blob: 532362fcfe31fd3c58b418ad54f9d42080b1a00e [file] [log] [blame]
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
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090063config CC_CAN_LINK
Masahiro Yamada9371f862020-04-29 12:45:13 +090064 bool
Elliot Bermanf67695c92022-02-01 13:35:42 -080065 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
66 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090067
Masahiro Yamadab1183b62020-05-09 16:39:15 +090068config CC_CAN_LINK_STATIC
69 bool
Elliot Bermanf67695c92022-02-01 13:35:42 -080070 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
71 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070072
Nick Desaulniers587f1702020-02-14 14:18:11 -080073config CC_HAS_ASM_GOTO_OUTPUT
Nick Desaulniers587f1702020-02-14 14:18:11 -080074 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)
75
Sean Christopherson1aa0e8b2022-02-02 00:49:41 +000076config CC_HAS_ASM_GOTO_TIED_OUTPUT
77 depends on CC_HAS_ASM_GOTO_OUTPUT
78 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
79 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .\n": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
80
Peter Collingbourne5cf896fb62019-07-31 18:18:42 -070081config TOOLS_SUPPORT_RELR
Will Deacon2d122942019-08-20 10:11:54 +010082 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 -070083
Rasmus Villemoeseb111862019-09-13 00:19:25 +020084config CC_HAS_ASM_INLINE
85 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
86
Nick Desaulniers51c2ee62021-06-21 16:18:22 -070087config CC_HAS_NO_PROFILE_FN_ATTR
88 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
89
Nathan Chancellor613fe162022-02-01 13:56:21 -070090config PAHOLE_VERSION
91 int
92 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
93
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -070094config CONSTRUCTORS
95 bool
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -070096
Peter Zijlstrae360adb2010-10-14 14:01:34 +080097config IRQ_WORK
98 bool
Peter Zijlstrae360adb2010-10-14 14:01:34 +080099
Shile Zhang10916702019-12-04 08:46:31 +0800100config BUILDTIME_TABLE_SORT
David Daney1dbdc6f2012-04-19 14:59:57 -0700101 bool
102
Andy Lutomirskic65eacb2016-09-13 14:29:24 -0700103config THREAD_INFO_IN_TASK
104 bool
105 help
106 Select this to move thread_info off the stack into task_struct. To
107 make this work, an arch will need to remove all thread_info fields
108 except flags and fix any runtime bugs.
109
Andy Lutomirskic6c314a2016-09-15 22:45:43 -0700110 One subtle change that will be needed is to use try_get_task_stack()
111 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
112
Al Boldiff0cfc62007-07-31 00:39:23 -0700113menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115config BROKEN
116 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117
118config BROKEN_ON_SMP
119 bool
120 depends on BROKEN || !SMP
121 default y
122
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123config INIT_ENV_ARG_LIMIT
124 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -0700125 default 32 if !UML
126 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 help
Randy Dunlap34ad92c22005-10-30 15:01:46 -0800128 Maximum of each of the number of arguments and environment
129 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
Jiri Slaby4bb16672013-05-22 10:56:24 +0200131config COMPILE_TEST
132 bool "Compile also drivers which will not load"
Masahiro Yamadaea29b202021-03-12 21:07:08 -0800133 depends on HAS_IOMEM
Jiri Slaby4bb16672013-05-22 10:56:24 +0200134 help
135 Some drivers can be compiled on a different platform than they are
136 intended to be run on. Despite they cannot be loaded there (or even
137 when they load they cannot be used due to missing HW support),
138 developers still, opposing to distributors, might want to build such
139 drivers to compile-test them.
140
141 If you are a developer and want to build everything available, say Y
142 here. If you are a user/distributor, say N here to exclude useless
143 drivers to be distributed.
144
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700145config WERROR
146 bool "Compile the kernel with warnings as errors"
Marco Elverb339ec92021-09-07 23:12:08 +0200147 default COMPILE_TEST
Linus Torvalds3fe617c2021-09-05 11:24:05 -0700148 help
149 A kernel build should not cause any compiler warnings, and this
150 enables the '-Werror' flag to enforce that rule by default.
151
152 However, if you have a new (or very old) compiler with odd and
153 unusual warnings, or you have some architecture with problems,
154 you may need to disable this config option in order to
155 successfully build the kernel.
156
157 If in doubt, say Y.
158
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900159config UAPI_HEADER_TEST
160 bool "Compile test UAPI headers"
Masahiro Yamadafcbb8462019-11-07 16:14:40 +0900161 depends on HEADERS_INSTALL && CC_CAN_LINK
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900162 help
163 Compile test headers exported to user-space to ensure they are
164 self-contained, i.e. compilable as standalone units.
165
166 If you are a developer or tester and want to ensure the exported
167 headers are self-contained, say Y here. Otherwise, choose N.
168
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169config LOCALVERSION
170 string "Local version - append to kernel release"
171 help
172 Append an extra string to the end of your kernel version.
173 This will show up when you type uname, for example.
174 The string you set here will be appended after the contents of
175 any files with a filename matching localversion* in your
176 object and source tree, in that order. Your total string can
177 be a maximum of 64 characters.
178
Ryan Andersonaaebf432005-07-31 04:57:49 -0400179config LOCALVERSION_AUTO
180 bool "Automatically append version information to the version string"
181 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -0700182 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -0400183 help
184 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200185 release tree by looking for git tags that belong to the current
186 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400187
188 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200189 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400190 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200191 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400192
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200193 (The actual string used here is the first eight characters produced
194 by running the command:
195
196 $ git rev-parse --verify HEAD
197
198 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400199
Laura Abbott9afb7192018-07-05 17:49:37 -0700200config BUILD_SALT
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800201 string "Build ID Salt"
202 default ""
203 help
204 The build ID is used to link binaries and their debug info. Setting
205 this option will use the value in the calculation of the build id.
206 This is mostly useful for distributions which want to ensure the
207 build is unique between builds. It's safe to leave the default.
Laura Abbott9afb7192018-07-05 17:49:37 -0700208
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800209config HAVE_KERNEL_GZIP
210 bool
211
212config HAVE_KERNEL_BZIP2
213 bool
214
215config HAVE_KERNEL_LZMA
216 bool
217
Lasse Collin3ebe1242011-01-12 17:01:23 -0800218config HAVE_KERNEL_XZ
219 bool
220
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800221config HAVE_KERNEL_LZO
222 bool
223
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700224config HAVE_KERNEL_LZ4
225 bool
226
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700227config HAVE_KERNEL_ZSTD
228 bool
229
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200230config HAVE_KERNEL_UNCOMPRESSED
231 bool
232
Alain Knaff30d65db2009-01-04 22:46:17 +0100233choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800234 prompt "Kernel compression mode"
235 default KERNEL_GZIP
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700236 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 -0800237 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100238 The linux kernel is a kind of self-extracting executable.
239 Several compression algorithms are available, which differ
240 in efficiency, compression and decompression speed.
241 Compression speed is only relevant when building a kernel.
242 Decompression speed is relevant at each boot.
243
244 If you have any problems with bzip2 or lzma compressed
245 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
246 version of this functionality (bzip2 only), for 2.4, was
247 supplied by Christian Ludwig)
248
249 High compression options are mostly useful for users, who
250 are low on disk space (embedded systems), but for whom ram
251 size matters less.
252
253 If in doubt, select 'gzip'
254
255config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800256 bool "Gzip"
257 depends on HAVE_KERNEL_GZIP
258 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800259 The old and tried gzip compression. It provides a good balance
260 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100261
262config KERNEL_BZIP2
263 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800264 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100265 help
266 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700267 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800268 size is about 10% smaller with bzip2, in comparison to gzip.
269 Bzip2 uses a large amount of memory. For modern kernels you
270 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100271
272config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800273 bool "LZMA"
274 depends on HAVE_KERNEL_LZMA
275 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700276 This compression algorithm's ratio is best. Decompression speed
277 is between gzip and bzip2. Compression is slowest.
278 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100279
Lasse Collin3ebe1242011-01-12 17:01:23 -0800280config KERNEL_XZ
281 bool "XZ"
282 depends on HAVE_KERNEL_XZ
283 help
284 XZ uses the LZMA2 algorithm and instruction set specific
285 BCJ filters which can improve compression ratio of executable
286 code. The size of the kernel is about 30% smaller with XZ in
287 comparison to gzip. On architectures for which there is a BCJ
288 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
289 will create a few percent smaller kernel than plain LZMA.
290
291 The speed is about the same as with LZMA: The decompression
292 speed of XZ is better than that of bzip2 but worse than gzip
293 and LZO. Compression is slow.
294
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800295config KERNEL_LZO
296 bool "LZO"
297 depends on HAVE_KERNEL_LZO
298 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700299 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200300 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800301 (both compression and decompression) is the fastest.
302
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700303config KERNEL_LZ4
304 bool "LZ4"
305 depends on HAVE_KERNEL_LZ4
306 help
307 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
308 A preliminary version of LZ4 de/compression tool is available at
309 <https://code.google.com/p/lz4/>.
