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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 Yamada104daea2018-05-28 18:21:40 +09009 default ARCH_DEFCONFIG
10 default "arch/$(ARCH)/defconfig"
Roman Zippelface4372006-06-08 22:12:45 -070011
Masahiro Yamadaa4353892018-05-28 18:22:01 +090012config CC_IS_GCC
13 def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
14
15config GCC_VERSION
16 int
Masahiro Yamadafa7295a2019-03-01 16:10:22 +090017 default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
Masahiro Yamadaa4353892018-05-28 18:22:01 +090018 default 0
19
Masahiro Yamada469cb732018-05-28 18:22:02 +090020config CC_IS_CLANG
21 def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
22
23config CLANG_VERSION
24 int
25 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
26
Masahiro Yamada1a927fd2019-07-01 09:58:39 +090027config CC_CAN_LINK
28 def_bool $(success,$(srctree)/scripts/cc-can-link.sh $(CC))
29
Masahiro Yamadae9666d12018-12-31 00:14:15 +090030config CC_HAS_ASM_GOTO
31 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
32
Peter Collingbourne5cf896fb62019-07-31 18:18:42 -070033config TOOLS_SUPPORT_RELR
Will Deacon2d122942019-08-20 10:11:54 +010034 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 -070035
Rasmus Villemoeseb111862019-09-13 00:19:25 +020036config CC_HAS_ASM_INLINE
37 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
38
Masahiro Yamadab303c6d2019-02-21 13:13:38 +090039config CC_HAS_WARN_MAYBE_UNINITIALIZED
40 def_bool $(cc-option,-Wmaybe-uninitialized)
41 help
42 GCC >= 4.7 supports this option.
43
44config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
45 bool
46 depends on CC_HAS_WARN_MAYBE_UNINITIALIZED
47 default CC_IS_GCC && GCC_VERSION < 40900 # unreliable for GCC < 4.9
48 help
49 GCC's -Wmaybe-uninitialized is not reliable by definition.
50 Lots of false positive warnings are produced in some cases.
51
52 If this option is enabled, -Wno-maybe-uninitialzed is passed
53 to the compiler to suppress maybe-uninitialized warnings.
54
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -070055config CONSTRUCTORS
56 bool
Peter Oberparleiterb99b87f72009-06-17 16:28:03 -070057
Peter Zijlstrae360adb2010-10-14 14:01:34 +080058config IRQ_WORK
59 bool
Peter Zijlstrae360adb2010-10-14 14:01:34 +080060
David Daney1dbdc6f2012-04-19 14:59:57 -070061config BUILDTIME_EXTABLE_SORT
62 bool
63
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070064config THREAD_INFO_IN_TASK
65 bool
66 help
67 Select this to move thread_info off the stack into task_struct. To
68 make this work, an arch will need to remove all thread_info fields
69 except flags and fix any runtime bugs.
70
Andy Lutomirskic6c314a2016-09-15 22:45:43 -070071 One subtle change that will be needed is to use try_get_task_stack()
72 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
73
Al Boldiff0cfc62007-07-31 00:39:23 -070074menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
Linus Torvalds1da177e2005-04-16 15:20:36 -070076config BROKEN
77 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -070078
79config BROKEN_ON_SMP
80 bool
81 depends on BROKEN || !SMP
82 default y
83
Linus Torvalds1da177e2005-04-16 15:20:36 -070084config INIT_ENV_ARG_LIMIT
85 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -070086 default 32 if !UML
87 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 help
Randy Dunlap34ad92c22005-10-30 15:01:46 -080089 Maximum of each of the number of arguments and environment
90 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070091
Jiri Slaby4bb16672013-05-22 10:56:24 +020092config COMPILE_TEST
93 bool "Compile also drivers which will not load"
Richard Weinbergerbc083a62016-08-02 14:03:27 -070094 depends on !UML
Jiri Slaby4bb16672013-05-22 10:56:24 +020095 default n
96 help
97 Some drivers can be compiled on a different platform than they are
98 intended to be run on. Despite they cannot be loaded there (or even
99 when they load they cannot be used due to missing HW support),
100 developers still, opposing to distributors, might want to build such
101 drivers to compile-test them.
102
103 If you are a developer and want to build everything available, say Y
104 here. If you are a user/distributor, say N here to exclude useless
105 drivers to be distributed.
106
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900107config UAPI_HEADER_TEST
108 bool "Compile test UAPI headers"
Masahiro Yamadafcbb8462019-11-07 16:14:40 +0900109 depends on HEADERS_INSTALL && CC_CAN_LINK
Masahiro Yamadad6fc9fc2019-07-01 09:58:40 +0900110 help
111 Compile test headers exported to user-space to ensure they are
112 self-contained, i.e. compilable as standalone units.
113
114 If you are a developer or tester and want to ensure the exported
115 headers are self-contained, say Y here. Otherwise, choose N.
116
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117config LOCALVERSION
118 string "Local version - append to kernel release"
119 help
120 Append an extra string to the end of your kernel version.
121 This will show up when you type uname, for example.
122 The string you set here will be appended after the contents of
123 any files with a filename matching localversion* in your
124 object and source tree, in that order. Your total string can
125 be a maximum of 64 characters.
126
Ryan Andersonaaebf432005-07-31 04:57:49 -0400127config LOCALVERSION_AUTO
128 bool "Automatically append version information to the version string"
129 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -0700130 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -0400131 help
132 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200133 release tree by looking for git tags that belong to the current
134 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400135
136 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200137 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400138 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200139 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400140
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200141 (The actual string used here is the first eight characters produced
142 by running the command:
143
144 $ git rev-parse --verify HEAD
145
146 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400147
Laura Abbott9afb7192018-07-05 17:49:37 -0700148config BUILD_SALT
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800149 string "Build ID Salt"
150 default ""
151 help
152 The build ID is used to link binaries and their debug info. Setting
153 this option will use the value in the calculation of the build id.
154 This is mostly useful for distributions which want to ensure the
155 build is unique between builds. It's safe to leave the default.
Laura Abbott9afb7192018-07-05 17:49:37 -0700156
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800157config HAVE_KERNEL_GZIP
158 bool
159
160config HAVE_KERNEL_BZIP2
161 bool
162
163config HAVE_KERNEL_LZMA
164 bool
165
Lasse Collin3ebe1242011-01-12 17:01:23 -0800166config HAVE_KERNEL_XZ
167 bool
168
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800169config HAVE_KERNEL_LZO
170 bool
171
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700172config HAVE_KERNEL_LZ4
173 bool
174
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200175config HAVE_KERNEL_UNCOMPRESSED
176 bool
177
Alain Knaff30d65db2009-01-04 22:46:17 +0100178choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800179 prompt "Kernel compression mode"
180 default KERNEL_GZIP
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200181 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 -0800182 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100183 The linux kernel is a kind of self-extracting executable.
184 Several compression algorithms are available, which differ
185 in efficiency, compression and decompression speed.
186 Compression speed is only relevant when building a kernel.
187 Decompression speed is relevant at each boot.
188
189 If you have any problems with bzip2 or lzma compressed
190 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
191 version of this functionality (bzip2 only), for 2.4, was
192 supplied by Christian Ludwig)
193
194 High compression options are mostly useful for users, who
195 are low on disk space (embedded systems), but for whom ram
196 size matters less.
197
198 If in doubt, select 'gzip'
199
200config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800201 bool "Gzip"
202 depends on HAVE_KERNEL_GZIP
203 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800204 The old and tried gzip compression. It provides a good balance
205 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100206
207config KERNEL_BZIP2
208 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800209 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100210 help
211 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700212 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800213 size is about 10% smaller with bzip2, in comparison to gzip.
214 Bzip2 uses a large amount of memory. For modern kernels you
215 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100216
217config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800218 bool "LZMA"
219 depends on HAVE_KERNEL_LZMA
220 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700221 This compression algorithm's ratio is best. Decompression speed
222 is between gzip and bzip2. Compression is slowest.
223 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100224
Lasse Collin3ebe1242011-01-12 17:01:23 -0800225config KERNEL_XZ
226 bool "XZ"
227 depends on HAVE_KERNEL_XZ
228 help
229 XZ uses the LZMA2 algorithm and instruction set specific
230 BCJ filters which can improve compression ratio of executable
231 code. The size of the kernel is about 30% smaller with XZ in
232 comparison to gzip. On architectures for which there is a BCJ
233 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
234 will create a few percent smaller kernel than plain LZMA.
235
236 The speed is about the same as with LZMA: The decompression
237 speed of XZ is better than that of bzip2 but worse than gzip
238 and LZO. Compression is slow.
239
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800240config KERNEL_LZO
241 bool "LZO"
242 depends on HAVE_KERNEL_LZO
243 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700244 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200245 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800246 (both compression and decompression) is the fastest.
247
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700248config KERNEL_LZ4
249 bool "LZ4"
250 depends on HAVE_KERNEL_LZ4
251 help
252 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
253 A preliminary version of LZ4 de/compression tool is available at
254 <https://code.google.com/p/lz4/>.
255
256 Its compression ratio is worse than LZO. The size of the kernel
257 is about 8% bigger than LZO. But the decompression speed is
258 faster than LZO.
259
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200260config KERNEL_UNCOMPRESSED
261 bool "None"
262 depends on HAVE_KERNEL_UNCOMPRESSED
263 help
264 Produce uncompressed kernel image. This option is usually not what
265 you want. It is useful for debugging the kernel in slow simulation
266 environments, where decompressing and moving the kernel is awfully
267 slow. This option allows early boot code to skip the decompressor
268 and jump right at uncompressed kernel image.
269
Alain Knaff30d65db2009-01-04 22:46:17 +0100270endchoice
271
Josh Triplettbd5dc172011-06-15 15:08:28 -0700272config DEFAULT_HOSTNAME
273 string "Default hostname"
274 default "(none)"
275 help
276 This option determines the default system hostname before userspace
277 calls sethostname(2). The kernel traditionally uses "(none)" here,
278 but you may wish to use a different default here to make a minimal
279 system more usable with less configuration.
280
Christoph Hellwig17c46a62018-07-31 13:39:29 +0200281#
282# For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
283# add proper SWAP support to them, in which case this can be remove.
284#
285config ARCH_NO_SWAP
286 bool
287
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288config SWAP
289 bool "Support for paging of anonymous memory (swap)"
Christoph Hellwig17c46a62018-07-31 13:39:29 +0200290 depends on MMU && BLOCK && !ARCH_NO_SWAP
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 default y
292 help
293 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100294 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 used to provide more virtual memory than the actual RAM present
296 in your computer. If unsure say Y.
