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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 Ojeda2f7ab122021-07-03 16:42:57 +020063config RUST_IS_AVAILABLE
64 def_bool $(success,$(srctree)/scripts/rust_is_available.sh)
65 help
66 This shows whether a suitable Rust toolchain is available (found).
67
68 Please see Documentation/rust/quick-start.rst for instructions on how
Colin Ian Kingeacf96d2022-10-07 21:43:39 +010069 to satisfy the build requirements of Rust support.
Miguel Ojeda2f7ab122021-07-03 16:42:57 +020070
71 In particular, the Makefile target 'rustavailable' is useful to check
72 why the Rust toolchain is not being detected.
73
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090074config CC_CAN_LINK
Masahiro Yamada9371f862020-04-29 12:45:13 +090075 bool
Elliot Bermanf67695c92022-02-01 13:35:42 -080076 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
77 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090078
Masahiro Yamadab1183b62020-05-09 16:39:15 +090079config CC_CAN_LINK_STATIC
80 bool
Elliot Bermanf67695c92022-02-01 13:35:42 -080081 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
82 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070083
Nick Desaulniers587f1702020-02-14 14:18:11 -080084config CC_HAS_ASM_GOTO_OUTPUT
Nick Desaulniers587f1702020-02-14 14:18:11 -080085 def_bool $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
86
Sean Christopherson1aa0e8b2022-02-02 00:49:41 +000087config CC_HAS_ASM_GOTO_TIED_OUTPUT
88 depends on CC_HAS_ASM_GOTO_OUTPUT
89 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
Alexandre Belloni534bd702022-11-15 12:01:58 +010090 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 +000091
Linus Torvalds68fb3ca2024-02-15 11:14:33 -080092config GCC_ASM_GOTO_OUTPUT_WORKAROUND
93 bool
94 depends on CC_IS_GCC && CC_HAS_ASM_GOTO_OUTPUT
95 # Fixed in GCC 14, 13.3, 12.4 and 11.5
96 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
97 default y if GCC_VERSION < 110500
98 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
99 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
100
Peter Collingbourne5cf896fb62019-07-31 18:18:42 -0700101config TOOLS_SUPPORT_RELR
Will Deacon2d122942019-08-20 10:11:54 +0100102 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 -0700103
Rasmus Villemoeseb111862019-09-13 00:19:25 +0200104config CC_HAS_ASM_INLINE
105 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
106
Nick Desaulniers51c2ee62021-06-21 16:18:22 -0700107config CC_HAS_NO_PROFILE_FN_ATTR
108 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
109
Nathan Chancellor613fe162022-02-01 13:56:21 -0700110config PAHOLE_VERSION
111 int
112 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
113
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -0700114config CONSTRUCTORS
115 bool
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -0700116
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800117config IRQ_WORK
Tejun Heofd0a68a2024-02-15 19:10:01 -1000118 def_bool y if SMP
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800119
Shile Zhang10916702019-12-04 08:46:31 +0800120config BUILDTIME_TABLE_SORT
David Daney1dbdc6f2012-04-19 14:59:57 -0700121 bool
122
Andy Lutomirskic65eacb2016-09-13 14:29:24 -0700123config THREAD_INFO_IN_TASK
124 bool
125 help
126 Select this to move thread_info off the stack into task_struct. To
127 make this work, an arch will need to remove all thread_info fields
128 except flags and fix any runtime bugs.
129
Andy Lutomirskic6c314a2016-09-15 22:45:43 -0700130 One subtle change that will be needed is to use try_get_task_stack()
131 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
132
Al Boldiff0cfc62007-07-31 00:39:23 -0700133menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135config BROKEN
136 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137
138config BROKEN_ON_SMP
139 bool
140 depends on BROKEN || !SMP
141 default y
142
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143config INIT_ENV_ARG_LIMIT
144 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -0700145 default 32 if !UML
146 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 help
Randy Dunlap34ad92c22005-10-30 15:01:46 -0800148 Maximum of each of the number of arguments and environment
149 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150
Jiri Slaby4bb16672013-05-22 10:56:24 +0200151config COMPILE_TEST
152 bool "Compile also drivers which will not load"
Masahiro Yamadaea29b202021-03-12 21:07:08 -0800153 depends on HAS_IOMEM
Jiri Slaby4bb16672013-05-22 10:56:24 +0200154 help
155 Some drivers can be compiled on a different platform than they are
156 intended to be run on. Despite they cannot be loaded there (or even
157 when they load they cannot be used due to missing HW support),
158 developers still, opposing to distributors, might want to build such
159 drivers to compile-test them.
160
161 If you are a developer and want to build everything available, say Y
162 here. If you are a user/distributor, say N here to exclude useless
163 drivers to be distributed.
164
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700165config WERROR
166 bool "Compile the kernel with warnings as errors"
Marco Elverb339ec92021-09-07 23:12:08 +0200167 default COMPILE_TEST
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700168 help
169 A kernel build should not cause any compiler warnings, and this
Miguel Ojeda2f7ab122021-07-03 16:42:57 +0200170 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
Xin Lie1789d72022-10-25 00:30:23 -0700171 to enforce that rule by default. Certain warnings from other tools
172 such as the linker may be upgraded to errors with this option as
173 well.
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700174
Xin Lie1789d72022-10-25 00:30:23 -0700175 However, if you have a new (or very old) compiler or linker with odd
176 and unusual warnings, or you have some architecture with problems,
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700177 you may need to disable this config option in order to
178 successfully build the kernel.
179
180 If in doubt, say Y.
181
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900182config UAPI_HEADER_TEST
183 bool "Compile test UAPI headers"
Masahiro Yamadafcbb8462019-11-07 16:14:40 +0900184 depends on HEADERS_INSTALL && CC_CAN_LINK
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900185 help
186 Compile test headers exported to user-space to ensure they are
187 self-contained, i.e. compilable as standalone units.
188
189 If you are a developer or tester and want to ensure the exported
190 headers are self-contained, say Y here. Otherwise, choose N.
191
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192config LOCALVERSION
193 string "Local version - append to kernel release"
194 help
195 Append an extra string to the end of your kernel version.
196 This will show up when you type uname, for example.
197 The string you set here will be appended after the contents of
198 any files with a filename matching localversion* in your
199 object and source tree, in that order. Your total string can
200 be a maximum of 64 characters.
201
Ryan Andersonaaebf432005-07-31 04:57:49 -0400202config LOCALVERSION_AUTO
203 bool "Automatically append version information to the version string"
204 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -0700205 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -0400206 help
207 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200208 release tree by looking for git tags that belong to the current
209 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400210
211 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200212 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400213 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200214 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400215
Rasmus Villemoes0f9c6082023-01-11 10:38:22 +0100216 (The actual string used here is the first 12 characters produced
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200217 by running the command:
218
219 $ git rev-parse --verify HEAD
220
221 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400222
Laura Abbott9afb7192018-07-05 17:49:37 -0700223config BUILD_SALT
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800224 string "Build ID Salt"
225 default ""
226 help
227 The build ID is used to link binaries and their debug info. Setting
228 this option will use the value in the calculation of the build id.
229 This is mostly useful for distributions which want to ensure the
230 build is unique between builds. It's safe to leave the default.
Laura Abbott9afb7192018-07-05 17:49:37 -0700231
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800232config HAVE_KERNEL_GZIP
233 bool
234
235config HAVE_KERNEL_BZIP2
236 bool
237
238config HAVE_KERNEL_LZMA
239 bool
240
Lasse Collin3ebe1242011-01-12 17:01:23 -0800241config HAVE_KERNEL_XZ
242 bool
243
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800244config HAVE_KERNEL_LZO
245 bool
246
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700247config HAVE_KERNEL_LZ4
248 bool
249
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700250config HAVE_KERNEL_ZSTD
251 bool
252
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200253config HAVE_KERNEL_UNCOMPRESSED
254 bool
255
Alain Knaff30d65db2009-01-04 22:46:17 +0100256choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800257 prompt "Kernel compression mode"
258 default KERNEL_GZIP
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700259 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 -0800260 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100261 The linux kernel is a kind of self-extracting executable.
262 Several compression algorithms are available, which differ
263 in efficiency, compression and decompression speed.
264 Compression speed is only relevant when building a kernel.
265 Decompression speed is relevant at each boot.
266
267 If you have any problems with bzip2 or lzma compressed
268 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
269 version of this functionality (bzip2 only), for 2.4, was
270 supplied by Christian Ludwig)
271
272 High compression options are mostly useful for users, who
273 are low on disk space (embedded systems), but for whom ram
274 size matters less.
275
276 If in doubt, select 'gzip'
277
278config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800279 bool "Gzip"
280 depends on HAVE_KERNEL_GZIP
281 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800282 The old and tried gzip compression. It provides a good balance
283 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100284
285config KERNEL_BZIP2
286 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800287 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100288 help
289 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700290 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800291 size is about 10% smaller with bzip2, in comparison to gzip.
292 Bzip2 uses a large amount of memory. For modern kernels you
293 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100294
295config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800296 bool "LZMA"
297 depends on HAVE_KERNEL_LZMA
298 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700299 This compression algorithm's ratio is best. Decompression speed
300 is between gzip and bzip2. Compression is slowest.
301 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100302
Lasse Collin3ebe1242011-01-12 17:01:23 -0800303config KERNEL_XZ
304 bool "XZ"
305 depends on HAVE_KERNEL_XZ
306 help
307 XZ uses the LZMA2 algorithm and instruction set specific
308 BCJ filters which can improve compression ratio of executable
309 code. The size of the kernel is about 30% smaller with XZ in
310 comparison to gzip. On architectures for which there is a BCJ
311 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
312 will create a few percent smaller kernel than plain LZMA.
