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Thomas Gleixnerec8f24b2019-05-19 13:07:45 +01001# SPDX-License-Identifier: GPL-2.0-only
Roman Zippelface4372006-06-08 22:12:45 -07002config DEFCONFIG_LIST
3 string
Paolo 'Blaisorblade' Giarrussob2670eac2006-10-19 23:28:23 -07004 depends on !UML
Roman Zippelface4372006-06-08 22:12:45 -07005 option defconfig_list
Rob Landley47f38ae2018-08-08 13:06:43 +09006 default "/lib/modules/$(shell,uname -r)/.config"
Roman Zippelface4372006-06-08 22:12:45 -07007 default "/etc/kernel-config"
Rob Landley47f38ae2018-08-08 13:06:43 +09008 default "/boot/config-$(shell,uname -r)"
Masahiro Yamada2a86f662020-02-28 12:46:40 +09009 default "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)"
Roman Zippelface4372006-06-08 22:12:45 -070010
Masahiro Yamada8b59cd82020-04-23 23:23:52 +090011config CC_VERSION_TEXT
12 string
13 default "$(CC_VERSION_TEXT)"
14 help
15 This is used in unclear ways:
16
17 - Re-run Kconfig when the compiler is updated
18 The 'default' property references the environment variable,
19 CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.
20 When the compiler is updated, Kconfig will be invoked.
21
22 - Ensure full rebuild when the compier is updated
23 include/linux/kconfig.h contains this option in the comment line so
24 fixdep adds include/config/cc/version/text.h into the auto-generated
25 dependency. When the compiler is updated, syncconfig will touch it
26 and then every file will be rebuilt.
27
Masahiro Yamadaa4353892018-05-28 18:22:01 +090028config CC_IS_GCC
Masahiro Yamadae33ae3e2020-04-23 23:23:51 +090029 def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q gcc)
Masahiro Yamadaa4353892018-05-28 18:22:01 +090030
31config GCC_VERSION
32 int
Masahiro Yamadafa7295a2019-03-01 16:10:22 +090033 default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
Masahiro Yamadaa4353892018-05-28 18:22:01 +090034 default 0
35
Amit Daniel Kachhap9553d162020-03-30 17:11:38 +053036config LD_VERSION
37 int
38 default $(shell,$(LD) --version | $(srctree)/scripts/ld-version.sh)
39
Masahiro Yamada469cb732018-05-28 18:22:02 +090040config CC_IS_CLANG
Masahiro Yamadae33ae3e2020-04-23 23:23:51 +090041 def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q clang)
Masahiro Yamada469cb732018-05-28 18:22:02 +090042
Sami Tolvanen79ae4ab2019-03-20 10:15:46 -070043config LD_IS_LLD
44 def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)
45
Masahiro Yamada469cb732018-05-28 18:22:02 +090046config CLANG_VERSION
47 int
48 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
49
Masahiro Yamada83f55e62023-03-28 17:08:29 -070050config AS_IS_GNU
51 def_bool $(success,test "$(as-name)" = GNU)
52
53config AS_IS_LLVM
54 def_bool $(success,test "$(as-name)" = LLVM)
55
56config AS_VERSION
57 int
58 # Use clang version if this is the integrated assembler
59 default CLANG_VERSION if AS_IS_LLVM
60 default $(as-version)
61
Nathan Chancellord5750cd2020-11-19 13:46:58 -070062config LLD_VERSION
63 int
64 default $(shell,$(srctree)/scripts/lld-version.sh $(LD))
65
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090066config CC_CAN_LINK
Masahiro Yamada9371f862020-04-29 12:45:13 +090067 bool
Elliot Berman3172c952022-01-12 12:14:58 -080068 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
69 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090070
Masahiro Yamadab1183b62020-05-09 16:39:15 +090071config CC_CAN_LINK_STATIC
72 bool
Elliot Berman3172c952022-01-12 12:14:58 -080073 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
74 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070075
Masahiro Yamadae9666d12018-12-31 00:14:15 +090076config CC_HAS_ASM_GOTO
77 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
78
Nick Desaulniers587f1702020-02-14 14:18:11 -080079config CC_HAS_ASM_GOTO_OUTPUT
80 depends on CC_HAS_ASM_GOTO
81 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)
82
Sean Christopherson09408082022-02-02 00:49:41 +000083config CC_HAS_ASM_GOTO_TIED_OUTPUT
84 depends on CC_HAS_ASM_GOTO_OUTPUT
85 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
Alexandre Bellonic0a9c992022-11-15 12:01:58 +010086 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
Sean Christopherson09408082022-02-02 00:49:41 +000087
Peter Collingbourne5cf896f2019-07-31 18:18:42 -070088config TOOLS_SUPPORT_RELR
Will Deacon2d122942019-08-20 10:11:54 +010089 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
Peter Collingbourne5cf896f2019-07-31 18:18:42 -070090
Rasmus Villemoeseb111862019-09-13 00:19:25 +020091config CC_HAS_ASM_INLINE
92 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
93
Peter Oberparleiterb99b87f2009-06-17 16:28:03 -070094config CONSTRUCTORS
95 bool
Johannes Berg87c93662019-12-04 17:43:46 +010096 depends on !UML
Peter Oberparleiterb99b87f2009-06-17 16:28:03 -070097
Peter Zijlstrae360adb2010-10-14 14:01:34 +080098config IRQ_WORK
99 bool
Peter Zijlstrae360adb2010-10-14 14:01:34 +0800100
Shile Zhang10916702019-12-04 08:46:31 +0800101config BUILDTIME_TABLE_SORT
David Daney1dbdc6f2012-04-19 14:59:57 -0700102 bool
103
Andy Lutomirskic65eacb2016-09-13 14:29:24 -0700104config THREAD_INFO_IN_TASK
105 bool
106 help
107 Select this to move thread_info off the stack into task_struct. To
108 make this work, an arch will need to remove all thread_info fields
109 except flags and fix any runtime bugs.
110
Andy Lutomirskic6c314a2016-09-15 22:45:43 -0700111 One subtle change that will be needed is to use try_get_task_stack()
112 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
113
Al Boldiff0cfc62007-07-31 00:39:23 -0700114menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116config BROKEN
117 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118
119config BROKEN_ON_SMP
120 bool
121 depends on BROKEN || !SMP
122 default y
123
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124config INIT_ENV_ARG_LIMIT
125 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -0700126 default 32 if !UML
127 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 help
Randy Dunlap34ad92c2005-10-30 15:01:46 -0800129 Maximum of each of the number of arguments and environment
130 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
Jiri Slaby4bb16672013-05-22 10:56:24 +0200132config COMPILE_TEST
133 bool "Compile also drivers which will not load"
Masahiro Yamadacef13a02021-03-12 21:07:08 -0800134 depends on HAS_IOMEM
Jiri Slaby4bb16672013-05-22 10:56:24 +0200135 help
136 Some drivers can be compiled on a different platform than they are
137 intended to be run on. Despite they cannot be loaded there (or even
138 when they load they cannot be used due to missing HW support),
139 developers still, opposing to distributors, might want to build such
140 drivers to compile-test them.
141
142 If you are a developer and want to build everything available, say Y
143 here. If you are a user/distributor, say N here to exclude useless
144 drivers to be distributed.
145
Linus Torvalds824c5552021-09-05 11:24:05 -0700146config WERROR
147 bool "Compile the kernel with warnings as errors"
148 default y
149 help
150 A kernel build should not cause any compiler warnings, and this
151 enables the '-Werror' flag to enforce that rule by default.
152
153 However, if you have a new (or very old) compiler with odd and
154 unusual warnings, or you have some architecture with problems,
155 you may need to disable this config option in order to
156 successfully build the kernel.
157
158 If in doubt, say Y.
159
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900160config UAPI_HEADER_TEST
161 bool "Compile test UAPI headers"
Masahiro Yamadafcbb8462019-11-07 16:14:40 +0900162 depends on HEADERS_INSTALL && CC_CAN_LINK
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900163 help
164 Compile test headers exported to user-space to ensure they are
165 self-contained, i.e. compilable as standalone units.
166
167 If you are a developer or tester and want to ensure the exported
168 headers are self-contained, say Y here. Otherwise, choose N.
169
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170config LOCALVERSION
171 string "Local version - append to kernel release"
172 help
173 Append an extra string to the end of your kernel version.
174 This will show up when you type uname, for example.
175 The string you set here will be appended after the contents of
176 any files with a filename matching localversion* in your
177 object and source tree, in that order. Your total string can
178 be a maximum of 64 characters.
179
Ryan Andersonaaebf432005-07-31 04:57:49 -0400180config LOCALVERSION_AUTO
181 bool "Automatically append version information to the version string"
182 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -0700183 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -0400184 help
185 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200186 release tree by looking for git tags that belong to the current
187 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400188
189 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200190 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400191 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200192 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400193
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200194 (The actual string used here is the first eight characters produced
195 by running the command:
196
197 $ git rev-parse --verify HEAD
198
199 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400200
Laura Abbott9afb7192018-07-05 17:49:37 -0700201config BUILD_SALT
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800202 string "Build ID Salt"
203 default ""
204 help
205 The build ID is used to link binaries and their debug info. Setting
206 this option will use the value in the calculation of the build id.
207 This is mostly useful for distributions which want to ensure the
208 build is unique between builds. It's safe to leave the default.
Laura Abbott9afb7192018-07-05 17:49:37 -0700209
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800210config HAVE_KERNEL_GZIP
211 bool
212
213config HAVE_KERNEL_BZIP2
214 bool
215
216config HAVE_KERNEL_LZMA
217 bool
218
Lasse Collin3ebe1242011-01-12 17:01:23 -0800219config HAVE_KERNEL_XZ
220 bool
221
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800222config HAVE_KERNEL_LZO
223 bool
224
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700225config HAVE_KERNEL_LZ4
226 bool
227
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700228config HAVE_KERNEL_ZSTD
229 bool
230
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200231config HAVE_KERNEL_UNCOMPRESSED
232 bool
233
Alain Knaff30d65db2009-01-04 22:46:17 +0100234choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800235 prompt "Kernel compression mode"
236 default KERNEL_GZIP
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700237 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 -0800238 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100239 The linux kernel is a kind of self-extracting executable.
240 Several compression algorithms are available, which differ
241 in efficiency, compression and decompression speed.
242 Compression speed is only relevant when building a kernel.
243 Decompression speed is relevant at each boot.
244
245 If you have any problems with bzip2 or lzma compressed
246 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
247 version of this functionality (bzip2 only), for 2.4, was
248 supplied by Christian Ludwig)
249
250 High compression options are mostly useful for users, who
251 are low on disk space (embedded systems), but for whom ram
252 size matters less.
253
254 If in doubt, select 'gzip'
255
256config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800257 bool "Gzip"
258 depends on HAVE_KERNEL_GZIP
259 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800260 The old and tried gzip compression. It provides a good balance
261 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100262
263config KERNEL_BZIP2
264 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800265 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100266 help
267 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700268 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800269 size is about 10% smaller with bzip2, in comparison to gzip.
270 Bzip2 uses a large amount of memory. For modern kernels you
271 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100272
273config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800274 bool "LZMA"
275 depends on HAVE_KERNEL_LZMA
276 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700277 This compression algorithm's ratio is best. Decompression speed
278 is between gzip and bzip2. Compression is slowest.