297
298config SYSVIPC
299 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 ---help---
301 Inter Process Communication is a suite of library functions and
302 system calls which let processes (running programs) synchronize and
303 exchange information. It is generally considered to be a good thing,
304 and some programs won't run unless you say Y here. In particular, if
305 you want to run the DOS emulator dosemu under Linux (read the
306 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
307 you'll need to say Y here.
308
309 You can find documentation about IPC with "info ipc" and also in
310 section 6.4 of the Linux Programmer's Guide, available from
311 <http://www.tldp.org/guides.html>.
312
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800313config SYSVIPC_SYSCTL
314 bool
315 depends on SYSVIPC
316 depends on SYSCTL
317 default y
318
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319config POSIX_MQUEUE
320 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700321 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 ---help---
323 POSIX variant of message queues is a part of IPC. In POSIX message
324 queues every message has a priority which decides about succession
325 of receiving it by a process. If you want to compile and run
326 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e376502007-05-09 07:25:13 +0200327 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328
329 POSIX message queues are visible as a filesystem called 'mqueue'
330 and can be mounted somewhere if you want to do filesystem
331 operations on message queues.
332
333 If unsure, say Y.
334
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700335config POSIX_MQUEUE_SYSCTL
336 bool
337 depends on POSIX_MQUEUE
338 depends on SYSCTL
339 default y
340
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700341config CROSS_MEMORY_ATTACH
342 bool "Enable process_vm_readv/writev syscalls"
343 depends on MMU
344 default y
345 help
346 Enabling this option adds the system calls process_vm_readv and
347 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700348 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700349 See the man page for more details.
350
Josh Triplett69369a72014-04-03 14:48:27 -0700351config USELIB
352 bool "uselib syscall"
Riku Voipiob2113a42016-01-15 16:58:13 -0800353 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
Josh Triplett69369a72014-04-03 14:48:27 -0700354 help
355 This option enables the uselib syscall, a system call used in the
356 dynamic linker from libc5 and earlier. glibc does not use this
357 system call. If you intend to run programs built on libc5 or
358 earlier, you may need to enable this syscall. Current systems
359 running glibc can safely disable this.
360
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361config AUDIT
362 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100363 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 help
365 Enable auditing infrastructure that can be used with another
366 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500367 logging of avc messages output). System call auditing is included
368 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900370config HAVE_ARCH_AUDITSYSCALL
371 bool
372
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500374 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900375 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500376 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400377
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000378source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200379source "kernel/time/Kconfig"
Christoph Hellwig87a4c372018-07-31 13:39:32 +0200380source "kernel/Kconfig.preempt"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000381
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200382menu "CPU/Task time and stats accounting"
383
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200384config VIRT_CPU_ACCOUNTING
385 bool
386
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200387choice
388 prompt "Cputime accounting"
389 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100390 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200391
392# Kind of a stub config for the pure tick based cputime accounting
393config TICK_CPU_ACCOUNTING
394 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200395 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200396 help
397 This is the basic tick based cputime accounting that maintains
398 statistics about user, system and idle time spent on per jiffies
399 granularity.
400
401 If unsure, say Y.
402
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200403config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200404 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200405 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200406 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200407 help
408 Select this option to enable more accurate task and CPU time
409 accounting. This is done by reading a CPU counter on each
410 kernel entry and exit and on transitions within the kernel
411 between system, softirq and hardirq state, so there is a
412 small performance impact. In the case of s390 or IBM POWER > 5,
413 this also enables accounting of stolen time on logically-partitioned
414 systems.
415
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200416config VIRT_CPU_ACCOUNTING_GEN
417 bool "Full dynticks CPU time accounting"
Kevin Hilmanff3fb252013-09-16 15:28:19 -0700418 depends on HAVE_CONTEXT_TRACKING
Kevin Hilman554b0002013-09-16 15:28:21 -0700419 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Arnd Bergmann041a1572019-03-04 21:01:31 +0100420 depends on GENERIC_CLOCKEVENTS
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200421 select VIRT_CPU_ACCOUNTING
422 select CONTEXT_TRACKING
423 help
424 Select this option to enable task and CPU time accounting on full
425 dynticks systems. This accounting is implemented by watching every
426 kernel-user boundaries using the context tracking subsystem.
427 The accounting is thus performed at the expense of some significant
428 overhead.
429
430 For now this is only useful if you are working on the full
431 dynticks subsystem development.
432
433 If unsure, say N.
434
Rik van Rielb58c3582016-07-13 16:50:02 +0200435endchoice
436
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200437config IRQ_TIME_ACCOUNTING
438 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200439 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200440 help
441 Select this option to enable fine granularity task irq time
442 accounting. This is done by reading a timestamp on each
443 transitions between softirq and hardirq state, so there can be a
444 small performance impact.
445
446 If in doubt, say N here.
447
Vincent Guittot11d4afd2018-09-25 11:17:42 +0200448config HAVE_SCHED_AVG_IRQ
449 def_bool y
450 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
451 depends on SMP
452
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200453config BSD_PROCESS_ACCT
454 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700455 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200456 help
457 If you say Y here, a user level program will be able to instruct the
458 kernel (via a special system call) to write process accounting
459 information to a file: whenever a process exits, information about
460 that process will be appended to the file by the kernel. The
461 information includes things such as creation time, owning user,
462 command name, memory usage, controlling terminal etc. (the complete
463 list is in the struct acct in <file:include/linux/acct.h>). It is
464 up to the user level program to do useful things with this
465 information. This is generally a good idea, so say Y.
466
467config BSD_PROCESS_ACCT_V3
468 bool "BSD Process Accounting version 3 file format"
469 depends on BSD_PROCESS_ACCT
470 default n
471 help
472 If you say Y here, the process accounting information is written
473 in a new file format that also logs the process IDs of each
Randy Dunlap3903bf92018-08-21 21:58:34 -0700474 process and its parent. Note that this file format is incompatible
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200475 with previous v0/v1/v2 file formats, so you will need updated tools
476 for processing it. A preliminary version of these tools is available
477 at <http://www.gnu.org/software/acct/>.
478
479config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700480 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200481 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700482 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200483 default n
484 help
485 Export selected statistics for tasks/processes through the
486 generic netlink interface. Unlike BSD process accounting, the
487 statistics are available during the lifetime of tasks/processes as
488 responses to commands. Like BSD accounting, they are sent to user
489 space on task exit.
490
491 Say N if unsure.
492
493config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700494 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200495 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530496 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200497 help
498 Collect information on time spent by a task waiting for system
499 resources like cpu, synchronous block I/O completion and swapping
500 in pages. Such statistics can help in setting a task's priorities
501 relative to other tasks for cpu, io, rss limits etc.
502
503 Say N if unsure.
504
505config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700506 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200507 depends on TASKSTATS
508 help
509 Collect extended task accounting data and send the data
510 to userland for processing over the taskstats interface.
511
512 Say N if unsure.
513
514config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700515 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200516 depends on TASK_XACCT
517 help
518 Collect information on the number of bytes of storage I/O which this
519 task has caused.
520
521 Say N if unsure.
522
Johannes Weinereb414682018-10-26 15:06:27 -0700523config PSI
524 bool "Pressure stall information tracking"
525 help
526 Collect metrics that indicate how overcommitted the CPU, memory,
527 and IO capacity are in the system.
528
529 If you say Y here, the kernel will create /proc/pressure/ with the
530 pressure statistics files cpu, memory, and io. These will indicate
531 the share of walltime in which some or all tasks in the system are
532 delayed due to contention of the respective resource.
533
Johannes Weiner2ce71352018-10-26 15:06:31 -0700534 In kernels with cgroup support, cgroups (cgroup2 only) will
535 have cpu.pressure, memory.pressure, and io.pressure files,
536 which aggregate pressure stalls for the grouped tasks only.
537
Mauro Carvalho Chehabc3123552019-04-17 05:46:08 -0300538 For more details see Documentation/accounting/psi.rst.
Johannes Weinereb414682018-10-26 15:06:27 -0700539
540 Say N if unsure.
541
Johannes Weinere0c27442018-11-30 14:09:58 -0800542config PSI_DEFAULT_DISABLED
543 bool "Require boot parameter to enable pressure stall information tracking"
544 default n
545 depends on PSI
546 help
547 If set, pressure stall information tracking will be disabled
Baruch Siach428a1cb2018-12-14 14:17:03 -0800548 per default but can be enabled through passing psi=1 on the
549 kernel commandline during boot.
Johannes Weinere0c27442018-11-30 14:09:58 -0800550
Johannes Weiner7b2489d2019-02-01 14:21:15 -0800551 This feature adds some code to the task wakeup and sleep
552 paths of the scheduler. The overhead is too low to affect
553 common scheduling-intense workloads in practice (such as
554 webservers, memcache), but it does show up in artificial
555 scheduler stress tests, such as hackbench.
556
557 If you are paranoid and not sure what the kernel will be
558 used for, say Y.
559
560 Say N if unsure.
561
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200562endmenu # "CPU/Task time and stats accounting"
563
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200564config CPU_ISOLATION
565 bool "CPU isolation"
Geert Uytterhoeven414a2dc2018-01-02 12:13:10 +0100566 depends on SMP || COMPILE_TEST
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100567 default y
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200568 help
569 Make sure that CPUs running critical tasks are not disturbed by
570 any source of "noise" such as unbound workqueues, timers, kthreads...
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100571 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
572 the "isolcpus=" boot parameter.
573
574 Say Y if unsure.
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200575
Paul E. McKenney0af92d42017-05-17 08:43:40 -0700576source "kernel/rcu/Kconfig"
Mike Travisc903ff82009-01-15 12:28:29 -0800577
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700578config BUILD_BIN2C
579 bool
580 default n
581
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700583 tristate "Kernel .config support"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 ---help---
585 This option enables the complete Linux kernel ".config" file
586 contents to be saved in the kernel. It provides documentation
587 of which kernel options are used in a running kernel or in an
588 on-disk kernel. This information can be extracted from the kernel
589 image file with the script scripts/extract-ikconfig and used as
590 input to rebuild the current kernel or to build another kernel.
591 It can also be extracted from a running kernel by reading
592 /proc/config.gz if enabled (below).
593
594config IKCONFIG_PROC
595 bool "Enable access to .config through /proc/config.gz"
596 depends on IKCONFIG && PROC_FS
597 ---help---
598 This option enables access to the kernel configuration file
599 through /proc/config.gz.