313
314 The speed is about the same as with LZMA: The decompression
315 speed of XZ is better than that of bzip2 but worse than gzip
316 and LZO. Compression is slow.
317
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800318config KERNEL_LZO
319 bool "LZO"
320 depends on HAVE_KERNEL_LZO
321 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700322 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200323 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800324 (both compression and decompression) is the fastest.
325
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700326config KERNEL_LZ4
327 bool "LZ4"
328 depends on HAVE_KERNEL_LZ4
329 help
330 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
331 A preliminary version of LZ4 de/compression tool is available at
332 <https://code.google.com/p/lz4/>.
333
334 Its compression ratio is worse than LZO. The size of the kernel
335 is about 8% bigger than LZO. But the decompression speed is
336 faster than LZO.
337
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700338config KERNEL_ZSTD
339 bool "ZSTD"
340 depends on HAVE_KERNEL_ZSTD
341 help
342 ZSTD is a compression algorithm targeting intermediate compression
343 with fast decompression speed. It will compress better than GZIP and
344 decompress around the same speed as LZO, but slower than LZ4. You
345 will need at least 192 KB RAM or more for booting. The zstd command
346 line tool is required for compression.
347
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200348config KERNEL_UNCOMPRESSED
349 bool "None"
350 depends on HAVE_KERNEL_UNCOMPRESSED
351 help
352 Produce uncompressed kernel image. This option is usually not what
353 you want. It is useful for debugging the kernel in slow simulation
354 environments, where decompressing and moving the kernel is awfully
355 slow. This option allows early boot code to skip the decompressor
356 and jump right at uncompressed kernel image.
357
Alain Knaff30d65db2009-01-04 22:46:17 +0100358endchoice
359
Chris Downada4ab72020-06-04 16:50:53 -0700360config DEFAULT_INIT
361 string "Default init path"
362 default ""
363 help
364 This option determines the default init for the system if no init=
365 option is passed on the kernel command line. If the requested path is
366 not present, we will still then move on to attempting further
367 locations (e.g. /sbin/init, etc). If this is empty, we will just use
368 the fallback list when init= is not passed.
369
Josh Triplettbd5dc172011-06-15 15:08:28 -0700370config DEFAULT_HOSTNAME
371 string "Default hostname"
372 default "(none)"
373 help
374 This option determines the default system hostname before userspace
375 calls sethostname(2). The kernel traditionally uses "(none)" here,
376 but you may wish to use a different default here to make a minimal
377 system more usable with less configuration.
378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379config SYSVIPC
380 bool "System V IPC"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900381 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 Inter Process Communication is a suite of library functions and
383 system calls which let processes (running programs) synchronize and
384 exchange information. It is generally considered to be a good thing,
385 and some programs won't run unless you say Y here. In particular, if
386 you want to run the DOS emulator dosemu under Linux (read the
387 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
388 you'll need to say Y here.
389
390 You can find documentation about IPC with "info ipc" and also in
391 section 6.4 of the Linux Programmer's Guide, available from
392 <http://www.tldp.org/guides.html>.
393
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800394config SYSVIPC_SYSCTL
395 bool
396 depends on SYSVIPC
397 depends on SYSCTL
398 default y
399
Guo Ren0cbed0e2022-04-05 15:12:58 +0800400config SYSVIPC_COMPAT
401 def_bool y
402 depends on COMPAT && SYSVIPC
403
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404config POSIX_MQUEUE
405 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700406 depends on NET
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900407 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 POSIX variant of message queues is a part of IPC. In POSIX message
409 queues every message has a priority which decides about succession
410 of receiving it by a process. If you want to compile and run
411 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e376502007-05-09 07:25:13 +0200412 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413
414 POSIX message queues are visible as a filesystem called 'mqueue'
415 and can be mounted somewhere if you want to do filesystem
416 operations on message queues.
417
418 If unsure, say Y.
419
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700420config POSIX_MQUEUE_SYSCTL
421 bool
422 depends on POSIX_MQUEUE
423 depends on SYSCTL
424 default y
425
David Howellsc73be612020-01-14 17:07:11 +0000426config WATCH_QUEUE
427 bool "General notification queue"
428 default n
429 help
430
431 This is a general notification queue for the kernel to pass events to
432 userspace by splicing them into pipes. It can be used in conjunction
433 with watches for key/keyring change notifications and device
434 notifications.
435
Mauro Carvalho Chehabc02b8722022-06-26 10:10:56 +0100436 See Documentation/core-api/watch_queue.rst
David Howellsc73be612020-01-14 17:07:11 +0000437
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700438config CROSS_MEMORY_ATTACH
439 bool "Enable process_vm_readv/writev syscalls"
440 depends on MMU
441 default y
442 help
443 Enabling this option adds the system calls process_vm_readv and
444 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700445 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700446 See the man page for more details.
447
Josh Triplett69369a72014-04-03 14:48:27 -0700448config USELIB
Kees Cook7374fa32022-04-29 14:38:01 -0700449 bool "uselib syscall (for libc5 and earlier)"
450 default ALPHA || M68K || SPARC
Josh Triplett69369a72014-04-03 14:48:27 -0700451 help
452 This option enables the uselib syscall, a system call used in the
453 dynamic linker from libc5 and earlier. glibc does not use this
454 system call. If you intend to run programs built on libc5 or
455 earlier, you may need to enable this syscall. Current systems
456 running glibc can safely disable this.
457
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458config AUDIT
459 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100460 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 help
462 Enable auditing infrastructure that can be used with another
463 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500464 logging of avc messages output). System call auditing is included
465 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900467config HAVE_ARCH_AUDITSYSCALL
468 bool
469
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500471 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900472 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500473 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400474
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000475source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200476source "kernel/time/Kconfig"
Daniel Borkmannb24abcf2021-05-11 22:35:16 +0200477source "kernel/bpf/Kconfig"
Christoph Hellwig87a4c372018-07-31 13:39:32 +0200478source "kernel/Kconfig.preempt"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000479
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200480menu "CPU/Task time and stats accounting"
481
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200482config VIRT_CPU_ACCOUNTING
483 bool
484
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200485choice
486 prompt "Cputime accounting"
Nicholas Piggin02382af2022-09-02 18:53:15 +1000487 default TICK_CPU_ACCOUNTING
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200488
489# Kind of a stub config for the pure tick based cputime accounting
490config TICK_CPU_ACCOUNTING
491 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200492 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200493 help
494 This is the basic tick based cputime accounting that maintains
495 statistics about user, system and idle time spent on per jiffies
496 granularity.
497
498 If unsure, say Y.
499
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200500config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200501 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200502 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200503 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200504 help
505 Select this option to enable more accurate task and CPU time
506 accounting. This is done by reading a CPU counter on each
507 kernel entry and exit and on transitions within the kernel
508 between system, softirq and hardirq state, so there is a
509 small performance impact. In the case of s390 or IBM POWER > 5,
510 this also enables accounting of stolen time on logically-partitioned
511 systems.
512
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200513config VIRT_CPU_ACCOUNTING_GEN
514 bool "Full dynticks CPU time accounting"
Frederic Weisbecker24a9c5412022-06-08 16:40:24 +0200515 depends on HAVE_CONTEXT_TRACKING_USER
Kevin Hilman554b0002013-09-16 15:28:21 -0700516 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Arnd Bergmann041a1572019-03-04 21:01:31 +0100517 depends on GENERIC_CLOCKEVENTS
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200518 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker24a9c5412022-06-08 16:40:24 +0200519 select CONTEXT_TRACKING_USER
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200520 help
521 Select this option to enable task and CPU time accounting on full
522 dynticks systems. This accounting is implemented by watching every
523 kernel-user boundaries using the context tracking subsystem.
524 The accounting is thus performed at the expense of some significant
525 overhead.
526
527 For now this is only useful if you are working on the full
528 dynticks subsystem development.
529
530 If unsure, say N.
531
Rik van Rielb58c3582016-07-13 16:50:02 +0200532endchoice
533
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200534config IRQ_TIME_ACCOUNTING
535 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200536 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200537 help
538 Select this option to enable fine granularity task irq time
539 accounting. This is done by reading a timestamp on each
540 transitions between softirq and hardirq state, so there can be a
541 small performance impact.
542
543 If in doubt, say N here.
544
Vincent Guittot11d4afd2018-09-25 11:17:42 +0200545config HAVE_SCHED_AVG_IRQ
546 def_bool y
547 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
548 depends on SMP
549
Vincent Guittotd4dbc992024-03-26 10:16:15 +0100550config SCHED_HW_PRESSURE
Valentin Schneider98eb4012020-07-12 17:59:16 +0100551 bool
Valentin Schneiderfcd7c9c2020-07-29 14:57:18 +0100552 default y if ARM && ARM_CPU_TOPOLOGY
553 default y if ARM64
Thara Gopinath76504792020-02-21 19:52:05 -0500554 depends on SMP
Valentin Schneider98eb4012020-07-12 17:59:16 +0100555 depends on CPU_FREQ_THERMAL
556 help
Vincent Guittotd4dbc992024-03-26 10:16:15 +0100557 Select this option to enable HW pressure accounting in the
558 scheduler. HW pressure is the value conveyed to the scheduler
Valentin Schneider98eb4012020-07-12 17:59:16 +0100559 that reflects the reduction in CPU compute capacity resulted from
Vincent Guittotd4dbc992024-03-26 10:16:15 +0100560 HW throttling. HW throttling occurs when the performance of
561 a CPU is capped due to high operating temperatures as an example.
