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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 Yamadaa4353892018-05-28 18:22:01 +090011config CC_IS_GCC
12 def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
13
14config GCC_VERSION
15 int
Masahiro Yamadafa7295a2019-03-01 16:10:22 +090016 default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
Masahiro Yamadaa4353892018-05-28 18:22:01 +090017 default 0
18
Amit Daniel Kachhap9553d162020-03-30 17:11:38 +053019config LD_VERSION
20 int
21 default $(shell,$(LD) --version | $(srctree)/scripts/ld-version.sh)
22
Masahiro Yamada469cb732018-05-28 18:22:02 +090023config CC_IS_CLANG
24 def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
25
26config CLANG_VERSION
27 int
28 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
29
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090030config CC_CAN_LINK
31 def_bool $(success,$(srctree)/scripts/cc-can-link.sh $(CC))
32
Masahiro Yamadae9666d12018-12-31 00:14:15 +090033config CC_HAS_ASM_GOTO
34 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
35
Peter Collingbourne5cf896fb62019-07-31 18:18:42 -070036config TOOLS_SUPPORT_RELR
Will Deacon2d122942019-08-20 10:11:54 +010037 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
Peter Collingbourne5cf896fb62019-07-31 18:18:42 -070038
Rasmus Villemoeseb111862019-09-13 00:19:25 +020039config CC_HAS_ASM_INLINE
40 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
41
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -070042config CONSTRUCTORS
43 bool
Johannes Berg87c93662019-12-04 17:43:46 +010044 depends on !UML
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -070045
Peter Zijlstrae360adb2010-10-14 14:01:34 +080046config IRQ_WORK
47 bool
Peter Zijlstrae360adb2010-10-14 14:01:34 +080048
Shile Zhang10916702019-12-04 08:46:31 +080049config BUILDTIME_TABLE_SORT
David Daney1dbdc6f2012-04-19 14:59:57 -070050 bool
51
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070052config THREAD_INFO_IN_TASK
53 bool
54 help
55 Select this to move thread_info off the stack into task_struct. To
56 make this work, an arch will need to remove all thread_info fields
57 except flags and fix any runtime bugs.
58
Andy Lutomirskic6c314a2016-09-15 22:45:43 -070059 One subtle change that will be needed is to use try_get_task_stack()
60 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
61
Al Boldiff0cfc62007-07-31 00:39:23 -070062menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -070063
Linus Torvalds1da177e2005-04-16 15:20:36 -070064config BROKEN
65 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -070066
67config BROKEN_ON_SMP
68 bool
69 depends on BROKEN || !SMP
70 default y
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072config INIT_ENV_ARG_LIMIT
73 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -070074 default 32 if !UML
75 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 help
Randy Dunlap34ad92c22005-10-30 15:01:46 -080077 Maximum of each of the number of arguments and environment
78 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
Jiri Slaby4bb16672013-05-22 10:56:24 +020080config COMPILE_TEST
81 bool "Compile also drivers which will not load"
Richard Weinbergerbc083a62016-08-02 14:03:27 -070082 depends on !UML
Jiri Slaby4bb16672013-05-22 10:56:24 +020083 default n
84 help
85 Some drivers can be compiled on a different platform than they are
86 intended to be run on. Despite they cannot be loaded there (or even
87 when they load they cannot be used due to missing HW support),
88 developers still, opposing to distributors, might want to build such
89 drivers to compile-test them.
90
91 If you are a developer and want to build everything available, say Y
92 here. If you are a user/distributor, say N here to exclude useless
93 drivers to be distributed.
94
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +090095config UAPI_HEADER_TEST
96 bool "Compile test UAPI headers"
Masahiro Yamadafcbb8462019-11-07 16:14:40 +090097 depends on HEADERS_INSTALL && CC_CAN_LINK
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +090098 help
99 Compile test headers exported to user-space to ensure they are
100 self-contained, i.e. compilable as standalone units.
101
102 If you are a developer or tester and want to ensure the exported
103 headers are self-contained, say Y here. Otherwise, choose N.
104
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105config LOCALVERSION
106 string "Local version - append to kernel release"
107 help
108 Append an extra string to the end of your kernel version.
109 This will show up when you type uname, for example.
110 The string you set here will be appended after the contents of
111 any files with a filename matching localversion* in your
112 object and source tree, in that order. Your total string can
113 be a maximum of 64 characters.
114
Ryan Andersonaaebf432005-07-31 04:57:49 -0400115config LOCALVERSION_AUTO
116 bool "Automatically append version information to the version string"
117 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -0700118 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -0400119 help
120 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200121 release tree by looking for git tags that belong to the current
122 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400123
124 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200125 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400126 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200127 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400128
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200129 (The actual string used here is the first eight characters produced
130 by running the command:
131
132 $ git rev-parse --verify HEAD
133
134 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400135
Laura Abbott9afb7192018-07-05 17:49:37 -0700136config BUILD_SALT
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800137 string "Build ID Salt"
138 default ""
139 help
140 The build ID is used to link binaries and their debug info. Setting
141 this option will use the value in the calculation of the build id.
142 This is mostly useful for distributions which want to ensure the
143 build is unique between builds. It's safe to leave the default.
Laura Abbott9afb7192018-07-05 17:49:37 -0700144
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800145config HAVE_KERNEL_GZIP
146 bool
147
148config HAVE_KERNEL_BZIP2
149 bool
150
151config HAVE_KERNEL_LZMA
152 bool
153
Lasse Collin3ebe1242011-01-12 17:01:23 -0800154config HAVE_KERNEL_XZ
155 bool
156
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800157config HAVE_KERNEL_LZO
158 bool
159
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700160config HAVE_KERNEL_LZ4
161 bool
162
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200163config HAVE_KERNEL_UNCOMPRESSED
164 bool
165
Alain Knaff30d65db2009-01-04 22:46:17 +0100166choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800167 prompt "Kernel compression mode"
168 default KERNEL_GZIP
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200169 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800170 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100171 The linux kernel is a kind of self-extracting executable.
172 Several compression algorithms are available, which differ
173 in efficiency, compression and decompression speed.
174 Compression speed is only relevant when building a kernel.
175 Decompression speed is relevant at each boot.
176
177 If you have any problems with bzip2 or lzma compressed
178 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
179 version of this functionality (bzip2 only), for 2.4, was
180 supplied by Christian Ludwig)
181
182 High compression options are mostly useful for users, who
183 are low on disk space (embedded systems), but for whom ram
184 size matters less.
185
186 If in doubt, select 'gzip'
187
188config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800189 bool "Gzip"
190 depends on HAVE_KERNEL_GZIP
191 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800192 The old and tried gzip compression. It provides a good balance
193 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100194
195config KERNEL_BZIP2
196 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800197 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100198 help
199 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700200 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800201 size is about 10% smaller with bzip2, in comparison to gzip.
202 Bzip2 uses a large amount of memory. For modern kernels you
203 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100204
205config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800206 bool "LZMA"
207 depends on HAVE_KERNEL_LZMA
208 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700209 This compression algorithm's ratio is best. Decompression speed
210 is between gzip and bzip2. Compression is slowest.
211 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100212
Lasse Collin3ebe1242011-01-12 17:01:23 -0800213config KERNEL_XZ
214 bool "XZ"
215 depends on HAVE_KERNEL_XZ
216 help
217 XZ uses the LZMA2 algorithm and instruction set specific
218 BCJ filters which can improve compression ratio of executable
219 code. The size of the kernel is about 30% smaller with XZ in
220 comparison to gzip. On architectures for which there is a BCJ
221 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
222 will create a few percent smaller kernel than plain LZMA.
223
224 The speed is about the same as with LZMA: The decompression
225 speed of XZ is better than that of bzip2 but worse than gzip
226 and LZO. Compression is slow.
227
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800228config KERNEL_LZO
229 bool "LZO"
230 depends on HAVE_KERNEL_LZO
231 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700232 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200233 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800234 (both compression and decompression) is the fastest.
235
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700236config KERNEL_LZ4
237 bool "LZ4"
238 depends on HAVE_KERNEL_LZ4
239 help
240 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
241 A preliminary version of LZ4 de/compression tool is available at
242 <https://code.google.com/p/lz4/>.
243
244 Its compression ratio is worse than LZO. The size of the kernel
245 is about 8% bigger than LZO. But the decompression speed is
246 faster than LZO.
247
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200248config KERNEL_UNCOMPRESSED
249 bool "None"
250 depends on HAVE_KERNEL_UNCOMPRESSED
251 help
252 Produce uncompressed kernel image. This option is usually not what
253 you want. It is useful for debugging the kernel in slow simulation
254 environments, where decompressing and moving the kernel is awfully
255 slow. This option allows early boot code to skip the decompressor
256 and jump right at uncompressed kernel image.
257
Alain Knaff30d65db2009-01-04 22:46:17 +0100258endchoice
259
Josh Triplettbd5dc172011-06-15 15:08:28 -0700260config DEFAULT_HOSTNAME
261 string "Default hostname"
262 default "(none)"
263 help
264 This option determines the default system hostname before userspace
265 calls sethostname(2). The kernel traditionally uses "(none)" here,
266 but you may wish to use a different default here to make a minimal
267 system more usable with less configuration.
268
Christoph Hellwig17c46a62018-07-31 13:39:29 +0200269#
270# For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
271# add proper SWAP support to them, in which case this can be remove.
272#
273config ARCH_NO_SWAP
274 bool
275
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276config SWAP
277 bool "Support for paging of anonymous memory (swap)"
Christoph Hellwig17c46a62018-07-31 13:39:29 +0200278 depends on MMU && BLOCK && !ARCH_NO_SWAP
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 default y
280 help
281 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100282 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 used to provide more virtual memory than the actual RAM present
284 in your computer. If unsure say Y.
285
286config SYSVIPC
287 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 ---help---
289 Inter Process Communication is a suite of library functions and
290 system calls which let processes (running programs) synchronize and
291 exchange information. It is generally considered to be a good thing,
292 and some programs won't run unless you say Y here. In particular, if
293 you want to run the DOS emulator dosemu under Linux (read the
294 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
295 you'll need to say Y here.
296
297 You can find documentation about IPC with "info ipc" and also in
298 section 6.4 of the Linux Programmer's Guide, available from
299 <http://www.tldp.org/guides.html>.
