627
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001628config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001629 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001630 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001631 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001632 default y
1633 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001634 This option allows to disable the internal PC-Speaker
1635 support, saving some memory.
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001636
Yoann Congal27021642024-05-05 10:03:43 +02001637config BASE_SMALL
1638 bool "Enable smaller-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001639 help
Yoann Congal27021642024-05-05 10:03:43 +02001640 Enabling this option reduces the size of miscellaneous core
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 kernel data structures. This saves memory on small machines,
1642 but may reduce performance.
1643
1644config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001645 bool "Enable futex support" if EXPERT
Arnd Bergmann3f2beda2021-10-26 12:03:47 +02001646 depends on !(SPARC32 && SMP)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647 default y
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001648 imply RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001649 help
1650 Disabling this option will cause the kernel to be built without
1651 support for "fast userspace mutexes". The resulting kernel may not
1652 run glibc-based applications correctly.
1653
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001654config FUTEX_PI
1655 bool
1656 depends on FUTEX && RT_MUTEXES
1657 default y
1658
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001660 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661 default y
1662 help
1663 Disabling this option will cause the kernel to be built without
1664 support for epoll family of system calls.
1665
Davide Libenzifba2afa2007-05-10 22:23:13 -07001666config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001667 bool "Enable signalfd() system call" if EXPERT
Davide Libenzifba2afa2007-05-10 22:23:13 -07001668 default y
1669 help
1670 Enable the signalfd() system call that allows to receive signals
1671 on a file descriptor.
1672
1673 If unsure, say Y.
1674
Davide Libenzib215e282007-05-10 22:23:16 -07001675config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001676 bool "Enable timerfd() system call" if EXPERT
Davide Libenzib215e282007-05-10 22:23:16 -07001677 default y
1678 help
1679 Enable the timerfd() system call that allows to receive timer
1680 events on a file descriptor.
1681
1682 If unsure, say Y.
1683
Davide Libenzie1ad7462007-05-10 22:23:19 -07001684config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001685 bool "Enable eventfd() system call" if EXPERT
Davide Libenzie1ad7462007-05-10 22:23:19 -07001686 default y
1687 help
1688 Enable the eventfd() system call that allows to receive both
1689 kernel notification (ie. KAIO) or userspace notifications.
1690
1691 If unsure, say Y.
1692
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001694 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 default y
1696 depends on MMU
1697 help
1698 The shmem is an internal filesystem used to manage shared memory.
1699 It is backed by swap and manages resource limits. It is also exported
1700 to userspace as tmpfs if TMPFS is enabled. Disabling this
1701 option replaces shmem and tmpfs with the much simpler ramfs code,
1702 which may be appropriate on small systems without swap.
1703
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001704config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001705 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001706 default y
1707 help
1708 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001709 by some high performance threaded applications. Disabling
1710 this option saves about 7k.
1711
Jens Axboe2b188cc2019-01-07 10:46:33 -07001712config IO_URING
1713 bool "Enable IO uring support" if EXPERT
Jens Axboe561fb042019-10-24 07:25:42 -06001714 select IO_WQ
Jens Axboe2b188cc2019-01-07 10:46:33 -07001715 default y
1716 help
1717 This option enables support for the io_uring interface, enabling
1718 applications to submit and complete IO through submission and
1719 completion rings that are shared between the kernel and application.
1720
Jens Axboe18026562024-08-30 10:52:02 -06001721config GCOV_PROFILE_URING
1722 bool "Enable GCOV profiling on the io_uring subsystem"
1723 depends on GCOV_KERNEL
1724 help
1725 Enable GCOV profiling on the io_uring subsystem, to facilitate
1726 code coverage testing.
1727
1728 If unsure, say N.
1729
1730 Note that this will have a negative impact on the performance of
1731 the io_uring subsystem, hence this should only be enabled for
1732 specific test purposes.
1733
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001734config ADVISE_SYSCALLS
1735 bool "Enable madvise/fadvise syscalls" if EXPERT
1736 default y
1737 help
1738 This option enables the madvise and fadvise syscalls, used by
1739 applications to advise the kernel about their future memory or file
1740 usage, improving performance. If building an embedded system where no
1741 applications use these syscalls, you can disable this option to save
1742 space.