279 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100280
Lasse Collin3ebe1242011-01-12 17:01:23 -0800281config KERNEL_XZ
282 bool "XZ"
283 depends on HAVE_KERNEL_XZ
284 help
285 XZ uses the LZMA2 algorithm and instruction set specific
286 BCJ filters which can improve compression ratio of executable
287 code. The size of the kernel is about 30% smaller with XZ in
288 comparison to gzip. On architectures for which there is a BCJ
289 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
290 will create a few percent smaller kernel than plain LZMA.
291
292 The speed is about the same as with LZMA: The decompression
293 speed of XZ is better than that of bzip2 but worse than gzip
294 and LZO. Compression is slow.
295
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800296config KERNEL_LZO
297 bool "LZO"
298 depends on HAVE_KERNEL_LZO
299 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700300 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200301 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800302 (both compression and decompression) is the fastest.
303
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700304config KERNEL_LZ4
305 bool "LZ4"
306 depends on HAVE_KERNEL_LZ4
307 help
308 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
309 A preliminary version of LZ4 de/compression tool is available at
310 <https://code.google.com/p/lz4/>.
311
312 Its compression ratio is worse than LZO. The size of the kernel
313 is about 8% bigger than LZO. But the decompression speed is
314 faster than LZO.
315
Nick Terrell48f7ddf2020-07-30 12:08:36 -0700316config KERNEL_ZSTD
317 bool "ZSTD"
318 depends on HAVE_KERNEL_ZSTD
319 help
320 ZSTD is a compression algorithm targeting intermediate compression
321 with fast decompression speed. It will compress better than GZIP and
322 decompress around the same speed as LZO, but slower than LZ4. You
323 will need at least 192 KB RAM or more for booting. The zstd command
324 line tool is required for compression.
325
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200326config KERNEL_UNCOMPRESSED
327 bool "None"
328 depends on HAVE_KERNEL_UNCOMPRESSED
329 help
330 Produce uncompressed kernel image. This option is usually not what
331 you want. It is useful for debugging the kernel in slow simulation
332 environments, where decompressing and moving the kernel is awfully
333 slow. This option allows early boot code to skip the decompressor
334 and jump right at uncompressed kernel image.
335
Alain Knaff30d65db2009-01-04 22:46:17 +0100336endchoice
337
Chris Downada4ab72020-06-04 16:50:53 -0700338config DEFAULT_INIT
339 string "Default init path"
340 default ""
341 help
342 This option determines the default init for the system if no init=
343 option is passed on the kernel command line. If the requested path is
344 not present, we will still then move on to attempting further
345 locations (e.g. /sbin/init, etc). If this is empty, we will just use
346 the fallback list when init= is not passed.
347
Josh Triplettbd5dc172011-06-15 15:08:28 -0700348config DEFAULT_HOSTNAME
349 string "Default hostname"
350 default "(none)"
351 help
352 This option determines the default system hostname before userspace
353 calls sethostname(2). The kernel traditionally uses "(none)" here,
354 but you may wish to use a different default here to make a minimal
355 system more usable with less configuration.
356
Christoph Hellwig17c46a62018-07-31 13:39:29 +0200357#
358# For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
359# add proper SWAP support to them, in which case this can be remove.
360#
361config ARCH_NO_SWAP
362 bool
363
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364config SWAP
365 bool "Support for paging of anonymous memory (swap)"
Christoph Hellwig17c46a62018-07-31 13:39:29 +0200366 depends on MMU && BLOCK && !ARCH_NO_SWAP
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 default y
368 help
369 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100370 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 used to provide more virtual memory than the actual RAM present
372 in your computer. If unsure say Y.
373
374config SYSVIPC
375 bool "System V IPC"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900376 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 Inter Process Communication is a suite of library functions and
378 system calls which let processes (running programs) synchronize and
379 exchange information. It is generally considered to be a good thing,
380 and some programs won't run unless you say Y here. In particular, if
381 you want to run the DOS emulator dosemu under Linux (read the
382 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
383 you'll need to say Y here.
384
385 You can find documentation about IPC with "info ipc" and also in
386 section 6.4 of the Linux Programmer's Guide, available from
387 <http://www.tldp.org/guides.html>.
388
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800389config SYSVIPC_SYSCTL
390 bool
391 depends on SYSVIPC
392 depends on SYSCTL
393 default y
394
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395config POSIX_MQUEUE
396 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700397 depends on NET
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900398 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 POSIX variant of message queues is a part of IPC. In POSIX message
400 queues every message has a priority which decides about succession
401 of receiving it by a process. If you want to compile and run
402 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200403 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404
405 POSIX message queues are visible as a filesystem called 'mqueue'
406 and can be mounted somewhere if you want to do filesystem
407 operations on message queues.
408
409 If unsure, say Y.
410
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700411config POSIX_MQUEUE_SYSCTL
412 bool
413 depends on POSIX_MQUEUE
414 depends on SYSCTL
415 default y
416
David Howellsc73be612020-01-14 17:07:11 +0000417config WATCH_QUEUE
418 bool "General notification queue"
419 default n
420 help
421
422 This is a general notification queue for the kernel to pass events to
423 userspace by splicing them into pipes. It can be used in conjunction
424 with watches for key/keyring change notifications and device
425 notifications.
426
427 See Documentation/watch_queue.rst
428
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700429config CROSS_MEMORY_ATTACH
430 bool "Enable process_vm_readv/writev syscalls"
431 depends on MMU
432 default y
433 help
434 Enabling this option adds the system calls process_vm_readv and
435 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700436 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700437 See the man page for more details.
438
Josh Triplett69369a72014-04-03 14:48:27 -0700439config USELIB
440 bool "uselib syscall"
Riku Voipiob2113a42016-01-15 16:58:13 -0800441 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
Josh Triplett69369a72014-04-03 14:48:27 -0700442 help
443 This option enables the uselib syscall, a system call used in the
444 dynamic linker from libc5 and earlier. glibc does not use this
445 system call. If you intend to run programs built on libc5 or
446 earlier, you may need to enable this syscall. Current systems
447 running glibc can safely disable this.
448
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449config AUDIT
450 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100451 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 help
453 Enable auditing infrastructure that can be used with another
454 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500455 logging of avc messages output). System call auditing is included
456 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900458config HAVE_ARCH_AUDITSYSCALL
459 bool
460
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500462 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900463 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500464 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400465
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000466source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200467source "kernel/time/Kconfig"
Christoph Hellwig87a4c372018-07-31 13:39:32 +0200468source "kernel/Kconfig.preempt"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000469
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200470menu "CPU/Task time and stats accounting"
471
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200472config VIRT_CPU_ACCOUNTING
473 bool
474
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200475choice
476 prompt "Cputime accounting"
477 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100478 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200479
480# Kind of a stub config for the pure tick based cputime accounting
481config TICK_CPU_ACCOUNTING
482 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200483 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200484 help
485 This is the basic tick based cputime accounting that maintains
486 statistics about user, system and idle time spent on per jiffies
487 granularity.
488
489 If unsure, say Y.
490
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200491config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200492 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200493 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200494 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200495 help
496 Select this option to enable more accurate task and CPU time
497 accounting. This is done by reading a CPU counter on each
498 kernel entry and exit and on transitions within the kernel
499 between system, softirq and hardirq state, so there is a
500 small performance impact. In the case of s390 or IBM POWER > 5,
501 this also enables accounting of stolen time on logically-partitioned
502 systems.
503
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200504config VIRT_CPU_ACCOUNTING_GEN
505 bool "Full dynticks CPU time accounting"
Kevin Hilmanff3fb252013-09-16 15:28:19 -0700506 depends on HAVE_CONTEXT_TRACKING
Kevin Hilman554b0002013-09-16 15:28:21 -0700507 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Arnd Bergmann041a1572019-03-04 21:01:31 +0100508 depends on GENERIC_CLOCKEVENTS
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200509 select VIRT_CPU_ACCOUNTING
510 select CONTEXT_TRACKING
511 help
512 Select this option to enable task and CPU time accounting on full
513 dynticks systems. This accounting is implemented by watching every
514 kernel-user boundaries using the context tracking subsystem.
515 The accounting is thus performed at the expense of some significant
516 overhead.
517
518 For now this is only useful if you are working on the full
519 dynticks subsystem development.
520
521 If unsure, say N.
522
Rik van Rielb58c3582016-07-13 16:50:02 +0200523endchoice
524
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200525config IRQ_TIME_ACCOUNTING
526 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200527 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200528 help
529 Select this option to enable fine granularity task irq time
530 accounting. This is done by reading a timestamp on each
531 transitions between softirq and hardirq state, so there can be a
532 small performance impact.
533
534 If in doubt, say N here.
535
Vincent Guittot11d4afd2018-09-25 11:17:42 +0200536config HAVE_SCHED_AVG_IRQ
537 def_bool y
538 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
539 depends on SMP
540
Thara Gopinath76504792020-02-21 19:52:05 -0500541config SCHED_THERMAL_PRESSURE
Valentin Schneider98eb4012020-07-12 17:59:16 +0100542 bool
Valentin Schneiderfcd7c9c2020-07-29 14:57:18 +0100543 default y if ARM && ARM_CPU_TOPOLOGY
544 default y if ARM64
Thara Gopinath76504792020-02-21 19:52:05 -0500545 depends on SMP
Valentin Schneider98eb4012020-07-12 17:59:16 +0100546 depends on CPU_FREQ_THERMAL
547 help
548 Select this option to enable thermal pressure accounting in the
549 scheduler. Thermal pressure is the value conveyed to the scheduler
550 that reflects the reduction in CPU compute capacity resulted from
551 thermal throttling. Thermal throttling occurs when the performance of
552 a CPU is capped due to high operating temperatures.
553
554 If selected, the scheduler will be able to balance tasks accordingly,
555 i.e. put less load on throttled CPUs than on non/less throttled ones.
556
557 This requires the architecture to implement
558 arch_set_thermal_pressure() and arch_get_thermal_pressure().
Thara Gopinath76504792020-02-21 19:52:05 -0500559
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200560config BSD_PROCESS_ACCT
561 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700562 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200563 help
564 If you say Y here, a user level program will be able to instruct the
565 kernel (via a special system call) to write process accounting
566 information to a file: whenever a process exits, information about
567 that process will be appended to the file by the kernel. The
568 information includes things such as creation time, owning user,
569 command name, memory usage, controlling terminal etc. (the complete
570 list is in the struct acct in <file:include/linux/acct.h>). It is
571 up to the user level program to do useful things with this
572 information. This is generally a good idea, so say Y.
573
574config BSD_PROCESS_ACCT_V3
575 bool "BSD Process Accounting version 3 file format"
576 depends on BSD_PROCESS_ACCT
577 default n
578 help
579 If you say Y here, the process accounting information is written
580 in a new file format that also logs the process IDs of each
Randy Dunlap3903bf92018-08-21 21:58:34 -0700581 process and its parent. Note that this file format is incompatible
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200582 with previous v0/v1/v2 file formats, so you will need updated tools
583 for processing it. A preliminary version of these tools is available
584 at <http://www.gnu.org/software/acct/>.
585
586config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700587 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200588 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700589 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200590 default n
591 help
592 Export selected statistics for tasks/processes through the
593 generic netlink interface. Unlike BSD process accounting, the
594 statistics are available during the lifetime of tasks/processes as
595 responses to commands. Like BSD accounting, they are sent to user
596 space on task exit.
597
598 Say N if unsure.
599
600config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700601 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200602 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530603 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200604 help
605 Collect information on time spent by a task waiting for system
606 resources like cpu, synchronous block I/O completion and swapping
607 in pages. Such statistics can help in setting a task's priorities
608 relative to other tasks for cpu, io, rss limits etc.
609
610 Say N if unsure.
611
612config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700613 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200614 depends on TASKSTATS
615 help
616 Collect extended task accounting data and send the data
617 to userland for processing over the taskstats interface.