Valentin Schneider98eb4012020-07-12 17:59:16 +0100562
563 If selected, the scheduler will be able to balance tasks accordingly,
564 i.e. put less load on throttled CPUs than on non/less throttled ones.
565
566 This requires the architecture to implement
Vincent Guittotd4dbc992024-03-26 10:16:15 +0100567 arch_update_hw_pressure() and arch_scale_thermal_pressure().
Thara Gopinath76504792020-02-21 19:52:05 -0500568
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200569config BSD_PROCESS_ACCT
570 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700571 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200572 help
573 If you say Y here, a user level program will be able to instruct the
574 kernel (via a special system call) to write process accounting
575 information to a file: whenever a process exits, information about
576 that process will be appended to the file by the kernel. The
577 information includes things such as creation time, owning user,
578 command name, memory usage, controlling terminal etc. (the complete
579 list is in the struct acct in <file:include/linux/acct.h>). It is
580 up to the user level program to do useful things with this
581 information. This is generally a good idea, so say Y.
582
583config BSD_PROCESS_ACCT_V3
584 bool "BSD Process Accounting version 3 file format"
585 depends on BSD_PROCESS_ACCT
586 default n
587 help
588 If you say Y here, the process accounting information is written
589 in a new file format that also logs the process IDs of each
Randy Dunlap3903bf92018-08-21 21:58:34 -0700590 process and its parent. Note that this file format is incompatible
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200591 with previous v0/v1/v2 file formats, so you will need updated tools
592 for processing it. A preliminary version of these tools is available
593 at <http://www.gnu.org/software/acct/>.
594
595config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700596 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200597 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700598 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200599 default n
600 help
601 Export selected statistics for tasks/processes through the
602 generic netlink interface. Unlike BSD process accounting, the
603 statistics are available during the lifetime of tasks/processes as
604 responses to commands. Like BSD accounting, they are sent to user
605 space on task exit.
606
607 Say N if unsure.
608
609config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700610 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200611 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530612 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200613 help
614 Collect information on time spent by a task waiting for system
615 resources like cpu, synchronous block I/O completion and swapping
616 in pages. Such statistics can help in setting a task's priorities
617 relative to other tasks for cpu, io, rss limits etc.
618
619 Say N if unsure.
620
621config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700622 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200623 depends on TASKSTATS
624 help
625 Collect extended task accounting data and send the data
626 to userland for processing over the taskstats interface.
627
628 Say N if unsure.
629
630config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700631 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200632 depends on TASK_XACCT
633 help
634 Collect information on the number of bytes of storage I/O which this
635 task has caused.
636
637 Say N if unsure.
638
Johannes Weinereb414682018-10-26 15:06:27 -0700639config PSI
640 bool "Pressure stall information tracking"
Randy Dunlap98dfdd92023-07-30 20:07:40 -0700641 select KERNFS
Johannes Weinereb414682018-10-26 15:06:27 -0700642 help
643 Collect metrics that indicate how overcommitted the CPU, memory,
644 and IO capacity are in the system.
645
646 If you say Y here, the kernel will create /proc/pressure/ with the
647 pressure statistics files cpu, memory, and io. These will indicate
648 the share of walltime in which some or all tasks in the system are
649 delayed due to contention of the respective resource.
650
Johannes Weiner2ce71352018-10-26 15:06:31 -0700651 In kernels with cgroup support, cgroups (cgroup2 only) will
652 have cpu.pressure, memory.pressure, and io.pressure files,
653 which aggregate pressure stalls for the grouped tasks only.
654
Mauro Carvalho Chehabc3123552019-04-17 05:46:08 -0300655 For more details see Documentation/accounting/psi.rst.
Johannes Weinereb414682018-10-26 15:06:27 -0700656
657 Say N if unsure.
658
Johannes Weinere0c27442018-11-30 14:09:58 -0800659config PSI_DEFAULT_DISABLED
660 bool "Require boot parameter to enable pressure stall information tracking"
661 default n
662 depends on PSI
663 help
664 If set, pressure stall information tracking will be disabled
Baruch Siach428a1cb2018-12-14 14:17:03 -0800665 per default but can be enabled through passing psi=1 on the
666 kernel commandline during boot.
Johannes Weinere0c27442018-11-30 14:09:58 -0800667
Johannes Weiner7b2489d2019-02-01 14:21:15 -0800668 This feature adds some code to the task wakeup and sleep
669 paths of the scheduler. The overhead is too low to affect
670 common scheduling-intense workloads in practice (such as
671 webservers, memcache), but it does show up in artificial
672 scheduler stress tests, such as hackbench.
673
674 If you are paranoid and not sure what the kernel will be
675 used for, say Y.
676
677 Say N if unsure.
678
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200679endmenu # "CPU/Task time and stats accounting"
680
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200681config CPU_ISOLATION
682 bool "CPU isolation"
Geert Uytterhoeven414a2dc2018-01-02 12:13:10 +0100683 depends on SMP || COMPILE_TEST
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100684 default y
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200685 help
686 Make sure that CPUs running critical tasks are not disturbed by
687 any source of "noise" such as unbound workqueues, timers, kthreads...
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100688 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
689 the "isolcpus=" boot parameter.
690
691 Say Y if unsure.
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200692
Paul E. McKenney0af92d42017-05-17 08:43:40 -0700693source "kernel/rcu/Kconfig"
Mike Travisc903ff82009-01-15 12:28:29 -0800694
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700696 tristate "Kernel .config support"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900697 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 This option enables the complete Linux kernel ".config" file
699 contents to be saved in the kernel. It provides documentation
700 of which kernel options are used in a running kernel or in an
701 on-disk kernel. This information can be extracted from the kernel
702 image file with the script scripts/extract-ikconfig and used as
703 input to rebuild the current kernel or to build another kernel.
704 It can also be extracted from a running kernel by reading
705 /proc/config.gz if enabled (below).
706
707config IKCONFIG_PROC
708 bool "Enable access to .config through /proc/config.gz"
709 depends on IKCONFIG && PROC_FS
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900710 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 This option enables access to the kernel configuration file
712 through /proc/config.gz.
713
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400714config IKHEADERS
715 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
716 depends on SYSFS
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400717 help
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400718 This option enables access to the in-kernel headers that are generated during
719 the build process. These can be used to build eBPF tracing programs,
720 or similar programs. If you build the headers as a module, a module called
721 kheaders.ko is built which can be loaded on-demand to get access to headers.
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400722
Alistair John Strachan794543a2007-05-08 00:31:15 -0700723config LOG_BUF_SHIFT
724 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Christoph Hellwig1c4b5ec2022-02-23 08:47:20 +0100725 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700726 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700727 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700728 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700729 Select the minimal kernel log buffer size as a power of 2.
730 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
731 parameter, see below. Any higher size also might be forced
732 by "log_buf_len" boot parameter.
733
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700734 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700735 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700736 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700737 15 => 32 KB
738 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700739 13 => 8 KB
740 12 => 4 KB
741
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700742config LOG_CPU_MAX_BUF_SHIFT
743 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700744 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700745 range 0 21
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700746 default 0 if BASE_SMALL
Yoann Congal320bf432024-05-05 10:03:41 +0200747 default 12
Josh Triplett361e9df2014-10-03 16:00:54 -0700748 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700749 help
750 This option allows to increase the default ring buffer size
751 according to the number of CPUs. The value defines the contribution
752 of each CPU as a power of 2. The used space is typically only few
753 lines however it might be much more when problems are reported,
754 e.g. backtraces.
755
756 The increased size means that a new buffer has to be allocated and
757 the original static one is unused. It makes sense only on systems
758 with more CPUs. Therefore this value is used only when the sum of
759 contributions is greater than the half of the default kernel ring
760 buffer as defined by LOG_BUF_SHIFT. The default values are set
Paul Menzel0f7636e12020-08-11 11:29:23 +0200761 so that more than 16 CPUs are needed to trigger the allocation.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700762
763 Also this option is ignored when "log_buf_len" kernel parameter is
764 used as it forces an exact (power of two) size of the ring buffer.
765
766 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200767 hotplugging making the computation optimal for the worst case
768 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700769
770 Examples shift values and their meaning:
771 17 => 128 KB for each CPU
772 16 => 64 KB for each CPU
773 15 => 32 KB for each CPU
774 14 => 16 KB for each CPU
775 13 => 8 KB for each CPU
776 12 => 4 KB for each CPU
777
Chris Down33701552021-06-15 17:52:53 +0100778config PRINTK_INDEX
779 bool "Printk indexing debugfs interface"
780 depends on PRINTK && DEBUG_FS
781 help
782 Add support for indexing of all printk formats known at compile time
783 at <debugfs>/printk/index/<module>.
784
785 This can be used as part of maintaining daemons which monitor
786 /dev/kmsg, as it permits auditing the printk formats present in a
787 kernel, allowing detection of cases where monitored printks are
788 changed or no longer present.
789
790 There is no additional runtime cost to printk with this enabled.
791
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800792#
793# Architectures with an unreliable sched_clock() should select this:
794#
795config HAVE_UNSTABLE_SCHED_CLOCK
796 bool
797
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700798config GENERIC_SCHED_CLOCK
799 bool
800
Patrick Bellasi69842cb2019-06-21 09:42:02 +0100801menu "Scheduler features"
802
803config UCLAMP_TASK
804 bool "Enable utilization clamping for RT/FAIR tasks"
805 depends on CPU_FREQ_GOV_SCHEDUTIL
806 help
807 This feature enables the scheduler to track the clamped utilization
808 of each CPU based on RUNNABLE tasks scheduled on that CPU.