300
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800301config SYSVIPC_SYSCTL
302 bool
303 depends on SYSVIPC
304 depends on SYSCTL
305 default y
306
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307config POSIX_MQUEUE
308 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700309 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 ---help---
311 POSIX variant of message queues is a part of IPC. In POSIX message
312 queues every message has a priority which decides about succession
313 of receiving it by a process. If you want to compile and run
314 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e376502007-05-09 07:25:13 +0200315 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316
317 POSIX message queues are visible as a filesystem called 'mqueue'
318 and can be mounted somewhere if you want to do filesystem
319 operations on message queues.
320
321 If unsure, say Y.
322
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700323config POSIX_MQUEUE_SYSCTL
324 bool
325 depends on POSIX_MQUEUE
326 depends on SYSCTL
327 default y
328
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700329config CROSS_MEMORY_ATTACH
330 bool "Enable process_vm_readv/writev syscalls"
331 depends on MMU
332 default y
333 help
334 Enabling this option adds the system calls process_vm_readv and
335 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700336 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700337 See the man page for more details.
338
Josh Triplett69369a72014-04-03 14:48:27 -0700339config USELIB
340 bool "uselib syscall"
Riku Voipiob2113a42016-01-15 16:58:13 -0800341 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
Josh Triplett69369a72014-04-03 14:48:27 -0700342 help
343 This option enables the uselib syscall, a system call used in the
344 dynamic linker from libc5 and earlier. glibc does not use this
345 system call. If you intend to run programs built on libc5 or
346 earlier, you may need to enable this syscall. Current systems
347 running glibc can safely disable this.
348
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349config AUDIT
350 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100351 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 help
353 Enable auditing infrastructure that can be used with another
354 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500355 logging of avc messages output). System call auditing is included
356 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900358config HAVE_ARCH_AUDITSYSCALL
359 bool
360
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500362 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900363 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500364 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400365
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000366source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200367source "kernel/time/Kconfig"
Christoph Hellwig87a4c372018-07-31 13:39:32 +0200368source "kernel/Kconfig.preempt"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000369
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200370menu "CPU/Task time and stats accounting"
371
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200372config VIRT_CPU_ACCOUNTING
373 bool
374
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200375choice
376 prompt "Cputime accounting"
377 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100378 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200379
380# Kind of a stub config for the pure tick based cputime accounting
381config TICK_CPU_ACCOUNTING
382 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200383 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200384 help
385 This is the basic tick based cputime accounting that maintains
386 statistics about user, system and idle time spent on per jiffies
387 granularity.
388
389 If unsure, say Y.
390
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200391config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200392 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200393 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200394 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200395 help
396 Select this option to enable more accurate task and CPU time
397 accounting. This is done by reading a CPU counter on each
398 kernel entry and exit and on transitions within the kernel
399 between system, softirq and hardirq state, so there is a
400 small performance impact. In the case of s390 or IBM POWER > 5,
401 this also enables accounting of stolen time on logically-partitioned
402 systems.
403
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200404config VIRT_CPU_ACCOUNTING_GEN
405 bool "Full dynticks CPU time accounting"
Kevin Hilmanff3fb252013-09-16 15:28:19 -0700406 depends on HAVE_CONTEXT_TRACKING
Kevin Hilman554b0002013-09-16 15:28:21 -0700407 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Arnd Bergmann041a1572019-03-04 21:01:31 +0100408 depends on GENERIC_CLOCKEVENTS
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200409 select VIRT_CPU_ACCOUNTING
410 select CONTEXT_TRACKING
411 help
412 Select this option to enable task and CPU time accounting on full
413 dynticks systems. This accounting is implemented by watching every
414 kernel-user boundaries using the context tracking subsystem.
415 The accounting is thus performed at the expense of some significant
416 overhead.
417
418 For now this is only useful if you are working on the full
419 dynticks subsystem development.
420
421 If unsure, say N.
422
Rik van Rielb58c3582016-07-13 16:50:02 +0200423endchoice
424
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200425config IRQ_TIME_ACCOUNTING
426 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200427 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200428 help
429 Select this option to enable fine granularity task irq time
430 accounting. This is done by reading a timestamp on each
431 transitions between softirq and hardirq state, so there can be a
432 small performance impact.
433
434 If in doubt, say N here.
435
Vincent Guittot11d4afd2018-09-25 11:17:42 +0200436config HAVE_SCHED_AVG_IRQ
437 def_bool y
438 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
439 depends on SMP
440
Thara Gopinath76504792020-02-21 19:52:05 -0500441config SCHED_THERMAL_PRESSURE
442 bool "Enable periodic averaging of thermal pressure"
443 depends on SMP
444
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200445config BSD_PROCESS_ACCT
446 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700447 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200448 help
449 If you say Y here, a user level program will be able to instruct the
450 kernel (via a special system call) to write process accounting
451 information to a file: whenever a process exits, information about
452 that process will be appended to the file by the kernel. The
453 information includes things such as creation time, owning user,
454 command name, memory usage, controlling terminal etc. (the complete
455 list is in the struct acct in <file:include/linux/acct.h>). It is
456 up to the user level program to do useful things with this
457 information. This is generally a good idea, so say Y.
458
459config BSD_PROCESS_ACCT_V3
460 bool "BSD Process Accounting version 3 file format"
461 depends on BSD_PROCESS_ACCT
462 default n
463 help
464 If you say Y here, the process accounting information is written
465 in a new file format that also logs the process IDs of each
Randy Dunlap3903bf92018-08-21 21:58:34 -0700466 process and its parent. Note that this file format is incompatible
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200467 with previous v0/v1/v2 file formats, so you will need updated tools
468 for processing it. A preliminary version of these tools is available
469 at <http://www.gnu.org/software/acct/>.
470
471config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700472 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200473 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700474 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200475 default n
476 help
477 Export selected statistics for tasks/processes through the
478 generic netlink interface. Unlike BSD process accounting, the
479 statistics are available during the lifetime of tasks/processes as
480 responses to commands. Like BSD accounting, they are sent to user
481 space on task exit.
482
483 Say N if unsure.
484
485config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700486 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200487 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530488 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200489 help
490 Collect information on time spent by a task waiting for system
491 resources like cpu, synchronous block I/O completion and swapping
492 in pages. Such statistics can help in setting a task's priorities
493 relative to other tasks for cpu, io, rss limits etc.
494
495 Say N if unsure.
496
497config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700498 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200499 depends on TASKSTATS
500 help
501 Collect extended task accounting data and send the data
502 to userland for processing over the taskstats interface.
503
504 Say N if unsure.
505
506config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700507 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200508 depends on TASK_XACCT
509 help
510 Collect information on the number of bytes of storage I/O which this
511 task has caused.
512
513 Say N if unsure.
514
Johannes Weinereb414682018-10-26 15:06:27 -0700515config PSI
516 bool "Pressure stall information tracking"
517 help
518 Collect metrics that indicate how overcommitted the CPU, memory,
519 and IO capacity are in the system.
520
521 If you say Y here, the kernel will create /proc/pressure/ with the
522 pressure statistics files cpu, memory, and io. These will indicate
523 the share of walltime in which some or all tasks in the system are
524 delayed due to contention of the respective resource.
525
Johannes Weiner2ce71352018-10-26 15:06:31 -0700526 In kernels with cgroup support, cgroups (cgroup2 only) will
527 have cpu.pressure, memory.pressure, and io.pressure files,
528 which aggregate pressure stalls for the grouped tasks only.
529
Mauro Carvalho Chehabc3123552019-04-17 05:46:08 -0300530 For more details see Documentation/accounting/psi.rst.
Johannes Weinereb414682018-10-26 15:06:27 -0700531
532 Say N if unsure.
533
Johannes Weinere0c27442018-11-30 14:09:58 -0800534config PSI_DEFAULT_DISABLED
535 bool "Require boot parameter to enable pressure stall information tracking"
536 default n
537 depends on PSI
538 help
539 If set, pressure stall information tracking will be disabled
Baruch Siach428a1cb2018-12-14 14:17:03 -0800540 per default but can be enabled through passing psi=1 on the
541 kernel commandline during boot.
Johannes Weinere0c27442018-11-30 14:09:58 -0800542
Johannes Weiner7b2489d2019-02-01 14:21:15 -0800543 This feature adds some code to the task wakeup and sleep
544 paths of the scheduler. The overhead is too low to affect
545 common scheduling-intense workloads in practice (such as
546 webservers, memcache), but it does show up in artificial
547 scheduler stress tests, such as hackbench.
548
549 If you are paranoid and not sure what the kernel will be
550 used for, say Y.
551
552 Say N if unsure.
553
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200554endmenu # "CPU/Task time and stats accounting"
555
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200556config CPU_ISOLATION
557 bool "CPU isolation"
Geert Uytterhoeven414a2dc2018-01-02 12:13:10 +0100558 depends on SMP || COMPILE_TEST
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100559 default y
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200560 help
561 Make sure that CPUs running critical tasks are not disturbed by
562 any source of "noise" such as unbound workqueues, timers, kthreads...
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100563 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
564 the "isolcpus=" boot parameter.
565
566 Say Y if unsure.
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200567
Paul E. McKenney0af92d42017-05-17 08:43:40 -0700568source "kernel/rcu/Kconfig"
Mike Travisc903ff82009-01-15 12:28:29 -0800569
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700570config BUILD_BIN2C
571 bool
572 default n
573
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700575 tristate "Kernel .config support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 ---help---
577 This option enables the complete Linux kernel ".config" file
578 contents to be saved in the kernel. It provides documentation
579 of which kernel options are used in a running kernel or in an
580 on-disk kernel. This information can be extracted from the kernel
581 image file with the script scripts/extract-ikconfig and used as
582 input to rebuild the current kernel or to build another kernel.
583 It can also be extracted from a running kernel by reading
584 /proc/config.gz if enabled (below).
585
586config IKCONFIG_PROC
587 bool "Enable access to .config through /proc/config.gz"
588 depends on IKCONFIG && PROC_FS
589 ---help---
590 This option enables access to the kernel configuration file
591 through /proc/config.gz.
592
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400593config IKHEADERS
594 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
595 depends on SYSFS
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400596 help
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400597 This option enables access to the in-kernel headers that are generated during
598 the build process. These can be used to build eBPF tracing programs,
599 or similar programs. If you build the headers as a module, a module called
600 kheaders.ko is built which can be loaded on-demand to get access to headers.
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400601
Alistair John Strachan794543a2007-05-08 00:31:15 -0700602config LOG_BUF_SHIFT
603 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Ingo Molnarfb39f982015-07-01 10:19:11 +0200604 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700605 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700606 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700607 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700608 Select the minimal kernel log buffer size as a power of 2.
609 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
610 parameter, see below. Any higher size also might be forced
611 by "log_buf_len" boot parameter.