310
311 Its compression ratio is worse than LZO. The size of the kernel
312 is about 8% bigger than LZO. But the decompression speed is
313 faster than LZO.
314
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700315config KERNEL_ZSTD
316 bool "ZSTD"
317 depends on HAVE_KERNEL_ZSTD
318 help
319 ZSTD is a compression algorithm targeting intermediate compression
320 with fast decompression speed. It will compress better than GZIP and
321 decompress around the same speed as LZO, but slower than LZ4. You
322 will need at least 192 KB RAM or more for booting. The zstd command
323 line tool is required for compression.
324
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200325config KERNEL_UNCOMPRESSED
326 bool "None"
327 depends on HAVE_KERNEL_UNCOMPRESSED
328 help
329 Produce uncompressed kernel image. This option is usually not what
330 you want. It is useful for debugging the kernel in slow simulation
331 environments, where decompressing and moving the kernel is awfully
332 slow. This option allows early boot code to skip the decompressor
333 and jump right at uncompressed kernel image.
334
Alain Knaff30d65db2009-01-04 22:46:17 +0100335endchoice
336
Chris Downada4ab72020-06-04 16:50:53 -0700337config DEFAULT_INIT
338 string "Default init path"
339 default ""
340 help
341 This option determines the default init for the system if no init=
342 option is passed on the kernel command line. If the requested path is
343 not present, we will still then move on to attempting further
344 locations (e.g. /sbin/init, etc). If this is empty, we will just use
345 the fallback list when init= is not passed.
346
Josh Triplettbd5dc172011-06-15 15:08:28 -0700347config DEFAULT_HOSTNAME
348 string "Default hostname"
349 default "(none)"
350 help
351 This option determines the default system hostname before userspace
352 calls sethostname(2). The kernel traditionally uses "(none)" here,
353 but you may wish to use a different default here to make a minimal
354 system more usable with less configuration.
355
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356config SYSVIPC
357 bool "System V IPC"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900358 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 Inter Process Communication is a suite of library functions and
360 system calls which let processes (running programs) synchronize and
361 exchange information. It is generally considered to be a good thing,
362 and some programs won't run unless you say Y here. In particular, if
363 you want to run the DOS emulator dosemu under Linux (read the
364 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
365 you'll need to say Y here.
366
367 You can find documentation about IPC with "info ipc" and also in
368 section 6.4 of the Linux Programmer's Guide, available from
369 <http://www.tldp.org/guides.html>.
370
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800371config SYSVIPC_SYSCTL
372 bool
373 depends on SYSVIPC
374 depends on SYSCTL
375 default y
376
Guo Ren0cbed0e2022-04-05 15:12:58 +0800377config SYSVIPC_COMPAT
378 def_bool y
379 depends on COMPAT && SYSVIPC
380
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381config POSIX_MQUEUE
382 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700383 depends on NET
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900384 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 POSIX variant of message queues is a part of IPC. In POSIX message
386 queues every message has a priority which decides about succession
387 of receiving it by a process. If you want to compile and run
388 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e376502007-05-09 07:25:13 +0200389 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390
391 POSIX message queues are visible as a filesystem called 'mqueue'
392 and can be mounted somewhere if you want to do filesystem
393 operations on message queues.
394
395 If unsure, say Y.
396
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700397config POSIX_MQUEUE_SYSCTL
398 bool
399 depends on POSIX_MQUEUE
400 depends on SYSCTL
401 default y
402
David Howellsc73be612020-01-14 17:07:11 +0000403config WATCH_QUEUE
404 bool "General notification queue"
405 default n
406 help
407
408 This is a general notification queue for the kernel to pass events to
409 userspace by splicing them into pipes. It can be used in conjunction
410 with watches for key/keyring change notifications and device
411 notifications.
412
Mauro Carvalho Chehabc02b8722022-06-26 10:10:56 +0100413 See Documentation/core-api/watch_queue.rst
David Howellsc73be612020-01-14 17:07:11 +0000414
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700415config CROSS_MEMORY_ATTACH
416 bool "Enable process_vm_readv/writev syscalls"
417 depends on MMU
418 default y
419 help
420 Enabling this option adds the system calls process_vm_readv and
421 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700422 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700423 See the man page for more details.
424
Josh Triplett69369a72014-04-03 14:48:27 -0700425config USELIB
Kees Cook7374fa32022-04-29 14:38:01 -0700426 bool "uselib syscall (for libc5 and earlier)"
427 default ALPHA || M68K || SPARC
Josh Triplett69369a72014-04-03 14:48:27 -0700428 help
429 This option enables the uselib syscall, a system call used in the
430 dynamic linker from libc5 and earlier. glibc does not use this
431 system call. If you intend to run programs built on libc5 or
432 earlier, you may need to enable this syscall. Current systems
433 running glibc can safely disable this.
434
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435config AUDIT
436 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100437 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 help
439 Enable auditing infrastructure that can be used with another
440 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500441 logging of avc messages output). System call auditing is included
442 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900444config HAVE_ARCH_AUDITSYSCALL
445 bool
446
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500448 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900449 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500450 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400451
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000452source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200453source "kernel/time/Kconfig"
Daniel Borkmannb24abcf2021-05-11 22:35:16 +0200454source "kernel/bpf/Kconfig"
Christoph Hellwig87a4c372018-07-31 13:39:32 +0200455source "kernel/Kconfig.preempt"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000456
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200457menu "CPU/Task time and stats accounting"
458
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200459config VIRT_CPU_ACCOUNTING
460 bool
461
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200462choice
463 prompt "Cputime accounting"
464 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100465 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200466
467# Kind of a stub config for the pure tick based cputime accounting
468config TICK_CPU_ACCOUNTING
469 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200470 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200471 help
472 This is the basic tick based cputime accounting that maintains
473 statistics about user, system and idle time spent on per jiffies
474 granularity.
475
476 If unsure, say Y.
477
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200478config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200479 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200480 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200481 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200482 help
483 Select this option to enable more accurate task and CPU time
484 accounting. This is done by reading a CPU counter on each
485 kernel entry and exit and on transitions within the kernel
486 between system, softirq and hardirq state, so there is a
487 small performance impact. In the case of s390 or IBM POWER > 5,
488 this also enables accounting of stolen time on logically-partitioned
489 systems.
490
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200491config VIRT_CPU_ACCOUNTING_GEN
492 bool "Full dynticks CPU time accounting"
Frederic Weisbecker24a9c5412022-06-08 16:40:24 +0200493 depends on HAVE_CONTEXT_TRACKING_USER
Kevin Hilman554b0002013-09-16 15:28:21 -0700494 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Arnd Bergmann041a1572019-03-04 21:01:31 +0100495 depends on GENERIC_CLOCKEVENTS
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200496 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker24a9c5412022-06-08 16:40:24 +0200497 select CONTEXT_TRACKING_USER
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200498 help
499 Select this option to enable task and CPU time accounting on full
500 dynticks systems. This accounting is implemented by watching every
501 kernel-user boundaries using the context tracking subsystem.
502 The accounting is thus performed at the expense of some significant
503 overhead.
504
505 For now this is only useful if you are working on the full
506 dynticks subsystem development.
507
508 If unsure, say N.
509
Rik van Rielb58c3582016-07-13 16:50:02 +0200510endchoice
511
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200512config IRQ_TIME_ACCOUNTING
513 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200514 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200515 help
516 Select this option to enable fine granularity task irq time
517 accounting. This is done by reading a timestamp on each
518 transitions between softirq and hardirq state, so there can be a
519 small performance impact.
520
521 If in doubt, say N here.
522
Vincent Guittot11d4afd2018-09-25 11:17:42 +0200523config HAVE_SCHED_AVG_IRQ
524 def_bool y
525 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
526 depends on SMP
527
Thara Gopinath76504792020-02-21 19:52:05 -0500528config SCHED_THERMAL_PRESSURE
Valentin Schneider98eb4012020-07-12 17:59:16 +0100529 bool
Valentin Schneiderfcd7c9c2020-07-29 14:57:18 +0100530 default y if ARM && ARM_CPU_TOPOLOGY
531 default y if ARM64
Thara Gopinath76504792020-02-21 19:52:05 -0500532 depends on SMP
Valentin Schneider98eb4012020-07-12 17:59:16 +0100533 depends on CPU_FREQ_THERMAL
534 help
535 Select this option to enable thermal pressure accounting in the
536 scheduler. Thermal pressure is the value conveyed to the scheduler
537 that reflects the reduction in CPU compute capacity resulted from
538 thermal throttling. Thermal throttling occurs when the performance of
539 a CPU is capped due to high operating temperatures.
540
541 If selected, the scheduler will be able to balance tasks accordingly,
542 i.e. put less load on throttled CPUs than on non/less throttled ones.
543
544 This requires the architecture to implement
Lukasz Luba7e97b3d2021-11-09 19:57:14 +0000545 arch_update_thermal_pressure() and arch_scale_thermal_pressure().