809
810 With this option, the user can specify the min and max CPU
811 utilization allowed for RUNNABLE tasks. The max utilization defines
812 the maximum frequency a task should use while the min utilization
813 defines the minimum frequency it should use.
814
815 Both min and max utilization clamp values are hints to the scheduler,
816 aiming at improving its frequency selection policy, but they do not
817 enforce or grant any specific bandwidth for tasks.
818
819 If in doubt, say N.
820
821config UCLAMP_BUCKETS_COUNT
822 int "Number of supported utilization clamp buckets"
823 range 5 20
824 default 5
825 depends on UCLAMP_TASK
826 help
827 Defines the number of clamp buckets to use. The range of each bucket
828 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
829 number of clamp buckets the finer their granularity and the higher
830 the precision of clamping aggregation and tracking at run-time.
831
832 For example, with the minimum configuration value we will have 5
833 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
834 be refcounted in the [20..39]% bucket and will set the bucket clamp
835 effective value to 25%.
836 If a second 30% boosted task should be co-scheduled on the same CPU,
837 that task will be refcounted in the same bucket of the first task and
838 it will boost the bucket clamp effective value to 30%.
839 The clamp effective value of a bucket is reset to its nominal value
840 (20% in the example above) when there are no more tasks refcounted in
841 that bucket.
842
843 An additional boost/capping margin can be added to some tasks. In the
844 example above the 25% task will be boosted to 30% until it exits the
845 CPU. If that should be considered not acceptable on certain systems,
846 it's always possible to reduce the margin by increasing the number of
847 clamp buckets to trade off used memory for run-time tracking
848 precision.
849
850 If in doubt, use the default value.
851
852endmenu
853
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200854#
855# For architectures that want to enable the support for NUMA-affine scheduler
856# balancing logic:
857#
858config ARCH_SUPPORTS_NUMA_BALANCING
859 bool
860
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100861#
Mel Gorman72b252a2015-09-04 15:47:32 -0700862# For architectures that prefer to flush all TLBs after a number of pages
863# are unmapped instead of sending one IPI per page to flush. The architecture
864# must provide guarantees on what happens if a clean TLB cache entry is
865# written after the unmap. Details are in mm/rmap.c near the check for
866# should_defer_flush. The architecture should also consider if the full flush
867# and the refill costs are offset by the savings of sending fewer IPIs.
868config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
869 bool
870
Ard Biesheuvelc12d3362019-11-08 13:22:27 +0100871config CC_HAS_INT128
Masahiro Yamada3a7c7332020-03-10 19:12:50 +0900872 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
Ard Biesheuvelc12d3362019-11-08 13:22:27 +0100873
Gustavo A. R. Silvadee2b7022021-11-13 18:57:25 -0600874config CC_IMPLICIT_FALLTHROUGH
875 string
Gustavo A. R. Silva158ea2d2021-11-14 20:48:44 -0600876 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
Gustavo A. R. Silvadee2b7022021-11-13 18:57:25 -0600877 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
878
Kees Cook3e00f582024-02-23 09:08:27 -0800879# Currently, disable gcc-10+ array-bounds globally.
Linus Torvalds0da6e5f2023-04-23 09:56:20 -0700880# It's still broken in gcc-13, so no upper bound yet.
Kees Cook3e00f582024-02-23 09:08:27 -0800881config GCC10_NO_ARRAY_BOUNDS
Linus Torvalds5a412372023-01-09 17:04:49 -0600882 def_bool y
883
Linus Torvaldsf0be87c2022-06-09 10:11:12 -0700884config CC_NO_ARRAY_BOUNDS
885 bool
Kees Cook3e00f582024-02-23 09:08:27 -0800886 default y if CC_IS_GCC && GCC_VERSION >= 100000 && GCC10_NO_ARRAY_BOUNDS
Linus Torvaldsf0be87c2022-06-09 10:11:12 -0700887
Linus Torvalds02153312024-02-01 14:57:17 -0800888# Currently, disable -Wstringop-overflow for GCC globally.
889config GCC_NO_STRINGOP_OVERFLOW
Gustavo A. R. Silvaa5e0ace02023-11-30 14:29:34 -0600890 def_bool y
891
892config CC_NO_STRINGOP_OVERFLOW
893 bool
Linus Torvalds02153312024-02-01 14:57:17 -0800894 default y if CC_IS_GCC && GCC_NO_STRINGOP_OVERFLOW
Gustavo A. R. Silvaa5e0ace02023-11-30 14:29:34 -0600895
896config CC_STRINGOP_OVERFLOW
897 bool
898 default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
899
Mel Gorman72b252a2015-09-04 15:47:32 -0700900#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100901# For architectures that know their GCC __int128 support is sound
902#
903config ARCH_SUPPORTS_INT128
904 bool
905
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200906# For architectures that (ab)use NUMA to represent different memory regions
907# all cpu-local but of different latencies, such as SuperH.
908#
909config ARCH_WANT_NUMA_VARIABLE_LOCALITY
910 bool
911
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200912config NUMA_BALANCING
913 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200914 depends on ARCH_SUPPORTS_NUMA_BALANCING
915 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
Sebastian Andrzej Siewior554b0f32021-11-05 13:35:27 -0700916 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200917 help
918 This option adds support for automatic NUMA aware memory/task placement.
919 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400920 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200921
922 This system will be inactive on UMA systems.
923
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800924config NUMA_BALANCING_DEFAULT_ENABLED
925 bool "Automatically enable NUMA aware memory/task placement"
926 default y
927 depends on NUMA_BALANCING
928 help
929 If set, automatic NUMA balancing will be enabled if running on a NUMA
930 machine.
931
Suren Baghdasaryan21c690a2024-03-21 09:36:28 -0700932config SLAB_OBJ_EXT
933 bool
934
Li Zefan23964d22009-01-15 13:50:58 -0800935menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500936 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500937 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700938 help
Li Zefan23964d22009-01-15 13:50:58 -0800939 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800940 use with process control subsystems such as Cpusets, CFS, memory
941 controls or device isolation.
942 See
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300943 - Documentation/scheduler/sched-design-CFS.rst (CFS)
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300944 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800945 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700946
947 Say N if unsure.
948
Li Zefan23964d22009-01-15 13:50:58 -0800949if CGROUPS
950
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800951config PAGE_COUNTER
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800952 bool
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800953
Tejun Heo6a010a42022-07-23 04:28:28 -1000954config CGROUP_FAVOR_DYNMODS
955 bool "Favor dynamic modification latency reduction by default"
956 help
957 This option enables the "favordynmods" mount option by default
958 which reduces the latencies of dynamic cgroup modifications such
959 as task migrations and controller on/offs at the cost of making
960 hot path operations such as forks and exits more expensive.
961
962 Say N if unsure.
963
Andrew Mortonc255a452012-07-31 16:43:02 -0700964config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500965 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800966 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500967 select EVENTFD
Suren Baghdasaryan21c690a2024-03-21 09:36:28 -0700968 select SLAB_OBJ_EXT
Balbir Singh00f0b822008-03-04 14:28:39 -0800969 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500970 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800971
Kirill Tkhai84c07d12018-08-17 15:47:25 -0700972config MEMCG_KMEM
973 bool
Vlastimil Babkac9929f02023-02-27 17:46:13 +0100974 depends on MEMCG
Kirill Tkhai84c07d12018-08-17 15:47:25 -0700975 default y
976
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500977config BLK_CGROUP
978 bool "IO controller"
979 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700980 default n
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900981 help
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500982 Generic block IO controller cgroup interface. This is the common
983 cgroup interface which should be used by various IO controlling
984 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700985
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500986 Currently, CFQ IO scheduler uses it to recognize task groups and
987 control disk bandwidth allocation (proportional time slice allocation)
988 to such task groups. It is also used by bio throttling logic in
989 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +0200990
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500991 This option only enables generic Block IO controller infrastructure.
992 One needs to also enable actual IO controlling logic/policy. For
993 enabling proportional weight division of disk bandwidth in CFQ, set
Krzysztof Kozlowski7baf2192020-04-06 20:12:02 -0700994 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500995 CONFIG_BLK_DEV_THROTTLING=y.
996
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300997 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500998
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500999config CGROUP_WRITEBACK
1000 bool
1001 depends on MEMCG && BLK_CGROUP
1002 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +02001003
Dhaval Giani7c941432010-01-20 13:26:18 +01001004menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -05001005 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +01001006 default n
1007 help
1008 This feature lets CPU scheduler recognize task groups and control CPU
1009 bandwidth allocation to such task groups. It uses cgroups to group
1010 tasks.
1011
1012if CGROUP_SCHED
1013config FAIR_GROUP_SCHED
1014 bool "Group scheduling for SCHED_OTHER"
1015 depends on CGROUP_SCHED
1016 default CGROUP_SCHED
1017
Paul Turnerab84d312011-07-21 09:43:28 -07001018config CFS_BANDWIDTH
1019 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -07001020 depends on FAIR_GROUP_SCHED
1021 default n
1022 help
1023 This option allows users to define CPU bandwidth rates (limits) for
1024 tasks running within the fair group scheduler. Groups with no limit
1025 set are considered to be unconstrained and will run with no
1026 restriction.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -03001027 See Documentation/scheduler/sched-bwc.rst for more information.