618
619 Say N if unsure.
620
621config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700622 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200623 depends on TASK_XACCT
624 help
625 Collect information on the number of bytes of storage I/O which this
626 task has caused.
627
628 Say N if unsure.
629
Johannes Weinereb414682018-10-26 15:06:27 -0700630config PSI
631 bool "Pressure stall information tracking"
632 help
633 Collect metrics that indicate how overcommitted the CPU, memory,
634 and IO capacity are in the system.
635
636 If you say Y here, the kernel will create /proc/pressure/ with the
637 pressure statistics files cpu, memory, and io. These will indicate
638 the share of walltime in which some or all tasks in the system are
639 delayed due to contention of the respective resource.
640
Johannes Weiner2ce71352018-10-26 15:06:31 -0700641 In kernels with cgroup support, cgroups (cgroup2 only) will
642 have cpu.pressure, memory.pressure, and io.pressure files,
643 which aggregate pressure stalls for the grouped tasks only.
644
Mauro Carvalho Chehabc3123552019-04-17 05:46:08 -0300645 For more details see Documentation/accounting/psi.rst.
Johannes Weinereb414682018-10-26 15:06:27 -0700646
647 Say N if unsure.
648
Johannes Weinere0c27442018-11-30 14:09:58 -0800649config PSI_DEFAULT_DISABLED
650 bool "Require boot parameter to enable pressure stall information tracking"
651 default n
652 depends on PSI
653 help
654 If set, pressure stall information tracking will be disabled
Baruch Siach428a1cb2018-12-14 14:17:03 -0800655 per default but can be enabled through passing psi=1 on the
656 kernel commandline during boot.
Johannes Weinere0c27442018-11-30 14:09:58 -0800657
Johannes Weiner7b2489d2019-02-01 14:21:15 -0800658 This feature adds some code to the task wakeup and sleep
659 paths of the scheduler. The overhead is too low to affect
660 common scheduling-intense workloads in practice (such as
661 webservers, memcache), but it does show up in artificial
662 scheduler stress tests, such as hackbench.
663
664 If you are paranoid and not sure what the kernel will be
665 used for, say Y.
666
667 Say N if unsure.
668
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200669endmenu # "CPU/Task time and stats accounting"
670
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200671config CPU_ISOLATION
672 bool "CPU isolation"
Geert Uytterhoeven414a2dc2018-01-02 12:13:10 +0100673 depends on SMP || COMPILE_TEST
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100674 default y
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200675 help
676 Make sure that CPUs running critical tasks are not disturbed by
677 any source of "noise" such as unbound workqueues, timers, kthreads...
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100678 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
679 the "isolcpus=" boot parameter.
680
681 Say Y if unsure.
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200682
Paul E. McKenney0af92d42017-05-17 08:43:40 -0700683source "kernel/rcu/Kconfig"
Mike Travisc903ff82009-01-15 12:28:29 -0800684
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700685config BUILD_BIN2C
686 bool
687 default n
688
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700690 tristate "Kernel .config support"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900691 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 This option enables the complete Linux kernel ".config" file
693 contents to be saved in the kernel. It provides documentation
694 of which kernel options are used in a running kernel or in an
695 on-disk kernel. This information can be extracted from the kernel
696 image file with the script scripts/extract-ikconfig and used as
697 input to rebuild the current kernel or to build another kernel.
698 It can also be extracted from a running kernel by reading
699 /proc/config.gz if enabled (below).
700
701config IKCONFIG_PROC
702 bool "Enable access to .config through /proc/config.gz"
703 depends on IKCONFIG && PROC_FS
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900704 help
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 This option enables access to the kernel configuration file
706 through /proc/config.gz.
707
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400708config IKHEADERS
709 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
710 depends on SYSFS
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400711 help
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400712 This option enables access to the in-kernel headers that are generated during
713 the build process. These can be used to build eBPF tracing programs,
714 or similar programs. If you build the headers as a module, a module called
715 kheaders.ko is built which can be loaded on-demand to get access to headers.
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400716
Alistair John Strachan794543a2007-05-08 00:31:15 -0700717config LOG_BUF_SHIFT
718 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
John Ogness550c10d2020-08-12 09:37:22 +0206719 range 12 25 if !H8300
720 range 12 19 if H8300
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700721 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700722 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700723 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700724 Select the minimal kernel log buffer size as a power of 2.
725 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
726 parameter, see below. Any higher size also might be forced
727 by "log_buf_len" boot parameter.
728
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700729 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700730 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700731 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700732 15 => 32 KB
733 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700734 13 => 8 KB
735 12 => 4 KB
736
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700737config LOG_CPU_MAX_BUF_SHIFT
738 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700739 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700740 range 0 21
741 default 12 if !BASE_SMALL
742 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700743 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700744 help
745 This option allows to increase the default ring buffer size
746 according to the number of CPUs. The value defines the contribution
747 of each CPU as a power of 2. The used space is typically only few
748 lines however it might be much more when problems are reported,
749 e.g. backtraces.
750
751 The increased size means that a new buffer has to be allocated and
752 the original static one is unused. It makes sense only on systems
753 with more CPUs. Therefore this value is used only when the sum of
754 contributions is greater than the half of the default kernel ring
755 buffer as defined by LOG_BUF_SHIFT. The default values are set
Paul Menzel0f7636e12020-08-11 11:29:23 +0200756 so that more than 16 CPUs are needed to trigger the allocation.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700757
758 Also this option is ignored when "log_buf_len" kernel parameter is
759 used as it forces an exact (power of two) size of the ring buffer.
760
761 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200762 hotplugging making the computation optimal for the worst case
763 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700764
765 Examples shift values and their meaning:
766 17 => 128 KB for each CPU
767 16 => 64 KB for each CPU
768 15 => 32 KB for each CPU
769 14 => 16 KB for each CPU
770 13 => 8 KB for each CPU
771 12 => 4 KB for each CPU
772
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900773config PRINTK_SAFE_LOG_BUF_SHIFT
774 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
Petr Mladek427934b2016-05-20 17:00:39 -0700775 range 10 21
776 default 13
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900777 depends on PRINTK
Petr Mladek427934b2016-05-20 17:00:39 -0700778 help
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900779 Select the size of an alternate printk per-CPU buffer where messages
780 printed from usafe contexts are temporary stored. One example would
781 be NMI messages, another one - printk recursion. The messages are
782 copied to the main log buffer in a safe context to avoid a deadlock.
783 The value defines the size as a power of 2.
Petr Mladek427934b2016-05-20 17:00:39 -0700784
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900785 Those messages are rare and limited. The largest one is when
Petr Mladek427934b2016-05-20 17:00:39 -0700786 a backtrace is printed. It usually fits into 4KB. Select
787 8KB if you want to be on the safe side.
788
789 Examples:
790 17 => 128 KB for each CPU
791 16 => 64 KB for each CPU
792 15 => 32 KB for each CPU
793 14 => 16 KB for each CPU
794 13 => 8 KB for each CPU
795 12 => 4 KB for each CPU
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
Mel Gorman72b252a2015-09-04 15:47:32 -0700879#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100880# For architectures that know their GCC __int128 support is sound
881#
882config ARCH_SUPPORTS_INT128
883 bool
884
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200885# For architectures that (ab)use NUMA to represent different memory regions
886# all cpu-local but of different latencies, such as SuperH.
887#
888config ARCH_WANT_NUMA_VARIABLE_LOCALITY
889 bool
890
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200891config NUMA_BALANCING
892 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200893 depends on ARCH_SUPPORTS_NUMA_BALANCING
894 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
895 depends on SMP && NUMA && MIGRATION
896 help
897 This option adds support for automatic NUMA aware memory/task placement.
898 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400899 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200900
901 This system will be inactive on UMA systems.
902
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800903config NUMA_BALANCING_DEFAULT_ENABLED
904 bool "Automatically enable NUMA aware memory/task placement"
905 default y
906 depends on NUMA_BALANCING
907 help
908 If set, automatic NUMA balancing will be enabled if running on a NUMA
909 machine.
910
Li Zefan23964d22009-01-15 13:50:58 -0800911menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500912 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500913 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700914 help
Li Zefan23964d22009-01-15 13:50:58 -0800915 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800916 use with process control subsystems such as Cpusets, CFS, memory
917 controls or device isolation.
918 See
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300919 - Documentation/scheduler/sched-design-CFS.rst (CFS)
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300920 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800921 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700922
923 Say N if unsure.
924
Li Zefan23964d22009-01-15 13:50:58 -0800925if CGROUPS
926
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800927config PAGE_COUNTER
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800928 bool
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800929
Andrew Mortonc255a452012-07-31 16:43:02 -0700930config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500931 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800932 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500933 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -0800934 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500935 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800936
Andrew Mortonc255a452012-07-31 16:43:02 -0700937config MEMCG_SWAP
Johannes Weiner2d1c4982020-06-03 16:02:14 -0700938 bool
Andrew Mortonc255a452012-07-31 16:43:02 -0700939 depends on MEMCG && SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -0800940 default y
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800941
Kirill Tkhai84c07d12018-08-17 15:47:25 -0700942config MEMCG_KMEM
943 bool
944 depends on MEMCG && !SLOB
945 default y
946
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500947config BLK_CGROUP
948 bool "IO controller"
949 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700950 default n
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900951 help
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500952 Generic block IO controller cgroup interface. This is the common
953 cgroup interface which should be used by various IO controlling
954 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700955
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500956 Currently, CFQ IO scheduler uses it to recognize task groups and
957 control disk bandwidth allocation (proportional time slice allocation)
958 to such task groups. It is also used by bio throttling logic in
959 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +0200960
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500961 This option only enables generic Block IO controller infrastructure.
962 One needs to also enable actual IO controlling logic/policy. For
963 enabling proportional weight division of disk bandwidth in CFQ, set
Krzysztof Kozlowski7baf2192020-04-06 20:12:02 -0700964 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500965 CONFIG_BLK_DEV_THROTTLING=y.
966
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300967 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500968
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500969config CGROUP_WRITEBACK
970 bool
971 depends on MEMCG && BLK_CGROUP
972 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +0200973
Dhaval Giani7c941432010-01-20 13:26:18 +0100974menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500975 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +0100976 default n
977 help
978 This feature lets CPU scheduler recognize task groups and control CPU
979 bandwidth allocation to such task groups. It uses cgroups to group
980 tasks.
981
982if CGROUP_SCHED
983config FAIR_GROUP_SCHED
984 bool "Group scheduling for SCHED_OTHER"
985 depends on CGROUP_SCHED
986 default CGROUP_SCHED
987
Paul Turnerab84d312011-07-21 09:43:28 -0700988config CFS_BANDWIDTH
989 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -0700990 depends on FAIR_GROUP_SCHED
991 default n
992 help
993 This option allows users to define CPU bandwidth rates (limits) for
994 tasks running within the fair group scheduler. Groups with no limit
995 set are considered to be unconstrained and will run with no
996 restriction.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300997 See Documentation/scheduler/sched-bwc.rst for more information.
Paul Turnerab84d312011-07-21 09:43:28 -0700998
Dhaval Giani7c941432010-01-20 13:26:18 +0100999config RT_GROUP_SCHED
1000 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +01001001 depends on CGROUP_SCHED
1002 default n
1003 help
1004 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +08001005 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +01001006 schedule realtime tasks for non-root users until you allocate
1007 realtime bandwidth for them.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -03001008 See Documentation/scheduler/sched-rt-group.rst for more information.