1743
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001744config MEMBARRIER
1745 bool "Enable membarrier() system call" if EXPERT
1746 default y
1747 help
1748 Enable the membarrier() system call that allows issuing memory
1749 barriers across all running threads, which can be used to distribute
1750 the cost of user-space memory barriers asymmetrically by transforming
1751 pairs of memory barriers into pairs consisting of membarrier() and a
1752 compiler barrier.
1753
1754 If unsure, say Y.
1755
Randy Dunlapa751ea32023-12-07 20:58:19 -08001756config KCMP
1757 bool "Enable kcmp() system call" if EXPERT
1758 help
1759 Enable the kernel resource comparison system call. It provides
1760 user-space with the ability to compare two processes to see if they
1761 share a common resource, such as a file descriptor or even virtual
1762 memory space.
1763
1764 If unsure, say N.
1765
1766config RSEQ
1767 bool "Enable rseq() system call" if EXPERT
1768 default y
1769 depends on HAVE_RSEQ
1770 select MEMBARRIER
1771 help
1772 Enable the restartable sequences system call. It provides a
1773 user-space cache for the current CPU number value, which
1774 speeds up getting the current CPU number from user-space,
1775 as well as an ABI to speed up user-space operations on
1776 per-CPU data.
1777
1778 If unsure, say Y.
1779
1780config DEBUG_RSEQ
1781 default n
1782 bool "Enable debugging of rseq() system call" if EXPERT
1783 depends on RSEQ && DEBUG_KERNEL
1784 help
1785 Enable extra debugging checks for the rseq system call.
1786
1787 If unsure, say N.
1788
1789config CACHESTAT_SYSCALL
1790 bool "Enable cachestat() system call" if EXPERT
1791 default y
1792 help
1793 Enable the cachestat system call, which queries the page cache
1794 statistics of a file (number of cached pages, dirty pages,
1795 pages marked for writeback, (recently) evicted pages).
1796
1797 If unsure say Y here.
1798
1799config PC104
1800 bool "PC/104 support" if EXPERT
1801 help
1802 Expose PC/104 form factor device drivers and options available for
1803 selection and configuration. Enable this option if your target
1804 machine has a PC/104 bus.
1805
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001806config KALLSYMS
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001807 bool "Load all symbols for debugging/ksymoops" if EXPERT
1808 default y
1809 help
1810 Say Y here to let the kernel print out symbolic crash information and
1811 symbolic stack backtraces. This increases the size of the kernel
1812 somewhat, as all symbols have to be loaded into the kernel image.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001813
Zhen Lei30f3bb02022-11-15 16:33:48 +08001814config KALLSYMS_SELFTEST
1815 bool "Test the basic functions and performance of kallsyms"
1816 depends on KALLSYMS
1817 default n
1818 help
1819 Test the basic functions and performance of some interfaces, such as
1820 kallsyms_lookup_name. It also calculates the compression rate of the
1821 kallsyms compression algorithm for the current symbol set.
1822
1823 Start self-test automatically after system startup. Suggest executing
1824 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
1825 displayed in the last line, indicating that the test is complete.