Thara Gopinath76504792020-02-21 19:52:05 -0500546
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200547config BSD_PROCESS_ACCT
548 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700549 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200550 help
551 If you say Y here, a user level program will be able to instruct the
552 kernel (via a special system call) to write process accounting
553 information to a file: whenever a process exits, information about
554 that process will be appended to the file by the kernel. The
555 information includes things such as creation time, owning user,
556 command name, memory usage, controlling terminal etc. (the complete
557 list is in the struct acct in <file:include/linux/acct.h>). It is
558 up to the user level program to do useful things with this
559 information. This is generally a good idea, so say Y.
560
561config BSD_PROCESS_ACCT_V3
562 bool "BSD Process Accounting version 3 file format"
563 depends on BSD_PROCESS_ACCT
564 default n
565 help
566 If you say Y here, the process accounting information is written
567 in a new file format that also logs the process IDs of each
Randy Dunlap3903bf92018-08-21 21:58:34 -0700568 process and its parent. Note that this file format is incompatible
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200569 with previous v0/v1/v2 file formats, so you will need updated tools
570 for processing it. A preliminary version of these tools is available
571 at <http://www.gnu.org/software/acct/>.
572
573config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700574 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200575 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700576 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200577 default n
578 help
579 Export selected statistics for tasks/processes through the
580 generic netlink interface. Unlike BSD process accounting, the
581 statistics are available during the lifetime of tasks/processes as
582 responses to commands. Like BSD accounting, they are sent to user
583 space on task exit.
584
585 Say N if unsure.
586
587config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700588 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200589 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530590 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200591 help
592 Collect information on time spent by a task waiting for system
593 resources like cpu, synchronous block I/O completion and swapping
594 in pages. Such statistics can help in setting a task's priorities
595 relative to other tasks for cpu, io, rss limits etc.
596
597 Say N if unsure.
598
599config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700600 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200601 depends on TASKSTATS
602 help
603 Collect extended task accounting data and send the data
604 to userland for processing over the taskstats interface.
605
606 Say N if unsure.
607
608config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700609 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200610 depends on TASK_XACCT
611 help
612 Collect information on the number of bytes of storage I/O which this
613 task has caused.
614
615 Say N if unsure.
616
Johannes Weinereb414682018-10-26 15:06:27 -0700617config PSI
618 bool "Pressure stall information tracking"
619 help
620 Collect metrics that indicate how overcommitted the CPU, memory,
621 and IO capacity are in the system.
622
623 If you say Y here, the kernel will create /proc/pressure/ with the
624 pressure statistics files cpu, memory, and io. These will indicate
625 the share of walltime in which some or all tasks in the system are
626 delayed due to contention of the respective resource.
627
Johannes Weiner2ce71352018-10-26 15:06:31 -0700628 In kernels with cgroup support, cgroups (cgroup2 only) will
629 have cpu.pressure, memory.pressure, and io.pressure files,
630 which aggregate pressure stalls for the grouped tasks only.
631
Mauro Carvalho Chehabc3123552019-04-17 05:46:08 -0300632 For more details see Documentation/accounting/psi.rst.
Johannes Weinereb414682018-10-26 15:06:27 -0700633
634 Say N if unsure.
635
Johannes Weinere0c27442018-11-30 14:09:58 -0800636config PSI_DEFAULT_DISABLED
637 bool "Require boot parameter to enable pressure stall information tracking"
638 default n
639 depends on PSI
640 help
641 If set, pressure stall information tracking will be disabled
Baruch Siach428a1cb2018-12-14 14:17:03 -0800642 per default but can be enabled through passing psi=1 on the
643 kernel commandline during boot.
Johannes Weinere0c27442018-11-30 14:09:58 -0800644
Johannes Weiner7b2489d2019-02-01 14:21:15 -0800645 This feature adds some code to the task wakeup and sleep
646 paths of the scheduler. The overhead is too low to affect
647 common scheduling-intense workloads in practice (such as
648 webservers, memcache), but it does show up in artificial
649 scheduler stress tests, such as hackbench.
650
651 If you are paranoid and not sure what the kernel will be
652 used for, say Y.
653
654 Say N if unsure.
655
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200656endmenu # "CPU/Task time and stats accounting"
657
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200658config CPU_ISOLATION
659 bool "CPU isolation"
Geert Uytterhoeven414a2dc2018-01-02 12:13:10 +0100660 depends on SMP || COMPILE_TEST
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100661 default y
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200662 help
663 Make sure that CPUs running critical tasks are not disturbed by
664 any source of "noise" such as unbound workqueues, timers, kthreads...
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100665 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
666 the "isolcpus=" boot parameter.
667
668 Say Y if unsure.
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200669
Paul E. McKenney0af92d42017-05-17 08:43:40 -0700670source "kernel/rcu/Kconfig"
Mike Travisc903ff82009-01-15 12:28:29 -0800671
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700672config BUILD_BIN2C
673 bool
674 default n
675
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700677 tristate "Kernel .config support"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900678 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 This option enables the complete Linux kernel ".config" file
680 contents to be saved in the kernel. It provides documentation
681 of which kernel options are used in a running kernel or in an
682 on-disk kernel. This information can be extracted from the kernel
683 image file with the script scripts/extract-ikconfig and used as
684 input to rebuild the current kernel or to build another kernel.
685 It can also be extracted from a running kernel by reading
686 /proc/config.gz if enabled (below).
687
688config IKCONFIG_PROC
689 bool "Enable access to .config through /proc/config.gz"
690 depends on IKCONFIG && PROC_FS
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900691 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 This option enables access to the kernel configuration file
693 through /proc/config.gz.
694
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400695config IKHEADERS
696 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
697 depends on SYSFS
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400698 help
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400699 This option enables access to the in-kernel headers that are generated during
700 the build process. These can be used to build eBPF tracing programs,
701 or similar programs. If you build the headers as a module, a module called
702 kheaders.ko is built which can be loaded on-demand to get access to headers.
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400703
Alistair John Strachan794543a2007-05-08 00:31:15 -0700704config LOG_BUF_SHIFT
705 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Christoph Hellwig1c4b5ec2022-02-23 08:47:20 +0100706 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700707 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700708 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700709 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700710 Select the minimal kernel log buffer size as a power of 2.
711 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
712 parameter, see below. Any higher size also might be forced
713 by "log_buf_len" boot parameter.
714
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700715 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700716 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700717 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700718 15 => 32 KB
719 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700720 13 => 8 KB
721 12 => 4 KB
722
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700723config LOG_CPU_MAX_BUF_SHIFT
724 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700725 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700726 range 0 21
727 default 12 if !BASE_SMALL
728 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700729 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700730 help
731 This option allows to increase the default ring buffer size
732 according to the number of CPUs. The value defines the contribution
733 of each CPU as a power of 2. The used space is typically only few
734 lines however it might be much more when problems are reported,
735 e.g. backtraces.
736
737 The increased size means that a new buffer has to be allocated and
738 the original static one is unused. It makes sense only on systems
739 with more CPUs. Therefore this value is used only when the sum of
740 contributions is greater than the half of the default kernel ring
741 buffer as defined by LOG_BUF_SHIFT. The default values are set
Paul Menzel0f7636e12020-08-11 11:29:23 +0200742 so that more than 16 CPUs are needed to trigger the allocation.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700743
744 Also this option is ignored when "log_buf_len" kernel parameter is
745 used as it forces an exact (power of two) size of the ring buffer.
746
747 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200748 hotplugging making the computation optimal for the worst case
749 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700750
751 Examples shift values and their meaning:
752 17 => 128 KB for each CPU
753 16 => 64 KB for each CPU
754 15 => 32 KB for each CPU
755 14 => 16 KB for each CPU
756 13 => 8 KB for each CPU
757 12 => 4 KB for each CPU
758
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900759config PRINTK_SAFE_LOG_BUF_SHIFT
760 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
Petr Mladek427934b2016-05-20 17:00:39 -0700761 range 10 21
762 default 13
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900763 depends on PRINTK
Petr Mladek427934b2016-05-20 17:00:39 -0700764 help
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900765 Select the size of an alternate printk per-CPU buffer where messages
766 printed from usafe contexts are temporary stored. One example would
767 be NMI messages, another one - printk recursion. The messages are
768 copied to the main log buffer in a safe context to avoid a deadlock.
769 The value defines the size as a power of 2.
Petr Mladek427934b2016-05-20 17:00:39 -0700770
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900771 Those messages are rare and limited. The largest one is when
Petr Mladek427934b2016-05-20 17:00:39 -0700772 a backtrace is printed. It usually fits into 4KB. Select
773 8KB if you want to be on the safe side.