Dhaval Giani7c941432010-01-20 13:26:18 +01001009
1010endif #CGROUP_SCHED
1011
Patrick Bellasi2480c092019-08-22 14:28:06 +01001012config UCLAMP_TASK_GROUP
1013 bool "Utilization clamping per group of tasks"
1014 depends on CGROUP_SCHED
1015 depends on UCLAMP_TASK
1016 default n
1017 help
1018 This feature enables the scheduler to track the clamped utilization
1019 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1020
1021 When this option is enabled, the user can specify a min and max
1022 CPU bandwidth which is allowed for each single task in a group.
1023 The max bandwidth allows to clamp the maximum frequency a task
1024 can use, while the min bandwidth allows to define a minimum
1025 frequency a task will always use.
1026
1027 When task group based utilization clamping is enabled, an eventually
1028 specified task-specific clamp value is constrained by the cgroup
1029 specified clamp value. Both minimum and maximum task clamping cannot
1030 be bigger than the corresponding clamping defined at task group level.
1031
1032 If in doubt, say N.
1033
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001034config CGROUP_PIDS
1035 bool "PIDs controller"
1036 help
1037 Provides enforcement of process number limits in the scope of a
1038 cgroup. Any attempt to fork more processes than is allowed in the
1039 cgroup will fail. PIDs are fundamentally a global resource because it
1040 is fairly trivial to reach PID exhaustion before you reach even a
1041 conservative kmemcg limit. As a result, it is possible to grind a
1042 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +05301043 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001044
1045 It should be noted that organisational operations (such as attaching
Jonathan Neuschäfer98076832019-02-01 14:21:01 -08001046 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001047 since the PIDs limit only affects a process's ability to fork, not to
1048 attach to a cgroup.
1049
Parav Pandit39d3e752017-01-10 00:02:13 +00001050config CGROUP_RDMA
1051 bool "RDMA controller"
1052 help
1053 Provides enforcement of RDMA resources defined by IB stack.
1054 It is fairly easy for consumers to exhaust RDMA resources, which
1055 can result into resource unavailability to other consumers.
1056 RDMA controller is designed to stop this from happening.
1057 Attaching processes with active RDMA resources to the cgroup
1058 hierarchy is allowed even if can cross the hierarchy's limit.
1059
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001060config CGROUP_FREEZER
1061 bool "Freezer controller"
1062 help
1063 Provides a way to freeze and unfreeze all tasks in a
1064 cgroup.
1065
Johannes Weiner489c2a22016-01-20 15:02:41 -08001066 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1067 controller includes important in-kernel memory consumers per default.
1068
1069 If you're using cgroup2, say N.
1070
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001071config CGROUP_HUGETLB
1072 bool "HugeTLB controller"
1073 depends on HUGETLB_PAGE
1074 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +02001075 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001076 help
1077 Provides a cgroup controller for HugeTLB pages.
1078 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1079 The limit is enforced during page fault. Since HugeTLB doesn't
1080 support page reclaim, enforcing the limit at page fault time implies
1081 that, the application will get SIGBUS signal if it tries to access
1082 HugeTLB pages beyond its limit. This requires the application to know
1083 beforehand how much HugeTLB pages it would require for its use. The
1084 control group is tracked in the third page lru pointer. This means
1085 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001086
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001087config CPUSETS
1088 bool "Cpuset controller"
Nicolas Pitree1d4eee2017-06-14 13:19:23 -04001089 depends on SMP
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001090 help
1091 This option will let you create and manage CPUSETs which
1092 allow dynamically partitioning a system into sets of CPUs and
1093 Memory Nodes and assigning tasks to run only within those sets.
1094 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001095
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001096 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001097
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001098config PROC_PID_CPUSET
1099 bool "Include legacy /proc/<pid>/cpuset file"
1100 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001101 default y
1102
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001103config CGROUP_DEVICE
1104 bool "Device controller"
1105 help
1106 Provides a cgroup controller implementing whitelists for
1107 devices which a process in the cgroup can mknod or open.
1108
1109config CGROUP_CPUACCT
1110 bool "Simple CPU accounting controller"
1111 help
1112 Provides a simple controller for monitoring the
1113 total CPU consumed by the tasks in a cgroup.
1114
1115config CGROUP_PERF
1116 bool "Perf controller"
1117 depends on PERF_EVENTS
1118 help
1119 This option extends the perf per-cpu mode to restrict monitoring
1120 to threads which belong to the cgroup specified and run on the
Namhyung Kim6546b192020-03-25 21:45:29 +09001121 designated cpu. Or this can be used to have cgroup ID in samples
1122 so that it can monitor performance events among cgroups.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001123
1124 Say N if unsure.
1125
Daniel Mack30070982016-11-23 16:52:26 +01001126config CGROUP_BPF
1127 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirski483c4932016-12-16 08:33:45 -08001128 depends on BPF_SYSCALL
1129 select SOCK_CGROUP_DATA
Daniel Mack30070982016-11-23 16:52:26 +01001130 help
1131 Allow attaching eBPF programs to a cgroup using the bpf(2)
1132 syscall command BPF_PROG_ATTACH.
1133
1134 In which context these programs are accessed depends on the type
1135 of attachment. For instance, programs that are attached using
1136 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1137 inet sockets.
1138
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001139config CGROUP_DEBUG
Waiman Long23b0be42017-06-13 17:18:03 -04001140 bool "Debug controller"
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001141 default n
Waiman Long23b0be42017-06-13 17:18:03 -04001142 depends on DEBUG_KERNEL
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001143 help
1144 This option enables a simple controller that exports
Waiman Long23b0be42017-06-13 17:18:03 -04001145 debugging information about the cgroups framework. This
1146 controller is for control cgroup debugging only. Its
1147 interfaces are not stable.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001148
1149 Say N.
1150
Arnd Bergmann73b35142017-01-10 13:08:06 +01001151config SOCK_CGROUP_DATA
1152 bool
1153 default n
1154
Li Zefan23964d22009-01-15 13:50:58 -08001155endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001156
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001157menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001158 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001159 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001160 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001161 help
1162 Provides the way to make tasks work with different objects using
1163 the same id. For example same IPC id may refer to different objects
1164 or same user id or pid may refer to different tasks when used in
1165 different namespaces.
1166
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001167if NAMESPACES
1168
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001169config UTS_NS
1170 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001171 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001172 help
1173 In this namespace tasks see different info provided with the
1174 uname() system call
1175
Andrei Vagin769071a2019-11-12 01:26:52 +00001176config TIME_NS
1177 bool "TIME namespace"
Thomas Gleixner660fd042019-11-12 01:27:09 +00001178 depends on GENERIC_VDSO_TIME_NS
Andrei Vagin769071a2019-11-12 01:26:52 +00001179 default y
1180 help
1181 In this namespace boottime and monotonic clocks can be set.
1182 The time will keep going with the same pace.
1183
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001184config IPC_NS
1185 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001186 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001187 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001188 help
1189 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001190 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001191
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001192config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001193 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001194 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001195 help
1196 This allows containers, i.e. vservers, to use user namespaces
1197 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001198
1199 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001200 recommended that the MEMCG option also be enabled and that
1201 user-space use the memory control groups to limit the amount
1202 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001203
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001204 If unsure, say N.
1205
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001206config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001207 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001208 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001209 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001210 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001211 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001212 pid namespaces. This is a building block of containers.
1213
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001214config NET_NS
1215 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001216 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001217 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001218 help
1219 Allow user space to create what appear to be multiple instances
1220 of the network stack.
1221
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001222endif # NAMESPACES
1223
Adrian Reber5cb366b2018-08-21 22:01:17 -07001224config CHECKPOINT_RESTORE
1225 bool "Checkpoint/restore support"
1226 select PROC_CHILDREN
Chris Wilson1ea36022021-02-05 22:00:12 +00001227 select KCMP
Adrian Reber5cb366b2018-08-21 22:01:17 -07001228 default n
1229 help
1230 Enables additional kernel features in a sake of checkpoint/restore.
1231 In particular it adds auxiliary prctl codes to setup process text,
1232 data and heap segment sizes, and a few additional /proc filesystem
1233 entries.
1234
1235 If unsure, say N here.
1236
Mike Galbraith5091faa2010-11-30 14:18:03 +01001237config SCHED_AUTOGROUP
1238 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001239 select CGROUPS
1240 select CGROUP_SCHED
1241 select FAIR_GROUP_SCHED
1242 help
1243 This option optimizes the scheduler for common desktop workloads by
1244 automatically creating and populating task groups. This separation
1245 of workloads isolates aggressive CPU burners (like build jobs) from
1246 desktop applications. Task group autogeneration is currently based
1247 upon task session.
1248
John Dias3adfd8e2016-09-15 08:52:27 -07001249config RT_SOFTINT_OPTIMIZATION
1250 bool "Improve RT scheduling during long softint execution"
1251 depends on ARM64
1252 depends on SMP
1253 default n
1254 help
1255 Enable an optimization which tries to avoid placing RT tasks on CPUs
1256 occupied by nonpreemptible tasks, such as a long softint, or CPUs
1257 which may soon block preemptions, such as a CPU running a ksoftirq
1258 thread which handles slow softints.
1259
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001260config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001261 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001262 depends on SYSFS
1263 default n
1264 help
1265 This option adds code that switches the layout of the "block" class
1266 devices, to not show up in /sys/class/block/, but only in
1267 /sys/block/.
1268
1269 This switch is only active when the sysfs.deprecated=1 boot option is
1270 passed or the SYSFS_DEPRECATED_V2 option is set.
1271
1272 This option allows new kernels to run on old distributions and tools,
1273 which might get confused by /sys/class/block/. Since 2007/2008 all
1274 major distributions and tools handle this just fine.
1275
1276 Recent distributions and userspace tools after 2009/2010 depend on
1277 the existence of /sys/class/block/, and will not work with this
1278 option enabled.
1279
1280 Only if you are using a new kernel on an old distribution, you might
1281 need to say Y here.
1282
1283config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001284 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001285 default n
1286 depends on SYSFS
1287 depends on SYSFS_DEPRECATED
1288 help
1289 Enable deprecated sysfs by default.
1290
1291 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1292 option.
1293
1294 Only if you are using a new kernel on an old distribution, you might
1295 need to say Y here. Even then, odds are you would not need it
1296 enabled, you can always pass the boot option if absolutely necessary.
1297
1298config RELAY
1299 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001300 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001301 help
1302 This option enables support for relay interface support in
1303 certain file systems (such as debugfs).
1304 It is designed to provide an efficient mechanism for tools and
1305 facilities to relay large amounts of data from kernel space to
1306 user space.
1307
1308 If unsure, say N.
1309
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001310config BLK_DEV_INITRD
1311 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001312 help
1313 The initial RAM filesystem is a ramfs which is loaded by the
1314 boot loader (loadlin or lilo) and that is mounted as root
1315 before the normal boot procedure. It is typically used to
1316 load modules needed to mount the "real" root file system,
Mauro Carvalho Chehab8c27ceff32016-10-18 10:12:27 -02001317 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001318
1319 If RAM disk support (BLK_DEV_RAM) is also included, this
1320 also enables initial RAM disk (initrd) support and adds
1321 15 Kbytes (more on some other architectures) to the kernel size.