Paul Turnerab84d312011-07-21 09:43:28 -07001028
Dhaval Giani7c941432010-01-20 13:26:18 +01001029config RT_GROUP_SCHED
1030 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +01001031 depends on CGROUP_SCHED
1032 default n
1033 help
1034 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +08001035 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +01001036 schedule realtime tasks for non-root users until you allocate
1037 realtime bandwidth for them.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -03001038 See Documentation/scheduler/sched-rt-group.rst for more information.
Dhaval Giani7c941432010-01-20 13:26:18 +01001039
1040endif #CGROUP_SCHED
1041
Mathieu Desnoyersaf7f5882022-11-22 15:39:09 -05001042config SCHED_MM_CID
1043 def_bool y
1044 depends on SMP && RSEQ
1045
Patrick Bellasi2480c092019-08-22 14:28:06 +01001046config UCLAMP_TASK_GROUP
1047 bool "Utilization clamping per group of tasks"
1048 depends on CGROUP_SCHED
1049 depends on UCLAMP_TASK
1050 default n
1051 help
1052 This feature enables the scheduler to track the clamped utilization
1053 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1054
1055 When this option is enabled, the user can specify a min and max
1056 CPU bandwidth which is allowed for each single task in a group.
1057 The max bandwidth allows to clamp the maximum frequency a task
1058 can use, while the min bandwidth allows to define a minimum
1059 frequency a task will always use.
1060
1061 When task group based utilization clamping is enabled, an eventually
1062 specified task-specific clamp value is constrained by the cgroup
1063 specified clamp value. Both minimum and maximum task clamping cannot
1064 be bigger than the corresponding clamping defined at task group level.
1065
1066 If in doubt, say N.
1067
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001068config CGROUP_PIDS
1069 bool "PIDs controller"
1070 help
1071 Provides enforcement of process number limits in the scope of a
1072 cgroup. Any attempt to fork more processes than is allowed in the
1073 cgroup will fail. PIDs are fundamentally a global resource because it
1074 is fairly trivial to reach PID exhaustion before you reach even a
1075 conservative kmemcg limit. As a result, it is possible to grind a
1076 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +05301077 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001078
1079 It should be noted that organisational operations (such as attaching
Jonathan Neuschäfer98076832019-02-01 14:21:01 -08001080 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001081 since the PIDs limit only affects a process's ability to fork, not to
1082 attach to a cgroup.
1083
Parav Pandit39d3e752017-01-10 00:02:13 +00001084config CGROUP_RDMA
1085 bool "RDMA controller"
1086 help
1087 Provides enforcement of RDMA resources defined by IB stack.
1088 It is fairly easy for consumers to exhaust RDMA resources, which
1089 can result into resource unavailability to other consumers.
1090 RDMA controller is designed to stop this from happening.
1091 Attaching processes with active RDMA resources to the cgroup
1092 hierarchy is allowed even if can cross the hierarchy's limit.
1093
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001094config CGROUP_FREEZER
1095 bool "Freezer controller"
1096 help
1097 Provides a way to freeze and unfreeze all tasks in a
1098 cgroup.
1099
Johannes Weiner489c2a22016-01-20 15:02:41 -08001100 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1101 controller includes important in-kernel memory consumers per default.
1102
1103 If you're using cgroup2, say N.
1104
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001105config CGROUP_HUGETLB
1106 bool "HugeTLB controller"
1107 depends on HUGETLB_PAGE
1108 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +02001109 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001110 help
1111 Provides a cgroup controller for HugeTLB pages.
1112 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1113 The limit is enforced during page fault. Since HugeTLB doesn't
1114 support page reclaim, enforcing the limit at page fault time implies
1115 that, the application will get SIGBUS signal if it tries to access
1116 HugeTLB pages beyond its limit. This requires the application to know
1117 beforehand how much HugeTLB pages it would require for its use. The
1118 control group is tracked in the third page lru pointer. This means
1119 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001120
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001121config CPUSETS
1122 bool "Cpuset controller"
Nicolas Pitree1d4eee2017-06-14 13:19:23 -04001123 depends on SMP
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001124 help
1125 This option will let you create and manage CPUSETs which
1126 allow dynamically partitioning a system into sets of CPUs and
1127 Memory Nodes and assigning tasks to run only within those sets.
1128 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001129
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001130 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001131
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001132config PROC_PID_CPUSET
1133 bool "Include legacy /proc/<pid>/cpuset file"
1134 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001135 default y
1136
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001137config CGROUP_DEVICE
1138 bool "Device controller"
1139 help
1140 Provides a cgroup controller implementing whitelists for
1141 devices which a process in the cgroup can mknod or open.
1142
1143config CGROUP_CPUACCT
1144 bool "Simple CPU accounting controller"
1145 help
1146 Provides a simple controller for monitoring the
1147 total CPU consumed by the tasks in a cgroup.
1148
1149config CGROUP_PERF
1150 bool "Perf controller"
1151 depends on PERF_EVENTS
1152 help
1153 This option extends the perf per-cpu mode to restrict monitoring
1154 to threads which belong to the cgroup specified and run on the
Namhyung Kim6546b192020-03-25 21:45:29 +09001155 designated cpu. Or this can be used to have cgroup ID in samples
1156 so that it can monitor performance events among cgroups.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001157
1158 Say N if unsure.
1159
Daniel Mack30070982016-11-23 16:52:26 +01001160config CGROUP_BPF
1161 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirski483c4932016-12-16 08:33:45 -08001162 depends on BPF_SYSCALL
1163 select SOCK_CGROUP_DATA
Daniel Mack30070982016-11-23 16:52:26 +01001164 help
1165 Allow attaching eBPF programs to a cgroup using the bpf(2)
1166 syscall command BPF_PROG_ATTACH.
1167
1168 In which context these programs are accessed depends on the type
1169 of attachment. For instance, programs that are attached using
1170 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1171 inet sockets.
1172
Vipin Sharmaa72232e2021-03-29 21:42:04 -07001173config CGROUP_MISC
1174 bool "Misc resource controller"
1175 default n
1176 help
1177 Provides a controller for miscellaneous resources on a host.
1178
1179 Miscellaneous scalar resources are the resources on the host system
1180 which cannot be abstracted like the other cgroups. This controller
1181 tracks and limits the miscellaneous resources used by a process
1182 attached to a cgroup hierarchy.
1183
1184 For more information, please check misc cgroup section in
1185 /Documentation/admin-guide/cgroup-v2.rst.
1186
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001187config CGROUP_DEBUG
Waiman Long23b0be42017-06-13 17:18:03 -04001188 bool "Debug controller"
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001189 default n
Waiman Long23b0be42017-06-13 17:18:03 -04001190 depends on DEBUG_KERNEL
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001191 help
1192 This option enables a simple controller that exports
Waiman Long23b0be42017-06-13 17:18:03 -04001193 debugging information about the cgroups framework. This
1194 controller is for control cgroup debugging only. Its
1195 interfaces are not stable.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001196
1197 Say N.
1198
Arnd Bergmann73b35142017-01-10 13:08:06 +01001199config SOCK_CGROUP_DATA
1200 bool
1201 default n
1202
Li Zefan23964d22009-01-15 13:50:58 -08001203endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001204
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001205menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001206 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001207 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001208 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001209 help
1210 Provides the way to make tasks work with different objects using
1211 the same id. For example same IPC id may refer to different objects
1212 or same user id or pid may refer to different tasks when used in
1213 different namespaces.
1214
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001215if NAMESPACES
1216
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001217config UTS_NS
1218 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001219 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001220 help
1221 In this namespace tasks see different info provided with the
1222 uname() system call
1223
Andrei Vagin769071a2019-11-12 01:26:52 +00001224config TIME_NS
1225 bool "TIME namespace"
Thomas Gleixner660fd042019-11-12 01:27:09 +00001226 depends on GENERIC_VDSO_TIME_NS
Andrei Vagin769071a2019-11-12 01:26:52 +00001227 default y
1228 help
1229 In this namespace boottime and monotonic clocks can be set.
1230 The time will keep going with the same pace.
1231
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001232config IPC_NS
1233 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001234 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001235 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001236 help
1237 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001238 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001239
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001240config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001241 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001242 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001243 help
1244 This allows containers, i.e. vservers, to use user namespaces
1245 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001246
1247 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001248 recommended that the MEMCG option also be enabled and that
1249 user-space use the memory control groups to limit the amount
1250 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001251
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001252 If unsure, say N.
1253
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001254config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001255 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001256 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001257 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001258 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001259 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001260 pid namespaces. This is a building block of containers.
1261
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001262config NET_NS
1263 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001264 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001265 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001266 help
1267 Allow user space to create what appear to be multiple instances
1268 of the network stack.
1269
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001270endif # NAMESPACES
1271
Adrian Reber5cb366b2018-08-21 22:01:17 -07001272config CHECKPOINT_RESTORE
1273 bool "Checkpoint/restore support"
Ren Zhijie30341ec2022-09-29 07:00:57 +00001274 depends on PROC_FS
Adrian Reber5cb366b2018-08-21 22:01:17 -07001275 select PROC_CHILDREN
Chris Wilsonbfe39112021-02-05 22:00:12 +00001276 select KCMP
Adrian Reber5cb366b2018-08-21 22:01:17 -07001277 default n
1278 help
1279 Enables additional kernel features in a sake of checkpoint/restore.
1280 In particular it adds auxiliary prctl codes to setup process text,
1281 data and heap segment sizes, and a few additional /proc filesystem
1282 entries.