612
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700613 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700614 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700615 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700616 15 => 32 KB
617 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700618 13 => 8 KB
619 12 => 4 KB
620
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700621config LOG_CPU_MAX_BUF_SHIFT
622 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700623 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700624 range 0 21
625 default 12 if !BASE_SMALL
626 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700627 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700628 help
629 This option allows to increase the default ring buffer size
630 according to the number of CPUs. The value defines the contribution
631 of each CPU as a power of 2. The used space is typically only few
632 lines however it might be much more when problems are reported,
633 e.g. backtraces.
634
635 The increased size means that a new buffer has to be allocated and
636 the original static one is unused. It makes sense only on systems
637 with more CPUs. Therefore this value is used only when the sum of
638 contributions is greater than the half of the default kernel ring
639 buffer as defined by LOG_BUF_SHIFT. The default values are set
640 so that more than 64 CPUs are needed to trigger the allocation.
641
642 Also this option is ignored when "log_buf_len" kernel parameter is
643 used as it forces an exact (power of two) size of the ring buffer.
644
645 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200646 hotplugging making the computation optimal for the worst case
647 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700648
649 Examples shift values and their meaning:
650 17 => 128 KB for each CPU
651 16 => 64 KB for each CPU
652 15 => 32 KB for each CPU
653 14 => 16 KB for each CPU
654 13 => 8 KB for each CPU
655 12 => 4 KB for each CPU
656
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900657config PRINTK_SAFE_LOG_BUF_SHIFT
658 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
Petr Mladek427934b2016-05-20 17:00:39 -0700659 range 10 21
660 default 13
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900661 depends on PRINTK
Petr Mladek427934b2016-05-20 17:00:39 -0700662 help
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900663 Select the size of an alternate printk per-CPU buffer where messages
664 printed from usafe contexts are temporary stored. One example would
665 be NMI messages, another one - printk recursion. The messages are
666 copied to the main log buffer in a safe context to avoid a deadlock.
667 The value defines the size as a power of 2.
Petr Mladek427934b2016-05-20 17:00:39 -0700668
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900669 Those messages are rare and limited. The largest one is when
Petr Mladek427934b2016-05-20 17:00:39 -0700670 a backtrace is printed. It usually fits into 4KB. Select
671 8KB if you want to be on the safe side.
672
673 Examples:
674 17 => 128 KB for each CPU
675 16 => 64 KB for each CPU
676 15 => 32 KB for each CPU
677 14 => 16 KB for each CPU
678 13 => 8 KB for each CPU
679 12 => 4 KB for each CPU
680
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800681#
682# Architectures with an unreliable sched_clock() should select this:
683#
684config HAVE_UNSTABLE_SCHED_CLOCK
685 bool
686
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700687config GENERIC_SCHED_CLOCK
688 bool
689
Patrick Bellasi69842cb2019-06-21 09:42:02 +0100690menu "Scheduler features"
691
692config UCLAMP_TASK
693 bool "Enable utilization clamping for RT/FAIR tasks"
694 depends on CPU_FREQ_GOV_SCHEDUTIL
695 help
696 This feature enables the scheduler to track the clamped utilization
697 of each CPU based on RUNNABLE tasks scheduled on that CPU.
698
699 With this option, the user can specify the min and max CPU
700 utilization allowed for RUNNABLE tasks. The max utilization defines
701 the maximum frequency a task should use while the min utilization
702 defines the minimum frequency it should use.
703
704 Both min and max utilization clamp values are hints to the scheduler,
705 aiming at improving its frequency selection policy, but they do not
706 enforce or grant any specific bandwidth for tasks.
707
708 If in doubt, say N.
709
710config UCLAMP_BUCKETS_COUNT
711 int "Number of supported utilization clamp buckets"
712 range 5 20
713 default 5
714 depends on UCLAMP_TASK
715 help
716 Defines the number of clamp buckets to use. The range of each bucket
717 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
718 number of clamp buckets the finer their granularity and the higher
719 the precision of clamping aggregation and tracking at run-time.
720
721 For example, with the minimum configuration value we will have 5
722 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
723 be refcounted in the [20..39]% bucket and will set the bucket clamp
724 effective value to 25%.
725 If a second 30% boosted task should be co-scheduled on the same CPU,
726 that task will be refcounted in the same bucket of the first task and
727 it will boost the bucket clamp effective value to 30%.
728 The clamp effective value of a bucket is reset to its nominal value
729 (20% in the example above) when there are no more tasks refcounted in
730 that bucket.
731
732 An additional boost/capping margin can be added to some tasks. In the
733 example above the 25% task will be boosted to 30% until it exits the
734 CPU. If that should be considered not acceptable on certain systems,
735 it's always possible to reduce the margin by increasing the number of
736 clamp buckets to trade off used memory for run-time tracking
737 precision.
738
739 If in doubt, use the default value.
740
741endmenu
742
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200743#
744# For architectures that want to enable the support for NUMA-affine scheduler
745# balancing logic:
746#
747config ARCH_SUPPORTS_NUMA_BALANCING
748 bool
749
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100750#
Mel Gorman72b252a2015-09-04 15:47:32 -0700751# For architectures that prefer to flush all TLBs after a number of pages
752# are unmapped instead of sending one IPI per page to flush. The architecture
753# must provide guarantees on what happens if a clean TLB cache entry is
754# written after the unmap. Details are in mm/rmap.c near the check for
755# should_defer_flush. The architecture should also consider if the full flush
756# and the refill costs are offset by the savings of sending fewer IPIs.
757config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
758 bool
759
Ard Biesheuvelc12d3362019-11-08 13:22:27 +0100760config CC_HAS_INT128
Masahiro Yamada3a7c7332020-03-10 19:12:50 +0900761 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
Ard Biesheuvelc12d3362019-11-08 13:22:27 +0100762
Mel Gorman72b252a2015-09-04 15:47:32 -0700763#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100764# For architectures that know their GCC __int128 support is sound
765#
766config ARCH_SUPPORTS_INT128
767 bool
768
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200769# For architectures that (ab)use NUMA to represent different memory regions
770# all cpu-local but of different latencies, such as SuperH.
771#
772config ARCH_WANT_NUMA_VARIABLE_LOCALITY
773 bool
774
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200775config NUMA_BALANCING
776 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200777 depends on ARCH_SUPPORTS_NUMA_BALANCING
778 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
779 depends on SMP && NUMA && MIGRATION
780 help
781 This option adds support for automatic NUMA aware memory/task placement.
782 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400783 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200784
785 This system will be inactive on UMA systems.
786
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800787config NUMA_BALANCING_DEFAULT_ENABLED
788 bool "Automatically enable NUMA aware memory/task placement"
789 default y
790 depends on NUMA_BALANCING
791 help
792 If set, automatic NUMA balancing will be enabled if running on a NUMA
793 machine.
794
Li Zefan23964d22009-01-15 13:50:58 -0800795menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500796 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500797 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700798 help
Li Zefan23964d22009-01-15 13:50:58 -0800799 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800800 use with process control subsystems such as Cpusets, CFS, memory
801 controls or device isolation.
802 See
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300803 - Documentation/scheduler/sched-design-CFS.rst (CFS)
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300804 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800805 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700806
807 Say N if unsure.
808
Li Zefan23964d22009-01-15 13:50:58 -0800809if CGROUPS
810
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800811config PAGE_COUNTER
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800812 bool
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800813
Andrew Mortonc255a452012-07-31 16:43:02 -0700814config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500815 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800816 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500817 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -0800818 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500819 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800820
Andrew Mortonc255a452012-07-31 16:43:02 -0700821config MEMCG_SWAP
Johannes Weiner2d1c4982020-06-03 16:02:14 -0700822 bool
Andrew Mortonc255a452012-07-31 16:43:02 -0700823 depends on MEMCG && SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -0800824 default y
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800825
Kirill Tkhai84c07d12018-08-17 15:47:25 -0700826config MEMCG_KMEM
827 bool
828 depends on MEMCG && !SLOB
829 default y
830
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500831config BLK_CGROUP
832 bool "IO controller"
833 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700834 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500835 ---help---
836 Generic block IO controller cgroup interface. This is the common
837 cgroup interface which should be used by various IO controlling
838 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700839
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500840 Currently, CFQ IO scheduler uses it to recognize task groups and
841 control disk bandwidth allocation (proportional time slice allocation)
842 to such task groups. It is also used by bio throttling logic in
843 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +0200844
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500845 This option only enables generic Block IO controller infrastructure.
846 One needs to also enable actual IO controlling logic/policy. For
847 enabling proportional weight division of disk bandwidth in CFQ, set
Krzysztof Kozlowski7baf2192020-04-06 20:12:02 -0700848 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500849 CONFIG_BLK_DEV_THROTTLING=y.
850
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300851 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500852
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500853config CGROUP_WRITEBACK
854 bool
855 depends on MEMCG && BLK_CGROUP
856 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +0200857
Dhaval Giani7c941432010-01-20 13:26:18 +0100858menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500859 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +0100860 default n
861 help
862 This feature lets CPU scheduler recognize task groups and control CPU
863 bandwidth allocation to such task groups. It uses cgroups to group
864 tasks.
865
866if CGROUP_SCHED
867config FAIR_GROUP_SCHED
868 bool "Group scheduling for SCHED_OTHER"
869 depends on CGROUP_SCHED
870 default CGROUP_SCHED
871
Paul Turnerab84d312011-07-21 09:43:28 -0700872config CFS_BANDWIDTH
873 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -0700874 depends on FAIR_GROUP_SCHED
875 default n
876 help
877 This option allows users to define CPU bandwidth rates (limits) for
878 tasks running within the fair group scheduler. Groups with no limit
879 set are considered to be unconstrained and will run with no
880 restriction.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300881 See Documentation/scheduler/sched-bwc.rst for more information.
Paul Turnerab84d312011-07-21 09:43:28 -0700882
Dhaval Giani7c941432010-01-20 13:26:18 +0100883config RT_GROUP_SCHED
884 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +0100885 depends on CGROUP_SCHED
886 default n
887 help
888 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +0800889 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +0100890 schedule realtime tasks for non-root users until you allocate
891 realtime bandwidth for them.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300892 See Documentation/scheduler/sched-rt-group.rst for more information.