600
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400601config IKHEADERS
602 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
603 depends on SYSFS
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400604 help
Joel Fernandes (Google)f7b101d2019-05-15 17:35:51 -0400605 This option enables access to the in-kernel headers that are generated during
606 the build process. These can be used to build eBPF tracing programs,
607 or similar programs. If you build the headers as a module, a module called
608 kheaders.ko is built which can be loaded on-demand to get access to headers.
Joel Fernandes (Google)43d8ce92019-04-26 15:04:29 -0400609
Alistair John Strachan794543a2007-05-08 00:31:15 -0700610config LOG_BUF_SHIFT
611 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Ingo Molnarfb39f982015-07-01 10:19:11 +0200612 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700613 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700614 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700615 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700616 Select the minimal kernel log buffer size as a power of 2.
617 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
618 parameter, see below. Any higher size also might be forced
619 by "log_buf_len" boot parameter.
620
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700621 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700622 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700623 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700624 15 => 32 KB
625 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700626 13 => 8 KB
627 12 => 4 KB
628
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700629config LOG_CPU_MAX_BUF_SHIFT
630 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700631 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700632 range 0 21
633 default 12 if !BASE_SMALL
634 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700635 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700636 help
637 This option allows to increase the default ring buffer size
638 according to the number of CPUs. The value defines the contribution
639 of each CPU as a power of 2. The used space is typically only few
640 lines however it might be much more when problems are reported,
641 e.g. backtraces.
642
643 The increased size means that a new buffer has to be allocated and
644 the original static one is unused. It makes sense only on systems
645 with more CPUs. Therefore this value is used only when the sum of
646 contributions is greater than the half of the default kernel ring
647 buffer as defined by LOG_BUF_SHIFT. The default values are set
648 so that more than 64 CPUs are needed to trigger the allocation.
649
650 Also this option is ignored when "log_buf_len" kernel parameter is
651 used as it forces an exact (power of two) size of the ring buffer.
652
653 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200654 hotplugging making the computation optimal for the worst case
655 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700656
657 Examples shift values and their meaning:
658 17 => 128 KB for each CPU
659 16 => 64 KB for each CPU
660 15 => 32 KB for each CPU
661 14 => 16 KB for each CPU
662 13 => 8 KB for each CPU
663 12 => 4 KB for each CPU
664
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900665config PRINTK_SAFE_LOG_BUF_SHIFT
666 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
Petr Mladek427934b2016-05-20 17:00:39 -0700667 range 10 21
668 default 13
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900669 depends on PRINTK
Petr Mladek427934b2016-05-20 17:00:39 -0700670 help
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900671 Select the size of an alternate printk per-CPU buffer where messages
672 printed from usafe contexts are temporary stored. One example would
673 be NMI messages, another one - printk recursion. The messages are
674 copied to the main log buffer in a safe context to avoid a deadlock.
675 The value defines the size as a power of 2.
Petr Mladek427934b2016-05-20 17:00:39 -0700676
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900677 Those messages are rare and limited. The largest one is when
Petr Mladek427934b2016-05-20 17:00:39 -0700678 a backtrace is printed. It usually fits into 4KB. Select
679 8KB if you want to be on the safe side.
680
681 Examples:
682 17 => 128 KB for each CPU
683 16 => 64 KB for each CPU
684 15 => 32 KB for each CPU
685 14 => 16 KB for each CPU
686 13 => 8 KB for each CPU
687 12 => 4 KB for each CPU
688
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800689#
690# Architectures with an unreliable sched_clock() should select this:
691#
692config HAVE_UNSTABLE_SCHED_CLOCK
693 bool
694
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700695config GENERIC_SCHED_CLOCK
696 bool
697
Patrick Bellasi69842cb2019-06-21 09:42:02 +0100698menu "Scheduler features"
699
700config UCLAMP_TASK
701 bool "Enable utilization clamping for RT/FAIR tasks"
702 depends on CPU_FREQ_GOV_SCHEDUTIL
703 help
704 This feature enables the scheduler to track the clamped utilization
705 of each CPU based on RUNNABLE tasks scheduled on that CPU.
706
707 With this option, the user can specify the min and max CPU
708 utilization allowed for RUNNABLE tasks. The max utilization defines
709 the maximum frequency a task should use while the min utilization
710 defines the minimum frequency it should use.
711
712 Both min and max utilization clamp values are hints to the scheduler,
713 aiming at improving its frequency selection policy, but they do not
714 enforce or grant any specific bandwidth for tasks.
715
716 If in doubt, say N.
717
718config UCLAMP_BUCKETS_COUNT
719 int "Number of supported utilization clamp buckets"
720 range 5 20
721 default 5
722 depends on UCLAMP_TASK
723 help
724 Defines the number of clamp buckets to use. The range of each bucket
725 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
726 number of clamp buckets the finer their granularity and the higher
727 the precision of clamping aggregation and tracking at run-time.
728
729 For example, with the minimum configuration value we will have 5
730 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
731 be refcounted in the [20..39]% bucket and will set the bucket clamp
732 effective value to 25%.
733 If a second 30% boosted task should be co-scheduled on the same CPU,
734 that task will be refcounted in the same bucket of the first task and
735 it will boost the bucket clamp effective value to 30%.
736 The clamp effective value of a bucket is reset to its nominal value
737 (20% in the example above) when there are no more tasks refcounted in
738 that bucket.
739
740 An additional boost/capping margin can be added to some tasks. In the
741 example above the 25% task will be boosted to 30% until it exits the
742 CPU. If that should be considered not acceptable on certain systems,
743 it's always possible to reduce the margin by increasing the number of
744 clamp buckets to trade off used memory for run-time tracking
745 precision.
746
747 If in doubt, use the default value.
748
749endmenu
750
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200751#
752# For architectures that want to enable the support for NUMA-affine scheduler
753# balancing logic:
754#
755config ARCH_SUPPORTS_NUMA_BALANCING
756 bool
757
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100758#
Mel Gorman72b252a2015-09-04 15:47:32 -0700759# For architectures that prefer to flush all TLBs after a number of pages
760# are unmapped instead of sending one IPI per page to flush. The architecture
761# must provide guarantees on what happens if a clean TLB cache entry is
762# written after the unmap. Details are in mm/rmap.c near the check for
763# should_defer_flush. The architecture should also consider if the full flush
764# and the refill costs are offset by the savings of sending fewer IPIs.
765config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
766 bool
767
Ard Biesheuvelc12d3362019-11-08 13:22:27 +0100768config CC_HAS_INT128
769 def_bool y
770 depends on !$(cc-option,-D__SIZEOF_INT128__=0)
771
Mel Gorman72b252a2015-09-04 15:47:32 -0700772#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100773# For architectures that know their GCC __int128 support is sound
774#
775config ARCH_SUPPORTS_INT128
776 bool
777
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200778# For architectures that (ab)use NUMA to represent different memory regions
779# all cpu-local but of different latencies, such as SuperH.
780#
781config ARCH_WANT_NUMA_VARIABLE_LOCALITY
782 bool
783
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200784config NUMA_BALANCING
785 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200786 depends on ARCH_SUPPORTS_NUMA_BALANCING
787 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
788 depends on SMP && NUMA && MIGRATION
789 help
790 This option adds support for automatic NUMA aware memory/task placement.
791 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400792 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200793
794 This system will be inactive on UMA systems.
795
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800796config NUMA_BALANCING_DEFAULT_ENABLED
797 bool "Automatically enable NUMA aware memory/task placement"
798 default y
799 depends on NUMA_BALANCING
800 help
801 If set, automatic NUMA balancing will be enabled if running on a NUMA
802 machine.
803
Li Zefan23964d22009-01-15 13:50:58 -0800804menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500805 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500806 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700807 help
Li Zefan23964d22009-01-15 13:50:58 -0800808 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800809 use with process control subsystems such as Cpusets, CFS, memory
810 controls or device isolation.
811 See
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300812 - Documentation/scheduler/sched-design-CFS.rst (CFS)
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300813 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800814 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700815
816 Say N if unsure.
817
Li Zefan23964d22009-01-15 13:50:58 -0800818if CGROUPS
819
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800820config PAGE_COUNTER
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -0800821 bool
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800822
Andrew Mortonc255a452012-07-31 16:43:02 -0700823config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500824 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800825 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500826 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -0800827 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500828 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800829
Andrew Mortonc255a452012-07-31 16:43:02 -0700830config MEMCG_SWAP
Johannes Weinera0166ec2015-12-17 17:19:56 -0500831 bool "Swap controller"
Andrew Mortonc255a452012-07-31 16:43:02 -0700832 depends on MEMCG && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800833 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500834 Provides control over the swap space consumed by tasks in a cgroup.
835
Andrew Mortonc255a452012-07-31 16:43:02 -0700836config MEMCG_SWAP_ENABLED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500837 bool "Swap controller enabled by default"
Andrew Mortonc255a452012-07-31 16:43:02 -0700838 depends on MEMCG_SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -0800839 default y
840 help
841 Memory Resource Controller Swap Extension comes with its price in
842 a bigger memory consumption. General purpose distribution kernels
Jim Cromie43d547f2010-12-17 14:32:36 -0700843 which want to enable the feature but keep it disabled by default
Michal Hocko07555ac2013-08-22 16:35:46 -0700844 and let the user enable it by swapaccount=1 boot command line
Michal Hockoa42c3902010-11-24 12:57:08 -0800845 parameter should have this option unselected.
846 For those who want to have the feature enabled by default should
847 select this option (if, for some reason, they need to disable it
WANG Cong00a66d22011-07-25 17:12:12 -0700848 then swapaccount=0 does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800849
Kirill Tkhai84c07d12018-08-17 15:47:25 -0700850config MEMCG_KMEM
851 bool
852 depends on MEMCG && !SLOB
853 default y
854
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500855config BLK_CGROUP
856 bool "IO controller"
857 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700858 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500859 ---help---
860 Generic block IO controller cgroup interface. This is the common
861 cgroup interface which should be used by various IO controlling
862 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700863
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500864 Currently, CFQ IO scheduler uses it to recognize task groups and
865 control disk bandwidth allocation (proportional time slice allocation)
866 to such task groups. It is also used by bio throttling logic in
867 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +0200868
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500869 This option only enables generic Block IO controller infrastructure.