1283
1284 If unsure, say N here.
1285
Mike Galbraith5091faa2010-11-30 14:18:03 +01001286config SCHED_AUTOGROUP
1287 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001288 select CGROUPS
1289 select CGROUP_SCHED
1290 select FAIR_GROUP_SCHED
1291 help
1292 This option optimizes the scheduler for common desktop workloads by
1293 automatically creating and populating task groups. This separation
1294 of workloads isolates aggressive CPU burners (like build jobs) from
1295 desktop applications. Task group autogeneration is currently based
1296 upon task session.
1297
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001298config RELAY
1299 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001300 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001301 help
1302 This option enables support for relay interface support in
1303 certain file systems (such as debugfs).
1304 It is designed to provide an efficient mechanism for tools and
1305 facilities to relay large amounts of data from kernel space to
1306 user space.
1307
1308 If unsure, say N.
1309
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001310config BLK_DEV_INITRD
1311 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001312 help
1313 The initial RAM filesystem is a ramfs which is loaded by the
1314 boot loader (loadlin or lilo) and that is mounted as root
1315 before the normal boot procedure. It is typically used to
1316 load modules needed to mount the "real" root file system,
Mauro Carvalho Chehab8c27ceff32016-10-18 10:12:27 -02001317 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001318
1319 If RAM disk support (BLK_DEV_RAM) is also included, this
1320 also enables initial RAM disk (initrd) support and adds
1321 15 Kbytes (more on some other architectures) to the kernel size.
1322
1323 If unsure say Y.
1324
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001325if BLK_DEV_INITRD
1326
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001327source "usr/Kconfig"
1328
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001329endif
1330
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001331config BOOT_CONFIG
1332 bool "Boot config support"
Masami Hiramatsua2a9d672022-04-06 11:31:19 +09001333 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001334 help
1335 Extra boot config allows system admin to pass a config file as
1336 complemental extension of kernel cmdline when booting.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001337 The boot config file must be attached at the end of initramfs
Masami Hiramatsu85c46b72020-02-20 21:18:42 +09001338 with checksum, size and magic word.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001339 See <file:Documentation/admin-guide/bootconfig.rst> for details.
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001340
1341 If unsure, say Y.
1342
Paul E. McKenneyb7438522023-02-22 08:27:48 +09001343config BOOT_CONFIG_FORCE
1344 bool "Force unconditional bootconfig processing"
1345 depends on BOOT_CONFIG
Paul E. McKenney6ded8a22023-02-22 08:27:49 +09001346 default y if BOOT_CONFIG_EMBED
Paul E. McKenneyb7438522023-02-22 08:27:48 +09001347 help
1348 With this Kconfig option set, BOOT_CONFIG processing is carried
1349 out even when the "bootconfig" kernel-boot parameter is omitted.
1350 In fact, with this Kconfig option set, there is no way to
1351 make the kernel ignore the BOOT_CONFIG-supplied kernel-boot
1352 parameters.
1353
1354 If unsure, say N.
1355
Masami Hiramatsua2a9d672022-04-06 11:31:19 +09001356config BOOT_CONFIG_EMBED
1357 bool "Embed bootconfig file in the kernel"
1358 depends on BOOT_CONFIG
1359 help
1360 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1361 kernel. Usually, the bootconfig file is loaded with the initrd
1362 image. But if the system doesn't support initrd, this option will
1363 help you by embedding a bootconfig file while building the kernel.
1364
1365 If unsure, say N.
1366
1367config BOOT_CONFIG_EMBED_FILE
1368 string "Embedded bootconfig file path"
1369 depends on BOOT_CONFIG_EMBED
1370 help
1371 Specify a bootconfig file which will be embedded to the kernel.
1372 This bootconfig will be used if there is no initrd or no other
1373 bootconfig in the initrd.
1374
David Disseldorp1274aea12022-05-09 18:29:19 -07001375config INITRAMFS_PRESERVE_MTIME
1376 bool "Preserve cpio archive mtimes in initramfs"
1377 default y
1378 help
1379 Each entry in an initramfs cpio archive carries an mtime value. When
1380 enabled, extracted cpio items take this mtime, with directory mtime
1381 setting deferred until after creation of any child entries.
1382
1383 If unsure, say Y.
1384
Arnd Bergmann877417e2016-04-25 17:35:27 +02001385choice
1386 prompt "Compiler optimization level"
Ulf Magnusson2cc3ce22017-10-04 01:53:26 +02001387 default CC_OPTIMIZE_FOR_PERFORMANCE
Arnd Bergmann877417e2016-04-25 17:35:27 +02001388
1389config CC_OPTIMIZE_FOR_PERFORMANCE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001390 bool "Optimize for performance (-O2)"
Arnd Bergmann877417e2016-04-25 17:35:27 +02001391 help
1392 This is the default optimization level for the kernel, building
1393 with the "-O2" compiler flag for best performance and most
1394 helpful compile-time warnings.
1395
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001396config CC_OPTIMIZE_FOR_SIZE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001397 bool "Optimize for size (-Os)"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001398 help
Masahiro Yamadace3b4872019-08-21 02:09:39 +09001399 Choosing this option will pass "-Os" to your compiler resulting
1400 in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001401
Arnd Bergmann877417e2016-04-25 17:35:27 +02001402endchoice
1403
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001404config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1405 bool
1406 help
1407 This requires that the arch annotates or otherwise protects
1408 its external entry points from being discarded. Linker scripts
1409 must also merge .text.*, .data.*, and .bss.* correctly into
1410 output sections. Care must be taken not to pull in unrelated
1411 sections (e.g., '.text.init'). Typically '.' in section names
1412 is used to distinguish them from label names / C identifiers.
1413
1414config LD_DEAD_CODE_DATA_ELIMINATION
1415 bool "Dead code and data elimination (EXPERIMENTAL)"
1416 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1417 depends on EXPERT
Masahiro Yamadae85d1d62018-08-22 22:51:09 +09001418 depends on $(cc-option,-ffunction-sections -fdata-sections)
1419 depends on $(ld-option,--gc-sections)
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001420 help
Masahiro Yamada8b9d2712018-06-24 01:41:51 +09001421 Enable this if you want to do dead code and data elimination with
1422 the linker by compiling with -ffunction-sections -fdata-sections,
1423 and linking with --gc-sections.
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001424
1425 This can reduce on disk and in-memory size of the kernel
1426 code and static data, particularly for small configs and
1427 on small systems. This has the possibility of introducing
1428 silently broken kernel if the required annotations are not
1429 present. This option is not well tested yet, so use at your
1430 own risk.
1431
Nathan Chancellor59612b22020-11-19 13:46:56 -07001432config LD_ORPHAN_WARN
1433 def_bool y
1434 depends on ARCH_WANT_LD_ORPHAN_WARN
1435 depends on $(ld-option,--orphan-handling=warn)
Xin Lie1789d72022-10-25 00:30:23 -07001436 depends on $(ld-option,--orphan-handling=error)
1437
1438config LD_ORPHAN_WARN_LEVEL
1439 string
1440 depends on LD_ORPHAN_WARN
1441 default "error" if WERROR
1442 default "warn"
Nathan Chancellor59612b22020-11-19 13:46:56 -07001443
Randy Dunlap08470622006-09-30 23:28:13 -07001444config SYSCTL
1445 bool
1446
Mike Frysinger657a5202013-04-30 15:28:45 -07001447config HAVE_UID16
1448 bool
1449
1450config SYSCTL_EXCEPTION_TRACE
1451 bool
1452 help
1453 Enable support for /proc/sys/debug/exception-trace.
1454
1455config SYSCTL_ARCH_UNALIGN_NO_WARN
1456 bool
1457 help
1458 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1459 Allows arch to define/use @no_unaligned_warning to possibly warn
1460 about unaligned access emulation going on under the hood.
1461
1462config SYSCTL_ARCH_UNALIGN_ALLOW
1463 bool
1464 help
1465 Enable support for /proc/sys/kernel/unaligned-trap
1466 Allows arches to define/use @unaligned_enabled to runtime toggle
1467 the unaligned access emulation.
1468 see arch/parisc/kernel/unaligned.c for reference
1469
Mike Frysinger657a5202013-04-30 15:28:45 -07001470config HAVE_PCSPKR_PLATFORM
1471 bool
1472
David Rientjes6a108a12011-01-20 14:44:16 -08001473menuconfig EXPERT
1474 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001475 # Unhide debug options, to make the on-by-default options visible
1476 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477 help
1478 This option allows certain base kernel options and settings
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001479 to be disabled or tweaked. This is for specialized
1480 environments which can tolerate a "non-standard" kernel.
1481 Only use this if you really know what you are doing.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001483config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001484 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001485 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001486 default y
1487 help
1488 This enables the legacy 16-bit UID syscall wrappers.
1489
Iulia Manda28138932015-04-15 16:16:41 -07001490config MULTIUSER
1491 bool "Multiple users, groups and capabilities support" if EXPERT
1492 default y
1493 help
1494 This option enables support for non-root users, groups and
1495 capabilities.
1496
1497 If you say N here, all processes will run with UID 0, GID 0, and all
1498 possible capabilities. Saying N here also compiles out support for
1499 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1500 setgid, and capset.