Dhaval Giani7c941432010-01-20 13:26:18 +0100893
894endif #CGROUP_SCHED
895
Patrick Bellasi2480c092019-08-22 14:28:06 +0100896config UCLAMP_TASK_GROUP
897 bool "Utilization clamping per group of tasks"
898 depends on CGROUP_SCHED
899 depends on UCLAMP_TASK
900 default n
901 help
902 This feature enables the scheduler to track the clamped utilization
903 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
904
905 When this option is enabled, the user can specify a min and max
906 CPU bandwidth which is allowed for each single task in a group.
907 The max bandwidth allows to clamp the maximum frequency a task
908 can use, while the min bandwidth allows to define a minimum
909 frequency a task will always use.
910
911 When task group based utilization clamping is enabled, an eventually
912 specified task-specific clamp value is constrained by the cgroup
913 specified clamp value. Both minimum and maximum task clamping cannot
914 be bigger than the corresponding clamping defined at task group level.
915
916 If in doubt, say N.
917
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500918config CGROUP_PIDS
919 bool "PIDs controller"
920 help
921 Provides enforcement of process number limits in the scope of a
922 cgroup. Any attempt to fork more processes than is allowed in the
923 cgroup will fail. PIDs are fundamentally a global resource because it
924 is fairly trivial to reach PID exhaustion before you reach even a
925 conservative kmemcg limit. As a result, it is possible to grind a
926 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +0530927 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500928
929 It should be noted that organisational operations (such as attaching
Jonathan Neuschäfer98076832019-02-01 14:21:01 -0800930 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500931 since the PIDs limit only affects a process's ability to fork, not to
932 attach to a cgroup.
933
Parav Pandit39d3e752017-01-10 00:02:13 +0000934config CGROUP_RDMA
935 bool "RDMA controller"
936 help
937 Provides enforcement of RDMA resources defined by IB stack.
938 It is fairly easy for consumers to exhaust RDMA resources, which
939 can result into resource unavailability to other consumers.
940 RDMA controller is designed to stop this from happening.
941 Attaching processes with active RDMA resources to the cgroup
942 hierarchy is allowed even if can cross the hierarchy's limit.
943
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500944config CGROUP_FREEZER
945 bool "Freezer controller"
946 help
947 Provides a way to freeze and unfreeze all tasks in a
948 cgroup.
949
Johannes Weiner489c2a22016-01-20 15:02:41 -0800950 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
951 controller includes important in-kernel memory consumers per default.
952
953 If you're using cgroup2, say N.
954
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500955config CGROUP_HUGETLB
956 bool "HugeTLB controller"
957 depends on HUGETLB_PAGE
958 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +0200959 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500960 help
961 Provides a cgroup controller for HugeTLB pages.
962 When you enable this, you can put a per cgroup limit on HugeTLB usage.
963 The limit is enforced during page fault. Since HugeTLB doesn't
964 support page reclaim, enforcing the limit at page fault time implies
965 that, the application will get SIGBUS signal if it tries to access
966 HugeTLB pages beyond its limit. This requires the application to know
967 beforehand how much HugeTLB pages it would require for its use. The
968 control group is tracked in the third page lru pointer. This means
969 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200970
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500971config CPUSETS
972 bool "Cpuset controller"
Nicolas Pitree1d4eee2017-06-14 13:19:23 -0400973 depends on SMP
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500974 help
975 This option will let you create and manage CPUSETs which
976 allow dynamically partitioning a system into sets of CPUs and
977 Memory Nodes and assigning tasks to run only within those sets.
978 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200979
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500980 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200981
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500982config PROC_PID_CPUSET
983 bool "Include legacy /proc/<pid>/cpuset file"
984 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -0400985 default y
986
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500987config CGROUP_DEVICE
988 bool "Device controller"
989 help
990 Provides a cgroup controller implementing whitelists for
991 devices which a process in the cgroup can mknod or open.
992
993config CGROUP_CPUACCT
994 bool "Simple CPU accounting controller"
995 help
996 Provides a simple controller for monitoring the
997 total CPU consumed by the tasks in a cgroup.
998
999config CGROUP_PERF
1000 bool "Perf controller"
1001 depends on PERF_EVENTS
1002 help
1003 This option extends the perf per-cpu mode to restrict monitoring
1004 to threads which belong to the cgroup specified and run on the
Namhyung Kim6546b192020-03-25 21:45:29 +09001005 designated cpu. Or this can be used to have cgroup ID in samples
1006 so that it can monitor performance events among cgroups.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001007
1008 Say N if unsure.
1009
Daniel Mack30070982016-11-23 16:52:26 +01001010config CGROUP_BPF
1011 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirski483c4932016-12-16 08:33:45 -08001012 depends on BPF_SYSCALL
1013 select SOCK_CGROUP_DATA
Daniel Mack30070982016-11-23 16:52:26 +01001014 help
1015 Allow attaching eBPF programs to a cgroup using the bpf(2)
1016 syscall command BPF_PROG_ATTACH.
1017
1018 In which context these programs are accessed depends on the type
1019 of attachment. For instance, programs that are attached using
1020 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1021 inet sockets.
1022
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001023config CGROUP_DEBUG
Waiman Long23b0be42017-06-13 17:18:03 -04001024 bool "Debug controller"
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001025 default n
Waiman Long23b0be42017-06-13 17:18:03 -04001026 depends on DEBUG_KERNEL
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001027 help
1028 This option enables a simple controller that exports
Waiman Long23b0be42017-06-13 17:18:03 -04001029 debugging information about the cgroups framework. This
1030 controller is for control cgroup debugging only. Its
1031 interfaces are not stable.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001032
1033 Say N.
1034
Arnd Bergmann73b35142017-01-10 13:08:06 +01001035config SOCK_CGROUP_DATA
1036 bool
1037 default n
1038
Li Zefan23964d22009-01-15 13:50:58 -08001039endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001040
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001041menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001042 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001043 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001044 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001045 help
1046 Provides the way to make tasks work with different objects using
1047 the same id. For example same IPC id may refer to different objects
1048 or same user id or pid may refer to different tasks when used in
1049 different namespaces.
1050
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001051if NAMESPACES
1052
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001053config UTS_NS
1054 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001055 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001056 help
1057 In this namespace tasks see different info provided with the
1058 uname() system call
1059
Andrei Vagin769071a2019-11-12 01:26:52 +00001060config TIME_NS
1061 bool "TIME namespace"
Thomas Gleixner660fd042019-11-12 01:27:09 +00001062 depends on GENERIC_VDSO_TIME_NS
Andrei Vagin769071a2019-11-12 01:26:52 +00001063 default y
1064 help
1065 In this namespace boottime and monotonic clocks can be set.
1066 The time will keep going with the same pace.
1067
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001068config IPC_NS
1069 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001070 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001071 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001072 help
1073 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001074 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001075
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001076config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001077 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001078 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001079 help
1080 This allows containers, i.e. vservers, to use user namespaces
1081 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001082
1083 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001084 recommended that the MEMCG option also be enabled and that
1085 user-space use the memory control groups to limit the amount
1086 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001087
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001088 If unsure, say N.
1089
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001090config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001091 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001092 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001093 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001094 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001095 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001096 pid namespaces. This is a building block of containers.
1097
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001098config NET_NS
1099 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001100 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001101 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001102 help
1103 Allow user space to create what appear to be multiple instances
1104 of the network stack.
1105
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001106endif # NAMESPACES
1107
Adrian Reber5cb366b2018-08-21 22:01:17 -07001108config CHECKPOINT_RESTORE
1109 bool "Checkpoint/restore support"
1110 select PROC_CHILDREN
1111 default n
1112 help
1113 Enables additional kernel features in a sake of checkpoint/restore.
1114 In particular it adds auxiliary prctl codes to setup process text,
1115 data and heap segment sizes, and a few additional /proc filesystem
1116 entries.
1117
1118 If unsure, say N here.
1119
Mike Galbraith5091faa2010-11-30 14:18:03 +01001120config SCHED_AUTOGROUP
1121 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001122 select CGROUPS
1123 select CGROUP_SCHED
1124 select FAIR_GROUP_SCHED
1125 help
1126 This option optimizes the scheduler for common desktop workloads by
1127 automatically creating and populating task groups. This separation
1128 of workloads isolates aggressive CPU burners (like build jobs) from
1129 desktop applications. Task group autogeneration is currently based
1130 upon task session.
1131
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001132config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001133 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001134 depends on SYSFS
1135 default n
1136 help
1137 This option adds code that switches the layout of the "block" class
1138 devices, to not show up in /sys/class/block/, but only in
1139 /sys/block/.
1140
1141 This switch is only active when the sysfs.deprecated=1 boot option is
1142 passed or the SYSFS_DEPRECATED_V2 option is set.
1143
1144 This option allows new kernels to run on old distributions and tools,
1145 which might get confused by /sys/class/block/. Since 2007/2008 all
1146 major distributions and tools handle this just fine.
1147
1148 Recent distributions and userspace tools after 2009/2010 depend on
1149 the existence of /sys/class/block/, and will not work with this
1150 option enabled.
1151
1152 Only if you are using a new kernel on an old distribution, you might
1153 need to say Y here.
1154
1155config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001156 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001157 default n
1158 depends on SYSFS
1159 depends on SYSFS_DEPRECATED
1160 help
1161 Enable deprecated sysfs by default.
1162
1163 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1164 option.
1165
1166 Only if you are using a new kernel on an old distribution, you might
1167 need to say Y here. Even then, odds are you would not need it
1168 enabled, you can always pass the boot option if absolutely necessary.
1169
1170config RELAY
1171 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001172 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001173 help
1174 This option enables support for relay interface support in
1175 certain file systems (such as debugfs).
1176 It is designed to provide an efficient mechanism for tools and
1177 facilities to relay large amounts of data from kernel space to
1178 user space.
1179
1180 If unsure, say N.
1181
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001182config BLK_DEV_INITRD
1183 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001184 help
1185 The initial RAM filesystem is a ramfs which is loaded by the
1186 boot loader (loadlin or lilo) and that is mounted as root
1187 before the normal boot procedure. It is typically used to
1188 load modules needed to mount the "real" root file system,
Mauro Carvalho Chehab8c27ceff32016-10-18 10:12:27 -02001189 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001190
1191 If RAM disk support (BLK_DEV_RAM) is also included, this
1192 also enables initial RAM disk (initrd) support and adds
1193 15 Kbytes (more on some other architectures) to the kernel size.
1194
1195 If unsure say Y.
1196
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001197if BLK_DEV_INITRD
1198
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001199source "usr/Kconfig"
1200
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001201endif
1202
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001203config BOOT_CONFIG
1204 bool "Boot config support"
Masami Hiramatsu2910b5a2020-02-25 23:36:41 +09001205 select BLK_DEV_INITRD
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001206 help
1207 Extra boot config allows system admin to pass a config file as
1208 complemental extension of kernel cmdline when booting.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001209 The boot config file must be attached at the end of initramfs
Masami Hiramatsu85c46b72020-02-20 21:18:42 +09001210 with checksum, size and magic word.