1322
1323 If unsure say Y.
1324
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001325if BLK_DEV_INITRD
1326
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001327source "usr/Kconfig"
1328
Liao Huaping7be803f2019-03-11 18:32:35 +08001329config INITRD_ASYNC
1330 bool "Initrd async"
Tao Huangd5b6ba62021-07-14 20:36:11 +08001331 depends on NO_GKI
Liao Huaping7be803f2019-03-11 18:32:35 +08001332 help
1333 Init ramdisk async, can reduce kernel init time.
1334
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001335endif
1336
Tao Huang463bcb62020-03-20 11:23:07 +08001337config INITCALL_ASYNC
1338 bool "Call initcall async"
1339 depends on ROCKCHIP_THUNDER_BOOT
1340 help
1341 Call same level initcall async in kthread.
1342 Kernel parameter "initcall_nr_threads" control how many threads.
1343 initcall_nr_threads default is 0, which disable intcall async.
1344 initcall_nr_threads=-1, auto selected the number of threads.
1345
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001346config BOOT_CONFIG
1347 bool "Boot config support"
Masami Hiramatsu2910b5a2020-02-25 23:36:41 +09001348 select BLK_DEV_INITRD
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001349 help
1350 Extra boot config allows system admin to pass a config file as
1351 complemental extension of kernel cmdline when booting.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001352 The boot config file must be attached at the end of initramfs
Masami Hiramatsu85c46b72020-02-20 21:18:42 +09001353 with checksum, size and magic word.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001354 See <file:Documentation/admin-guide/bootconfig.rst> for details.
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001355
1356 If unsure, say Y.
1357
Arnd Bergmann877417e2016-04-25 17:35:27 +02001358choice
1359 prompt "Compiler optimization level"
Ulf Magnusson2cc3ce22017-10-04 01:53:26 +02001360 default CC_OPTIMIZE_FOR_PERFORMANCE
Arnd Bergmann877417e2016-04-25 17:35:27 +02001361
1362config CC_OPTIMIZE_FOR_PERFORMANCE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001363 bool "Optimize for performance (-O2)"
Arnd Bergmann877417e2016-04-25 17:35:27 +02001364 help
1365 This is the default optimization level for the kernel, building
1366 with the "-O2" compiler flag for best performance and most
1367 helpful compile-time warnings.
1368
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001369config CC_OPTIMIZE_FOR_PERFORMANCE_O3
1370 bool "Optimize more for performance (-O3)"
1371 depends on ARC
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001372 help
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001373 Choosing this option will pass "-O3" to your compiler to optimize
1374 the kernel yet more for performance.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001375
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001376config CC_OPTIMIZE_FOR_SIZE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001377 bool "Optimize for size (-Os)"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001378 help
Masahiro Yamadace3b4872019-08-21 02:09:39 +09001379 Choosing this option will pass "-Os" to your compiler resulting
1380 in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001381
Arnd Bergmann877417e2016-04-25 17:35:27 +02001382endchoice
1383
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001384config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1385 bool
1386 help
1387 This requires that the arch annotates or otherwise protects
1388 its external entry points from being discarded. Linker scripts
1389 must also merge .text.*, .data.*, and .bss.* correctly into
1390 output sections. Care must be taken not to pull in unrelated
1391 sections (e.g., '.text.init'). Typically '.' in section names
1392 is used to distinguish them from label names / C identifiers.
1393
1394config LD_DEAD_CODE_DATA_ELIMINATION
1395 bool "Dead code and data elimination (EXPERIMENTAL)"
1396 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1397 depends on EXPERT
Masahiro Yamadae85d1d62018-08-22 22:51:09 +09001398 depends on $(cc-option,-ffunction-sections -fdata-sections)
1399 depends on $(ld-option,--gc-sections)
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001400 help
Masahiro Yamada8b9d2712018-06-24 01:41:51 +09001401 Enable this if you want to do dead code and data elimination with
1402 the linker by compiling with -ffunction-sections -fdata-sections,
1403 and linking with --gc-sections.
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001404
1405 This can reduce on disk and in-memory size of the kernel
1406 code and static data, particularly for small configs and
1407 on small systems. This has the possibility of introducing
1408 silently broken kernel if the required annotations are not
1409 present. This option is not well tested yet, so use at your
1410 own risk.
1411
Nathan Chancellor59612b22020-11-19 13:46:56 -07001412config LD_ORPHAN_WARN
1413 def_bool y
1414 depends on ARCH_WANT_LD_ORPHAN_WARN
Nathan Chancellord5750cd2020-11-19 13:46:58 -07001415 depends on !LD_IS_LLD || LLD_VERSION >= 110000
Nathan Chancellor59612b22020-11-19 13:46:56 -07001416 depends on $(ld-option,--orphan-handling=warn)
1417
Randy Dunlap08470622006-09-30 23:28:13 -07001418config SYSCTL
1419 bool
1420
Mike Frysinger657a5202013-04-30 15:28:45 -07001421config HAVE_UID16
1422 bool
1423
1424config SYSCTL_EXCEPTION_TRACE
1425 bool
1426 help
1427 Enable support for /proc/sys/debug/exception-trace.
1428
1429config SYSCTL_ARCH_UNALIGN_NO_WARN
1430 bool
1431 help
1432 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1433 Allows arch to define/use @no_unaligned_warning to possibly warn
1434 about unaligned access emulation going on under the hood.
1435
1436config SYSCTL_ARCH_UNALIGN_ALLOW
1437 bool
1438 help
1439 Enable support for /proc/sys/kernel/unaligned-trap
1440 Allows arches to define/use @unaligned_enabled to runtime toggle
1441 the unaligned access emulation.
1442 see arch/parisc/kernel/unaligned.c for reference
1443
Mike Frysinger657a5202013-04-30 15:28:45 -07001444config HAVE_PCSPKR_PLATFORM
1445 bool
1446
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001447# interpreter that classic socket filters depend on
1448config BPF
1449 bool
1450
David Rientjes6a108a12011-01-20 14:44:16 -08001451menuconfig EXPERT
1452 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001453 # Unhide debug options, to make the on-by-default options visible
1454 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455 help
1456 This option allows certain base kernel options and settings
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001457 to be disabled or tweaked. This is for specialized
1458 environments which can tolerate a "non-standard" kernel.
1459 Only use this if you really know what you are doing.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001461config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001462 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001463 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001464 default y
1465 help
1466 This enables the legacy 16-bit UID syscall wrappers.
1467
Iulia Manda28138932015-04-15 16:16:41 -07001468config MULTIUSER
1469 bool "Multiple users, groups and capabilities support" if EXPERT
1470 default y
1471 help
1472 This option enables support for non-root users, groups and
1473 capabilities.
1474
1475 If you say N here, all processes will run with UID 0, GID 0, and all
1476 possible capabilities. Saying N here also compiles out support for
1477 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1478 setgid, and capset.
1479
1480 If unsure, say Y here.
1481
Fabian Frederickf6187762014-06-04 16:11:12 -07001482config SGETMASK_SYSCALL
1483 bool "sgetmask/ssetmask syscalls support" if EXPERT
Arnd Bergmanna687a532018-03-07 23:30:54 +01001484 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09001485 help
Fabian Frederickf6187762014-06-04 16:11:12 -07001486 sys_sgetmask and sys_ssetmask are obsolete system calls
1487 no longer supported in libc but still enabled by default in some
1488 architectures.
1489
1490 If unsure, leave the default option here.
1491
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001492config SYSFS_SYSCALL
1493 bool "Sysfs syscall support" if EXPERT
1494 default y
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09001495 help
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001496 sys_sysfs is an obsolete system call no longer supported in libc.
1497 Note that disabling this option is more secure but might break
1498 compatibility with some systems.
1499
1500 If unsure say Y here.
1501
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001502config FHANDLE
1503 bool "open by fhandle syscalls" if EXPERT
1504 select EXPORTFS
1505 default y
1506 help
1507 If you say Y here, a user level program will be able to map
1508 file names to handle and then later use the handle for
1509 different file system operations. This is useful in implementing
1510 userspace file servers, which now track files using handles instead
1511 of names. The handle would remain the same even if file names
1512 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1513 syscalls.
1514
Nicolas Pitrebaa73d92016-11-11 00:10:10 -05001515config POSIX_TIMERS
1516 bool "Posix Clocks & timers" if EXPERT
1517 default y
1518 help
1519 This includes native support for POSIX timers to the kernel.
1520 Some embedded systems have no use for them and therefore they
1521 can be configured out to reduce the size of the kernel image.
1522
1523 When this option is disabled, the following syscalls won't be
1524 available: timer_create, timer_gettime: timer_getoverrun,
1525 timer_settime, timer_delete, clock_adjtime, getitimer,
1526 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1527 clock_getres and clock_nanosleep syscalls will be limited to
1528 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1529
1530 If unsure say y.
1531
Matt Mackalld59745c2005-05-01 08:59:02 -07001532config PRINTK
1533 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001534 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001535 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001536 help
1537 This option enables normal printk support. Removing it
1538 eliminates most of the message strings from the kernel image
1539 and makes the kernel more or less silent. As this makes it
1540 very difficult to diagnose system problems, saying N here is
1541 strongly discouraged.
1542
Petr Mladek42a0bb32016-05-20 17:00:33 -07001543config PRINTK_NMI
1544 def_bool y
1545 depends on PRINTK
1546 depends on HAVE_NMI
1547
Matt Mackallc8538a72005-05-01 08:59:01 -07001548config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001549 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001550 default y
1551 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001552 Disabling this option eliminates support for BUG and WARN, reducing
1553 the size of your kernel image and potentially quietly ignoring
1554 numerous fatal conditions. You should only consider disabling this
1555 option for embedded systems with no facilities for reporting errors.
1556 Just say Y.
Matt Mackallc8538a72005-05-01 08:59:01 -07001557
Matt Mackall708e9a72006-01-08 01:05:25 -08001558config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001559 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001560 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001561 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001562 help
1563 Enable support for generating core dumps. Disabling saves about 4k.
1564
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001565
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001566config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001567 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001568 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001569 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001570 default y
1571 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001572 This option allows to disable the internal PC-Speaker
1573 support, saving some memory.
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001574
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575config BASE_FULL
1576 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001577 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001578 help
1579 Disabling this option reduces the size of miscellaneous core
1580 kernel data structures. This saves memory on small machines,
1581 but may reduce performance.
1582
1583config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001584 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585 default y
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001586 imply RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 help
1588 Disabling this option will cause the kernel to be built without
1589 support for "fast userspace mutexes". The resulting kernel may not
1590 run glibc-based applications correctly.
1591
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001592config FUTEX_PI
1593 bool
1594 depends on FUTEX && RT_MUTEXES
1595 default y
1596
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001597config HAVE_FUTEX_CMPXCHG
1598 bool
Josh Triplett62b4d202014-10-03 16:19:24 -07001599 depends on FUTEX
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001600 help
1601 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1602 is implemented and always working. This removes a couple of runtime
1603 checks.
1604
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001606 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607 default y
1608 help
1609 Disabling this option will cause the kernel to be built without
1610 support for epoll family of system calls.
1611
Davide Libenzifba2afa2007-05-10 22:23:13 -07001612config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001613 bool "Enable signalfd() system call" if EXPERT
Davide Libenzifba2afa2007-05-10 22:23:13 -07001614 default y
1615 help
1616 Enable the signalfd() system call that allows to receive signals
1617 on a file descriptor.
1618
1619 If unsure, say Y.
1620
Davide Libenzib215e282007-05-10 22:23:16 -07001621config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001622 bool "Enable timerfd() system call" if EXPERT
Davide Libenzib215e282007-05-10 22:23:16 -07001623 default y
1624 help
1625 Enable the timerfd() system call that allows to receive timer
1626 events on a file descriptor.