774
775 Examples:
776 17 => 128 KB for each CPU
777 16 => 64 KB for each CPU
778 15 => 32 KB for each CPU
779 14 => 16 KB for each CPU
780 13 => 8 KB for each CPU
781 12 => 4 KB for each CPU
782
Chris Down33701552021-06-15 17:52:53 +0100783config PRINTK_INDEX
784 bool "Printk indexing debugfs interface"
785 depends on PRINTK && DEBUG_FS
786 help
787 Add support for indexing of all printk formats known at compile time
788 at <debugfs>/printk/index/<module>.
789
790 This can be used as part of maintaining daemons which monitor
791 /dev/kmsg, as it permits auditing the printk formats present in a
792 kernel, allowing detection of cases where monitored printks are
793 changed or no longer present.
794
795 There is no additional runtime cost to printk with this enabled.
796
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800797#
798# Architectures with an unreliable sched_clock() should select this:
799#
800config HAVE_UNSTABLE_SCHED_CLOCK
801 bool
802
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700803config GENERIC_SCHED_CLOCK
804 bool
805
Patrick Bellasi69842cb2019-06-21 09:42:02 +0100806menu "Scheduler features"
807
808config UCLAMP_TASK
809 bool "Enable utilization clamping for RT/FAIR tasks"
810 depends on CPU_FREQ_GOV_SCHEDUTIL
811 help
812 This feature enables the scheduler to track the clamped utilization
813 of each CPU based on RUNNABLE tasks scheduled on that CPU.
814
815 With this option, the user can specify the min and max CPU
816 utilization allowed for RUNNABLE tasks. The max utilization defines
817 the maximum frequency a task should use while the min utilization
818 defines the minimum frequency it should use.
819
820 Both min and max utilization clamp values are hints to the scheduler,
821 aiming at improving its frequency selection policy, but they do not
822 enforce or grant any specific bandwidth for tasks.
823
824 If in doubt, say N.
825
826config UCLAMP_BUCKETS_COUNT
827 int "Number of supported utilization clamp buckets"
828 range 5 20
829 default 5
830 depends on UCLAMP_TASK
831 help
832 Defines the number of clamp buckets to use. The range of each bucket
833 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
834 number of clamp buckets the finer their granularity and the higher
835 the precision of clamping aggregation and tracking at run-time.
836
837 For example, with the minimum configuration value we will have 5
838 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
839 be refcounted in the [20..39]% bucket and will set the bucket clamp
840 effective value to 25%.
841 If a second 30% boosted task should be co-scheduled on the same CPU,
842 that task will be refcounted in the same bucket of the first task and
843 it will boost the bucket clamp effective value to 30%.
844 The clamp effective value of a bucket is reset to its nominal value
845 (20% in the example above) when there are no more tasks refcounted in
846 that bucket.
847
848 An additional boost/capping margin can be added to some tasks. In the
849 example above the 25% task will be boosted to 30% until it exits the
850 CPU. If that should be considered not acceptable on certain systems,
851 it's always possible to reduce the margin by increasing the number of
852 clamp buckets to trade off used memory for run-time tracking
853 precision.
854
855 If in doubt, use the default value.
856
857endmenu
858
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200859#
860# For architectures that want to enable the support for NUMA-affine scheduler
861# balancing logic:
862#
863config ARCH_SUPPORTS_NUMA_BALANCING
864 bool
865
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100866#
Mel Gorman72b252a2015-09-04 15:47:32 -0700867# For architectures that prefer to flush all TLBs after a number of pages
868# are unmapped instead of sending one IPI per page to flush. The architecture
869# must provide guarantees on what happens if a clean TLB cache entry is
870# written after the unmap. Details are in mm/rmap.c near the check for
871# should_defer_flush. The architecture should also consider if the full flush
872# and the refill costs are offset by the savings of sending fewer IPIs.
873config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
874 bool
875
Ard Biesheuvelc12d3362019-11-08 13:22:27 +0100876config CC_HAS_INT128
Masahiro Yamada3a7c7332020-03-10 19:12:50 +0900877 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
Ard Biesheuvelc12d3362019-11-08 13:22:27 +0100878
Gustavo A. R. Silvadee2b7022021-11-13 18:57:25 -0600879config CC_IMPLICIT_FALLTHROUGH
880 string
Gustavo A. R. Silva158ea2d2021-11-14 20:48:44 -0600881 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
Gustavo A. R. Silvadee2b7022021-11-13 18:57:25 -0600882 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
883
Linus Torvaldsf0be87c2022-06-09 10:11:12 -0700884# Currently, disable gcc-12 array-bounds globally.
885# We may want to target only particular configurations some day.
886config GCC12_NO_ARRAY_BOUNDS
887 def_bool y
888
889config CC_NO_ARRAY_BOUNDS
890 bool
891 default y if CC_IS_GCC && GCC_VERSION >= 120000 && GCC_VERSION < 130000 && GCC12_NO_ARRAY_BOUNDS
892
Mel Gorman72b252a2015-09-04 15:47:32 -0700893#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100894# For architectures that know their GCC __int128 support is sound
895#
896config ARCH_SUPPORTS_INT128
897 bool
898
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200899# For architectures that (ab)use NUMA to represent different memory regions
900# all cpu-local but of different latencies, such as SuperH.
901#
902config ARCH_WANT_NUMA_VARIABLE_LOCALITY
903 bool
904
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200905config NUMA_BALANCING
906 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200907 depends on ARCH_SUPPORTS_NUMA_BALANCING
908 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
Sebastian Andrzej Siewior554b0f32021-11-05 13:35:27 -0700909 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200910 help
911 This option adds support for automatic NUMA aware memory/task placement.
912 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400913 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200914
915 This system will be inactive on UMA systems.
916
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800917config NUMA_BALANCING_DEFAULT_ENABLED
918 bool "Automatically enable NUMA aware memory/task placement"
919 default y
920 depends on NUMA_BALANCING
921 help
922 If set, automatic NUMA balancing will be enabled if running on a NUMA
923 machine.
924
Li Zefan23964d22009-01-15 13:50:58 -0800925menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500926 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500927 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700928 help
Li Zefan23964d22009-01-15 13:50:58 -0800929 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800930 use with process control subsystems such as Cpusets, CFS, memory
931 controls or device isolation.
932 See
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300933 - Documentation/scheduler/sched-design-CFS.rst (CFS)
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300934 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800935 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700936
937 Say N if unsure.
938
Li Zefan23964d22009-01-15 13:50:58 -0800939if CGROUPS
940
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800941config PAGE_COUNTER
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800942 bool
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800943
Tejun Heo6a010a42022-07-23 04:28:28 -1000944config CGROUP_FAVOR_DYNMODS
945 bool "Favor dynamic modification latency reduction by default"
946 help
947 This option enables the "favordynmods" mount option by default
948 which reduces the latencies of dynamic cgroup modifications such
949 as task migrations and controller on/offs at the cost of making
950 hot path operations such as forks and exits more expensive.
951
952 Say N if unsure.
953
Andrew Mortonc255a452012-07-31 16:43:02 -0700954config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500955 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800956 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500957 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -0800958 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500959 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800960
Andrew Mortonc255a452012-07-31 16:43:02 -0700961config MEMCG_SWAP
Johannes Weiner2d1c4982020-06-03 16:02:14 -0700962 bool
Andrew Mortonc255a452012-07-31 16:43:02 -0700963 depends on MEMCG && SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -0800964 default y
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800965
Kirill Tkhai84c07d12018-08-17 15:47:25 -0700966config MEMCG_KMEM
967 bool
968 depends on MEMCG && !SLOB
969 default y
970
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500971config BLK_CGROUP
972 bool "IO controller"
973 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700974 default n
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900975 help
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500976 Generic block IO controller cgroup interface. This is the common
977 cgroup interface which should be used by various IO controlling
978 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700979
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500980 Currently, CFQ IO scheduler uses it to recognize task groups and
981 control disk bandwidth allocation (proportional time slice allocation)
982 to such task groups. It is also used by bio throttling logic in
983 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +0200984
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500985 This option only enables generic Block IO controller infrastructure.
986 One needs to also enable actual IO controlling logic/policy. For
987 enabling proportional weight division of disk bandwidth in CFQ, set
Krzysztof Kozlowski7baf2192020-04-06 20:12:02 -0700988 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500989 CONFIG_BLK_DEV_THROTTLING=y.
990
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300991 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500992
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500993config CGROUP_WRITEBACK
994 bool
995 depends on MEMCG && BLK_CGROUP
996 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +0200997
Dhaval Giani7c941432010-01-20 13:26:18 +0100998menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500999 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +01001000 default n
1001 help
1002 This feature lets CPU scheduler recognize task groups and control CPU
1003 bandwidth allocation to such task groups. It uses cgroups to group
1004 tasks.
1005
1006if CGROUP_SCHED
1007config FAIR_GROUP_SCHED
1008 bool "Group scheduling for SCHED_OTHER"
1009 depends on CGROUP_SCHED
1010 default CGROUP_SCHED
1011
Paul Turnerab84d312011-07-21 09:43:28 -07001012config CFS_BANDWIDTH
1013 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -07001014 depends on FAIR_GROUP_SCHED
1015 default n
1016 help
1017 This option allows users to define CPU bandwidth rates (limits) for
1018 tasks running within the fair group scheduler. Groups with no limit
1019 set are considered to be unconstrained and will run with no
1020 restriction.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -03001021 See Documentation/scheduler/sched-bwc.rst for more information.