Masami Hiramatsu0947db02020-01-20 12:23:00 +09001211 See <file:Documentation/admin-guide/bootconfig.rst> for details.
Masami Hiramatsu76db5a22020-01-11 01:03:32 +09001212
1213 If unsure, say Y.
1214
Arnd Bergmann877417e2016-04-25 17:35:27 +02001215choice
1216 prompt "Compiler optimization level"
Ulf Magnusson2cc3ce22017-10-04 01:53:26 +02001217 default CC_OPTIMIZE_FOR_PERFORMANCE
Arnd Bergmann877417e2016-04-25 17:35:27 +02001218
1219config CC_OPTIMIZE_FOR_PERFORMANCE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001220 bool "Optimize for performance (-O2)"
Arnd Bergmann877417e2016-04-25 17:35:27 +02001221 help
1222 This is the default optimization level for the kernel, building
1223 with the "-O2" compiler flag for best performance and most
1224 helpful compile-time warnings.
1225
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001226config CC_OPTIMIZE_FOR_PERFORMANCE_O3
1227 bool "Optimize more for performance (-O3)"
1228 depends on ARC
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001229 help
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001230 Choosing this option will pass "-O3" to your compiler to optimize
1231 the kernel yet more for performance.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001232
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001233config CC_OPTIMIZE_FOR_SIZE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001234 bool "Optimize for size (-Os)"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001235 help
Masahiro Yamadace3b4872019-08-21 02:09:39 +09001236 Choosing this option will pass "-Os" to your compiler resulting
1237 in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001238
Arnd Bergmann877417e2016-04-25 17:35:27 +02001239endchoice
1240
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001241config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1242 bool
1243 help
1244 This requires that the arch annotates or otherwise protects
1245 its external entry points from being discarded. Linker scripts
1246 must also merge .text.*, .data.*, and .bss.* correctly into
1247 output sections. Care must be taken not to pull in unrelated
1248 sections (e.g., '.text.init'). Typically '.' in section names
1249 is used to distinguish them from label names / C identifiers.
1250
1251config LD_DEAD_CODE_DATA_ELIMINATION
1252 bool "Dead code and data elimination (EXPERIMENTAL)"
1253 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1254 depends on EXPERT
Paul Burton16fd20a2019-01-11 19:06:44 +00001255 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
Masahiro Yamadae85d1d62018-08-22 22:51:09 +09001256 depends on $(cc-option,-ffunction-sections -fdata-sections)
1257 depends on $(ld-option,--gc-sections)
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001258 help
Masahiro Yamada8b9d2712018-06-24 01:41:51 +09001259 Enable this if you want to do dead code and data elimination with
1260 the linker by compiling with -ffunction-sections -fdata-sections,
1261 and linking with --gc-sections.
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001262
1263 This can reduce on disk and in-memory size of the kernel
1264 code and static data, particularly for small configs and
1265 on small systems. This has the possibility of introducing
1266 silently broken kernel if the required annotations are not
1267 present. This option is not well tested yet, so use at your
1268 own risk.
1269
Randy Dunlap08470622006-09-30 23:28:13 -07001270config SYSCTL
1271 bool
1272
Mike Frysinger657a5202013-04-30 15:28:45 -07001273config HAVE_UID16
1274 bool
1275
1276config SYSCTL_EXCEPTION_TRACE
1277 bool
1278 help
1279 Enable support for /proc/sys/debug/exception-trace.
1280
1281config SYSCTL_ARCH_UNALIGN_NO_WARN
1282 bool
1283 help
1284 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1285 Allows arch to define/use @no_unaligned_warning to possibly warn
1286 about unaligned access emulation going on under the hood.
1287
1288config SYSCTL_ARCH_UNALIGN_ALLOW
1289 bool
1290 help
1291 Enable support for /proc/sys/kernel/unaligned-trap
1292 Allows arches to define/use @unaligned_enabled to runtime toggle
1293 the unaligned access emulation.
1294 see arch/parisc/kernel/unaligned.c for reference
1295
Mike Frysinger657a5202013-04-30 15:28:45 -07001296config HAVE_PCSPKR_PLATFORM
1297 bool
1298
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001299# interpreter that classic socket filters depend on
1300config BPF
1301 bool
1302
David Rientjes6a108a12011-01-20 14:44:16 -08001303menuconfig EXPERT
1304 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001305 # Unhide debug options, to make the on-by-default options visible
1306 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 help
1308 This option allows certain base kernel options and settings
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001309 to be disabled or tweaked. This is for specialized
1310 environments which can tolerate a "non-standard" kernel.
1311 Only use this if you really know what you are doing.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001313config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001314 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001315 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001316 default y
1317 help
1318 This enables the legacy 16-bit UID syscall wrappers.
1319
Iulia Manda28138932015-04-15 16:16:41 -07001320config MULTIUSER
1321 bool "Multiple users, groups and capabilities support" if EXPERT
1322 default y
1323 help
1324 This option enables support for non-root users, groups and
1325 capabilities.
1326
1327 If you say N here, all processes will run with UID 0, GID 0, and all
1328 possible capabilities. Saying N here also compiles out support for
1329 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1330 setgid, and capset.
1331
1332 If unsure, say Y here.
1333
Fabian Frederickf6187762014-06-04 16:11:12 -07001334config SGETMASK_SYSCALL
1335 bool "sgetmask/ssetmask syscalls support" if EXPERT
Arnd Bergmanna687a532018-03-07 23:30:54 +01001336 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
Fabian Frederickf6187762014-06-04 16:11:12 -07001337 ---help---
1338 sys_sgetmask and sys_ssetmask are obsolete system calls
1339 no longer supported in libc but still enabled by default in some
1340 architectures.
1341
1342 If unsure, leave the default option here.
1343
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001344config SYSFS_SYSCALL
1345 bool "Sysfs syscall support" if EXPERT
1346 default y
1347 ---help---
1348 sys_sysfs is an obsolete system call no longer supported in libc.
1349 Note that disabling this option is more secure but might break
1350 compatibility with some systems.
1351
1352 If unsure say Y here.
1353
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001354config FHANDLE
1355 bool "open by fhandle syscalls" if EXPERT
1356 select EXPORTFS
1357 default y
1358 help
1359 If you say Y here, a user level program will be able to map
1360 file names to handle and then later use the handle for
1361 different file system operations. This is useful in implementing
1362 userspace file servers, which now track files using handles instead
1363 of names. The handle would remain the same even if file names
1364 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1365 syscalls.
1366
Nicolas Pitrebaa73d92016-11-11 00:10:10 -05001367config POSIX_TIMERS
1368 bool "Posix Clocks & timers" if EXPERT
1369 default y
1370 help
1371 This includes native support for POSIX timers to the kernel.
1372 Some embedded systems have no use for them and therefore they
1373 can be configured out to reduce the size of the kernel image.
1374
1375 When this option is disabled, the following syscalls won't be
1376 available: timer_create, timer_gettime: timer_getoverrun,
1377 timer_settime, timer_delete, clock_adjtime, getitimer,
1378 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1379 clock_getres and clock_nanosleep syscalls will be limited to
1380 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1381
1382 If unsure say y.
1383
Matt Mackalld59745c2005-05-01 08:59:02 -07001384config PRINTK
1385 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001386 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001387 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001388 help
1389 This option enables normal printk support. Removing it
1390 eliminates most of the message strings from the kernel image
1391 and makes the kernel more or less silent. As this makes it
1392 very difficult to diagnose system problems, saying N here is
1393 strongly discouraged.
1394
Petr Mladek42a0bb32016-05-20 17:00:33 -07001395config PRINTK_NMI
1396 def_bool y
1397 depends on PRINTK
1398 depends on HAVE_NMI
1399
Matt Mackallc8538a72005-05-01 08:59:01 -07001400config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001401 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001402 default y
1403 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001404 Disabling this option eliminates support for BUG and WARN, reducing
1405 the size of your kernel image and potentially quietly ignoring
1406 numerous fatal conditions. You should only consider disabling this
1407 option for embedded systems with no facilities for reporting errors.
1408 Just say Y.
Matt Mackallc8538a72005-05-01 08:59:01 -07001409
Matt Mackall708e9a72006-01-08 01:05:25 -08001410config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001411 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001412 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001413 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001414 help
1415 Enable support for generating core dumps. Disabling saves about 4k.
1416
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001417
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001418config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001419 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001420 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001421 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001422 default y
1423 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001424 This option allows to disable the internal PC-Speaker
1425 support, saving some memory.
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001426
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427config BASE_FULL
1428 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001429 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430 help
1431 Disabling this option reduces the size of miscellaneous core
1432 kernel data structures. This saves memory on small machines,
1433 but may reduce performance.
1434
1435config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001436 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 default y
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001438 imply RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 help
1440 Disabling this option will cause the kernel to be built without
1441 support for "fast userspace mutexes". The resulting kernel may not
1442 run glibc-based applications correctly.
1443
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001444config FUTEX_PI
1445 bool
1446 depends on FUTEX && RT_MUTEXES
1447 default y
1448
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001449config HAVE_FUTEX_CMPXCHG
1450 bool
Josh Triplett62b4d202014-10-03 16:19:24 -07001451 depends on FUTEX
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001452 help
1453 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1454 is implemented and always working. This removes a couple of runtime
1455 checks.
1456
Linus Torvalds1da177e2005-04-16 15:20:36 -07001457config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001458 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459 default y
1460 help
1461 Disabling this option will cause the kernel to be built without
1462 support for epoll family of system calls.
1463
Davide Libenzifba2afa2007-05-10 22:23:13 -07001464config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001465 bool "Enable signalfd() system call" if EXPERT
Davide Libenzifba2afa2007-05-10 22:23:13 -07001466 default y
1467 help
1468 Enable the signalfd() system call that allows to receive signals
1469 on a file descriptor.
1470
1471 If unsure, say Y.
1472
Davide Libenzib215e282007-05-10 22:23:16 -07001473config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001474 bool "Enable timerfd() system call" if EXPERT
Davide Libenzib215e282007-05-10 22:23:16 -07001475 default y
1476 help
1477 Enable the timerfd() system call that allows to receive timer
1478 events on a file descriptor.