1826
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001827config KALLSYMS_ALL
1828 bool "Include all symbols in kallsyms"
1829 depends on DEBUG_KERNEL && KALLSYMS
1830 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001831 Normally kallsyms only contains the symbols of functions for nicer
1832 OOPS messages and backtraces (i.e., symbols from the text and inittext
Baruch Siachbdf0fe32022-07-07 07:43:29 +03001833 sections). This is sufficient for most cases. And only if you want to
1834 enable kernel live patching, or other less common use cases (e.g.,
1835 when a debugger is used) all symbols are required (i.e., names of
1836 variables from the data sections, etc).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001837
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001838 This option makes sure that all symbols are loaded into the kernel
1839 image (i.e., symbols from all sections) in cost of increased kernel
1840 size (depending on the kernel configuration, it may be 300KiB or
1841 something like this).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001842
Baruch Siachbdf0fe32022-07-07 07:43:29 +03001843 Say N unless you really need all symbols, or kernel live patching.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001844
1845config KALLSYMS_ABSOLUTE_PERCPU
1846 bool
1847 depends on KALLSYMS
1848 default X86_64 && SMP
1849
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001850# end of the "standard kernel features (expert users)" menu
1851
Mathieu Desnoyers3ccfebe2018-01-29 15:20:11 -05001852config ARCH_HAS_MEMBARRIER_CALLBACKS
1853 bool
1854
Mathieu Desnoyers70216e12018-01-29 15:20:17 -05001855config ARCH_HAS_MEMBARRIER_SYNC_CORE
1856 bool
1857
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001858config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001859 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001860 help
1861 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001862
Sean Christopherson2aef6f32021-11-11 02:07:29 +00001863config GUEST_PERF_EVENTS
1864 bool
1865 depends on HAVE_PERF_EVENTS
1866
Peter Zijlstra906010b2009-09-21 16:08:49 +02001867config PERF_USE_VMALLOC
1868 bool
1869 help
1870 See tools/perf/design.txt for details
1871
Ingo Molnar57c0c152009-09-21 12:20:38 +02001872menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001873
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001874config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001875 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001876 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001877 depends on HAVE_PERF_EVENTS
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001878 select IRQ_WORK
Thomas Gleixner0793a612008-12-04 20:12:29 +01001879 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001880 Enable kernel support for various performance events provided
1881 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001882
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001883 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001884 use of generic tracepoints.
1885
1886 Most modern CPUs support performance events via performance
1887 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001888 types of hw events: such as instructions executed, cachemisses
1889 suffered, or branches mis-predicted - without slowing down the
1890 kernel or applications. These registers can also trigger interrupts
1891 when a threshold number of events have passed - and can thus be
1892 used to profile the code that runs on that CPU.
1893
Ingo Molnar57c0c152009-09-21 12:20:38 +02001894 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001895 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001896 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001897 provides per task and per CPU counters, and it provides event
1898 capabilities on top of those.
1899
1900 Say Y if unsure.
1901
Peter Zijlstra906010b2009-09-21 16:08:49 +02001902config DEBUG_PERF_USE_VMALLOC
1903 default n
1904 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb3071132015-05-04 16:26:39 +10001905 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001906 select PERF_USE_VMALLOC
1907 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001908 Use vmalloc memory to back perf mmap() buffers.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001909
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001910 Mostly useful for debugging the vmalloc code on platforms
1911 that don't require it.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001912
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001913 Say N if unsure.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001914
Thomas Gleixner0793a612008-12-04 20:12:29 +01001915endmenu
1916
David Howells091f6e22015-07-20 21:16:28 +01001917config SYSTEM_DATA_VERIFICATION
1918 def_bool n
1919 select SYSTEM_TRUSTED_KEYRING
1920 select KEYS
1921 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00001922 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01001923 select ASYMMETRIC_KEY_TYPE
1924 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01001925 select ASN1
1926 select OID_REGISTRY
1927 select X509_CERTIFICATE_PARSER
1928 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07001929 help
David Howells091f6e22015-07-20 21:16:28 +01001930 Provide PKCS#7 message verification using the contents of the system
1931 trusted keyring to provide public keys. This then can be used for
1932 module verification, kexec image verification and firmware blob
1933 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07001934
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001935config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001936 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001937 help
1938 Say Y here to enable the extended profiling support mechanisms used
Viresh Kumarf8408262021-01-14 17:05:30 +05301939 by profilers.
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001940
Miguel Ojeda2f7ab122021-07-03 16:42:57 +02001941config RUST
1942 bool "Rust support"
1943 depends on HAVE_RUST
1944 depends on RUST_IS_AVAILABLE
1945 depends on !MODVERSIONS
Neal Gompaf1385dc2024-07-31 08:54:28 -04001946 depends on !GCC_PLUGIN_RANDSTRUCT
Miguel Ojeda2f7ab122021-07-03 16:42:57 +02001947 depends on !RANDSTRUCT
Martin Rodriguez Reboredoc1177972023-01-11 12:20:50 -03001948 depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
Matthew Maurerca627e62024-09-12 21:00:44 +02001949 depends on !CFI_CLANG || RUSTC_VERSION >= 107900 && $(cc-option,-fsanitize=kcfi -fsanitize-cfi-icall-experimental-normalize-integers)
1950 select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG
1951 depends on !CALL_PADDING || RUSTC_VERSION >= 108000
Matthew Maurerf64e2f32024-08-20 19:48:57 +00001952 depends on !KASAN_SW_TAGS
Miguel Ojeda2f7ab122021-07-03 16:42:57 +02001953 help
1954 Enables Rust support in the kernel.
1955
1956 This allows other Rust-related options, like drivers written in Rust,
1957 to be selected.