870 One needs to also enable actual IO controlling logic/policy. For
871 enabling proportional weight division of disk bandwidth in CFQ, set
872 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
873 CONFIG_BLK_DEV_THROTTLING=y.
874
Mauro Carvalho Chehabda82c922019-06-27 13:08:35 -0300875 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500876
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500877config CGROUP_WRITEBACK
878 bool
879 depends on MEMCG && BLK_CGROUP
880 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +0200881
Dhaval Giani7c941432010-01-20 13:26:18 +0100882menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500883 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +0100884 default n
885 help
886 This feature lets CPU scheduler recognize task groups and control CPU
887 bandwidth allocation to such task groups. It uses cgroups to group
888 tasks.
889
890if CGROUP_SCHED
891config FAIR_GROUP_SCHED
892 bool "Group scheduling for SCHED_OTHER"
893 depends on CGROUP_SCHED
894 default CGROUP_SCHED
895
Paul Turnerab84d312011-07-21 09:43:28 -0700896config CFS_BANDWIDTH
897 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -0700898 depends on FAIR_GROUP_SCHED
899 default n
900 help
901 This option allows users to define CPU bandwidth rates (limits) for
902 tasks running within the fair group scheduler. Groups with no limit
903 set are considered to be unconstrained and will run with no
904 restriction.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300905 See Documentation/scheduler/sched-bwc.rst for more information.
Paul Turnerab84d312011-07-21 09:43:28 -0700906
Dhaval Giani7c941432010-01-20 13:26:18 +0100907config RT_GROUP_SCHED
908 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +0100909 depends on CGROUP_SCHED
910 default n
911 help
912 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +0800913 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +0100914 schedule realtime tasks for non-root users until you allocate
915 realtime bandwidth for them.
Mauro Carvalho Chehabd6a3b242019-06-12 14:53:03 -0300916 See Documentation/scheduler/sched-rt-group.rst for more information.
Dhaval Giani7c941432010-01-20 13:26:18 +0100917
918endif #CGROUP_SCHED
919
Patrick Bellasi2480c092019-08-22 14:28:06 +0100920config UCLAMP_TASK_GROUP
921 bool "Utilization clamping per group of tasks"
922 depends on CGROUP_SCHED
923 depends on UCLAMP_TASK
924 default n
925 help
926 This feature enables the scheduler to track the clamped utilization
927 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
928
929 When this option is enabled, the user can specify a min and max
930 CPU bandwidth which is allowed for each single task in a group.
931 The max bandwidth allows to clamp the maximum frequency a task
932 can use, while the min bandwidth allows to define a minimum
933 frequency a task will always use.
934
935 When task group based utilization clamping is enabled, an eventually
936 specified task-specific clamp value is constrained by the cgroup
937 specified clamp value. Both minimum and maximum task clamping cannot
938 be bigger than the corresponding clamping defined at task group level.
939
940 If in doubt, say N.
941
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500942config CGROUP_PIDS
943 bool "PIDs controller"
944 help
945 Provides enforcement of process number limits in the scope of a
946 cgroup. Any attempt to fork more processes than is allowed in the
947 cgroup will fail. PIDs are fundamentally a global resource because it
948 is fairly trivial to reach PID exhaustion before you reach even a
949 conservative kmemcg limit. As a result, it is possible to grind a
950 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +0530951 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500952
953 It should be noted that organisational operations (such as attaching
Jonathan Neuschäfer98076832019-02-01 14:21:01 -0800954 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500955 since the PIDs limit only affects a process's ability to fork, not to
956 attach to a cgroup.
957
Parav Pandit39d3e752017-01-10 00:02:13 +0000958config CGROUP_RDMA
959 bool "RDMA controller"
960 help
961 Provides enforcement of RDMA resources defined by IB stack.
962 It is fairly easy for consumers to exhaust RDMA resources, which
963 can result into resource unavailability to other consumers.
964 RDMA controller is designed to stop this from happening.
965 Attaching processes with active RDMA resources to the cgroup
966 hierarchy is allowed even if can cross the hierarchy's limit.
967
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500968config CGROUP_FREEZER
969 bool "Freezer controller"
970 help
971 Provides a way to freeze and unfreeze all tasks in a
972 cgroup.
973
Johannes Weiner489c2a22016-01-20 15:02:41 -0800974 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
975 controller includes important in-kernel memory consumers per default.
976
977 If you're using cgroup2, say N.
978
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500979config CGROUP_HUGETLB
980 bool "HugeTLB controller"
981 depends on HUGETLB_PAGE
982 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +0200983 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500984 help
985 Provides a cgroup controller for HugeTLB pages.
986 When you enable this, you can put a per cgroup limit on HugeTLB usage.
987 The limit is enforced during page fault. Since HugeTLB doesn't
988 support page reclaim, enforcing the limit at page fault time implies
989 that, the application will get SIGBUS signal if it tries to access
990 HugeTLB pages beyond its limit. This requires the application to know
991 beforehand how much HugeTLB pages it would require for its use. The
992 control group is tracked in the third page lru pointer. This means
993 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200994
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500995config CPUSETS
996 bool "Cpuset controller"
Nicolas Pitree1d4eee2017-06-14 13:19:23 -0400997 depends on SMP
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500998 help
999 This option will let you create and manage CPUSETs which
1000 allow dynamically partitioning a system into sets of CPUs and
1001 Memory Nodes and assigning tasks to run only within those sets.
1002 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001003
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001004 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001005
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001006config PROC_PID_CPUSET
1007 bool "Include legacy /proc/<pid>/cpuset file"
1008 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001009 default y
1010
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001011config CGROUP_DEVICE
1012 bool "Device controller"
1013 help
1014 Provides a cgroup controller implementing whitelists for
1015 devices which a process in the cgroup can mknod or open.
1016
1017config CGROUP_CPUACCT
1018 bool "Simple CPU accounting controller"
1019 help
1020 Provides a simple controller for monitoring the
1021 total CPU consumed by the tasks in a cgroup.
1022
1023config CGROUP_PERF
1024 bool "Perf controller"
1025 depends on PERF_EVENTS
1026 help
1027 This option extends the perf per-cpu mode to restrict monitoring
1028 to threads which belong to the cgroup specified and run on the
1029 designated cpu.
1030
1031 Say N if unsure.
1032
Daniel Mack30070982016-11-23 16:52:26 +01001033config CGROUP_BPF
1034 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirski483c4932016-12-16 08:33:45 -08001035 depends on BPF_SYSCALL
1036 select SOCK_CGROUP_DATA
Daniel Mack30070982016-11-23 16:52:26 +01001037 help
1038 Allow attaching eBPF programs to a cgroup using the bpf(2)
1039 syscall command BPF_PROG_ATTACH.
1040
1041 In which context these programs are accessed depends on the type
1042 of attachment. For instance, programs that are attached using
1043 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1044 inet sockets.
1045
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001046config CGROUP_DEBUG
Waiman Long23b0be42017-06-13 17:18:03 -04001047 bool "Debug controller"
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001048 default n
Waiman Long23b0be42017-06-13 17:18:03 -04001049 depends on DEBUG_KERNEL
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001050 help
1051 This option enables a simple controller that exports
Waiman Long23b0be42017-06-13 17:18:03 -04001052 debugging information about the cgroups framework. This
1053 controller is for control cgroup debugging only. Its
1054 interfaces are not stable.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001055
1056 Say N.
1057
Arnd Bergmann73b35142017-01-10 13:08:06 +01001058config SOCK_CGROUP_DATA
1059 bool
1060 default n
1061
Li Zefan23964d22009-01-15 13:50:58 -08001062endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001063
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001064menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001065 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001066 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001067 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001068 help
1069 Provides the way to make tasks work with different objects using
1070 the same id. For example same IPC id may refer to different objects
1071 or same user id or pid may refer to different tasks when used in
1072 different namespaces.
1073
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001074if NAMESPACES
1075
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001076config UTS_NS
1077 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001078 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001079 help
1080 In this namespace tasks see different info provided with the
1081 uname() system call
1082
Andrei Vagin769071a2019-11-12 01:26:52 +00001083config TIME_NS
1084 bool "TIME namespace"
Thomas Gleixner660fd042019-11-12 01:27:09 +00001085 depends on GENERIC_VDSO_TIME_NS
Andrei Vagin769071a2019-11-12 01:26:52 +00001086 default y
1087 help
1088 In this namespace boottime and monotonic clocks can be set.
1089 The time will keep going with the same pace.
1090
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001091config IPC_NS
1092 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001093 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001094 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001095 help
1096 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001097 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001098
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001099config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001100 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001101 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001102 help
1103 This allows containers, i.e. vservers, to use user namespaces
1104 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001105
1106 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001107 recommended that the MEMCG option also be enabled and that
1108 user-space use the memory control groups to limit the amount
1109 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001110
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001111 If unsure, say N.
1112
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001113config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001114 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001115 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001116 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001117 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001118 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001119 pid namespaces. This is a building block of containers.
1120
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001121config NET_NS
1122 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001123 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001124 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001125 help
1126 Allow user space to create what appear to be multiple instances
1127 of the network stack.
1128
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001129endif # NAMESPACES
1130
Adrian Reber5cb366b2018-08-21 22:01:17 -07001131config CHECKPOINT_RESTORE
1132 bool "Checkpoint/restore support"
1133 select PROC_CHILDREN
1134 default n
1135 help
1136 Enables additional kernel features in a sake of checkpoint/restore.
1137 In particular it adds auxiliary prctl codes to setup process text,
1138 data and heap segment sizes, and a few additional /proc filesystem
1139 entries.
1140
1141 If unsure, say N here.
1142
Mike Galbraith5091faa2010-11-30 14:18:03 +01001143config SCHED_AUTOGROUP
1144 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001145 select CGROUPS
1146 select CGROUP_SCHED
1147 select FAIR_GROUP_SCHED
1148 help
1149 This option optimizes the scheduler for common desktop workloads by
1150 automatically creating and populating task groups. This separation
1151 of workloads isolates aggressive CPU burners (like build jobs) from
1152 desktop applications. Task group autogeneration is currently based
1153 upon task session.
1154
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001155config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001156 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001157 depends on SYSFS
1158 default n
1159 help
1160 This option adds code that switches the layout of the "block" class
1161 devices, to not show up in /sys/class/block/, but only in
1162 /sys/block/.
1163
1164 This switch is only active when the sysfs.deprecated=1 boot option is
1165 passed or the SYSFS_DEPRECATED_V2 option is set.