1479
1480 If unsure, say Y.
1481
Davide Libenzie1ad7462007-05-10 22:23:19 -07001482config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001483 bool "Enable eventfd() system call" if EXPERT
Davide Libenzie1ad7462007-05-10 22:23:19 -07001484 default y
1485 help
1486 Enable the eventfd() system call that allows to receive both
1487 kernel notification (ie. KAIO) or userspace notifications.
1488
1489 If unsure, say Y.
1490
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001492 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493 default y
1494 depends on MMU
1495 help
1496 The shmem is an internal filesystem used to manage shared memory.
1497 It is backed by swap and manages resource limits. It is also exported
1498 to userspace as tmpfs if TMPFS is enabled. Disabling this
1499 option replaces shmem and tmpfs with the much simpler ramfs code,
1500 which may be appropriate on small systems without swap.
1501
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001502config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001503 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001504 default y
1505 help
1506 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001507 by some high performance threaded applications. Disabling
1508 this option saves about 7k.
1509
Jens Axboe2b188cc2019-01-07 10:46:33 -07001510config IO_URING
1511 bool "Enable IO uring support" if EXPERT
Jens Axboe561fb042019-10-24 07:25:42 -06001512 select IO_WQ
Jens Axboe2b188cc2019-01-07 10:46:33 -07001513 default y
1514 help
1515 This option enables support for the io_uring interface, enabling
1516 applications to submit and complete IO through submission and
1517 completion rings that are shared between the kernel and application.
1518
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001519config ADVISE_SYSCALLS
1520 bool "Enable madvise/fadvise syscalls" if EXPERT
1521 default y
1522 help
1523 This option enables the madvise and fadvise syscalls, used by
1524 applications to advise the kernel about their future memory or file
1525 usage, improving performance. If building an embedded system where no
1526 applications use these syscalls, you can disable this option to save
1527 space.
1528
Andrea Arcangeli5a281062020-04-06 20:05:33 -07001529config HAVE_ARCH_USERFAULTFD_WP
1530 bool
1531 help
1532 Arch has userfaultfd write protection support
1533
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001534config MEMBARRIER
1535 bool "Enable membarrier() system call" if EXPERT
1536 default y
1537 help
1538 Enable the membarrier() system call that allows issuing memory
1539 barriers across all running threads, which can be used to distribute
1540 the cost of user-space memory barriers asymmetrically by transforming
1541 pairs of memory barriers into pairs consisting of membarrier() and a
1542 compiler barrier.
1543
1544 If unsure, say Y.
1545
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001546config KALLSYMS
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001547 bool "Load all symbols for debugging/ksymoops" if EXPERT
1548 default y
1549 help
1550 Say Y here to let the kernel print out symbolic crash information and
1551 symbolic stack backtraces. This increases the size of the kernel
1552 somewhat, as all symbols have to be loaded into the kernel image.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001553
1554config KALLSYMS_ALL
1555 bool "Include all symbols in kallsyms"
1556 depends on DEBUG_KERNEL && KALLSYMS
1557 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001558 Normally kallsyms only contains the symbols of functions for nicer
1559 OOPS messages and backtraces (i.e., symbols from the text and inittext
1560 sections). This is sufficient for most cases. And only in very rare
1561 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1562 names of variables from the data sections, etc).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001563
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001564 This option makes sure that all symbols are loaded into the kernel
1565 image (i.e., symbols from all sections) in cost of increased kernel
1566 size (depending on the kernel configuration, it may be 300KiB or
1567 something like this).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001568
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001569 Say N unless you really need all symbols.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001570
1571config KALLSYMS_ABSOLUTE_PERCPU
1572 bool
1573 depends on KALLSYMS
1574 default X86_64 && SMP
1575
1576config KALLSYMS_BASE_RELATIVE
1577 bool
1578 depends on KALLSYMS
Arnd Bergmanna687a532018-03-07 23:30:54 +01001579 default !IA64
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001580 help
1581 Instead of emitting them as absolute values in the native word size,
1582 emit the symbol references in the kallsyms table as 32-bit entries,
1583 each containing a relative value in the range [base, base + U32_MAX]
1584 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1585 an absolute value in the range [0, S32_MAX] or a relative value in the
1586 range [base, base + S32_MAX], where base is the lowest relative symbol
1587 address encountered in the image.
1588
1589 On 64-bit builds, this reduces the size of the address table by 50%,
1590 but more importantly, it results in entries whose values are build
1591 time constants, and no relocation pass is required at runtime to fix
1592 up the entries based on the runtime load address of the kernel.
1593
1594# end of the "standard kernel features (expert users)" menu
1595
1596# syscall, maps, verifier
KP Singhfc611f42020-03-29 01:43:49 +01001597
1598config BPF_LSM
1599 bool "LSM Instrumentation with BPF"
KP Singh4edf16b2020-03-30 22:40:59 +02001600 depends on BPF_EVENTS
KP Singhfc611f42020-03-29 01:43:49 +01001601 depends on BPF_SYSCALL
1602 depends on SECURITY
1603 depends on BPF_JIT
1604 help
1605 Enables instrumentation of the security hooks with eBPF programs for
1606 implementing dynamic MAC and Audit Policies.
1607
1608 If you are unsure how to answer this question, answer N.
1609
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001610config BPF_SYSCALL
1611 bool "Enable bpf() system call"
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001612 select BPF
Song Liubae77c52018-05-07 10:50:48 -07001613 select IRQ_WORK
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001614 default n
1615 help
1616 Enable the bpf() system call that allows to manipulate eBPF
1617 programs and maps via file descriptors.
1618
Daniel Borkmann81c22042019-12-09 16:08:03 +01001619config ARCH_WANT_DEFAULT_BPF_JIT
1620 bool
1621
Alexei Starovoitov290af862018-01-09 10:04:29 -08001622config BPF_JIT_ALWAYS_ON
1623 bool "Permanently enable BPF JIT and remove BPF interpreter"
1624 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1625 help
1626 Enables BPF JIT and removes BPF interpreter to avoid
1627 speculative execution of BPF instructions by the interpreter
1628
Daniel Borkmann81c22042019-12-09 16:08:03 +01001629config BPF_JIT_DEFAULT_ON
1630 def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
1631 depends on HAVE_EBPF_JIT && BPF_JIT
1632
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001633config USERFAULTFD
1634 bool "Enable userfaultfd() system call"
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001635 depends on MMU
1636 help
1637 Enable the userfaultfd() system call that allows to intercept and
1638 handle page faults in userland.
1639
Mathieu Desnoyers3ccfebe2018-01-29 15:20:11 -05001640config ARCH_HAS_MEMBARRIER_CALLBACKS
1641 bool
1642
Mathieu Desnoyers70216e12018-01-29 15:20:17 -05001643config ARCH_HAS_MEMBARRIER_SYNC_CORE
1644 bool
1645
Mathieu Desnoyersd7822b12018-06-02 08:43:54 -04001646config RSEQ
1647 bool "Enable rseq() system call" if EXPERT
1648 default y
1649 depends on HAVE_RSEQ
1650 select MEMBARRIER
1651 help
1652 Enable the restartable sequences system call. It provides a
1653 user-space cache for the current CPU number value, which
1654 speeds up getting the current CPU number from user-space,
1655 as well as an ABI to speed up user-space operations on
1656 per-CPU data.
1657
1658 If unsure, say Y.
1659
1660config DEBUG_RSEQ
1661 default n
1662 bool "Enabled debugging of rseq() system call" if EXPERT
1663 depends on RSEQ && DEBUG_KERNEL
1664 help
1665 Enable extra debugging checks for the rseq system call.
1666
1667 If unsure, say N.
1668
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001669config EMBEDDED
1670 bool "Embedded system"
Josh Triplett5d2acfc2014-04-07 15:39:09 -07001671 option allnoconfig_y
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001672 select EXPERT
1673 help
1674 This option should be enabled if compiling the kernel for
1675 an embedded system so certain expert options are available
1676 for configuration.
1677
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001678config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001679 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001680 help
1681 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001682
Peter Zijlstra906010b2009-09-21 16:08:49 +02001683config PERF_USE_VMALLOC
1684 bool
1685 help
1686 See tools/perf/design.txt for details
1687
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001688config PC104
William Breathitt Gray424529f2017-12-29 15:14:59 -05001689 bool "PC/104 support" if EXPERT
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001690 help
1691 Expose PC/104 form factor device drivers and options available for
1692 selection and configuration. Enable this option if your target
1693 machine has a PC/104 bus.
1694
Ingo Molnar57c0c152009-09-21 12:20:38 +02001695menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001696
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001697config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001698 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001699 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001700 depends on HAVE_PERF_EVENTS
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001701 select IRQ_WORK
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001702 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001703 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001704 Enable kernel support for various performance events provided
1705 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001706
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001707 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001708 use of generic tracepoints.
1709
1710 Most modern CPUs support performance events via performance
1711 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001712 types of hw events: such as instructions executed, cachemisses
1713 suffered, or branches mis-predicted - without slowing down the
1714 kernel or applications. These registers can also trigger interrupts
1715 when a threshold number of events have passed - and can thus be
1716 used to profile the code that runs on that CPU.
1717
Ingo Molnar57c0c152009-09-21 12:20:38 +02001718 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001719 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001720 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001721 provides per task and per CPU counters, and it provides event
1722 capabilities on top of those.
1723
1724 Say Y if unsure.
1725
Peter Zijlstra906010b2009-09-21 16:08:49 +02001726config DEBUG_PERF_USE_VMALLOC
1727 default n
1728 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb3071132015-05-04 16:26:39 +10001729 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001730 select PERF_USE_VMALLOC
1731 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001732 Use vmalloc memory to back perf mmap() buffers.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001733
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001734 Mostly useful for debugging the vmalloc code on platforms
1735 that don't require it.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001736
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001737 Say N if unsure.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001738
Thomas Gleixner0793a612008-12-04 20:12:29 +01001739endmenu
1740
Christoph Lameterf8891e52006-06-30 01:55:45 -07001741config VM_EVENT_COUNTERS
1742 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001743 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001744 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001745 VM event counters are needed for event counts to be shown.
1746 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001747 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001748 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001749
Christoph Lameter41ecc552007-05-09 02:32:44 -07001750config SLUB_DEBUG
1751 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001752 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001753 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001754 help
1755 SLUB has extensive debug support features. Disabling these can
1756 result in significant savings in code size. This also disables
1757 SLUB sysfs support. /sys/slab will not exist and there will be
1758 no support for cache validation etc.