Paul Turnerab84d312011-07-21 09:43:28 -07001022
Dhaval Giani7c941432010-01-20 13:26:18 +01001023config RT_GROUP_SCHED
1024 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +01001025 depends on CGROUP_SCHED
1026 default n
1027 help
1028 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +08001029 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +01001030 schedule realtime tasks for non-root users until you allocate
1031 realtime bandwidth for them.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -03001032 See Documentation/scheduler/sched-rt-group.rst for more information.
Dhaval Giani7c941432010-01-20 13:26:18 +01001033
1034endif #CGROUP_SCHED
1035
Patrick Bellasi2480c092019-08-22 14:28:06 +01001036config UCLAMP_TASK_GROUP
1037 bool "Utilization clamping per group of tasks"
1038 depends on CGROUP_SCHED
1039 depends on UCLAMP_TASK
1040 default n
1041 help
1042 This feature enables the scheduler to track the clamped utilization
1043 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1044
1045 When this option is enabled, the user can specify a min and max
1046 CPU bandwidth which is allowed for each single task in a group.
1047 The max bandwidth allows to clamp the maximum frequency a task
1048 can use, while the min bandwidth allows to define a minimum
1049 frequency a task will always use.
1050
1051 When task group based utilization clamping is enabled, an eventually
1052 specified task-specific clamp value is constrained by the cgroup
1053 specified clamp value. Both minimum and maximum task clamping cannot
1054 be bigger than the corresponding clamping defined at task group level.
1055
1056 If in doubt, say N.
1057
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001058config CGROUP_PIDS
1059 bool "PIDs controller"
1060 help
1061 Provides enforcement of process number limits in the scope of a
1062 cgroup. Any attempt to fork more processes than is allowed in the
1063 cgroup will fail. PIDs are fundamentally a global resource because it
1064 is fairly trivial to reach PID exhaustion before you reach even a
1065 conservative kmemcg limit. As a result, it is possible to grind a
1066 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +05301067 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001068
1069 It should be noted that organisational operations (such as attaching
Jonathan Neuschäfer98076832019-02-01 14:21:01 -08001070 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001071 since the PIDs limit only affects a process's ability to fork, not to
1072 attach to a cgroup.
1073
Parav Pandit39d3e752017-01-10 00:02:13 +00001074config CGROUP_RDMA
1075 bool "RDMA controller"
1076 help
1077 Provides enforcement of RDMA resources defined by IB stack.
1078 It is fairly easy for consumers to exhaust RDMA resources, which
1079 can result into resource unavailability to other consumers.
1080 RDMA controller is designed to stop this from happening.
1081 Attaching processes with active RDMA resources to the cgroup
1082 hierarchy is allowed even if can cross the hierarchy's limit.
1083
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001084config CGROUP_FREEZER
1085 bool "Freezer controller"
1086 help
1087 Provides a way to freeze and unfreeze all tasks in a
1088 cgroup.
1089
Johannes Weiner489c2a22016-01-20 15:02:41 -08001090 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1091 controller includes important in-kernel memory consumers per default.
1092
1093 If you're using cgroup2, say N.
1094
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001095config CGROUP_HUGETLB
1096 bool "HugeTLB controller"
1097 depends on HUGETLB_PAGE
1098 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +02001099 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001100 help
1101 Provides a cgroup controller for HugeTLB pages.
1102 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1103 The limit is enforced during page fault. Since HugeTLB doesn't
1104 support page reclaim, enforcing the limit at page fault time implies
1105 that, the application will get SIGBUS signal if it tries to access
1106 HugeTLB pages beyond its limit. This requires the application to know
1107 beforehand how much HugeTLB pages it would require for its use. The
1108 control group is tracked in the third page lru pointer. This means
1109 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001110
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001111config CPUSETS
1112 bool "Cpuset controller"
Nicolas Pitree1d4eee2017-06-14 13:19:23 -04001113 depends on SMP
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001114 help
1115 This option will let you create and manage CPUSETs which
1116 allow dynamically partitioning a system into sets of CPUs and
1117 Memory Nodes and assigning tasks to run only within those sets.
1118 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001119
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001120 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001121
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001122config PROC_PID_CPUSET
1123 bool "Include legacy /proc/<pid>/cpuset file"
1124 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001125 default y
1126
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001127config CGROUP_DEVICE
1128 bool "Device controller"
1129 help
1130 Provides a cgroup controller implementing whitelists for
1131 devices which a process in the cgroup can mknod or open.
1132
1133config CGROUP_CPUACCT
1134 bool "Simple CPU accounting controller"
1135 help
1136 Provides a simple controller for monitoring the
1137 total CPU consumed by the tasks in a cgroup.
1138
1139config CGROUP_PERF
1140 bool "Perf controller"
1141 depends on PERF_EVENTS
1142 help
1143 This option extends the perf per-cpu mode to restrict monitoring
1144 to threads which belong to the cgroup specified and run on the
Namhyung Kim6546b192020-03-25 21:45:29 +09001145 designated cpu. Or this can be used to have cgroup ID in samples
1146 so that it can monitor performance events among cgroups.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001147
1148 Say N if unsure.
1149
Daniel Mack30070982016-11-23 16:52:26 +01001150config CGROUP_BPF
1151 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirski483c4932016-12-16 08:33:45 -08001152 depends on BPF_SYSCALL
1153 select SOCK_CGROUP_DATA
Daniel Mack30070982016-11-23 16:52:26 +01001154 help
1155 Allow attaching eBPF programs to a cgroup using the bpf(2)
1156 syscall command BPF_PROG_ATTACH.
1157
1158 In which context these programs are accessed depends on the type
1159 of attachment. For instance, programs that are attached using
1160 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1161 inet sockets.
1162
Vipin Sharmaa72232e2021-03-29 21:42:04 -07001163config CGROUP_MISC
1164 bool "Misc resource controller"
1165 default n
1166 help
1167 Provides a controller for miscellaneous resources on a host.
1168
1169 Miscellaneous scalar resources are the resources on the host system
1170 which cannot be abstracted like the other cgroups. This controller
1171 tracks and limits the miscellaneous resources used by a process
1172 attached to a cgroup hierarchy.
1173
1174 For more information, please check misc cgroup section in
1175 /Documentation/admin-guide/cgroup-v2.rst.
1176
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001177config CGROUP_DEBUG
Waiman Long23b0be42017-06-13 17:18:03 -04001178 bool "Debug controller"
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001179 default n
Waiman Long23b0be42017-06-13 17:18:03 -04001180 depends on DEBUG_KERNEL
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001181 help
1182 This option enables a simple controller that exports
Waiman Long23b0be42017-06-13 17:18:03 -04001183 debugging information about the cgroups framework. This
1184 controller is for control cgroup debugging only. Its
1185 interfaces are not stable.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001186
1187 Say N.
1188
Arnd Bergmann73b35142017-01-10 13:08:06 +01001189config SOCK_CGROUP_DATA
1190 bool
1191 default n
1192
Li Zefan23964d22009-01-15 13:50:58 -08001193endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001194
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001195menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001196 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001197 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001198 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001199 help
1200 Provides the way to make tasks work with different objects using
1201 the same id. For example same IPC id may refer to different objects
1202 or same user id or pid may refer to different tasks when used in
1203 different namespaces.
1204
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001205if NAMESPACES
1206
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001207config UTS_NS
1208 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001209 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001210 help
1211 In this namespace tasks see different info provided with the
1212 uname() system call
1213
Andrei Vagin769071a2019-11-12 01:26:52 +00001214config TIME_NS
1215 bool "TIME namespace"
Thomas Gleixner660fd042019-11-12 01:27:09 +00001216 depends on GENERIC_VDSO_TIME_NS
Andrei Vagin769071a2019-11-12 01:26:52 +00001217 default y
1218 help
1219 In this namespace boottime and monotonic clocks can be set.
1220 The time will keep going with the same pace.
1221
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001222config IPC_NS
1223 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001224 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001225 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001226 help
1227 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001228 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001229
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001230config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001231 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001232 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001233 help
1234 This allows containers, i.e. vservers, to use user namespaces
1235 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001236
1237 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001238 recommended that the MEMCG option also be enabled and that
1239 user-space use the memory control groups to limit the amount
1240 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001241
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001242 If unsure, say N.
1243
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001244config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001245 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001246 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001247 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001248 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001249 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001250 pid namespaces. This is a building block of containers.
1251
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001252config NET_NS
1253 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001254 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001255 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001256 help
1257 Allow user space to create what appear to be multiple instances
1258 of the network stack.