1166
1167 This option allows new kernels to run on old distributions and tools,
1168 which might get confused by /sys/class/block/. Since 2007/2008 all
1169 major distributions and tools handle this just fine.
1170
1171 Recent distributions and userspace tools after 2009/2010 depend on
1172 the existence of /sys/class/block/, and will not work with this
1173 option enabled.
1174
1175 Only if you are using a new kernel on an old distribution, you might
1176 need to say Y here.
1177
1178config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001179 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001180 default n
1181 depends on SYSFS
1182 depends on SYSFS_DEPRECATED
1183 help
1184 Enable deprecated sysfs by default.
1185
1186 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1187 option.
1188
1189 Only if you are using a new kernel on an old distribution, you might
1190 need to say Y here. Even then, odds are you would not need it
1191 enabled, you can always pass the boot option if absolutely necessary.
1192
1193config RELAY
1194 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001195 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001196 help
1197 This option enables support for relay interface support in
1198 certain file systems (such as debugfs).
1199 It is designed to provide an efficient mechanism for tools and
1200 facilities to relay large amounts of data from kernel space to
1201 user space.
1202
1203 If unsure, say N.
1204
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001205config BLK_DEV_INITRD
1206 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001207 help
1208 The initial RAM filesystem is a ramfs which is loaded by the
1209 boot loader (loadlin or lilo) and that is mounted as root
1210 before the normal boot procedure. It is typically used to
1211 load modules needed to mount the "real" root file system,
Mauro Carvalho Chehab8c27ceff32016-10-18 10:12:27 -02001212 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001213
1214 If RAM disk support (BLK_DEV_RAM) is also included, this
1215 also enables initial RAM disk (initrd) support and adds
1216 15 Kbytes (more on some other architectures) to the kernel size.
1217
1218 If unsure say Y.
1219
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001220if BLK_DEV_INITRD
1221
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001222source "usr/Kconfig"
1223
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001224endif
1225
Arnd Bergmann877417e2016-04-25 17:35:27 +02001226choice
1227 prompt "Compiler optimization level"
Ulf Magnusson2cc3ce22017-10-04 01:53:26 +02001228 default CC_OPTIMIZE_FOR_PERFORMANCE
Arnd Bergmann877417e2016-04-25 17:35:27 +02001229
1230config CC_OPTIMIZE_FOR_PERFORMANCE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001231 bool "Optimize for performance (-O2)"
Arnd Bergmann877417e2016-04-25 17:35:27 +02001232 help
1233 This is the default optimization level for the kernel, building
1234 with the "-O2" compiler flag for best performance and most
1235 helpful compile-time warnings.
1236
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001237config CC_OPTIMIZE_FOR_PERFORMANCE_O3
1238 bool "Optimize more for performance (-O3)"
1239 depends on ARC
Masahiro Yamadab303c6d2019-02-21 13:13:38 +09001240 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001241 help
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001242 Choosing this option will pass "-O3" to your compiler to optimize
1243 the kernel yet more for performance.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001244
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001245config CC_OPTIMIZE_FOR_SIZE
Masahiro Yamada15f5db62019-08-21 02:09:40 +09001246 bool "Optimize for size (-Os)"
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001247 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
1248 help
Masahiro Yamadace3b4872019-08-21 02:09:39 +09001249 Choosing this option will pass "-Os" to your compiler resulting
1250 in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001251
Arnd Bergmann877417e2016-04-25 17:35:27 +02001252endchoice
1253
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001254config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1255 bool
1256 help
1257 This requires that the arch annotates or otherwise protects
1258 its external entry points from being discarded. Linker scripts
1259 must also merge .text.*, .data.*, and .bss.* correctly into
1260 output sections. Care must be taken not to pull in unrelated
1261 sections (e.g., '.text.init'). Typically '.' in section names
1262 is used to distinguish them from label names / C identifiers.
1263
1264config LD_DEAD_CODE_DATA_ELIMINATION
1265 bool "Dead code and data elimination (EXPERIMENTAL)"
1266 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1267 depends on EXPERT
Paul Burton16fd20a2019-01-11 19:06:44 +00001268 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
Masahiro Yamadae85d1d62018-08-22 22:51:09 +09001269 depends on $(cc-option,-ffunction-sections -fdata-sections)
1270 depends on $(ld-option,--gc-sections)
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001271 help
Masahiro Yamada8b9d2712018-06-24 01:41:51 +09001272 Enable this if you want to do dead code and data elimination with
1273 the linker by compiling with -ffunction-sections -fdata-sections,
1274 and linking with --gc-sections.
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001275
1276 This can reduce on disk and in-memory size of the kernel
1277 code and static data, particularly for small configs and
1278 on small systems. This has the possibility of introducing
1279 silently broken kernel if the required annotations are not
1280 present. This option is not well tested yet, so use at your
1281 own risk.
1282
Randy Dunlap08470622006-09-30 23:28:13 -07001283config SYSCTL
1284 bool
1285
Mike Frysinger657a5202013-04-30 15:28:45 -07001286config HAVE_UID16
1287 bool
1288
1289config SYSCTL_EXCEPTION_TRACE
1290 bool
1291 help
1292 Enable support for /proc/sys/debug/exception-trace.
1293
1294config SYSCTL_ARCH_UNALIGN_NO_WARN
1295 bool
1296 help
1297 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1298 Allows arch to define/use @no_unaligned_warning to possibly warn
1299 about unaligned access emulation going on under the hood.
1300
1301config SYSCTL_ARCH_UNALIGN_ALLOW
1302 bool
1303 help
1304 Enable support for /proc/sys/kernel/unaligned-trap
1305 Allows arches to define/use @unaligned_enabled to runtime toggle
1306 the unaligned access emulation.
1307 see arch/parisc/kernel/unaligned.c for reference
1308
Mike Frysinger657a5202013-04-30 15:28:45 -07001309config HAVE_PCSPKR_PLATFORM
1310 bool
1311
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001312# interpreter that classic socket filters depend on
1313config BPF
1314 bool
1315
David Rientjes6a108a12011-01-20 14:44:16 -08001316menuconfig EXPERT
1317 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001318 # Unhide debug options, to make the on-by-default options visible
1319 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320 help
1321 This option allows certain base kernel options and settings
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001322 to be disabled or tweaked. This is for specialized
1323 environments which can tolerate a "non-standard" kernel.
1324 Only use this if you really know what you are doing.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001326config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001327 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001328 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001329 default y
1330 help
1331 This enables the legacy 16-bit UID syscall wrappers.
1332
Iulia Manda28138932015-04-15 16:16:41 -07001333config MULTIUSER
1334 bool "Multiple users, groups and capabilities support" if EXPERT
1335 default y
1336 help
1337 This option enables support for non-root users, groups and
1338 capabilities.
1339
1340 If you say N here, all processes will run with UID 0, GID 0, and all
1341 possible capabilities. Saying N here also compiles out support for
1342 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1343 setgid, and capset.
1344
1345 If unsure, say Y here.
1346
Fabian Frederickf6187762014-06-04 16:11:12 -07001347config SGETMASK_SYSCALL
1348 bool "sgetmask/ssetmask syscalls support" if EXPERT
Arnd Bergmanna687a532018-03-07 23:30:54 +01001349 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
Fabian Frederickf6187762014-06-04 16:11:12 -07001350 ---help---
1351 sys_sgetmask and sys_ssetmask are obsolete system calls
1352 no longer supported in libc but still enabled by default in some
1353 architectures.
1354
1355 If unsure, leave the default option here.
1356
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001357config SYSFS_SYSCALL
1358 bool "Sysfs syscall support" if EXPERT
1359 default y
1360 ---help---
1361 sys_sysfs is an obsolete system call no longer supported in libc.
1362 Note that disabling this option is more secure but might break
1363 compatibility with some systems.
1364
1365 If unsure say Y here.
1366
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001367config FHANDLE
1368 bool "open by fhandle syscalls" if EXPERT
1369 select EXPORTFS
1370 default y
1371 help
1372 If you say Y here, a user level program will be able to map
1373 file names to handle and then later use the handle for
1374 different file system operations. This is useful in implementing
1375 userspace file servers, which now track files using handles instead
1376 of names. The handle would remain the same even if file names
1377 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1378 syscalls.
1379
Nicolas Pitrebaa73d92016-11-11 00:10:10 -05001380config POSIX_TIMERS
1381 bool "Posix Clocks & timers" if EXPERT
1382 default y
1383 help
1384 This includes native support for POSIX timers to the kernel.
1385 Some embedded systems have no use for them and therefore they
1386 can be configured out to reduce the size of the kernel image.
1387
1388 When this option is disabled, the following syscalls won't be
1389 available: timer_create, timer_gettime: timer_getoverrun,
1390 timer_settime, timer_delete, clock_adjtime, getitimer,
1391 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1392 clock_getres and clock_nanosleep syscalls will be limited to
1393 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1394
1395 If unsure say y.
1396
Matt Mackalld59745c2005-05-01 08:59:02 -07001397config PRINTK
1398 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001399 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001400 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001401 help
1402 This option enables normal printk support. Removing it
1403 eliminates most of the message strings from the kernel image
1404 and makes the kernel more or less silent. As this makes it
1405 very difficult to diagnose system problems, saying N here is
1406 strongly discouraged.
1407
Petr Mladek42a0bb32016-05-20 17:00:33 -07001408config PRINTK_NMI
1409 def_bool y
1410 depends on PRINTK
1411 depends on HAVE_NMI
1412
Matt Mackallc8538a72005-05-01 08:59:01 -07001413config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001414 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001415 default y
1416 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001417 Disabling this option eliminates support for BUG and WARN, reducing
1418 the size of your kernel image and potentially quietly ignoring
1419 numerous fatal conditions. You should only consider disabling this
1420 option for embedded systems with no facilities for reporting errors.
1421 Just say Y.
Matt Mackallc8538a72005-05-01 08:59:01 -07001422
Matt Mackall708e9a72006-01-08 01:05:25 -08001423config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001424 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001425 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001426 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001427 help
1428 Enable support for generating core dumps. Disabling saves about 4k.
1429
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001430
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001431config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001432 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001433 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001434 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001435 default y
1436 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001437 This option allows to disable the internal PC-Speaker
1438 support, saving some memory.
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001439
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440config BASE_FULL
1441 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001442 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 help
1444 Disabling this option reduces the size of miscellaneous core
1445 kernel data structures. This saves memory on small machines,
1446 but may reduce performance.