1501
1502 If unsure, say Y here.
1503
Fabian Frederickf6187762014-06-04 16:11:12 -07001504config SGETMASK_SYSCALL
1505 bool "sgetmask/ssetmask syscalls support" if EXPERT
Masahiro Yamadacd14b012024-02-11 21:48:08 +09001506 default PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09001507 help
Fabian Frederickf6187762014-06-04 16:11:12 -07001508 sys_sgetmask and sys_ssetmask are obsolete system calls
1509 no longer supported in libc but still enabled by default in some
1510 architectures.
1511
1512 If unsure, leave the default option here.
1513
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001514config SYSFS_SYSCALL
1515 bool "Sysfs syscall support" if EXPERT
1516 default y
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09001517 help
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001518 sys_sysfs is an obsolete system call no longer supported in libc.
1519 Note that disabling this option is more secure but might break
1520 compatibility with some systems.
1521
1522 If unsure say Y here.
1523
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001524config FHANDLE
1525 bool "open by fhandle syscalls" if EXPERT
1526 select EXPORTFS
1527 default y
1528 help
1529 If you say Y here, a user level program will be able to map
1530 file names to handle and then later use the handle for
1531 different file system operations. This is useful in implementing
1532 userspace file servers, which now track files using handles instead
1533 of names. The handle would remain the same even if file names
1534 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1535 syscalls.
1536
Nicolas Pitrebaa73d92016-11-11 00:10:10 -05001537config POSIX_TIMERS
1538 bool "Posix Clocks & timers" if EXPERT
1539 default y
1540 help
1541 This includes native support for POSIX timers to the kernel.
1542 Some embedded systems have no use for them and therefore they
1543 can be configured out to reduce the size of the kernel image.
1544
1545 When this option is disabled, the following syscalls won't be
1546 available: timer_create, timer_gettime: timer_getoverrun,
1547 timer_settime, timer_delete, clock_adjtime, getitimer,
1548 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1549 clock_getres and clock_nanosleep syscalls will be limited to
1550 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1551
1552 If unsure say y.
1553
Matt Mackalld59745c2005-05-01 08:59:02 -07001554config PRINTK
1555 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001556 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001557 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001558 help
1559 This option enables normal printk support. Removing it
1560 eliminates most of the message strings from the kernel image
1561 and makes the kernel more or less silent. As this makes it
1562 very difficult to diagnose system problems, saying N here is
1563 strongly discouraged.
1564
Matt Mackallc8538a72005-05-01 08:59:01 -07001565config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001566 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001567 default y
1568 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001569 Disabling this option eliminates support for BUG and WARN, reducing
1570 the size of your kernel image and potentially quietly ignoring
1571 numerous fatal conditions. You should only consider disabling this
1572 option for embedded systems with no facilities for reporting errors.
1573 Just say Y.
Matt Mackallc8538a72005-05-01 08:59:01 -07001574
Matt Mackall708e9a72006-01-08 01:05:25 -08001575config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001576 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001577 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001578 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001579 help
1580 Enable support for generating core dumps. Disabling saves about 4k.
1581
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001582
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001583config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001584 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001585 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001586 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001587 default y
1588 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001589 This option allows to disable the internal PC-Speaker
1590 support, saving some memory.
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001591
Yoann Congal27021642024-05-05 10:03:43 +02001592config BASE_SMALL
1593 bool "Enable smaller-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 help
Yoann Congal27021642024-05-05 10:03:43 +02001595 Enabling this option reduces the size of miscellaneous core
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 kernel data structures. This saves memory on small machines,
1597 but may reduce performance.
1598
1599config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001600 bool "Enable futex support" if EXPERT
Arnd Bergmann3f2beda2021-10-26 12:03:47 +02001601 depends on !(SPARC32 && SMP)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602 default y
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001603 imply RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 help
1605 Disabling this option will cause the kernel to be built without
1606 support for "fast userspace mutexes". The resulting kernel may not
1607 run glibc-based applications correctly.
1608
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001609config FUTEX_PI
1610 bool
1611 depends on FUTEX && RT_MUTEXES
1612 default y
1613
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001615 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 default y
1617 help
1618 Disabling this option will cause the kernel to be built without
1619 support for epoll family of system calls.
1620
Davide Libenzifba2afa2007-05-10 22:23:13 -07001621config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001622 bool "Enable signalfd() system call" if EXPERT
Davide Libenzifba2afa2007-05-10 22:23:13 -07001623 default y
1624 help
1625 Enable the signalfd() system call that allows to receive signals
1626 on a file descriptor.
1627
1628 If unsure, say Y.
1629
Davide Libenzib215e282007-05-10 22:23:16 -07001630config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001631 bool "Enable timerfd() system call" if EXPERT
Davide Libenzib215e282007-05-10 22:23:16 -07001632 default y
1633 help
1634 Enable the timerfd() system call that allows to receive timer
1635 events on a file descriptor.
1636
1637 If unsure, say Y.
1638
Davide Libenzie1ad7462007-05-10 22:23:19 -07001639config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001640 bool "Enable eventfd() system call" if EXPERT
Davide Libenzie1ad7462007-05-10 22:23:19 -07001641 default y
1642 help
1643 Enable the eventfd() system call that allows to receive both
1644 kernel notification (ie. KAIO) or userspace notifications.
1645
1646 If unsure, say Y.
1647
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001649 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 default y
1651 depends on MMU
1652 help
1653 The shmem is an internal filesystem used to manage shared memory.
1654 It is backed by swap and manages resource limits. It is also exported
1655 to userspace as tmpfs if TMPFS is enabled. Disabling this
1656 option replaces shmem and tmpfs with the much simpler ramfs code,
1657 which may be appropriate on small systems without swap.
1658
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001659config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001660 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001661 default y
1662 help
1663 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001664 by some high performance threaded applications. Disabling
1665 this option saves about 7k.
1666
Jens Axboe2b188cc2019-01-07 10:46:33 -07001667config IO_URING
1668 bool "Enable IO uring support" if EXPERT
Jens Axboe561fb042019-10-24 07:25:42 -06001669 select IO_WQ
Jens Axboe2b188cc2019-01-07 10:46:33 -07001670 default y
1671 help
1672 This option enables support for the io_uring interface, enabling
1673 applications to submit and complete IO through submission and
1674 completion rings that are shared between the kernel and application.
1675
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001676config ADVISE_SYSCALLS
1677 bool "Enable madvise/fadvise syscalls" if EXPERT
1678 default y
1679 help
1680 This option enables the madvise and fadvise syscalls, used by
1681 applications to advise the kernel about their future memory or file
1682 usage, improving performance. If building an embedded system where no
1683 applications use these syscalls, you can disable this option to save
1684 space.
1685
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001686config MEMBARRIER
1687 bool "Enable membarrier() system call" if EXPERT
1688 default y
1689 help
1690 Enable the membarrier() system call that allows issuing memory
1691 barriers across all running threads, which can be used to distribute
1692 the cost of user-space memory barriers asymmetrically by transforming
1693 pairs of memory barriers into pairs consisting of membarrier() and a
1694 compiler barrier.
1695
1696 If unsure, say Y.
1697
Randy Dunlapa751ea32023-12-07 20:58:19 -08001698config KCMP
1699 bool "Enable kcmp() system call" if EXPERT
1700 help
1701 Enable the kernel resource comparison system call. It provides
1702 user-space with the ability to compare two processes to see if they
1703 share a common resource, such as a file descriptor or even virtual
1704 memory space.
1705
1706 If unsure, say N.
1707
1708config RSEQ
1709 bool "Enable rseq() system call" if EXPERT
1710 default y
1711 depends on HAVE_RSEQ
1712 select MEMBARRIER
1713 help
1714 Enable the restartable sequences system call. It provides a
1715 user-space cache for the current CPU number value, which
1716 speeds up getting the current CPU number from user-space,
1717 as well as an ABI to speed up user-space operations on
1718 per-CPU data.
1719
1720 If unsure, say Y.
1721
1722config DEBUG_RSEQ
1723 default n
1724 bool "Enable debugging of rseq() system call" if EXPERT
1725 depends on RSEQ && DEBUG_KERNEL
1726 help
1727 Enable extra debugging checks for the rseq system call.
1728
1729 If unsure, say N.
1730
1731config CACHESTAT_SYSCALL
1732 bool "Enable cachestat() system call" if EXPERT
1733 default y
1734 help
1735 Enable the cachestat system call, which queries the page cache
1736 statistics of a file (number of cached pages, dirty pages,
1737 pages marked for writeback, (recently) evicted pages).
1738
1739 If unsure say Y here.
1740
1741config PC104
1742 bool "PC/104 support" if EXPERT
1743 help
1744 Expose PC/104 form factor device drivers and options available for
1745 selection and configuration. Enable this option if your target
1746 machine has a PC/104 bus.
1747
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001748config KALLSYMS
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001749 bool "Load all symbols for debugging/ksymoops" if EXPERT
1750 default y
1751 help
1752 Say Y here to let the kernel print out symbolic crash information and
1753 symbolic stack backtraces. This increases the size of the kernel
1754 somewhat, as all symbols have to be loaded into the kernel image.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001755
Zhen Lei30f3bb02022-11-15 16:33:48 +08001756config KALLSYMS_SELFTEST
1757 bool "Test the basic functions and performance of kallsyms"
1758 depends on KALLSYMS
1759 default n
1760 help
1761 Test the basic functions and performance of some interfaces, such as
1762 kallsyms_lookup_name. It also calculates the compression rate of the
1763 kallsyms compression algorithm for the current symbol set.
1764
1765 Start self-test automatically after system startup. Suggest executing
1766 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
1767 displayed in the last line, indicating that the test is complete.