1259
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001260endif # NAMESPACES
1261
Adrian Reber5cb366b2018-08-21 22:01:17 -07001262config CHECKPOINT_RESTORE
1263 bool "Checkpoint/restore support"
1264 select PROC_CHILDREN
Chris Wilsonbfe39112021-02-05 22:00:12 +00001265 select KCMP
Adrian Reber5cb366b2018-08-21 22:01:17 -07001266 default n
1267 help
1268 Enables additional kernel features in a sake of checkpoint/restore.
1269 In particular it adds auxiliary prctl codes to setup process text,
1270 data and heap segment sizes, and a few additional /proc filesystem
1271 entries.
1272
1273 If unsure, say N here.
1274
Mike Galbraith5091faa2010-11-30 14:18:03 +01001275config SCHED_AUTOGROUP
1276 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001277 select CGROUPS
1278 select CGROUP_SCHED
1279 select FAIR_GROUP_SCHED
1280 help
1281 This option optimizes the scheduler for common desktop workloads by
1282 automatically creating and populating task groups. This separation
1283 of workloads isolates aggressive CPU burners (like build jobs) from
1284 desktop applications. Task group autogeneration is currently based
1285 upon task session.
1286
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001287config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001288 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001289 depends on SYSFS
1290 default n
1291 help
1292 This option adds code that switches the layout of the "block" class
1293 devices, to not show up in /sys/class/block/, but only in
1294 /sys/block/.
1295
1296 This switch is only active when the sysfs.deprecated=1 boot option is
1297 passed or the SYSFS_DEPRECATED_V2 option is set.
1298
1299 This option allows new kernels to run on old distributions and tools,
1300 which might get confused by /sys/class/block/. Since 2007/2008 all
1301 major distributions and tools handle this just fine.
1302
1303 Recent distributions and userspace tools after 2009/2010 depend on
1304 the existence of /sys/class/block/, and will not work with this
1305 option enabled.
1306
1307 Only if you are using a new kernel on an old distribution, you might
1308 need to say Y here.
1309
1310config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001311 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001312 default n
1313 depends on SYSFS
1314 depends on SYSFS_DEPRECATED
1315 help
1316 Enable deprecated sysfs by default.
1317
1318 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1319 option.
1320
1321 Only if you are using a new kernel on an old distribution, you might
1322 need to say Y here. Even then, odds are you would not need it
1323 enabled, you can always pass the boot option if absolutely necessary.
1324
1325config RELAY
1326 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001327 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001328 help
1329 This option enables support for relay interface support in
1330 certain file systems (such as debugfs).
1331 It is designed to provide an efficient mechanism for tools and
1332 facilities to relay large amounts of data from kernel space to
1333 user space.
1334
1335 If unsure, say N.
1336
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001337config BLK_DEV_INITRD
1338 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001339 help
1340 The initial RAM filesystem is a ramfs which is loaded by the
1341 boot loader (loadlin or lilo) and that is mounted as root
1342 before the normal boot procedure. It is typically used to
1343 load modules needed to mount the "real" root file system,
Mauro Carvalho Chehab8c27ceff32016-10-18 10:12:27 -02001344 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001345
1346 If RAM disk support (BLK_DEV_RAM) is also included, this
1347 also enables initial RAM disk (initrd) support and adds
1348 15 Kbytes (more on some other architectures) to the kernel size.
1349
1350 If unsure say Y.
1351
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001352if BLK_DEV_INITRD
1353
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001354source "usr/Kconfig"
1355
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001356endif
1357
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001358config BOOT_CONFIG
1359 bool "Boot config support"
Masami Hiramatsua2a9d672022-04-06 11:31:19 +09001360 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001361 help
1362 Extra boot config allows system admin to pass a config file as
1363 complemental extension of kernel cmdline when booting.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001364 The boot config file must be attached at the end of initramfs
Masami Hiramatsu85c46b72020-02-20 21:18:42 +09001365 with checksum, size and magic word.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001366 See <file:Documentation/admin-guide/bootconfig.rst> for details.
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001367
1368 If unsure, say Y.
1369
Masami Hiramatsua2a9d672022-04-06 11:31:19 +09001370config BOOT_CONFIG_EMBED
1371 bool "Embed bootconfig file in the kernel"
1372 depends on BOOT_CONFIG
1373 help
1374 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1375 kernel. Usually, the bootconfig file is loaded with the initrd
1376 image. But if the system doesn't support initrd, this option will
1377 help you by embedding a bootconfig file while building the kernel.
1378
1379 If unsure, say N.
1380
1381config BOOT_CONFIG_EMBED_FILE
1382 string "Embedded bootconfig file path"
1383 depends on BOOT_CONFIG_EMBED
1384 help
1385 Specify a bootconfig file which will be embedded to the kernel.
1386 This bootconfig will be used if there is no initrd or no other
1387 bootconfig in the initrd.
1388
David Disseldorp1274aea12022-05-09 18:29:19 -07001389config INITRAMFS_PRESERVE_MTIME
1390 bool "Preserve cpio archive mtimes in initramfs"
1391 default y
1392 help
1393 Each entry in an initramfs cpio archive carries an mtime value. When
1394 enabled, extracted cpio items take this mtime, with directory mtime
1395 setting deferred until after creation of any child entries.
1396
1397 If unsure, say Y.
1398
Arnd Bergmann877417e2016-04-25 17:35:27 +02001399choice
1400 prompt "Compiler optimization level"
Ulf Magnusson2cc3ce22017-10-04 01:53:26 +02001401 default CC_OPTIMIZE_FOR_PERFORMANCE
Arnd Bergmann877417e2016-04-25 17:35:27 +02001402
1403config CC_OPTIMIZE_FOR_PERFORMANCE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001404 bool "Optimize for performance (-O2)"
Arnd Bergmann877417e2016-04-25 17:35:27 +02001405 help
1406 This is the default optimization level for the kernel, building
1407 with the "-O2" compiler flag for best performance and most
1408 helpful compile-time warnings.
1409
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001410config CC_OPTIMIZE_FOR_SIZE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001411 bool "Optimize for size (-Os)"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001412 help
Masahiro Yamadace3b4872019-08-21 02:09:39 +09001413 Choosing this option will pass "-Os" to your compiler resulting
1414 in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001415
Arnd Bergmann877417e2016-04-25 17:35:27 +02001416endchoice
1417
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001418config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1419 bool
1420 help
1421 This requires that the arch annotates or otherwise protects
1422 its external entry points from being discarded. Linker scripts
1423 must also merge .text.*, .data.*, and .bss.* correctly into
1424 output sections. Care must be taken not to pull in unrelated
1425 sections (e.g., '.text.init'). Typically '.' in section names
1426 is used to distinguish them from label names / C identifiers.
1427
1428config LD_DEAD_CODE_DATA_ELIMINATION
1429 bool "Dead code and data elimination (EXPERIMENTAL)"
1430 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1431 depends on EXPERT
Masahiro Yamadae85d1d62018-08-22 22:51:09 +09001432 depends on $(cc-option,-ffunction-sections -fdata-sections)
1433 depends on $(ld-option,--gc-sections)
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001434 help
Masahiro Yamada8b9d2712018-06-24 01:41:51 +09001435 Enable this if you want to do dead code and data elimination with
1436 the linker by compiling with -ffunction-sections -fdata-sections,
1437 and linking with --gc-sections.
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001438
1439 This can reduce on disk and in-memory size of the kernel
1440 code and static data, particularly for small configs and
1441 on small systems. This has the possibility of introducing
1442 silently broken kernel if the required annotations are not
1443 present. This option is not well tested yet, so use at your
1444 own risk.
1445
Nathan Chancellor59612b22020-11-19 13:46:56 -07001446config LD_ORPHAN_WARN
1447 def_bool y
1448 depends on ARCH_WANT_LD_ORPHAN_WARN
1449 depends on $(ld-option,--orphan-handling=warn)
1450
Randy Dunlap08470622006-09-30 23:28:13 -07001451config SYSCTL
1452 bool
1453
Mike Frysinger657a5202013-04-30 15:28:45 -07001454config HAVE_UID16
1455 bool
1456
1457config SYSCTL_EXCEPTION_TRACE
1458 bool
1459 help
1460 Enable support for /proc/sys/debug/exception-trace.
1461
1462config SYSCTL_ARCH_UNALIGN_NO_WARN
1463 bool
1464 help
1465 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1466 Allows arch to define/use @no_unaligned_warning to possibly warn
1467 about unaligned access emulation going on under the hood.
1468
1469config SYSCTL_ARCH_UNALIGN_ALLOW
1470 bool
1471 help
1472 Enable support for /proc/sys/kernel/unaligned-trap
1473 Allows arches to define/use @unaligned_enabled to runtime toggle
1474 the unaligned access emulation.