1447
1448config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001449 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 default y
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001451 imply RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 help
1453 Disabling this option will cause the kernel to be built without
1454 support for "fast userspace mutexes". The resulting kernel may not
1455 run glibc-based applications correctly.
1456
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001457config FUTEX_PI
1458 bool
1459 depends on FUTEX && RT_MUTEXES
1460 default y
1461
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001462config HAVE_FUTEX_CMPXCHG
1463 bool
Josh Triplett62b4d202014-10-03 16:19:24 -07001464 depends on FUTEX
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001465 help
1466 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1467 is implemented and always working. This removes a couple of runtime
1468 checks.
1469
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001471 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 default y
1473 help
1474 Disabling this option will cause the kernel to be built without
1475 support for epoll family of system calls.
1476
Davide Libenzifba2afa2007-05-10 22:23:13 -07001477config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001478 bool "Enable signalfd() system call" if EXPERT
Davide Libenzifba2afa2007-05-10 22:23:13 -07001479 default y
1480 help
1481 Enable the signalfd() system call that allows to receive signals
1482 on a file descriptor.
1483
1484 If unsure, say Y.
1485
Davide Libenzib215e282007-05-10 22:23:16 -07001486config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001487 bool "Enable timerfd() system call" if EXPERT
Davide Libenzib215e282007-05-10 22:23:16 -07001488 default y
1489 help
1490 Enable the timerfd() system call that allows to receive timer
1491 events on a file descriptor.
1492
1493 If unsure, say Y.
1494
Davide Libenzie1ad7462007-05-10 22:23:19 -07001495config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001496 bool "Enable eventfd() system call" if EXPERT
Davide Libenzie1ad7462007-05-10 22:23:19 -07001497 default y
1498 help
1499 Enable the eventfd() system call that allows to receive both
1500 kernel notification (ie. KAIO) or userspace notifications.
1501
1502 If unsure, say Y.
1503
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001505 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001506 default y
1507 depends on MMU
1508 help
1509 The shmem is an internal filesystem used to manage shared memory.
1510 It is backed by swap and manages resource limits. It is also exported
1511 to userspace as tmpfs if TMPFS is enabled. Disabling this
1512 option replaces shmem and tmpfs with the much simpler ramfs code,
1513 which may be appropriate on small systems without swap.
1514
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001515config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001516 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001517 default y
1518 help
1519 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001520 by some high performance threaded applications. Disabling
1521 this option saves about 7k.
1522
Jens Axboe2b188cc2019-01-07 10:46:33 -07001523config IO_URING
1524 bool "Enable IO uring support" if EXPERT
1525 select ANON_INODES
Jens Axboe561fb042019-10-24 07:25:42 -06001526 select IO_WQ
Jens Axboe2b188cc2019-01-07 10:46:33 -07001527 default y
1528 help
1529 This option enables support for the io_uring interface, enabling
1530 applications to submit and complete IO through submission and
1531 completion rings that are shared between the kernel and application.
1532
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001533config ADVISE_SYSCALLS
1534 bool "Enable madvise/fadvise syscalls" if EXPERT
1535 default y
1536 help
1537 This option enables the madvise and fadvise syscalls, used by
1538 applications to advise the kernel about their future memory or file
1539 usage, improving performance. If building an embedded system where no
1540 applications use these syscalls, you can disable this option to save
1541 space.
1542
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001543config MEMBARRIER
1544 bool "Enable membarrier() system call" if EXPERT
1545 default y
1546 help
1547 Enable the membarrier() system call that allows issuing memory
1548 barriers across all running threads, which can be used to distribute
1549 the cost of user-space memory barriers asymmetrically by transforming
1550 pairs of memory barriers into pairs consisting of membarrier() and a
1551 compiler barrier.
1552
1553 If unsure, say Y.
1554
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001555config KALLSYMS
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001556 bool "Load all symbols for debugging/ksymoops" if EXPERT
1557 default y
1558 help
1559 Say Y here to let the kernel print out symbolic crash information and
1560 symbolic stack backtraces. This increases the size of the kernel
1561 somewhat, as all symbols have to be loaded into the kernel image.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001562
1563config KALLSYMS_ALL
1564 bool "Include all symbols in kallsyms"
1565 depends on DEBUG_KERNEL && KALLSYMS
1566 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001567 Normally kallsyms only contains the symbols of functions for nicer
1568 OOPS messages and backtraces (i.e., symbols from the text and inittext
1569 sections). This is sufficient for most cases. And only in very rare
1570 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1571 names of variables from the data sections, etc).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001572
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001573 This option makes sure that all symbols are loaded into the kernel
1574 image (i.e., symbols from all sections) in cost of increased kernel
1575 size (depending on the kernel configuration, it may be 300KiB or
1576 something like this).
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001577
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001578 Say N unless you really need all symbols.
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001579
1580config KALLSYMS_ABSOLUTE_PERCPU
1581 bool
1582 depends on KALLSYMS
1583 default X86_64 && SMP
1584
1585config KALLSYMS_BASE_RELATIVE
1586 bool
1587 depends on KALLSYMS
Arnd Bergmanna687a532018-03-07 23:30:54 +01001588 default !IA64
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001589 help
1590 Instead of emitting them as absolute values in the native word size,
1591 emit the symbol references in the kallsyms table as 32-bit entries,
1592 each containing a relative value in the range [base, base + U32_MAX]
1593 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1594 an absolute value in the range [0, S32_MAX] or a relative value in the
1595 range [base, base + S32_MAX], where base is the lowest relative symbol
1596 address encountered in the image.
1597
1598 On 64-bit builds, this reduces the size of the address table by 50%,
1599 but more importantly, it results in entries whose values are build
1600 time constants, and no relocation pass is required at runtime to fix
1601 up the entries based on the runtime load address of the kernel.
1602
1603# end of the "standard kernel features (expert users)" menu
1604
1605# syscall, maps, verifier
1606config BPF_SYSCALL
1607 bool "Enable bpf() system call"
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001608 select BPF
Song Liubae77c52018-05-07 10:50:48 -07001609 select IRQ_WORK
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001610 default n
1611 help
1612 Enable the bpf() system call that allows to manipulate eBPF
1613 programs and maps via file descriptors.
1614
Alexei Starovoitov290af862018-01-09 10:04:29 -08001615config BPF_JIT_ALWAYS_ON
1616 bool "Permanently enable BPF JIT and remove BPF interpreter"
1617 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1618 help
1619 Enables BPF JIT and removes BPF interpreter to avoid
1620 speculative execution of BPF instructions by the interpreter
1621
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001622config USERFAULTFD
1623 bool "Enable userfaultfd() system call"
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001624 depends on MMU
1625 help
1626 Enable the userfaultfd() system call that allows to intercept and
1627 handle page faults in userland.
1628
Mathieu Desnoyers3ccfebe2018-01-29 15:20:11 -05001629config ARCH_HAS_MEMBARRIER_CALLBACKS
1630 bool
1631
Mathieu Desnoyers70216e12018-01-29 15:20:17 -05001632config ARCH_HAS_MEMBARRIER_SYNC_CORE
1633 bool
1634
Mathieu Desnoyersd7822b12018-06-02 08:43:54 -04001635config RSEQ
1636 bool "Enable rseq() system call" if EXPERT
1637 default y
1638 depends on HAVE_RSEQ
1639 select MEMBARRIER
1640 help
1641 Enable the restartable sequences system call. It provides a
1642 user-space cache for the current CPU number value, which
1643 speeds up getting the current CPU number from user-space,
1644 as well as an ABI to speed up user-space operations on
1645 per-CPU data.
1646
1647 If unsure, say Y.
1648
1649config DEBUG_RSEQ
1650 default n
1651 bool "Enabled debugging of rseq() system call" if EXPERT
1652 depends on RSEQ && DEBUG_KERNEL
1653 help
1654 Enable extra debugging checks for the rseq system call.
1655
1656 If unsure, say N.
1657
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001658config EMBEDDED
1659 bool "Embedded system"
Josh Triplett5d2acfc2014-04-07 15:39:09 -07001660 option allnoconfig_y
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001661 select EXPERT
1662 help
1663 This option should be enabled if compiling the kernel for
1664 an embedded system so certain expert options are available
1665 for configuration.
1666
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001667config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001668 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001669 help
1670 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001671
Peter Zijlstra906010b2009-09-21 16:08:49 +02001672config PERF_USE_VMALLOC
1673 bool
1674 help
1675 See tools/perf/design.txt for details
1676
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001677config PC104
William Breathitt Gray424529f2017-12-29 15:14:59 -05001678 bool "PC/104 support" if EXPERT
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001679 help
1680 Expose PC/104 form factor device drivers and options available for
1681 selection and configuration. Enable this option if your target
1682 machine has a PC/104 bus.
1683
Ingo Molnar57c0c152009-09-21 12:20:38 +02001684menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001685
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001686config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001687 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001688 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001689 depends on HAVE_PERF_EVENTS
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001690 select IRQ_WORK
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001691 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001692 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001693 Enable kernel support for various performance events provided
1694 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001695
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001696 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001697 use of generic tracepoints.
1698
1699 Most modern CPUs support performance events via performance
1700 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001701 types of hw events: such as instructions executed, cachemisses
1702 suffered, or branches mis-predicted - without slowing down the
1703 kernel or applications. These registers can also trigger interrupts
1704 when a threshold number of events have passed - and can thus be
1705 used to profile the code that runs on that CPU.
1706
Ingo Molnar57c0c152009-09-21 12:20:38 +02001707 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001708 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001709 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001710 provides per task and per CPU counters, and it provides event
1711 capabilities on top of those.
1712
1713 Say Y if unsure.
1714
Peter Zijlstra906010b2009-09-21 16:08:49 +02001715config DEBUG_PERF_USE_VMALLOC
1716 default n
1717 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb3071132015-05-04 16:26:39 +10001718 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001719 select PERF_USE_VMALLOC
1720 help
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001721 Use vmalloc memory to back perf mmap() buffers.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001722
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001723 Mostly useful for debugging the vmalloc code on platforms
1724 that don't require it.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001725
Krzysztof Kozlowskie8cf4e92019-12-04 16:52:28 -08001726 Say N if unsure.
Peter Zijlstra906010b2009-09-21 16:08:49 +02001727
Thomas Gleixner0793a612008-12-04 20:12:29 +01001728endmenu
1729
Christoph Lameterf8891e52006-06-30 01:55:45 -07001730config VM_EVENT_COUNTERS
1731 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001732 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001733 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001734 VM event counters are needed for event counts to be shown.