1627
1628 If unsure, say Y.
1629
Davide Libenzie1ad7462007-05-10 22:23:19 -07001630config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001631 bool "Enable eventfd() system call" if EXPERT
Davide Libenzie1ad7462007-05-10 22:23:19 -07001632 default y
1633 help
1634 Enable the eventfd() system call that allows to receive both
1635 kernel notification (ie. KAIO) or userspace notifications.
1636
1637 If unsure, say Y.
1638
Linus Torvalds1da177e2005-04-16 15:20:36 -07001639config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001640 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 default y
1642 depends on MMU
1643 help
1644 The shmem is an internal filesystem used to manage shared memory.
1645 It is backed by swap and manages resource limits. It is also exported
1646 to userspace as tmpfs if TMPFS is enabled. Disabling this
1647 option replaces shmem and tmpfs with the much simpler ramfs code,
1648 which may be appropriate on small systems without swap.
1649
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001650config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001651 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001652 default y
1653 help
1654 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001655 by some high performance threaded applications. Disabling
1656 this option saves about 7k.
1657
Jens Axboe2b188cc2019-01-07 10:46:33 -07001658config IO_URING
1659 bool "Enable IO uring support" if EXPERT
Jens Axboe561fb042019-10-24 07:25:42 -06001660 select IO_WQ
Jens Axboe2b188cc2019-01-07 10:46:33 -07001661 default y
1662 help
1663 This option enables support for the io_uring interface, enabling
1664 applications to submit and complete IO through submission and
1665 completion rings that are shared between the kernel and application.
1666
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001667config ADVISE_SYSCALLS
1668 bool "Enable madvise/fadvise syscalls" if EXPERT
1669 default y
1670 help
1671 This option enables the madvise and fadvise syscalls, used by
1672 applications to advise the kernel about their future memory or file
1673 usage, improving performance. If building an embedded system where no
1674 applications use these syscalls, you can disable this option to save
1675 space.
1676
Andrea Arcangeli5a281062020-04-06 20:05:33 -07001677config HAVE_ARCH_USERFAULTFD_WP
1678 bool
1679 help
1680 Arch has userfaultfd write protection support
1681
Axel Rasmussen4d3dd332021-03-18 17:01:50 +11001682config HAVE_ARCH_USERFAULTFD_MINOR
1683 bool
1684 help
1685 Arch has userfaultfd minor fault support
1686
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001687config MEMBARRIER
1688 bool "Enable membarrier() system call" if EXPERT
1689 default y
1690 help
1691 Enable the membarrier() system call that allows issuing memory
1692 barriers across all running threads, which can be used to distribute
1693 the cost of user-space memory barriers asymmetrically by transforming
1694 pairs of memory barriers into pairs consisting of membarrier() and a
1695 compiler barrier.
1696
1697 If unsure, say Y.
1698
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001699config KALLSYMS
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001700 bool "Load all symbols for debugging/ksymoops" if EXPERT
1701 default y
1702 help
1703 Say Y here to let the kernel print out symbolic crash information and
1704 symbolic stack backtraces. This increases the size of the kernel
1705 somewhat, as all symbols have to be loaded into the kernel image.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001706
1707config KALLSYMS_ALL
1708 bool "Include all symbols in kallsyms"
1709 depends on DEBUG_KERNEL && KALLSYMS
1710 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001711 Normally kallsyms only contains the symbols of functions for nicer
1712 OOPS messages and backtraces (i.e., symbols from the text and inittext
1713 sections). This is sufficient for most cases. And only in very rare
1714 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1715 names of variables from the data sections, etc).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001716
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001717 This option makes sure that all symbols are loaded into the kernel
1718 image (i.e., symbols from all sections) in cost of increased kernel
1719 size (depending on the kernel configuration, it may be 300KiB or
1720 something like this).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001721
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001722 Say N unless you really need all symbols.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001723
1724config KALLSYMS_ABSOLUTE_PERCPU
1725 bool
1726 depends on KALLSYMS
1727 default X86_64 && SMP
1728
1729config KALLSYMS_BASE_RELATIVE
1730 bool
1731 depends on KALLSYMS
Arnd Bergmanna687a532018-03-07 23:30:54 +01001732 default !IA64
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001733 help
1734 Instead of emitting them as absolute values in the native word size,
1735 emit the symbol references in the kallsyms table as 32-bit entries,
1736 each containing a relative value in the range [base, base + U32_MAX]
1737 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1738 an absolute value in the range [0, S32_MAX] or a relative value in the
1739 range [base, base + S32_MAX], where base is the lowest relative symbol
1740 address encountered in the image.
1741
1742 On 64-bit builds, this reduces the size of the address table by 50%,
1743 but more importantly, it results in entries whose values are build
1744 time constants, and no relocation pass is required at runtime to fix
1745 up the entries based on the runtime load address of the kernel.
1746
1747# end of the "standard kernel features (expert users)" menu
1748
1749# syscall, maps, verifier
KP Singhfc611f42020-03-29 01:43:49 +01001750
1751config BPF_LSM
1752 bool "LSM Instrumentation with BPF"
KP Singh4edf16b2020-03-30 22:40:59 +02001753 depends on BPF_EVENTS
KP Singhfc611f42020-03-29 01:43:49 +01001754 depends on BPF_SYSCALL
1755 depends on SECURITY
1756 depends on BPF_JIT
1757 help
1758 Enables instrumentation of the security hooks with eBPF programs for
1759 implementing dynamic MAC and Audit Policies.
1760
1761 If you are unsure how to answer this question, answer N.
1762
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001763config BPF_SYSCALL
1764 bool "Enable bpf() system call"
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001765 select BPF
Song Liubae77c52018-05-07 10:50:48 -07001766 select IRQ_WORK
Alexei Starovoitov1e6c62a2020-08-27 15:01:11 -07001767 select TASKS_TRACE_RCU
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001768 default n
1769 help
1770 Enable the bpf() system call that allows to manipulate eBPF
1771 programs and maps via file descriptors.
1772
Daniel Borkmann81c22042019-12-09 16:08:03 +01001773config ARCH_WANT_DEFAULT_BPF_JIT
1774 bool
1775
Alexei Starovoitov290af862018-01-09 10:04:29 -08001776config BPF_JIT_ALWAYS_ON
1777 bool "Permanently enable BPF JIT and remove BPF interpreter"
1778 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1779 help
1780 Enables BPF JIT and removes BPF interpreter to avoid
1781 speculative execution of BPF instructions by the interpreter
1782
Daniel Borkmann81c22042019-12-09 16:08:03 +01001783config BPF_JIT_DEFAULT_ON
1784 def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
1785 depends on HAVE_EBPF_JIT && BPF_JIT
1786
Daniel Borkmannf27f62f2021-05-11 22:35:17 +02001787config BPF_UNPRIV_DEFAULT_OFF
1788 bool "Disable unprivileged BPF by default"
1789 depends on BPF_SYSCALL
1790 help
1791 Disables unprivileged BPF by default by setting the corresponding
1792 /proc/sys/kernel/unprivileged_bpf_disabled knob to 2. An admin can
1793 still reenable it by setting it to 0 later on, or permanently
1794 disable it by setting it to 1 (from which no other transition to
1795 0 is possible anymore).
1796
Alexei Starovoitovd71fa5c2020-08-18 21:27:58 -07001797source "kernel/bpf/preload/Kconfig"
1798
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001799config USERFAULTFD
1800 bool "Enable userfaultfd() system call"
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001801 depends on MMU
1802 help
1803 Enable the userfaultfd() system call that allows to intercept and
1804 handle page faults in userland.
1805
Mathieu Desnoyers3ccfebe2018-01-29 15:20:11 -05001806config ARCH_HAS_MEMBARRIER_CALLBACKS
1807 bool
1808
Mathieu Desnoyers70216e12018-01-29 15:20:17 -05001809config ARCH_HAS_MEMBARRIER_SYNC_CORE
1810 bool
1811
Chris Wilson1ea36022021-02-05 22:00:12 +00001812config KCMP
1813 bool "Enable kcmp() system call" if EXPERT
1814 help
1815 Enable the kernel resource comparison system call. It provides
1816 user-space with the ability to compare two processes to see if they
1817 share a common resource, such as a file descriptor or even virtual
1818 memory space.
1819
1820 If unsure, say N.
1821
Mathieu Desnoyersd7822b12018-06-02 08:43:54 -04001822config RSEQ
1823 bool "Enable rseq() system call" if EXPERT
1824 default y
1825 depends on HAVE_RSEQ
1826 select MEMBARRIER
1827 help
1828 Enable the restartable sequences system call. It provides a
1829 user-space cache for the current CPU number value, which
1830 speeds up getting the current CPU number from user-space,
1831 as well as an ABI to speed up user-space operations on
1832 per-CPU data.
1833
1834 If unsure, say Y.
1835
1836config DEBUG_RSEQ
1837 default n
1838 bool "Enabled debugging of rseq() system call" if EXPERT
1839 depends on RSEQ && DEBUG_KERNEL
1840 help
1841 Enable extra debugging checks for the rseq system call.
1842
1843 If unsure, say N.
1844
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001845config EMBEDDED
1846 bool "Embedded system"
Josh Triplett5d2acfc2014-04-07 15:39:09 -07001847 option allnoconfig_y
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001848 select EXPERT
1849 help
1850 This option should be enabled if compiling the kernel for
1851 an embedded system so certain expert options are available
1852 for configuration.
1853
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001854config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001855 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001856 help
1857 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001858
Peter Zijlstra906010b2009-09-21 16:08:49 +02001859config PERF_USE_VMALLOC
1860 bool
1861 help
1862 See tools/perf/design.txt for details
1863
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001864config PC104
William Breathitt Gray424529f2017-12-29 15:14:59 -05001865 bool "PC/104 support" if EXPERT
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001866 help
1867 Expose PC/104 form factor device drivers and options available for
1868 selection and configuration. Enable this option if your target
1869 machine has a PC/104 bus.
1870
Ingo Molnar57c0c152009-09-21 12:20:38 +02001871menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001872
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001873config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001874 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001875 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001876 depends on HAVE_PERF_EVENTS
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001877 select IRQ_WORK
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001878 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001879 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001880 Enable kernel support for various performance events provided
1881 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001882
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001883 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001884 use of generic tracepoints.
1885
1886 Most modern CPUs support performance events via performance
1887 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001888 types of hw events: such as instructions executed, cachemisses
1889 suffered, or branches mis-predicted - without slowing down the
1890 kernel or applications. These registers can also trigger interrupts
1891 when a threshold number of events have passed - and can thus be
1892 used to profile the code that runs on that CPU.
1893
Ingo Molnar57c0c152009-09-21 12:20:38 +02001894 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001895 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001896 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001897 provides per task and per CPU counters, and it provides event
1898 capabilities on top of those.
1899
1900 Say Y if unsure.
1901
Peter Zijlstra906010b2009-09-21 16:08:49 +02001902config DEBUG_PERF_USE_VMALLOC
1903 default n
1904 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb3071132015-05-04 16:26:39 +10001905 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001906 select PERF_USE_VMALLOC
1907 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001908 Use vmalloc memory to back perf mmap() buffers.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001909
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001910 Mostly useful for debugging the vmalloc code on platforms
1911 that don't require it.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001912
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001913 Say N if unsure.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001914
Thomas Gleixner0793a612008-12-04 20:12:29 +01001915endmenu
1916
Christoph Lameterf8891e52006-06-30 01:55:45 -07001917config VM_EVENT_COUNTERS
1918 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001919 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001920 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001921 VM event counters are needed for event counts to be shown.