1475 see arch/parisc/kernel/unaligned.c for reference
1476
Mike Frysinger657a5202013-04-30 15:28:45 -07001477config HAVE_PCSPKR_PLATFORM
1478 bool
1479
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001480# interpreter that classic socket filters depend on
1481config BPF
1482 bool
Eric Biggersec8f7f42022-07-09 14:18:49 -07001483 select CRYPTO_LIB_SHA1
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001484
David Rientjes6a108a12011-01-20 14:44:16 -08001485menuconfig EXPERT
1486 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001487 # Unhide debug options, to make the on-by-default options visible
1488 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489 help
1490 This option allows certain base kernel options and settings
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001491 to be disabled or tweaked. This is for specialized
1492 environments which can tolerate a "non-standard" kernel.
1493 Only use this if you really know what you are doing.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001495config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001496 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001497 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001498 default y
1499 help
1500 This enables the legacy 16-bit UID syscall wrappers.
1501
Iulia Manda28138932015-04-15 16:16:41 -07001502config MULTIUSER
1503 bool "Multiple users, groups and capabilities support" if EXPERT
1504 default y
1505 help
1506 This option enables support for non-root users, groups and
1507 capabilities.
1508
1509 If you say N here, all processes will run with UID 0, GID 0, and all
1510 possible capabilities. Saying N here also compiles out support for
1511 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1512 setgid, and capset.
1513
1514 If unsure, say Y here.
1515
Fabian Frederickf6187762014-06-04 16:11:12 -07001516config SGETMASK_SYSCALL
1517 bool "sgetmask/ssetmask syscalls support" if EXPERT
Arnd Bergmanna687a532018-03-07 23:30:54 +01001518 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09001519 help
Fabian Frederickf6187762014-06-04 16:11:12 -07001520 sys_sgetmask and sys_ssetmask are obsolete system calls
1521 no longer supported in libc but still enabled by default in some
1522 architectures.
1523
1524 If unsure, leave the default option here.
1525
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001526config SYSFS_SYSCALL
1527 bool "Sysfs syscall support" if EXPERT
1528 default y
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09001529 help
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001530 sys_sysfs is an obsolete system call no longer supported in libc.
1531 Note that disabling this option is more secure but might break
1532 compatibility with some systems.
1533
1534 If unsure say Y here.
1535
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001536config FHANDLE
1537 bool "open by fhandle syscalls" if EXPERT
1538 select EXPORTFS
1539 default y
1540 help
1541 If you say Y here, a user level program will be able to map
1542 file names to handle and then later use the handle for
1543 different file system operations. This is useful in implementing
1544 userspace file servers, which now track files using handles instead
1545 of names. The handle would remain the same even if file names
1546 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1547 syscalls.
1548
Nicolas Pitrebaa73d92016-11-11 00:10:10 -05001549config POSIX_TIMERS
1550 bool "Posix Clocks & timers" if EXPERT
1551 default y
1552 help
1553 This includes native support for POSIX timers to the kernel.
1554 Some embedded systems have no use for them and therefore they
1555 can be configured out to reduce the size of the kernel image.
1556
1557 When this option is disabled, the following syscalls won't be
1558 available: timer_create, timer_gettime: timer_getoverrun,
1559 timer_settime, timer_delete, clock_adjtime, getitimer,
1560 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1561 clock_getres and clock_nanosleep syscalls will be limited to
1562 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1563
1564 If unsure say y.
1565
Matt Mackalld59745c2005-05-01 08:59:02 -07001566config PRINTK
1567 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001568 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001569 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001570 help
1571 This option enables normal printk support. Removing it
1572 eliminates most of the message strings from the kernel image
1573 and makes the kernel more or less silent. As this makes it
1574 very difficult to diagnose system problems, saying N here is
1575 strongly discouraged.
1576
Matt Mackallc8538a72005-05-01 08:59:01 -07001577config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001578 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001579 default y
1580 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001581 Disabling this option eliminates support for BUG and WARN, reducing
1582 the size of your kernel image and potentially quietly ignoring
1583 numerous fatal conditions. You should only consider disabling this
1584 option for embedded systems with no facilities for reporting errors.
1585 Just say Y.
Matt Mackallc8538a72005-05-01 08:59:01 -07001586
Matt Mackall708e9a72006-01-08 01:05:25 -08001587config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001588 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001589 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001590 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001591 help
1592 Enable support for generating core dumps. Disabling saves about 4k.
1593
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001594
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001595config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001596 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001597 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001598 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001599 default y
1600 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001601 This option allows to disable the internal PC-Speaker
1602 support, saving some memory.
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001603
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604config BASE_FULL
1605 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001606 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607 help
1608 Disabling this option reduces the size of miscellaneous core
1609 kernel data structures. This saves memory on small machines,
1610 but may reduce performance.
1611
1612config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001613 bool "Enable futex support" if EXPERT
Arnd Bergmann3f2beda2021-10-26 12:03:47 +02001614 depends on !(SPARC32 && SMP)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001615 default y
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001616 imply RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 help
1618 Disabling this option will cause the kernel to be built without
1619 support for "fast userspace mutexes". The resulting kernel may not
1620 run glibc-based applications correctly.
1621
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001622config FUTEX_PI
1623 bool
1624 depends on FUTEX && RT_MUTEXES
1625 default y
1626
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001628 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 default y
1630 help
1631 Disabling this option will cause the kernel to be built without
1632 support for epoll family of system calls.
1633
Davide Libenzifba2afa2007-05-10 22:23:13 -07001634config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001635 bool "Enable signalfd() system call" if EXPERT
Davide Libenzifba2afa2007-05-10 22:23:13 -07001636 default y
1637 help
1638 Enable the signalfd() system call that allows to receive signals
1639 on a file descriptor.
1640
1641 If unsure, say Y.
1642
Davide Libenzib215e282007-05-10 22:23:16 -07001643config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001644 bool "Enable timerfd() system call" if EXPERT
Davide Libenzib215e282007-05-10 22:23:16 -07001645 default y
1646 help
1647 Enable the timerfd() system call that allows to receive timer
1648 events on a file descriptor.
1649
1650 If unsure, say Y.
1651
Davide Libenzie1ad7462007-05-10 22:23:19 -07001652config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001653 bool "Enable eventfd() system call" if EXPERT
Davide Libenzie1ad7462007-05-10 22:23:19 -07001654 default y
1655 help
1656 Enable the eventfd() system call that allows to receive both
1657 kernel notification (ie. KAIO) or userspace notifications.
1658
1659 If unsure, say Y.
1660
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001662 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001663 default y
1664 depends on MMU
1665 help
1666 The shmem is an internal filesystem used to manage shared memory.
1667 It is backed by swap and manages resource limits. It is also exported
1668 to userspace as tmpfs if TMPFS is enabled. Disabling this
1669 option replaces shmem and tmpfs with the much simpler ramfs code,
1670 which may be appropriate on small systems without swap.
1671
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001672config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001673 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001674 default y
1675 help
1676 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001677 by some high performance threaded applications. Disabling
1678 this option saves about 7k.
1679
Jens Axboe2b188cc2019-01-07 10:46:33 -07001680config IO_URING
1681 bool "Enable IO uring support" if EXPERT
Jens Axboe561fb042019-10-24 07:25:42 -06001682 select IO_WQ
Jens Axboe2b188cc2019-01-07 10:46:33 -07001683 default y
1684 help
1685 This option enables support for the io_uring interface, enabling
1686 applications to submit and complete IO through submission and
1687 completion rings that are shared between the kernel and application.
1688
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001689config ADVISE_SYSCALLS
1690 bool "Enable madvise/fadvise syscalls" if EXPERT
1691 default y
1692 help
1693 This option enables the madvise and fadvise syscalls, used by
1694 applications to advise the kernel about their future memory or file
1695 usage, improving performance. If building an embedded system where no
1696 applications use these syscalls, you can disable this option to save
1697 space.
1698
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001699config MEMBARRIER
1700 bool "Enable membarrier() system call" if EXPERT
1701 default y
1702 help
1703 Enable the membarrier() system call that allows issuing memory
1704 barriers across all running threads, which can be used to distribute
1705 the cost of user-space memory barriers asymmetrically by transforming
1706 pairs of memory barriers into pairs consisting of membarrier() and a
1707 compiler barrier.