1958
1959 It is also required to be able to load external kernel modules
1960 written in Rust.
1961
1962 See Documentation/rust/ for more information.
1963
1964 If unsure, say N.
1965
1966config RUSTC_VERSION_TEXT
1967 string
1968 depends on RUST
Miguel Ojeda5134a332024-09-02 18:55:29 +02001969 default "$(RUSTC_VERSION_TEXT)"
1970 help
1971 See `CC_VERSION_TEXT`.
Miguel Ojeda2f7ab122021-07-03 16:42:57 +02001972
1973config BINDGEN_VERSION_TEXT
1974 string
1975 depends on RUST
Miguel Ojeda9e98db12024-07-09 18:06:03 +02001976 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
1977 # (https://github.com/rust-lang/rust-bindgen/pull/2678). It can be removed when
1978 # the minimum version is upgraded past that (0.69.1 already fixed the issue).
Masahiro Yamadaaacf93e2024-07-27 23:03:00 +09001979 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
Miguel Ojeda2f7ab122021-07-03 16:42:57 +02001980
Ingo Molnar5f87f112008-07-23 14:15:22 +02001981#
1982# Place an empty function call at each tracepoint site. Can be
1983# dynamically changed for a probe function.
1984#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001985config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001986 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001987
Eric DeVolder89cde452023-07-12 12:15:32 -04001988source "kernel/Kconfig.kexec"
1989
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990endmenu # General setup
1991
Christoph Hellwig15724972018-07-31 13:39:30 +02001992source "arch/Kconfig"
1993
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001994config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05001995 bool
Sebastian Andrzej Siewior1c6f9ec2022-02-08 18:21:10 +01001996 default y if PREEMPT_RT
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001997
Thiago Jung Bauermannc8424e72019-07-04 15:57:34 -03001998config MODULE_SIG_FORMAT
1999 def_bool n
2000 select SYSTEM_DATA_VERIFICATION
2001
Christophe Leroy73b4fc92022-07-12 07:52:33 +02002002source "kernel/module/Kconfig"
Peter Zijlstra6c9692e22015-05-27 11:09:37 +09302003
Rusty Russell98a79d62008-12-13 21:19:41 +10302004config INIT_ALL_POSSIBLE
2005 bool
2006 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302007 Back when each arch used to define their own cpu_online_mask and
2008 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302009 with all 1s, and others with all 0s. When they were centralised,
2010 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002011 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302012
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002013source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002014
2015config PREEMPT_NOTIFIERS
2016 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002017
Steffen Klassert16295be2010-01-06 19:47:10 +11002018config PADATA
2019 depends on SMP
2020 bool
2021
David Howells4520c6a2012-09-21 23:31:13 +01002022config ASN1
2023 tristate
2024 help
2025 Build a simple ASN.1 grammar compiler that produces a bytecode output
2026 that can be interpreted by the ASN.1 stream decoder and used to
2027 inform it as to what tags are to be expected in a stream and what
2028 functions to call on what tags.
2029
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002030source "kernel/Kconfig.locks"
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05002031
Daniel Borkmann0ebeea82020-05-15 12:11:16 +02002032config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2033 bool
2034
Andrea Parri4ff4c742024-01-31 15:49:35 +01002035config ARCH_HAS_PREPARE_SYNC_CORE_CMD
2036 bool
2037
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05002038config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2039 bool
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002040
2041# It may be useful for an architecture to override the definitions of the
Dominik Brodowski7303e302018-04-05 11:53:03 +02002042# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2043# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2044# different calling convention for syscalls. They can also override the
2045# macros for not-implemented syscalls in kernel/sys_ni.c and
2046# kernel/time/posix-stubs.c. All these overrides need to be available in
2047# <asm/syscall_wrapper.h>.
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002048config ARCH_HAS_SYSCALL_WRAPPER
2049 def_bool n