1922 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001923 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001924 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001925
Tao Huangff4142e2019-09-17 18:20:52 +08001926config SLUB_SYSFS
1927 bool "Enable SLUB sysfs interface"
1928 depends on SLUB && SYSFS
1929 default y
1930
Christoph Lameter41ecc552007-05-09 02:32:44 -07001931config SLUB_DEBUG
1932 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001933 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001934 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001935 help
1936 SLUB has extensive debug support features. Disabling these can
1937 result in significant savings in code size. This also disables
1938 SLUB sysfs support. /sys/slab will not exist and there will be
1939 no support for cache validation etc.
1940
Tejun Heo1663f262017-02-22 15:41:39 -08001941config SLUB_MEMCG_SYSFS_ON
1942 default n
1943 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1944 depends on SLUB && SYSFS && MEMCG
1945 help
1946 SLUB creates a directory under /sys/kernel/slab for each
1947 allocation cache to host info and debug files. If memory
1948 cgroup is enabled, each cache can have per memory cgroup
1949 caches. SLUB can create the same sysfs directories for these
1950 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1951 to a very high number of debug files being created. This is
1952 controlled by slub_memcg_sysfs boot parameter and this
1953 config option determines the parameter's default value.
1954
Randy Dunlapb943c462009-03-10 12:55:46 -07001955config COMPAT_BRK
1956 bool "Disable heap randomization"
1957 default y
1958 help
1959 Randomizing heap placement makes heap exploits harder, but it
1960 also breaks ancient binaries (including anything libc5 based).
1961 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001962 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001963 /proc/sys/kernel/randomize_va_space to 2.
1964
1965 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1966
Christoph Lameter81819f02007-05-06 14:49:36 -07001967choice
1968 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001969 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001970 help
1971 This option allows to select a slab allocator.
1972
1973config SLAB
1974 bool "SLAB"
Kees Cook04385fc2016-06-23 15:20:59 -07001975 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001976 help
1977 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001978 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001979 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001980
1981config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001982 bool "SLUB (Unqueued Allocator)"
Kees Cooked18adc2016-06-23 15:24:05 -07001983 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001984 help
1985 SLUB is a slab allocator that minimizes cache line usage
1986 instead of managing queues of cached objects (SLAB approach).
1987 Per cpu caching is realized using slabs of objects instead
1988 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001989 and has enhanced diagnostics. SLUB is the default choice for
1990 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001991
1992config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001993 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001994 bool "SLOB (Simple Allocator)"
1995 help
Matt Mackall37291452008-02-04 22:29:38 -08001996 SLOB replaces the stock allocator with a drastically simpler
1997 allocator. SLOB is generally more space efficient but
1998 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001999
2000endchoice
2001
Kees Cook7660a6f2017-07-06 15:36:40 -07002002config SLAB_MERGE_DEFAULT
2003 bool "Allow slab caches to be merged"
2004 default y
2005 help
2006 For reduced kernel memory fragmentation, slab caches can be
2007 merged when they share the same size and other characteristics.
2008 This carries a risk of kernel heap overflows being able to
2009 overwrite objects from merged caches (and more easily control
2010 cache layout), which makes such heap attacks easier to exploit
2011 by attackers. By keeping caches unmerged, these kinds of exploits
2012 can usually only damage objects in the same cache. To disable
2013 merging at runtime, "slab_nomerge" can be passed on the kernel
2014 command line.
2015
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07002016config SLAB_FREELIST_RANDOM
Kees Cook3404be62020-08-06 23:18:20 -07002017 bool "Randomize slab freelist"
Thomas Garnier210e7a42016-07-26 15:21:59 -07002018 depends on SLAB || SLUB
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07002019 help
Thomas Garnier210e7a42016-07-26 15:21:59 -07002020 Randomizes the freelist order used on creating new pages. This
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07002021 security feature reduces the predictability of the kernel slab
2022 allocator against heap overflows.
2023
Kees Cook2482ddec2017-09-06 16:19:18 -07002024config SLAB_FREELIST_HARDENED
2025 bool "Harden slab freelist metadata"
Kees Cook3404be62020-08-06 23:18:20 -07002026 depends on SLAB || SLUB
Kees Cook2482ddec2017-09-06 16:19:18 -07002027 help
2028 Many kernel heap attacks try to target slab cache metadata and
2029 other infrastructure. This options makes minor performance
Kees Cook92bae782019-07-16 16:27:57 -07002030 sacrifices to harden the kernel slab allocator against common
Kees Cook3404be62020-08-06 23:18:20 -07002031 freelist exploit methods. Some slab implementations have more
2032 sanity-checking than others. This option is most effective with
2033 CONFIG_SLUB.
Kees Cook2482ddec2017-09-06 16:19:18 -07002034
Dan Williamse900a912019-05-14 15:41:28 -07002035config SHUFFLE_PAGE_ALLOCATOR
2036 bool "Page allocator randomization"
2037 default SLAB_FREELIST_RANDOM && ACPI_NUMA
2038 help
2039 Randomization of the page allocator improves the average
2040 utilization of a direct-mapped memory-side-cache. See section
2041 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
2042 6.2a specification for an example of how a platform advertises
2043 the presence of a memory-side-cache. There are also incidental
2044 security benefits as it reduces the predictability of page
2045 allocations to compliment SLAB_FREELIST_RANDOM, but the
2046 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
2047 10th order of pages is selected based on cache utilization
2048 benefits on x86.
2049
2050 While the randomization improves cache utilization it may
2051 negatively impact workloads on platforms without a cache. For
2052 this reason, by default, the randomization is enabled only
2053 after runtime detection of a direct-mapped memory-side-cache.
2054 Otherwise, the randomization may be force enabled with the
2055 'page_alloc.shuffle' kernel command line parameter.
2056
2057 Say Y if unsure.
2058
Joonsoo Kim345c9052013-06-19 14:05:52 +09002059config SLUB_CPU_PARTIAL
2060 default y
Uwe Kleine-Königb39ffbf2013-07-17 16:54:59 +02002061 depends on SLUB && SMP
Joonsoo Kim345c9052013-06-19 14:05:52 +09002062 bool "SLUB per cpu partial cache"
2063 help
Kees Cook92bae782019-07-16 16:27:57 -07002064 Per cpu partial caches accelerate objects allocation and freeing
Joonsoo Kim345c9052013-06-19 14:05:52 +09002065 that is local to a processor at the price of more indeterminism
2066 in the latency of the free. On overflow these caches will be cleared
2067 which requires the taking of locks that may cause latency spikes.
2068 Typically one would choose no for a realtime system.
2069
Jie Zhangea637632009-12-14 18:00:02 -08002070config MMAP_ALLOW_UNINITIALIZED
2071 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08002072 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08002073 default n
2074 help
2075 Normally, and according to the Linux spec, anonymous memory obtained
Randy Dunlap3903bf92018-08-21 21:58:34 -07002076 from mmap() has its contents cleared before it is passed to
Jie Zhangea637632009-12-14 18:00:02 -08002077 userspace. Enabling this config option allows you to request that
2078 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
2079 providing a huge performance boost. If this option is not enabled,
2080 then the flag will be ignored.
2081
2082 This is taken advantage of by uClibc's malloc(), and also by
2083 ELF-FDPIC binfmt's brk and stack allocator.
2084
2085 Because of the obvious security issues, this option should only be
2086 enabled on embedded devices where you control what is run in
2087 userspace. Since that isn't generally a problem on no-MMU systems,
2088 it is normally safe to say Y here.
2089
Stephen Kittdd19d292020-08-12 11:22:30 +02002090 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
Jie Zhangea637632009-12-14 18:00:02 -08002091
David Howells091f6e22015-07-20 21:16:28 +01002092config SYSTEM_DATA_VERIFICATION
2093 def_bool n
2094 select SYSTEM_TRUSTED_KEYRING
2095 select KEYS
2096 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00002097 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01002098 select ASYMMETRIC_KEY_TYPE
2099 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01002100 select ASN1
2101 select OID_REGISTRY
2102 select X509_CERTIFICATE_PARSER
2103 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07002104 help
David Howells091f6e22015-07-20 21:16:28 +01002105 Provide PKCS#7 message verification using the contents of the system
2106 trusted keyring to provide public keys. This then can be used for
2107 module verification, kexec image verification and firmware blob
2108 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07002109
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05002110config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01002111 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05002112 help
2113 Say Y here to enable the extended profiling support mechanisms used
2114 by profilers such as OProfile.
2115
Ingo Molnar5f87f112008-07-23 14:15:22 +02002116#
2117# Place an empty function call at each tracepoint site. Can be
2118# dynamically changed for a probe function.
2119#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04002120config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02002121 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04002122
Linus Torvalds1da177e2005-04-16 15:20:36 -07002123endmenu # General setup
2124
Christoph Hellwig15724972018-07-31 13:39:30 +02002125source "arch/Kconfig"
2126
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07002127config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05002128 bool
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07002129
Linus Torvalds1da177e2005-04-16 15:20:36 -07002130config BASE_SMALL
2131 int
2132 default 0 if BASE_FULL
2133 default 1 if !BASE_FULL
2134
Thiago Jung Bauermannc8424e72019-07-04 15:57:34 -03002135config MODULE_SIG_FORMAT
2136 def_bool n
2137 select SYSTEM_DATA_VERIFICATION
2138
Jan Engelhardt66da5732007-07-15 23:39:29 -07002139menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140 bool "Enable loadable module support"
Yann E. MORIN11097a02013-08-11 16:07:50 +02002141 option modules
Linus Torvalds1da177e2005-04-16 15:20:36 -07002142 help
2143 Kernel modules are small pieces of compiled code which can
2144 be inserted in the running kernel, rather than being
2145 permanently built into the kernel. You use the "modprobe"
2146 tool to add (and sometimes remove) them. If you say Y here,
2147 many parts of the kernel can be built as modules (by
2148 answering M instead of Y where indicated): this is most
2149 useful for infrequently used options which are not required
2150 for booting. For more information, see the man pages for
2151 modprobe, lsmod, modinfo, insmod and rmmod.
2152
2153 If you say Y here, you will need to run "make
2154 modules_install" to put the modules under /lib/modules/
2155 where modprobe can find them (you may need to be root to do
2156 this).
2157
2158 If unsure, say Y.
2159
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002160if MODULES
2161
Linus Torvalds826e4502008-05-04 17:04:16 -07002162config MODULE_FORCE_LOAD
2163 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07002164 default n
2165 help
Rusty Russell91e37a72008-05-09 16:25:28 +10002166 Allow loading of modules without version information (ie. modprobe
2167 --force). Forced module loading sets the 'F' (forced) taint flag and
2168 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07002169
Linus Torvalds1da177e2005-04-16 15:20:36 -07002170config MODULE_UNLOAD
2171 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002172 help
2173 Without this option you will not be able to unload any
2174 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05002175 anyway), which makes your kernel smaller, faster
2176 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177
2178config MODULE_FORCE_UNLOAD
2179 bool "Forced module unloading"
Kees Cook19c92392012-10-02 11:19:29 -07002180 depends on MODULE_UNLOAD
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181 help
2182 This option allows you to force a module to unload, even if the
2183 kernel believes it is unsafe: the kernel will remove the module
2184 without waiting for anyone to stop using it (using the -f option to
2185 rmmod). This is mainly for kernel developers and desperate users.
2186 If unsure, say N.
2187
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01002189 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002190 help
2191 Usually, you have to use modules compiled with your kernel.
2192 Saying Y here makes it sometimes possible to use modules
2193 compiled for different kernels, by adding enough information
2194 to the modules to (hopefully) spot any changes which would
2195 make them incompatible with the kernel you are running. If
2196 unsure, say N.