1735 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001736 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001737 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001738
Christoph Lameter41ecc552007-05-09 02:32:44 -07001739config SLUB_DEBUG
1740 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001741 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001742 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001743 help
1744 SLUB has extensive debug support features. Disabling these can
1745 result in significant savings in code size. This also disables
1746 SLUB sysfs support. /sys/slab will not exist and there will be
1747 no support for cache validation etc.
1748
Tejun Heo1663f262017-02-22 15:41:39 -08001749config SLUB_MEMCG_SYSFS_ON
1750 default n
1751 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1752 depends on SLUB && SYSFS && MEMCG
1753 help
1754 SLUB creates a directory under /sys/kernel/slab for each
1755 allocation cache to host info and debug files. If memory
1756 cgroup is enabled, each cache can have per memory cgroup
1757 caches. SLUB can create the same sysfs directories for these
1758 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1759 to a very high number of debug files being created. This is
1760 controlled by slub_memcg_sysfs boot parameter and this
1761 config option determines the parameter's default value.
1762
Randy Dunlapb943c462009-03-10 12:55:46 -07001763config COMPAT_BRK
1764 bool "Disable heap randomization"
1765 default y
1766 help
1767 Randomizing heap placement makes heap exploits harder, but it
1768 also breaks ancient binaries (including anything libc5 based).
1769 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001770 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001771 /proc/sys/kernel/randomize_va_space to 2.
1772
1773 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1774
Christoph Lameter81819f02007-05-06 14:49:36 -07001775choice
1776 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001777 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001778 help
1779 This option allows to select a slab allocator.
1780
1781config SLAB
1782 bool "SLAB"
Kees Cook04385fc2016-06-23 15:20:59 -07001783 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001784 help
1785 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001786 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001787 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001788
1789config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001790 bool "SLUB (Unqueued Allocator)"
Kees Cooked18adc2016-06-23 15:24:05 -07001791 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001792 help
1793 SLUB is a slab allocator that minimizes cache line usage
1794 instead of managing queues of cached objects (SLAB approach).
1795 Per cpu caching is realized using slabs of objects instead
1796 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001797 and has enhanced diagnostics. SLUB is the default choice for
1798 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001799
1800config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001801 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001802 bool "SLOB (Simple Allocator)"
1803 help
Matt Mackall37291452008-02-04 22:29:38 -08001804 SLOB replaces the stock allocator with a drastically simpler
1805 allocator. SLOB is generally more space efficient but
1806 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001807
1808endchoice
1809
Kees Cook7660a6f2017-07-06 15:36:40 -07001810config SLAB_MERGE_DEFAULT
1811 bool "Allow slab caches to be merged"
1812 default y
1813 help
1814 For reduced kernel memory fragmentation, slab caches can be
1815 merged when they share the same size and other characteristics.
1816 This carries a risk of kernel heap overflows being able to
1817 overwrite objects from merged caches (and more easily control
1818 cache layout), which makes such heap attacks easier to exploit
1819 by attackers. By keeping caches unmerged, these kinds of exploits
1820 can usually only damage objects in the same cache. To disable
1821 merging at runtime, "slab_nomerge" can be passed on the kernel
1822 command line.
1823
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001824config SLAB_FREELIST_RANDOM
1825 default n
Thomas Garnier210e7a42016-07-26 15:21:59 -07001826 depends on SLAB || SLUB
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001827 bool "SLAB freelist randomization"
1828 help
Thomas Garnier210e7a42016-07-26 15:21:59 -07001829 Randomizes the freelist order used on creating new pages. This
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001830 security feature reduces the predictability of the kernel slab
1831 allocator against heap overflows.
1832
Kees Cook2482ddec2017-09-06 16:19:18 -07001833config SLAB_FREELIST_HARDENED
1834 bool "Harden slab freelist metadata"
1835 depends on SLUB
1836 help
1837 Many kernel heap attacks try to target slab cache metadata and
1838 other infrastructure. This options makes minor performance
Kees Cook92bae782019-07-16 16:27:57 -07001839 sacrifices to harden the kernel slab allocator against common
Kees Cook2482ddec2017-09-06 16:19:18 -07001840 freelist exploit methods.
1841
Dan Williamse900a912019-05-14 15:41:28 -07001842config SHUFFLE_PAGE_ALLOCATOR
1843 bool "Page allocator randomization"
1844 default SLAB_FREELIST_RANDOM && ACPI_NUMA
1845 help
1846 Randomization of the page allocator improves the average
1847 utilization of a direct-mapped memory-side-cache. See section
1848 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
1849 6.2a specification for an example of how a platform advertises
1850 the presence of a memory-side-cache. There are also incidental
1851 security benefits as it reduces the predictability of page
1852 allocations to compliment SLAB_FREELIST_RANDOM, but the
1853 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
1854 10th order of pages is selected based on cache utilization
1855 benefits on x86.
1856
1857 While the randomization improves cache utilization it may
1858 negatively impact workloads on platforms without a cache. For
1859 this reason, by default, the randomization is enabled only
1860 after runtime detection of a direct-mapped memory-side-cache.
1861 Otherwise, the randomization may be force enabled with the
1862 'page_alloc.shuffle' kernel command line parameter.
1863
1864 Say Y if unsure.
1865
Joonsoo Kim345c9052013-06-19 14:05:52 +09001866config SLUB_CPU_PARTIAL
1867 default y
Uwe Kleine-Königb39ffbf2013-07-17 16:54:59 +02001868 depends on SLUB && SMP
Joonsoo Kim345c9052013-06-19 14:05:52 +09001869 bool "SLUB per cpu partial cache"
1870 help
Kees Cook92bae782019-07-16 16:27:57 -07001871 Per cpu partial caches accelerate objects allocation and freeing
Joonsoo Kim345c9052013-06-19 14:05:52 +09001872 that is local to a processor at the price of more indeterminism
1873 in the latency of the free. On overflow these caches will be cleared
1874 which requires the taking of locks that may cause latency spikes.
1875 Typically one would choose no for a realtime system.
1876
Jie Zhangea637632009-12-14 18:00:02 -08001877config MMAP_ALLOW_UNINITIALIZED
1878 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08001879 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08001880 default n
1881 help
1882 Normally, and according to the Linux spec, anonymous memory obtained
Randy Dunlap3903bf92018-08-21 21:58:34 -07001883 from mmap() has its contents cleared before it is passed to
Jie Zhangea637632009-12-14 18:00:02 -08001884 userspace. Enabling this config option allows you to request that
1885 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1886 providing a huge performance boost. If this option is not enabled,
1887 then the flag will be ignored.
1888
1889 This is taken advantage of by uClibc's malloc(), and also by
1890 ELF-FDPIC binfmt's brk and stack allocator.
1891
1892 Because of the obvious security issues, this option should only be
1893 enabled on embedded devices where you control what is run in
1894 userspace. Since that isn't generally a problem on no-MMU systems,
1895 it is normally safe to say Y here.
1896
1897 See Documentation/nommu-mmap.txt for more information.
1898
David Howells091f6e22015-07-20 21:16:28 +01001899config SYSTEM_DATA_VERIFICATION
1900 def_bool n
1901 select SYSTEM_TRUSTED_KEYRING
1902 select KEYS
1903 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00001904 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01001905 select ASYMMETRIC_KEY_TYPE
1906 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01001907 select ASN1
1908 select OID_REGISTRY
1909 select X509_CERTIFICATE_PARSER
1910 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07001911 help
David Howells091f6e22015-07-20 21:16:28 +01001912 Provide PKCS#7 message verification using the contents of the system
1913 trusted keyring to provide public keys. This then can be used for
1914 module verification, kexec image verification and firmware blob
1915 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07001916
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001917config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001918 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001919 help
1920 Say Y here to enable the extended profiling support mechanisms used
1921 by profilers such as OProfile.
1922
Ingo Molnar5f87f112008-07-23 14:15:22 +02001923#
1924# Place an empty function call at each tracepoint site. Can be
1925# dynamically changed for a probe function.
1926#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001927config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001928 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001929
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930endmenu # General setup
1931
Christoph Hellwig15724972018-07-31 13:39:30 +02001932source "arch/Kconfig"
1933
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001934config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05001935 bool
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001936
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937config BASE_SMALL
1938 int
1939 default 0 if BASE_FULL
1940 default 1 if !BASE_FULL
1941
Thiago Jung Bauermannc8424e72019-07-04 15:57:34 -03001942config MODULE_SIG_FORMAT
1943 def_bool n
1944 select SYSTEM_DATA_VERIFICATION
1945
Jan Engelhardt66da5732007-07-15 23:39:29 -07001946menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001947 bool "Enable loadable module support"
Yann E. MORIN11097a02013-08-11 16:07:50 +02001948 option modules
Linus Torvalds1da177e2005-04-16 15:20:36 -07001949 help
1950 Kernel modules are small pieces of compiled code which can
1951 be inserted in the running kernel, rather than being
1952 permanently built into the kernel. You use the "modprobe"
1953 tool to add (and sometimes remove) them. If you say Y here,
1954 many parts of the kernel can be built as modules (by
1955 answering M instead of Y where indicated): this is most
1956 useful for infrequently used options which are not required
1957 for booting. For more information, see the man pages for
1958 modprobe, lsmod, modinfo, insmod and rmmod.
1959
1960 If you say Y here, you will need to run "make
1961 modules_install" to put the modules under /lib/modules/
1962 where modprobe can find them (you may need to be root to do
1963 this).
1964
1965 If unsure, say Y.
1966
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001967if MODULES
1968
Linus Torvalds826e4502008-05-04 17:04:16 -07001969config MODULE_FORCE_LOAD
1970 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07001971 default n
1972 help
Rusty Russell91e37a72008-05-09 16:25:28 +10001973 Allow loading of modules without version information (ie. modprobe
1974 --force). Forced module loading sets the 'F' (forced) taint flag and
1975 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07001976
Linus Torvalds1da177e2005-04-16 15:20:36 -07001977config MODULE_UNLOAD
1978 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979 help
1980 Without this option you will not be able to unload any
1981 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05001982 anyway), which makes your kernel smaller, faster
1983 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001984
1985config MODULE_FORCE_UNLOAD
1986 bool "Forced module unloading"
Kees Cook19c92392012-10-02 11:19:29 -07001987 depends on MODULE_UNLOAD
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988 help
1989 This option allows you to force a module to unload, even if the
1990 kernel believes it is unsafe: the kernel will remove the module
1991 without waiting for anyone to stop using it (using the -f option to
1992 rmmod). This is mainly for kernel developers and desperate users.