1759
Tejun Heo1663f262017-02-22 15:41:39 -08001760config SLUB_MEMCG_SYSFS_ON
1761 default n
1762 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1763 depends on SLUB && SYSFS && MEMCG
1764 help
1765 SLUB creates a directory under /sys/kernel/slab for each
1766 allocation cache to host info and debug files. If memory
1767 cgroup is enabled, each cache can have per memory cgroup
1768 caches. SLUB can create the same sysfs directories for these
1769 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1770 to a very high number of debug files being created. This is
1771 controlled by slub_memcg_sysfs boot parameter and this
1772 config option determines the parameter's default value.
1773
Randy Dunlapb943c462009-03-10 12:55:46 -07001774config COMPAT_BRK
1775 bool "Disable heap randomization"
1776 default y
1777 help
1778 Randomizing heap placement makes heap exploits harder, but it
1779 also breaks ancient binaries (including anything libc5 based).
1780 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001781 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001782 /proc/sys/kernel/randomize_va_space to 2.
1783
1784 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1785
Christoph Lameter81819f02007-05-06 14:49:36 -07001786choice
1787 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001788 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001789 help
1790 This option allows to select a slab allocator.
1791
1792config SLAB
1793 bool "SLAB"
Kees Cook04385fc2016-06-23 15:20:59 -07001794 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001795 help
1796 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001797 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001798 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001799
1800config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001801 bool "SLUB (Unqueued Allocator)"
Kees Cooked18adc2016-06-23 15:24:05 -07001802 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001803 help
1804 SLUB is a slab allocator that minimizes cache line usage
1805 instead of managing queues of cached objects (SLAB approach).
1806 Per cpu caching is realized using slabs of objects instead
1807 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001808 and has enhanced diagnostics. SLUB is the default choice for
1809 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001810
1811config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001812 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001813 bool "SLOB (Simple Allocator)"
1814 help
Matt Mackall37291452008-02-04 22:29:38 -08001815 SLOB replaces the stock allocator with a drastically simpler
1816 allocator. SLOB is generally more space efficient but
1817 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001818
1819endchoice
1820
Kees Cook7660a6f2017-07-06 15:36:40 -07001821config SLAB_MERGE_DEFAULT
1822 bool "Allow slab caches to be merged"
1823 default y
1824 help
1825 For reduced kernel memory fragmentation, slab caches can be
1826 merged when they share the same size and other characteristics.
1827 This carries a risk of kernel heap overflows being able to
1828 overwrite objects from merged caches (and more easily control
1829 cache layout), which makes such heap attacks easier to exploit
1830 by attackers. By keeping caches unmerged, these kinds of exploits
1831 can usually only damage objects in the same cache. To disable
1832 merging at runtime, "slab_nomerge" can be passed on the kernel
1833 command line.
1834
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001835config SLAB_FREELIST_RANDOM
1836 default n
Thomas Garnier210e7a42016-07-26 15:21:59 -07001837 depends on SLAB || SLUB
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001838 bool "SLAB freelist randomization"
1839 help
Thomas Garnier210e7a42016-07-26 15:21:59 -07001840 Randomizes the freelist order used on creating new pages. This
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001841 security feature reduces the predictability of the kernel slab
1842 allocator against heap overflows.
1843
Kees Cook2482ddec2017-09-06 16:19:18 -07001844config SLAB_FREELIST_HARDENED
1845 bool "Harden slab freelist metadata"
1846 depends on SLUB
1847 help
1848 Many kernel heap attacks try to target slab cache metadata and
1849 other infrastructure. This options makes minor performance
Kees Cook92bae782019-07-16 16:27:57 -07001850 sacrifices to harden the kernel slab allocator against common
Kees Cook2482ddec2017-09-06 16:19:18 -07001851 freelist exploit methods.
1852
Dan Williamse900a912019-05-14 15:41:28 -07001853config SHUFFLE_PAGE_ALLOCATOR
1854 bool "Page allocator randomization"
1855 default SLAB_FREELIST_RANDOM && ACPI_NUMA
1856 help
1857 Randomization of the page allocator improves the average
1858 utilization of a direct-mapped memory-side-cache. See section
1859 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
1860 6.2a specification for an example of how a platform advertises
1861 the presence of a memory-side-cache. There are also incidental
1862 security benefits as it reduces the predictability of page
1863 allocations to compliment SLAB_FREELIST_RANDOM, but the
1864 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
1865 10th order of pages is selected based on cache utilization
1866 benefits on x86.
1867
1868 While the randomization improves cache utilization it may
1869 negatively impact workloads on platforms without a cache. For
1870 this reason, by default, the randomization is enabled only
1871 after runtime detection of a direct-mapped memory-side-cache.
1872 Otherwise, the randomization may be force enabled with the
1873 'page_alloc.shuffle' kernel command line parameter.
1874
1875 Say Y if unsure.
1876
Joonsoo Kim345c9052013-06-19 14:05:52 +09001877config SLUB_CPU_PARTIAL
1878 default y
Uwe Kleine-Königb39ffbf2013-07-17 16:54:59 +02001879 depends on SLUB && SMP
Joonsoo Kim345c9052013-06-19 14:05:52 +09001880 bool "SLUB per cpu partial cache"
1881 help
Kees Cook92bae782019-07-16 16:27:57 -07001882 Per cpu partial caches accelerate objects allocation and freeing
Joonsoo Kim345c9052013-06-19 14:05:52 +09001883 that is local to a processor at the price of more indeterminism
1884 in the latency of the free. On overflow these caches will be cleared
1885 which requires the taking of locks that may cause latency spikes.
1886 Typically one would choose no for a realtime system.
1887
Jie Zhangea637632009-12-14 18:00:02 -08001888config MMAP_ALLOW_UNINITIALIZED
1889 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08001890 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08001891 default n
1892 help
1893 Normally, and according to the Linux spec, anonymous memory obtained
Randy Dunlap3903bf92018-08-21 21:58:34 -07001894 from mmap() has its contents cleared before it is passed to
Jie Zhangea637632009-12-14 18:00:02 -08001895 userspace. Enabling this config option allows you to request that
1896 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1897 providing a huge performance boost. If this option is not enabled,
1898 then the flag will be ignored.
1899
1900 This is taken advantage of by uClibc's malloc(), and also by
1901 ELF-FDPIC binfmt's brk and stack allocator.
1902
1903 Because of the obvious security issues, this option should only be
1904 enabled on embedded devices where you control what is run in
1905 userspace. Since that isn't generally a problem on no-MMU systems,
1906 it is normally safe to say Y here.
1907
1908 See Documentation/nommu-mmap.txt for more information.
1909
David Howells091f6e22015-07-20 21:16:28 +01001910config SYSTEM_DATA_VERIFICATION
1911 def_bool n
1912 select SYSTEM_TRUSTED_KEYRING
1913 select KEYS
1914 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00001915 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01001916 select ASYMMETRIC_KEY_TYPE
1917 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01001918 select ASN1
1919 select OID_REGISTRY
1920 select X509_CERTIFICATE_PARSER
1921 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07001922 help
David Howells091f6e22015-07-20 21:16:28 +01001923 Provide PKCS#7 message verification using the contents of the system
1924 trusted keyring to provide public keys. This then can be used for
1925 module verification, kexec image verification and firmware blob
1926 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07001927
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001928config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001929 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001930 help
1931 Say Y here to enable the extended profiling support mechanisms used
1932 by profilers such as OProfile.
1933
Ingo Molnar5f87f112008-07-23 14:15:22 +02001934#
1935# Place an empty function call at each tracepoint site. Can be
1936# dynamically changed for a probe function.
1937#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001938config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001939 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001940
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941endmenu # General setup
1942
Christoph Hellwig15724972018-07-31 13:39:30 +02001943source "arch/Kconfig"
1944
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001945config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05001946 bool
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001947
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948config BASE_SMALL
1949 int
1950 default 0 if BASE_FULL
1951 default 1 if !BASE_FULL
1952
Thiago Jung Bauermannc8424e72019-07-04 15:57:34 -03001953config MODULE_SIG_FORMAT
1954 def_bool n
1955 select SYSTEM_DATA_VERIFICATION
1956
Jan Engelhardt66da5732007-07-15 23:39:29 -07001957menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958 bool "Enable loadable module support"
Yann E. MORIN11097a02013-08-11 16:07:50 +02001959 option modules
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960 help
1961 Kernel modules are small pieces of compiled code which can
1962 be inserted in the running kernel, rather than being
1963 permanently built into the kernel. You use the "modprobe"
1964 tool to add (and sometimes remove) them. If you say Y here,
1965 many parts of the kernel can be built as modules (by
1966 answering M instead of Y where indicated): this is most
1967 useful for infrequently used options which are not required
1968 for booting. For more information, see the man pages for
1969 modprobe, lsmod, modinfo, insmod and rmmod.
1970
1971 If you say Y here, you will need to run "make
1972 modules_install" to put the modules under /lib/modules/
1973 where modprobe can find them (you may need to be root to do
1974 this).
1975
1976 If unsure, say Y.
1977
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001978if MODULES
1979
Linus Torvalds826e4502008-05-04 17:04:16 -07001980config MODULE_FORCE_LOAD
1981 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07001982 default n
1983 help
Rusty Russell91e37a72008-05-09 16:25:28 +10001984 Allow loading of modules without version information (ie. modprobe
1985 --force). Forced module loading sets the 'F' (forced) taint flag and
1986 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07001987
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988config MODULE_UNLOAD
1989 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990 help
1991 Without this option you will not be able to unload any
1992 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05001993 anyway), which makes your kernel smaller, faster
1994 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995
1996config MODULE_FORCE_UNLOAD
1997 bool "Forced module unloading"
Kees Cook19c92392012-10-02 11:19:29 -07001998 depends on MODULE_UNLOAD
Linus Torvalds1da177e2005-04-16 15:20:36 -07001999 help
2000 This option allows you to force a module to unload, even if the
2001 kernel believes it is unsafe: the kernel will remove the module
2002 without waiting for anyone to stop using it (using the -f option to
2003 rmmod). This is mainly for kernel developers and desperate users.
2004 If unsure, say N.
2005
Linus Torvalds1da177e2005-04-16 15:20:36 -07002006config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01002007 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002008 help
2009 Usually, you have to use modules compiled with your kernel.
2010 Saying Y here makes it sometimes possible to use modules
2011 compiled for different kernels, by adding enough information
2012 to the modules to (hopefully) spot any changes which would
2013 make them incompatible with the kernel you are running. If
2014 unsure, say N.
2015
Masahiro Yamada2ff2b7e2019-08-19 14:54:20 +09002016config ASM_MODVERSIONS
2017 bool
2018 default HAVE_ASM_MODVERSIONS && MODVERSIONS
2019 help
2020 This enables module versioning for exported symbols also from
2021 assembly. This can be enabled only when the target architecture
2022 supports it.