2197
Masahiro Yamada2ff2b7e2019-08-19 14:54:20 +09002198config ASM_MODVERSIONS
2199 bool
2200 default HAVE_ASM_MODVERSIONS && MODVERSIONS
2201 help
2202 This enables module versioning for exported symbols also from
2203 assembly. This can be enabled only when the target architecture
2204 supports it.
2205
Ard Biesheuvel56067812017-02-03 09:54:05 +00002206config MODULE_REL_CRCS
2207 bool
2208 depends on MODVERSIONS
2209
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210config MODULE_SRCVERSION_ALL
2211 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212 help
2213 Modules which contain a MODULE_VERSION get an extra "srcversion"
2214 field inserted into their modinfo section, which contains a
2215 sum of the source files which made it. This helps maintainers
2216 see exactly which source was used to build a module (since
2217 others sometimes change the module source without updating
2218 the version). With this option, such a "srcversion" field
2219 will be created for all modules. If unsure, say N.
2220
Will McVickerda2089a2020-11-19 13:46:37 -08002221config MODULE_SCMVERSION
2222 bool "SCM version for modules"
2223 depends on LOCALVERSION_AUTO
2224 help
2225 This enables the module attribute "scmversion" which can be used
2226 by developers to identify the SCM version of a given module, e.g.
2227 git sha1 or hg sha1. The SCM version can be queried by modinfo or
2228 via the sysfs node: /sys/modules/MODULENAME/scmversion. This is
2229 useful when the kernel or kernel modules are updated separately
2230 since that causes the vermagic of the kernel and the module to
2231 differ.
2232
2233 If unsure, say N.
2234
Rusty Russell106a4ee2012-09-26 10:09:40 +01002235config MODULE_SIG
2236 bool "Module signature verification"
Matthias Maennich537d1f72019-11-11 14:56:43 +00002237 select MODULE_SIG_FORMAT
Rusty Russell106a4ee2012-09-26 10:09:40 +01002238 help
2239 Check modules for valid signatures upon load: the signature
2240 is simply appended to the module. For more information see
Nathan Chancellorcbdc8212017-09-10 02:48:29 -07002241 <file:Documentation/admin-guide/module-signing.rst>.
Rusty Russell106a4ee2012-09-26 10:09:40 +01002242
David Howells228c37f2015-08-11 12:38:54 +01002243 Note that this option adds the OpenSSL development packages as a
2244 kernel build dependency so that the signing tool can use its crypto
2245 library.
2246
David Howells49fcf732019-08-19 17:17:40 -07002247 You should enable this option if you wish to use either
2248 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
2249 another LSM - otherwise unsigned modules will be loadable regardless
2250 of the lockdown policy.
2251
David Howellsea0b6dc2012-09-26 10:09:50 +01002252 !!!WARNING!!! If you enable this option, you MUST make sure that the
2253 module DOES NOT get stripped after being signed. This includes the
2254 debuginfo strip done by some packagers (such as rpmbuild) and
2255 inclusion into an initramfs that wants the module size reduced.
2256
Rusty Russell106a4ee2012-09-26 10:09:40 +01002257config MODULE_SIG_FORCE
2258 bool "Require modules to be validly signed"
2259 depends on MODULE_SIG
2260 help
2261 Reject unsigned modules or signed modules for which we don't have a
2262 key. Without this, such modules will simply taint the kernel.
David Howellsea0b6dc2012-09-26 10:09:50 +01002263
Michal Marekd9d8d7e2013-01-25 13:41:31 +10302264config MODULE_SIG_ALL
2265 bool "Automatically sign all modules"
2266 default y
2267 depends on MODULE_SIG
2268 help
2269 Sign all modules during make modules_install. Without this option,
2270 modules must be signed manually, using the scripts/sign-file tool.
2271
2272comment "Do not forget to sign required modules with scripts/sign-file"
2273 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
2274
David Howellsea0b6dc2012-09-26 10:09:50 +01002275choice
2276 prompt "Which hash algorithm should modules be signed with?"
2277 depends on MODULE_SIG
2278 help
2279 This determines which sort of hashing algorithm will be used during
2280 signature generation. This algorithm _must_ be built into the kernel
2281 directly so that signature verification can take place. It is not
2282 possible to load a signed module containing the algorithm to check
2283 the signature on that module.
2284
2285config MODULE_SIG_SHA1
2286 bool "Sign modules with SHA-1"
2287 select CRYPTO_SHA1
2288
2289config MODULE_SIG_SHA224
2290 bool "Sign modules with SHA-224"
2291 select CRYPTO_SHA256
2292
2293config MODULE_SIG_SHA256
2294 bool "Sign modules with SHA-256"
2295 select CRYPTO_SHA256
2296
2297config MODULE_SIG_SHA384
2298 bool "Sign modules with SHA-384"
2299 select CRYPTO_SHA512
2300
2301config MODULE_SIG_SHA512
2302 bool "Sign modules with SHA-512"
2303 select CRYPTO_SHA512
2304
2305endchoice
2306
Michal Marek22753672013-01-25 13:41:00 +10302307config MODULE_SIG_HASH
2308 string
2309 depends on MODULE_SIG
2310 default "sha1" if MODULE_SIG_SHA1
2311 default "sha224" if MODULE_SIG_SHA224
2312 default "sha256" if MODULE_SIG_SHA256
2313 default "sha384" if MODULE_SIG_SHA384
2314 default "sha512" if MODULE_SIG_SHA512
2315
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302316config MODULE_COMPRESS
2317 bool "Compress modules on installation"
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302318 help
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302319
Rusty Russellb6c09b52015-06-16 12:16:22 +09302320 Compresses kernel modules when 'make modules_install' is run; gzip or
2321 xz depending on "Compression algorithm" below.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302322
Rusty Russellb6c09b52015-06-16 12:16:22 +09302323 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302324
Rusty Russellb6c09b52015-06-16 12:16:22 +09302325 Out-of-tree kernel modules installed using Kbuild will also be
2326 compressed upon installation.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302327
Rusty Russellb6c09b52015-06-16 12:16:22 +09302328 Note: for modules inside an initrd or initramfs, it's more efficient
2329 to compress the whole initrd or initramfs instead.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302330
Rusty Russellb6c09b52015-06-16 12:16:22 +09302331 Note: This is fully compatible with signed modules.
2332
2333 If in doubt, say N.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302334
2335choice
2336 prompt "Compression algorithm"
2337 depends on MODULE_COMPRESS
2338 default MODULE_COMPRESS_GZIP
2339 help
2340 This determines which sort of compression will be used during
2341 'make modules_install'.
2342
2343 GZIP (default) and XZ are supported.
2344
2345config MODULE_COMPRESS_GZIP
2346 bool "GZIP"
2347
2348config MODULE_COMPRESS_XZ
2349 bool "XZ"
2350
2351endchoice
2352
Matthias Maennich537d1f72019-11-11 14:56:43 +00002353config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
2354 bool "Allow loading of modules with missing namespace imports"
2355 help
2356 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
2357 a namespace. A module that makes use of a symbol exported with such a
2358 namespace is required to import the namespace via MODULE_IMPORT_NS().
2359 There is no technical reason to enforce correct namespace imports,
2360 but it creates consistency between symbols defining namespaces and
2361 users importing namespaces they make use of. This option relaxes this
2362 requirement and lifts the enforcement when loading a module.
2363
2364 If unsure, say N.
2365
2366config UNUSED_SYMBOLS
2367 bool "Enable unused/obsolete exported symbols"
2368 default y if X86
2369 help
2370 Unused but exported symbols make the kernel needlessly bigger. For
2371 that reason most of these unused exports will soon be removed. This
2372 option is provided temporarily to provide a transition period in case
2373 some external kernel module needs one of these symbols anyway. If you
2374 encounter such a case in your module, consider if you are actually
2375 using the right API. (rationale: since nobody in the kernel is using
2376 this in a module, there is a pretty good chance it's actually the
2377 wrong interface to use). If you really need the symbol, please send a
2378 mail to the linux kernel mailing list mentioning the symbol and why
2379 you really need it, and what the merge plan to the mainline kernel for
2380 your module is.
2381
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002382config TRIM_UNUSED_KSYMS
2383 bool "Trim unused exported kernel symbols"
Matthias Maennich537d1f72019-11-11 14:56:43 +00002384 depends on !UNUSED_SYMBOLS
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002385 help
2386 The kernel and some modules make many symbols available for
2387 other modules to use via EXPORT_SYMBOL() and variants. Depending
2388 on the set of modules being selected in your kernel configuration,
2389 many of those exported symbols might never be used.
2390
2391 This option allows for unused exported symbols to be dropped from
2392 the build. In turn, this provides the compiler more opportunities
2393 (especially when using LTO) for optimizing the code and reducing
2394 binary size. This might have some security advantages as well.
2395
Valdis Kletnieksf1cb6372016-08-02 14:07:27 -07002396 If unsure, or if you need to build out-of-tree modules, say N.
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002397
Quentin Perret92f76ef2020-02-18 09:41:37 +00002398config UNUSED_KSYMS_WHITELIST
2399 string "Whitelist of symbols to keep in ksymtab"
2400 depends on TRIM_UNUSED_KSYMS
2401 help
2402 By default, all unused exported symbols will be un-exported from the
2403 build when TRIM_UNUSED_KSYMS is selected.
2404
2405 UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
2406 exported at all times, even in absence of in-tree users. The value to
2407 set here is the path to a text file containing the list of symbols,
2408 one per line. The path can be absolute, or relative to the kernel
2409 source tree.
2410
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002411endif # MODULES
2412
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302413config MODULES_TREE_LOOKUP
2414 def_bool y
Sami Tolvanen2c351bb2019-04-25 16:09:05 -07002415 depends on PERF_EVENTS || TRACING || CFI_CLANG
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302416
Rusty Russell98a79d62008-12-13 21:19:41 +10302417config INIT_ALL_POSSIBLE
2418 bool
2419 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302420 Back when each arch used to define their own cpu_online_mask and
2421 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302422 with all 1s, and others with all 0s. When they were centralised,
2423 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002424 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302425
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002426source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002427
2428config PREEMPT_NOTIFIERS
2429 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002430
Steffen Klassert16295be2010-01-06 19:47:10 +11002431config PADATA
2432 depends on SMP
2433 bool
2434
David Howells4520c6a2012-09-21 23:31:13 +01002435config ASN1
2436 tristate
2437 help
2438 Build a simple ASN.1 grammar compiler that produces a bytecode output
2439 that can be interpreted by the ASN.1 stream decoder and used to
2440 inform it as to what tags are to be expected in a stream and what
2441 functions to call on what tags.
2442
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002443source "kernel/Kconfig.locks"
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05002444
Daniel Borkmann0ebeea82020-05-15 12:11:16 +02002445config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2446 bool
2447
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05002448config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2449 bool
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002450
2451# It may be useful for an architecture to override the definitions of the
Dominik Brodowski7303e302018-04-05 11:53:03 +02002452# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2453# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2454# different calling convention for syscalls. They can also override the
2455# macros for not-implemented syscalls in kernel/sys_ni.c and
2456# kernel/time/posix-stubs.c. All these overrides need to be available in
2457# <asm/syscall_wrapper.h>.
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002458config ARCH_HAS_SYSCALL_WRAPPER
2459 def_bool n
Todd Kjos2de45b62019-08-28 15:52:02 -07002460
Tao Huang5e8a9b42022-02-27 15:16:12 +08002461if !ROCKCHIP_MINI_KERNEL
Todd Kjos2de45b62019-08-28 15:52:02 -07002462source "init/Kconfig.gki"
Tao Huang5e8a9b42022-02-27 15:16:12 +08002463endif