1993 If unsure, say N.
1994
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01001996 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997 help
1998 Usually, you have to use modules compiled with your kernel.
1999 Saying Y here makes it sometimes possible to use modules
2000 compiled for different kernels, by adding enough information
2001 to the modules to (hopefully) spot any changes which would
2002 make them incompatible with the kernel you are running. If
2003 unsure, say N.
2004
Masahiro Yamada2ff2b7e2019-08-19 14:54:20 +09002005config ASM_MODVERSIONS
2006 bool
2007 default HAVE_ASM_MODVERSIONS && MODVERSIONS
2008 help
2009 This enables module versioning for exported symbols also from
2010 assembly. This can be enabled only when the target architecture
2011 supports it.
2012
Ard Biesheuvel56067812017-02-03 09:54:05 +00002013config MODULE_REL_CRCS
2014 bool
2015 depends on MODVERSIONS
2016
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017config MODULE_SRCVERSION_ALL
2018 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019 help
2020 Modules which contain a MODULE_VERSION get an extra "srcversion"
2021 field inserted into their modinfo section, which contains a
2022 sum of the source files which made it. This helps maintainers
2023 see exactly which source was used to build a module (since
2024 others sometimes change the module source without updating
2025 the version). With this option, such a "srcversion" field
2026 will be created for all modules. If unsure, say N.
2027
Rusty Russell106a4ee2012-09-26 10:09:40 +01002028config MODULE_SIG
2029 bool "Module signature verification"
Thiago Jung Bauermannc8424e72019-07-04 15:57:34 -03002030 select MODULE_SIG_FORMAT
Rusty Russell106a4ee2012-09-26 10:09:40 +01002031 help
2032 Check modules for valid signatures upon load: the signature
2033 is simply appended to the module. For more information see
Nathan Chancellorcbdc8212017-09-10 02:48:29 -07002034 <file:Documentation/admin-guide/module-signing.rst>.
Rusty Russell106a4ee2012-09-26 10:09:40 +01002035
David Howells228c37f2015-08-11 12:38:54 +01002036 Note that this option adds the OpenSSL development packages as a
2037 kernel build dependency so that the signing tool can use its crypto
2038 library.
2039
David Howells49fcf732019-08-19 17:17:40 -07002040 You should enable this option if you wish to use either
2041 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
2042 another LSM - otherwise unsigned modules will be loadable regardless
2043 of the lockdown policy.
2044
David Howellsea0b6dc2012-09-26 10:09:50 +01002045 !!!WARNING!!! If you enable this option, you MUST make sure that the
2046 module DOES NOT get stripped after being signed. This includes the
2047 debuginfo strip done by some packagers (such as rpmbuild) and
2048 inclusion into an initramfs that wants the module size reduced.
2049
Rusty Russell106a4ee2012-09-26 10:09:40 +01002050config MODULE_SIG_FORCE
2051 bool "Require modules to be validly signed"
2052 depends on MODULE_SIG
2053 help
2054 Reject unsigned modules or signed modules for which we don't have a
2055 key. Without this, such modules will simply taint the kernel.
David Howellsea0b6dc2012-09-26 10:09:50 +01002056
Michal Marekd9d8d7e2013-01-25 13:41:31 +10302057config MODULE_SIG_ALL
2058 bool "Automatically sign all modules"
2059 default y
2060 depends on MODULE_SIG
2061 help
2062 Sign all modules during make modules_install. Without this option,
2063 modules must be signed manually, using the scripts/sign-file tool.
2064
2065comment "Do not forget to sign required modules with scripts/sign-file"
2066 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
2067
David Howellsea0b6dc2012-09-26 10:09:50 +01002068choice
2069 prompt "Which hash algorithm should modules be signed with?"
2070 depends on MODULE_SIG
2071 help
2072 This determines which sort of hashing algorithm will be used during
2073 signature generation. This algorithm _must_ be built into the kernel
2074 directly so that signature verification can take place. It is not
2075 possible to load a signed module containing the algorithm to check
2076 the signature on that module.
2077
2078config MODULE_SIG_SHA1
2079 bool "Sign modules with SHA-1"
2080 select CRYPTO_SHA1
2081
2082config MODULE_SIG_SHA224
2083 bool "Sign modules with SHA-224"
2084 select CRYPTO_SHA256
2085
2086config MODULE_SIG_SHA256
2087 bool "Sign modules with SHA-256"
2088 select CRYPTO_SHA256
2089
2090config MODULE_SIG_SHA384
2091 bool "Sign modules with SHA-384"
2092 select CRYPTO_SHA512
2093
2094config MODULE_SIG_SHA512
2095 bool "Sign modules with SHA-512"
2096 select CRYPTO_SHA512
2097
2098endchoice
2099
Michal Marek22753672013-01-25 13:41:00 +10302100config MODULE_SIG_HASH
2101 string
2102 depends on MODULE_SIG
2103 default "sha1" if MODULE_SIG_SHA1
2104 default "sha224" if MODULE_SIG_SHA224
2105 default "sha256" if MODULE_SIG_SHA256
2106 default "sha384" if MODULE_SIG_SHA384
2107 default "sha512" if MODULE_SIG_SHA512
2108
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302109config MODULE_COMPRESS
2110 bool "Compress modules on installation"
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302111 help
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302112
Rusty Russellb6c09b52015-06-16 12:16:22 +09302113 Compresses kernel modules when 'make modules_install' is run; gzip or
2114 xz depending on "Compression algorithm" below.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302115
Rusty Russellb6c09b52015-06-16 12:16:22 +09302116 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302117
Rusty Russellb6c09b52015-06-16 12:16:22 +09302118 Out-of-tree kernel modules installed using Kbuild will also be
2119 compressed upon installation.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302120
Rusty Russellb6c09b52015-06-16 12:16:22 +09302121 Note: for modules inside an initrd or initramfs, it's more efficient
2122 to compress the whole initrd or initramfs instead.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302123
Rusty Russellb6c09b52015-06-16 12:16:22 +09302124 Note: This is fully compatible with signed modules.
2125
2126 If in doubt, say N.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302127
2128choice
2129 prompt "Compression algorithm"
2130 depends on MODULE_COMPRESS
2131 default MODULE_COMPRESS_GZIP
2132 help
2133 This determines which sort of compression will be used during
2134 'make modules_install'.
2135
2136 GZIP (default) and XZ are supported.
2137
2138config MODULE_COMPRESS_GZIP
2139 bool "GZIP"
2140
2141config MODULE_COMPRESS_XZ
2142 bool "XZ"
2143
2144endchoice
2145
Matthias Maennich3d52ec52019-09-06 11:32:29 +01002146config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
2147 bool "Allow loading of modules with missing namespace imports"
2148 help
2149 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
2150 a namespace. A module that makes use of a symbol exported with such a
2151 namespace is required to import the namespace via MODULE_IMPORT_NS().
2152 There is no technical reason to enforce correct namespace imports,
2153 but it creates consistency between symbols defining namespaces and
2154 users importing namespaces they make use of. This option relaxes this
2155 requirement and lifts the enforcement when loading a module.
2156
2157 If unsure, say N.
2158
Masahiro Yamadaefd97632019-09-09 20:04:08 +09002159config UNUSED_SYMBOLS
2160 bool "Enable unused/obsolete exported symbols"
2161 default y if X86
2162 help
2163 Unused but exported symbols make the kernel needlessly bigger. For
2164 that reason most of these unused exports will soon be removed. This
2165 option is provided temporarily to provide a transition period in case
2166 some external kernel module needs one of these symbols anyway. If you
2167 encounter such a case in your module, consider if you are actually
2168 using the right API. (rationale: since nobody in the kernel is using
2169 this in a module, there is a pretty good chance it's actually the
2170 wrong interface to use). If you really need the symbol, please send a
2171 mail to the linux kernel mailing list mentioning the symbol and why
2172 you really need it, and what the merge plan to the mainline kernel for
2173 your module is.
2174
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002175config TRIM_UNUSED_KSYMS
2176 bool "Trim unused exported kernel symbols"
Masahiro Yamadad189c2a2019-09-09 20:04:07 +09002177 depends on !UNUSED_SYMBOLS
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002178 help
2179 The kernel and some modules make many symbols available for
2180 other modules to use via EXPORT_SYMBOL() and variants. Depending
2181 on the set of modules being selected in your kernel configuration,
2182 many of those exported symbols might never be used.
2183
2184 This option allows for unused exported symbols to be dropped from
2185 the build. In turn, this provides the compiler more opportunities
2186 (especially when using LTO) for optimizing the code and reducing
2187 binary size. This might have some security advantages as well.
2188
Valdis Kletnieksf1cb6372016-08-02 14:07:27 -07002189 If unsure, or if you need to build out-of-tree modules, say N.
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002190
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002191endif # MODULES
2192
Peter Zijlstra6c9692e22015-05-27 11:09:37 +09302193config MODULES_TREE_LOOKUP
2194 def_bool y
2195 depends on PERF_EVENTS || TRACING
2196
Rusty Russell98a79d62008-12-13 21:19:41 +10302197config INIT_ALL_POSSIBLE
2198 bool
2199 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302200 Back when each arch used to define their own cpu_online_mask and
2201 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302202 with all 1s, and others with all 0s. When they were centralised,
2203 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002204 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302205
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002206source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002207
2208config PREEMPT_NOTIFIERS
2209 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002210
Steffen Klassert16295be2010-01-06 19:47:10 +11002211config PADATA
2212 depends on SMP
2213 bool
2214
David Howells4520c6a2012-09-21 23:31:13 +01002215config ASN1
2216 tristate
2217 help
2218 Build a simple ASN.1 grammar compiler that produces a bytecode output
2219 that can be interpreted by the ASN.1 stream decoder and used to
2220 inform it as to what tags are to be expected in a stream and what
2221 functions to call on what tags.
2222
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002223source "kernel/Kconfig.locks"
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05002224
2225config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2226 bool
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002227
2228# It may be useful for an architecture to override the definitions of the
Dominik Brodowski7303e302018-04-05 11:53:03 +02002229# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2230# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2231# different calling convention for syscalls. They can also override the
2232# macros for not-implemented syscalls in kernel/sys_ni.c and
2233# kernel/time/posix-stubs.c. All these overrides need to be available in
2234# <asm/syscall_wrapper.h>.
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002235config ARCH_HAS_SYSCALL_WRAPPER
2236 def_bool n