1768
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001769config KALLSYMS_ALL
1770 bool "Include all symbols in kallsyms"
1771 depends on DEBUG_KERNEL && KALLSYMS
1772 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001773 Normally kallsyms only contains the symbols of functions for nicer
1774 OOPS messages and backtraces (i.e., symbols from the text and inittext
Baruch Siachbdf0fe32022-07-07 07:43:29 +03001775 sections). This is sufficient for most cases. And only if you want to
1776 enable kernel live patching, or other less common use cases (e.g.,
1777 when a debugger is used) all symbols are required (i.e., names of
1778 variables from the data sections, etc).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001779
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001780 This option makes sure that all symbols are loaded into the kernel
1781 image (i.e., symbols from all sections) in cost of increased kernel
1782 size (depending on the kernel configuration, it may be 300KiB or
1783 something like this).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001784
Baruch Siachbdf0fe32022-07-07 07:43:29 +03001785 Say N unless you really need all symbols, or kernel live patching.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001786
1787config KALLSYMS_ABSOLUTE_PERCPU
1788 bool
1789 depends on KALLSYMS
1790 default X86_64 && SMP
1791
1792config KALLSYMS_BASE_RELATIVE
1793 bool
1794 depends on KALLSYMS
Ard Biesheuvelcf8e8652022-10-20 15:54:33 +02001795 default y
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001796 help
1797 Instead of emitting them as absolute values in the native word size,
1798 emit the symbol references in the kallsyms table as 32-bit entries,
1799 each containing a relative value in the range [base, base + U32_MAX]
1800 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1801 an absolute value in the range [0, S32_MAX] or a relative value in the
1802 range [base, base + S32_MAX], where base is the lowest relative symbol
1803 address encountered in the image.
1804
1805 On 64-bit builds, this reduces the size of the address table by 50%,
1806 but more importantly, it results in entries whose values are build
1807 time constants, and no relocation pass is required at runtime to fix
1808 up the entries based on the runtime load address of the kernel.
1809
1810# end of the "standard kernel features (expert users)" menu
1811
Mathieu Desnoyers3ccfebe2018-01-29 15:20:11 -05001812config ARCH_HAS_MEMBARRIER_CALLBACKS
1813 bool
1814
Mathieu Desnoyers70216e12018-01-29 15:20:17 -05001815config ARCH_HAS_MEMBARRIER_SYNC_CORE
1816 bool
1817
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001818config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001819 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001820 help
1821 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001822
Sean Christopherson2aef6f32021-11-11 02:07:29 +00001823config GUEST_PERF_EVENTS
1824 bool
1825 depends on HAVE_PERF_EVENTS
1826
Peter Zijlstra906010b2009-09-21 16:08:49 +02001827config PERF_USE_VMALLOC
1828 bool
1829 help
1830 See tools/perf/design.txt for details
1831
Ingo Molnar57c0c152009-09-21 12:20:38 +02001832menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001833
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001834config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001835 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001836 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001837 depends on HAVE_PERF_EVENTS
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001838 select IRQ_WORK
Thomas Gleixner0793a612008-12-04 20:12:29 +01001839 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001840 Enable kernel support for various performance events provided
1841 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001842
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001843 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001844 use of generic tracepoints.
1845
1846 Most modern CPUs support performance events via performance
1847 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001848 types of hw events: such as instructions executed, cachemisses
1849 suffered, or branches mis-predicted - without slowing down the
1850 kernel or applications. These registers can also trigger interrupts
1851 when a threshold number of events have passed - and can thus be
1852 used to profile the code that runs on that CPU.
1853
Ingo Molnar57c0c152009-09-21 12:20:38 +02001854 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001855 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001856 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001857 provides per task and per CPU counters, and it provides event
1858 capabilities on top of those.
1859
1860 Say Y if unsure.
1861
Peter Zijlstra906010b2009-09-21 16:08:49 +02001862config DEBUG_PERF_USE_VMALLOC
1863 default n
1864 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb3071132015-05-04 16:26:39 +10001865 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001866 select PERF_USE_VMALLOC
1867 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001868 Use vmalloc memory to back perf mmap() buffers.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001869
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001870 Mostly useful for debugging the vmalloc code on platforms
1871 that don't require it.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001872
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001873 Say N if unsure.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001874
Thomas Gleixner0793a612008-12-04 20:12:29 +01001875endmenu
1876
David Howells091f6e22015-07-20 21:16:28 +01001877config SYSTEM_DATA_VERIFICATION
1878 def_bool n
1879 select SYSTEM_TRUSTED_KEYRING
1880 select KEYS
1881 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00001882 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01001883 select ASYMMETRIC_KEY_TYPE
1884 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01001885 select ASN1
1886 select OID_REGISTRY
1887 select X509_CERTIFICATE_PARSER
1888 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07001889 help
David Howells091f6e22015-07-20 21:16:28 +01001890 Provide PKCS#7 message verification using the contents of the system
1891 trusted keyring to provide public keys. This then can be used for
1892 module verification, kexec image verification and firmware blob
1893 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07001894
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001895config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001896 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001897 help
1898 Say Y here to enable the extended profiling support mechanisms used
Viresh Kumarf8408262021-01-14 17:05:30 +05301899 by profilers.
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001900
Miguel Ojeda2f7ab122021-07-03 16:42:57 +02001901config RUST
1902 bool "Rust support"
1903 depends on HAVE_RUST
1904 depends on RUST_IS_AVAILABLE
Conor Dooley8933cf42024-04-04 15:17:02 +01001905 depends on !CFI_CLANG
Miguel Ojeda2f7ab122021-07-03 16:42:57 +02001906 depends on !MODVERSIONS
1907 depends on !GCC_PLUGINS
1908 depends on !RANDSTRUCT
Martin Rodriguez Reboredoc1177972023-01-11 12:20:50 -03001909 depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
Miguel Ojeda2f7ab122021-07-03 16:42:57 +02001910 help
1911 Enables Rust support in the kernel.
1912
1913 This allows other Rust-related options, like drivers written in Rust,
1914 to be selected.
1915
1916 It is also required to be able to load external kernel modules
1917 written in Rust.
1918
1919 See Documentation/rust/ for more information.
1920
1921 If unsure, say N.
1922
1923config RUSTC_VERSION_TEXT
1924 string
1925 depends on RUST
1926 default $(shell,command -v $(RUSTC) >/dev/null 2>&1 && $(RUSTC) --version || echo n)
1927
1928config BINDGEN_VERSION_TEXT
1929 string
1930 depends on RUST
1931 default $(shell,command -v $(BINDGEN) >/dev/null 2>&1 && $(BINDGEN) --version || echo n)
1932
Ingo Molnar5f87f112008-07-23 14:15:22 +02001933#
1934# Place an empty function call at each tracepoint site. Can be
1935# dynamically changed for a probe function.
1936#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001937config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001938 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001939
Eric DeVolder89cde452023-07-12 12:15:32 -04001940source "kernel/Kconfig.kexec"
1941
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942endmenu # General setup
1943
Christoph Hellwig15724972018-07-31 13:39:30 +02001944source "arch/Kconfig"
1945
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001946config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05001947 bool
Sebastian Andrzej Siewior1c6f9ec2022-02-08 18:21:10 +01001948 default y if PREEMPT_RT
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001949
Thiago Jung Bauermannc8424e72019-07-04 15:57:34 -03001950config MODULE_SIG_FORMAT
1951 def_bool n
1952 select SYSTEM_DATA_VERIFICATION
1953
Christophe Leroy73b4fc92022-07-12 07:52:33 +02001954source "kernel/module/Kconfig"
Peter Zijlstra6c9692e22015-05-27 11:09:37 +09301955
Rusty Russell98a79d62008-12-13 21:19:41 +10301956config INIT_ALL_POSSIBLE
1957 bool
1958 help
Rusty Russell5f054e32012-03-29 15:38:31 +10301959 Back when each arch used to define their own cpu_online_mask and
1960 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10301961 with all 1s, and others with all 0s. When they were centralised,
1962 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01001963 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10301964
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001965source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07001966
1967config PREEMPT_NOTIFIERS
1968 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01001969
Steffen Klassert16295be2010-01-06 19:47:10 +11001970config PADATA
1971 depends on SMP
1972 bool
1973
David Howells4520c6a2012-09-21 23:31:13 +01001974config ASN1
1975 tristate
1976 help
1977 Build a simple ASN.1 grammar compiler that produces a bytecode output
1978 that can be interpreted by the ASN.1 stream decoder and used to
1979 inform it as to what tags are to be expected in a stream and what
1980 functions to call on what tags.
1981
Thomas Gleixner6beb0002009-11-09 15:21:34 +00001982source "kernel/Kconfig.locks"
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05001983
Daniel Borkmann0ebeea82020-05-15 12:11:16 +02001984config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
1985 bool
1986
Andrea Parri4ff4c742024-01-31 15:49:35 +01001987config ARCH_HAS_PREPARE_SYNC_CORE_CMD
1988 bool
1989
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05001990config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
1991 bool
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02001992
1993# It may be useful for an architecture to override the definitions of the
Dominik Brodowski7303e302018-04-05 11:53:03 +02001994# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
1995# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
1996# different calling convention for syscalls. They can also override the
1997# macros for not-implemented syscalls in kernel/sys_ni.c and
1998# kernel/time/posix-stubs.c. All these overrides need to be available in
1999# <asm/syscall_wrapper.h>.
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002000config ARCH_HAS_SYSCALL_WRAPPER
2001 def_bool n