2023
Ard Biesheuvel56067812017-02-03 09:54:05 +00002024config MODULE_REL_CRCS
2025 bool
2026 depends on MODVERSIONS
2027
Linus Torvalds1da177e2005-04-16 15:20:36 -07002028config MODULE_SRCVERSION_ALL
2029 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030 help
2031 Modules which contain a MODULE_VERSION get an extra "srcversion"
2032 field inserted into their modinfo section, which contains a
2033 sum of the source files which made it. This helps maintainers
2034 see exactly which source was used to build a module (since
2035 others sometimes change the module source without updating
2036 the version). With this option, such a "srcversion" field
2037 will be created for all modules. If unsure, say N.
2038
Rusty Russell106a4ee2012-09-26 10:09:40 +01002039config MODULE_SIG
2040 bool "Module signature verification"
Thiago Jung Bauermannc8424e72019-07-04 15:57:34 -03002041 select MODULE_SIG_FORMAT
Rusty Russell106a4ee2012-09-26 10:09:40 +01002042 help
2043 Check modules for valid signatures upon load: the signature
2044 is simply appended to the module. For more information see
Nathan Chancellorcbdc8212017-09-10 02:48:29 -07002045 <file:Documentation/admin-guide/module-signing.rst>.
Rusty Russell106a4ee2012-09-26 10:09:40 +01002046
David Howells228c37f2015-08-11 12:38:54 +01002047 Note that this option adds the OpenSSL development packages as a
2048 kernel build dependency so that the signing tool can use its crypto
2049 library.
2050
David Howells49fcf732019-08-19 17:17:40 -07002051 You should enable this option if you wish to use either
2052 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
2053 another LSM - otherwise unsigned modules will be loadable regardless
2054 of the lockdown policy.
2055
David Howellsea0b6dc2012-09-26 10:09:50 +01002056 !!!WARNING!!! If you enable this option, you MUST make sure that the
2057 module DOES NOT get stripped after being signed. This includes the
2058 debuginfo strip done by some packagers (such as rpmbuild) and
2059 inclusion into an initramfs that wants the module size reduced.
2060
Rusty Russell106a4ee2012-09-26 10:09:40 +01002061config MODULE_SIG_FORCE
2062 bool "Require modules to be validly signed"
2063 depends on MODULE_SIG
2064 help
2065 Reject unsigned modules or signed modules for which we don't have a
2066 key. Without this, such modules will simply taint the kernel.
David Howellsea0b6dc2012-09-26 10:09:50 +01002067
Michal Marekd9d8d7e2013-01-25 13:41:31 +10302068config MODULE_SIG_ALL
2069 bool "Automatically sign all modules"
2070 default y
2071 depends on MODULE_SIG
2072 help
2073 Sign all modules during make modules_install. Without this option,
2074 modules must be signed manually, using the scripts/sign-file tool.
2075
2076comment "Do not forget to sign required modules with scripts/sign-file"
2077 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
2078
David Howellsea0b6dc2012-09-26 10:09:50 +01002079choice
2080 prompt "Which hash algorithm should modules be signed with?"
2081 depends on MODULE_SIG
2082 help
2083 This determines which sort of hashing algorithm will be used during
2084 signature generation. This algorithm _must_ be built into the kernel
2085 directly so that signature verification can take place. It is not
2086 possible to load a signed module containing the algorithm to check
2087 the signature on that module.
2088
2089config MODULE_SIG_SHA1
2090 bool "Sign modules with SHA-1"
2091 select CRYPTO_SHA1
2092
2093config MODULE_SIG_SHA224
2094 bool "Sign modules with SHA-224"
2095 select CRYPTO_SHA256
2096
2097config MODULE_SIG_SHA256
2098 bool "Sign modules with SHA-256"
2099 select CRYPTO_SHA256
2100
2101config MODULE_SIG_SHA384
2102 bool "Sign modules with SHA-384"
2103 select CRYPTO_SHA512
2104
2105config MODULE_SIG_SHA512
2106 bool "Sign modules with SHA-512"
2107 select CRYPTO_SHA512
2108
2109endchoice
2110
Michal Marek22753672013-01-25 13:41:00 +10302111config MODULE_SIG_HASH
2112 string
2113 depends on MODULE_SIG
2114 default "sha1" if MODULE_SIG_SHA1
2115 default "sha224" if MODULE_SIG_SHA224
2116 default "sha256" if MODULE_SIG_SHA256
2117 default "sha384" if MODULE_SIG_SHA384
2118 default "sha512" if MODULE_SIG_SHA512
2119
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302120config MODULE_COMPRESS
2121 bool "Compress modules on installation"
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302122 help
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302123
Rusty Russellb6c09b52015-06-16 12:16:22 +09302124 Compresses kernel modules when 'make modules_install' is run; gzip or
2125 xz depending on "Compression algorithm" below.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302126
Rusty Russellb6c09b52015-06-16 12:16:22 +09302127 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302128
Rusty Russellb6c09b52015-06-16 12:16:22 +09302129 Out-of-tree kernel modules installed using Kbuild will also be
2130 compressed upon installation.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302131
Rusty Russellb6c09b52015-06-16 12:16:22 +09302132 Note: for modules inside an initrd or initramfs, it's more efficient
2133 to compress the whole initrd or initramfs instead.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302134
Rusty Russellb6c09b52015-06-16 12:16:22 +09302135 Note: This is fully compatible with signed modules.
2136
2137 If in doubt, say N.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302138
2139choice
2140 prompt "Compression algorithm"
2141 depends on MODULE_COMPRESS
2142 default MODULE_COMPRESS_GZIP
2143 help
2144 This determines which sort of compression will be used during
2145 'make modules_install'.
2146
2147 GZIP (default) and XZ are supported.
2148
2149config MODULE_COMPRESS_GZIP
2150 bool "GZIP"
2151
2152config MODULE_COMPRESS_XZ
2153 bool "XZ"
2154
2155endchoice
2156
Matthias Maennich3d52ec52019-09-06 11:32:29 +01002157config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
2158 bool "Allow loading of modules with missing namespace imports"
2159 help
2160 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
2161 a namespace. A module that makes use of a symbol exported with such a
2162 namespace is required to import the namespace via MODULE_IMPORT_NS().
2163 There is no technical reason to enforce correct namespace imports,
2164 but it creates consistency between symbols defining namespaces and
2165 users importing namespaces they make use of. This option relaxes this
2166 requirement and lifts the enforcement when loading a module.
2167
2168 If unsure, say N.
2169
Masahiro Yamadaefd97632019-09-09 20:04:08 +09002170config UNUSED_SYMBOLS
2171 bool "Enable unused/obsolete exported symbols"
2172 default y if X86
2173 help
2174 Unused but exported symbols make the kernel needlessly bigger. For
2175 that reason most of these unused exports will soon be removed. This
2176 option is provided temporarily to provide a transition period in case
2177 some external kernel module needs one of these symbols anyway. If you
2178 encounter such a case in your module, consider if you are actually
2179 using the right API. (rationale: since nobody in the kernel is using
2180 this in a module, there is a pretty good chance it's actually the
2181 wrong interface to use). If you really need the symbol, please send a
2182 mail to the linux kernel mailing list mentioning the symbol and why
2183 you really need it, and what the merge plan to the mainline kernel for
2184 your module is.
2185
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002186config TRIM_UNUSED_KSYMS
2187 bool "Trim unused exported kernel symbols"
Masahiro Yamadad189c2a2019-09-09 20:04:07 +09002188 depends on !UNUSED_SYMBOLS
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002189 help
2190 The kernel and some modules make many symbols available for
2191 other modules to use via EXPORT_SYMBOL() and variants. Depending
2192 on the set of modules being selected in your kernel configuration,
2193 many of those exported symbols might never be used.
2194
2195 This option allows for unused exported symbols to be dropped from
2196 the build. In turn, this provides the compiler more opportunities
2197 (especially when using LTO) for optimizing the code and reducing
2198 binary size. This might have some security advantages as well.
2199
Valdis Kletnieksf1cb6372016-08-02 14:07:27 -07002200 If unsure, or if you need to build out-of-tree modules, say N.
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002201
Quentin Perret1518c632020-02-28 17:20:13 +00002202config UNUSED_KSYMS_WHITELIST
2203 string "Whitelist of symbols to keep in ksymtab"
2204 depends on TRIM_UNUSED_KSYMS
2205 help
2206 By default, all unused exported symbols will be un-exported from the
2207 build when TRIM_UNUSED_KSYMS is selected.
2208
2209 UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
2210 exported at all times, even in absence of in-tree users. The value to
2211 set here is the path to a text file containing the list of symbols,
2212 one per line. The path can be absolute, or relative to the kernel
2213 source tree.
2214
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002215endif # MODULES
2216
Peter Zijlstra6c9692e22015-05-27 11:09:37 +09302217config MODULES_TREE_LOOKUP
2218 def_bool y
2219 depends on PERF_EVENTS || TRACING
2220
Rusty Russell98a79d62008-12-13 21:19:41 +10302221config INIT_ALL_POSSIBLE
2222 bool
2223 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302224 Back when each arch used to define their own cpu_online_mask and
2225 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302226 with all 1s, and others with all 0s. When they were centralised,
2227 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002228 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302229
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002230source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002231
2232config PREEMPT_NOTIFIERS
2233 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002234
Steffen Klassert16295be2010-01-06 19:47:10 +11002235config PADATA
2236 depends on SMP
2237 bool
2238
David Howells4520c6a2012-09-21 23:31:13 +01002239config ASN1
2240 tristate
2241 help
2242 Build a simple ASN.1 grammar compiler that produces a bytecode output
2243 that can be interpreted by the ASN.1 stream decoder and used to
2244 inform it as to what tags are to be expected in a stream and what
2245 functions to call on what tags.
2246
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002247source "kernel/Kconfig.locks"
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05002248
Daniel Borkmann0ebeea82020-05-15 12:11:16 +02002249config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2250 bool
2251
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05002252config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2253 bool
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002254
2255# It may be useful for an architecture to override the definitions of the
Dominik Brodowski7303e302018-04-05 11:53:03 +02002256# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2257# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2258# different calling convention for syscalls. They can also override the
2259# macros for not-implemented syscalls in kernel/sys_ni.c and
2260# kernel/time/posix-stubs.c. All these overrides need to be available in
2261# <asm/syscall_wrapper.h>.
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002262config ARCH_HAS_SYSCALL_WRAPPER
2263 def_bool n