1708
1709 If unsure, say Y.
1710
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001711config KALLSYMS
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001712 bool "Load all symbols for debugging/ksymoops" if EXPERT
1713 default y
1714 help
1715 Say Y here to let the kernel print out symbolic crash information and
1716 symbolic stack backtraces. This increases the size of the kernel
1717 somewhat, as all symbols have to be loaded into the kernel image.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001718
1719config KALLSYMS_ALL
1720 bool "Include all symbols in kallsyms"
1721 depends on DEBUG_KERNEL && KALLSYMS
1722 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001723 Normally kallsyms only contains the symbols of functions for nicer
1724 OOPS messages and backtraces (i.e., symbols from the text and inittext
Baruch Siachbdf0fe32022-07-07 07:43:29 +03001725 sections). This is sufficient for most cases. And only if you want to
1726 enable kernel live patching, or other less common use cases (e.g.,
1727 when a debugger is used) all symbols are required (i.e., names of
1728 variables from the data sections, etc).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001729
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001730 This option makes sure that all symbols are loaded into the kernel
1731 image (i.e., symbols from all sections) in cost of increased kernel
1732 size (depending on the kernel configuration, it may be 300KiB or
1733 something like this).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001734
Baruch Siachbdf0fe32022-07-07 07:43:29 +03001735 Say N unless you really need all symbols, or kernel live patching.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001736
1737config KALLSYMS_ABSOLUTE_PERCPU
1738 bool
1739 depends on KALLSYMS
1740 default X86_64 && SMP
1741
1742config KALLSYMS_BASE_RELATIVE
1743 bool
1744 depends on KALLSYMS
Arnd Bergmanna687a532018-03-07 23:30:54 +01001745 default !IA64
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001746 help
1747 Instead of emitting them as absolute values in the native word size,
1748 emit the symbol references in the kallsyms table as 32-bit entries,
1749 each containing a relative value in the range [base, base + U32_MAX]
1750 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1751 an absolute value in the range [0, S32_MAX] or a relative value in the
1752 range [base, base + S32_MAX], where base is the lowest relative symbol
1753 address encountered in the image.
1754
1755 On 64-bit builds, this reduces the size of the address table by 50%,
1756 but more importantly, it results in entries whose values are build
1757 time constants, and no relocation pass is required at runtime to fix
1758 up the entries based on the runtime load address of the kernel.
1759
1760# end of the "standard kernel features (expert users)" menu
1761
1762# syscall, maps, verifier
KP Singhfc611f42020-03-29 01:43:49 +01001763
Mathieu Desnoyers3ccfebe2018-01-29 15:20:11 -05001764config ARCH_HAS_MEMBARRIER_CALLBACKS
1765 bool
1766
Mathieu Desnoyers70216e12018-01-29 15:20:17 -05001767config ARCH_HAS_MEMBARRIER_SYNC_CORE
1768 bool
1769
Chris Wilsonbfe39112021-02-05 22:00:12 +00001770config KCMP
1771 bool "Enable kcmp() system call" if EXPERT
1772 help
1773 Enable the kernel resource comparison system call. It provides
1774 user-space with the ability to compare two processes to see if they
1775 share a common resource, such as a file descriptor or even virtual
1776 memory space.
1777
1778 If unsure, say N.
1779
Mathieu Desnoyersd7822b12018-06-02 08:43:54 -04001780config RSEQ
1781 bool "Enable rseq() system call" if EXPERT
1782 default y
1783 depends on HAVE_RSEQ
1784 select MEMBARRIER
1785 help
1786 Enable the restartable sequences system call. It provides a
1787 user-space cache for the current CPU number value, which
1788 speeds up getting the current CPU number from user-space,
1789 as well as an ABI to speed up user-space operations on
1790 per-CPU data.
1791
1792 If unsure, say Y.
1793
1794config DEBUG_RSEQ
1795 default n
1796 bool "Enabled debugging of rseq() system call" if EXPERT
1797 depends on RSEQ && DEBUG_KERNEL
1798 help
1799 Enable extra debugging checks for the rseq system call.
1800
1801 If unsure, say N.
1802
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001803config EMBEDDED
1804 bool "Embedded system"
1805 select EXPERT
1806 help
1807 This option should be enabled if compiling the kernel for
1808 an embedded system so certain expert options are available
1809 for configuration.
1810
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001811config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001812 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001813 help
1814 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001815
Sean Christopherson2aef6f32021-11-11 02:07:29 +00001816config GUEST_PERF_EVENTS
1817 bool
1818 depends on HAVE_PERF_EVENTS
1819
Peter Zijlstra906010b2009-09-21 16:08:49 +02001820config PERF_USE_VMALLOC
1821 bool
1822 help
1823 See tools/perf/design.txt for details
1824
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001825config PC104
William Breathitt Gray424529f2017-12-29 15:14:59 -05001826 bool "PC/104 support" if EXPERT
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001827 help
1828 Expose PC/104 form factor device drivers and options available for
1829 selection and configuration. Enable this option if your target
1830 machine has a PC/104 bus.
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
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001839 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001840 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001841 Enable kernel support for various performance events provided
1842 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001843
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001844 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001845 use of generic tracepoints.
1846
1847 Most modern CPUs support performance events via performance
1848 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001849 types of hw events: such as instructions executed, cachemisses
1850 suffered, or branches mis-predicted - without slowing down the
1851 kernel or applications. These registers can also trigger interrupts
1852 when a threshold number of events have passed - and can thus be
1853 used to profile the code that runs on that CPU.
1854
Ingo Molnar57c0c152009-09-21 12:20:38 +02001855 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001856 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001857 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001858 provides per task and per CPU counters, and it provides event
1859 capabilities on top of those.
1860
1861 Say Y if unsure.
1862
Peter Zijlstra906010b2009-09-21 16:08:49 +02001863config DEBUG_PERF_USE_VMALLOC
1864 default n
1865 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb3071132015-05-04 16:26:39 +10001866 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001867 select PERF_USE_VMALLOC
1868 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001869 Use vmalloc memory to back perf mmap() buffers.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001870
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001871 Mostly useful for debugging the vmalloc code on platforms
1872 that don't require it.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001873
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001874 Say N if unsure.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001875
Thomas Gleixner0793a612008-12-04 20:12:29 +01001876endmenu
1877
David Howells091f6e22015-07-20 21:16:28 +01001878config SYSTEM_DATA_VERIFICATION
1879 def_bool n
1880 select SYSTEM_TRUSTED_KEYRING
1881 select KEYS
1882 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00001883 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01001884 select ASYMMETRIC_KEY_TYPE
1885 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01001886 select ASN1
1887 select OID_REGISTRY
1888 select X509_CERTIFICATE_PARSER
1889 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07001890 help
David Howells091f6e22015-07-20 21:16:28 +01001891 Provide PKCS#7 message verification using the contents of the system
1892 trusted keyring to provide public keys. This then can be used for
1893 module verification, kexec image verification and firmware blob
1894 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07001895
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001896config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001897 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001898 help
1899 Say Y here to enable the extended profiling support mechanisms used
Viresh Kumarf8408262021-01-14 17:05:30 +05301900 by profilers.
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001901
Ingo Molnar5f87f112008-07-23 14:15:22 +02001902#
1903# Place an empty function call at each tracepoint site. Can be
1904# dynamically changed for a probe function.
1905#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001906config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001907 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001908
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909endmenu # General setup
1910
Christoph Hellwig15724972018-07-31 13:39:30 +02001911source "arch/Kconfig"
1912
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001913config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05001914 bool
Sebastian Andrzej Siewior1c6f9ec2022-02-08 18:21:10 +01001915 default y if PREEMPT_RT
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001916
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917config BASE_SMALL
1918 int
1919 default 0 if BASE_FULL
1920 default 1 if !BASE_FULL
1921
Thiago Jung Bauermannc8424e72019-07-04 15:57:34 -03001922config MODULE_SIG_FORMAT
1923 def_bool n
1924 select SYSTEM_DATA_VERIFICATION
1925
Christophe Leroy73b4fc92022-07-12 07:52:33 +02001926source "kernel/module/Kconfig"
Peter Zijlstra6c9692e22015-05-27 11:09:37 +09301927
Rusty Russell98a79d62008-12-13 21:19:41 +10301928config INIT_ALL_POSSIBLE
1929 bool
1930 help
Rusty Russell5f054e32012-03-29 15:38:31 +10301931 Back when each arch used to define their own cpu_online_mask and
1932 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10301933 with all 1s, and others with all 0s. When they were centralised,
1934 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01001935 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10301936
Jens Axboe3a65dfe2005-11-04 08:43:35 +01001937source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07001938
1939config PREEMPT_NOTIFIERS
1940 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01001941
Steffen Klassert16295be2010-01-06 19:47:10 +11001942config PADATA
1943 depends on SMP
1944 bool
1945
David Howells4520c6a2012-09-21 23:31:13 +01001946config ASN1
1947 tristate
1948 help
1949 Build a simple ASN.1 grammar compiler that produces a bytecode output
1950 that can be interpreted by the ASN.1 stream decoder and used to
1951 inform it as to what tags are to be expected in a stream and what
1952 functions to call on what tags.
1953
Thomas Gleixner6beb0002009-11-09 15:21:34 +00001954source "kernel/Kconfig.locks"
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05001955
Daniel Borkmann0ebeea82020-05-15 12:11:16 +02001956config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
1957 bool
1958
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05001959config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
1960 bool
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02001961
1962# It may be useful for an architecture to override the definitions of the
Dominik Brodowski7303e302018-04-05 11:53:03 +02001963# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
1964# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
1965# different calling convention for syscalls. They can also override the
1966# macros for not-implemented syscalls in kernel/sys_ni.c and
1967# kernel/time/posix-stubs.c. All these overrides need to be available in
1968# <asm/syscall_wrapper.h>.
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02001969config ARCH_HAS_SYSCALL_WRAPPER
1970 def_bool n