blob: 51c7105771c902d9231d41c75f3b45f3d7021e9c [file] [log] [blame]
Roman Zippelface4372006-06-08 22:12:45 -07001config DEFCONFIG_LIST
2 string
Paolo 'Blaisorblade' Giarrussob2670eac2006-10-19 23:28:23 -07003 depends on !UML
Roman Zippelface4372006-06-08 22:12:45 -07004 option defconfig_list
Rob Landley47f38ae2018-08-08 13:06:43 +09005 default "/lib/modules/$(shell,uname -r)/.config"
Roman Zippelface4372006-06-08 22:12:45 -07006 default "/etc/kernel-config"
Rob Landley47f38ae2018-08-08 13:06:43 +09007 default "/boot/config-$(shell,uname -r)"
Masahiro Yamada104daea2018-05-28 18:21:40 +09008 default ARCH_DEFCONFIG
9 default "arch/$(ARCH)/defconfig"
Roman Zippelface4372006-06-08 22:12:45 -070010
Masahiro Yamadaa4353892018-05-28 18:22:01 +090011config CC_IS_GCC
12 def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
13
14config GCC_VERSION
15 int
16 default $(shell,$(srctree)/scripts/gcc-version.sh -p $(CC) | sed 's/^0*//') if CC_IS_GCC
17 default 0
18
Masahiro Yamada469cb732018-05-28 18:22:02 +090019config CC_IS_CLANG
20 def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
21
Sami Tolvanen4c3e84f2019-03-20 10:15:46 -070022config LD_IS_LLD
23 def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)
24
Masahiro Yamada469cb732018-05-28 18:22:02 +090025config CLANG_VERSION
26 int
27 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
28
Masahiro Yamada0276ebf2018-12-31 00:14:15 +090029config CC_HAS_ASM_GOTO
30 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
31
Peter Collingbourne9e01e8f2019-07-31 18:18:42 -070032config TOOLS_SUPPORT_RELR
33 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
34
Peter Oberparleiterb99b87f2009-06-17 16:28:03 -070035config CONSTRUCTORS
36 bool
37 depends on !UML
Peter Oberparleiterb99b87f2009-06-17 16:28:03 -070038
Peter Zijlstrae360adb2010-10-14 14:01:34 +080039config IRQ_WORK
40 bool
Peter Zijlstrae360adb2010-10-14 14:01:34 +080041
David Daney1dbdc6f2012-04-19 14:59:57 -070042config BUILDTIME_EXTABLE_SORT
43 bool
44
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070045config THREAD_INFO_IN_TASK
46 bool
47 help
48 Select this to move thread_info off the stack into task_struct. To
49 make this work, an arch will need to remove all thread_info fields
50 except flags and fix any runtime bugs.
51
Andy Lutomirskic6c314a2016-09-15 22:45:43 -070052 One subtle change that will be needed is to use try_get_task_stack()
53 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
54
Al Boldiff0cfc62007-07-31 00:39:23 -070055menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
Linus Torvalds1da177e2005-04-16 15:20:36 -070057config BROKEN
58 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
60config BROKEN_ON_SMP
61 bool
62 depends on BROKEN || !SMP
63 default y
64
Linus Torvalds1da177e2005-04-16 15:20:36 -070065config INIT_ENV_ARG_LIMIT
66 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -070067 default 32 if !UML
68 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 help
Randy Dunlap34ad92c2005-10-30 15:01:46 -080070 Maximum of each of the number of arguments and environment
71 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
Jiri Slaby4bb16672013-05-22 10:56:24 +020073config COMPILE_TEST
74 bool "Compile also drivers which will not load"
Richard Weinbergerbc083a62016-08-02 14:03:27 -070075 depends on !UML
Jiri Slaby4bb16672013-05-22 10:56:24 +020076 default n
77 help
78 Some drivers can be compiled on a different platform than they are
79 intended to be run on. Despite they cannot be loaded there (or even
80 when they load they cannot be used due to missing HW support),
81 developers still, opposing to distributors, might want to build such
82 drivers to compile-test them.
83
84 If you are a developer and want to build everything available, say Y
85 here. If you are a user/distributor, say N here to exclude useless
86 drivers to be distributed.
87
Linus Torvalds1da177e2005-04-16 15:20:36 -070088config LOCALVERSION
89 string "Local version - append to kernel release"
90 help
91 Append an extra string to the end of your kernel version.
92 This will show up when you type uname, for example.
93 The string you set here will be appended after the contents of
94 any files with a filename matching localversion* in your
95 object and source tree, in that order. Your total string can
96 be a maximum of 64 characters.
97
Ryan Andersonaaebf432005-07-31 04:57:49 -040098config LOCALVERSION_AUTO
99 bool "Automatically append version information to the version string"
100 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -0700101 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -0400102 help
103 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200104 release tree by looking for git tags that belong to the current
105 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400106
107 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200108 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400109 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200110 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400111
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200112 (The actual string used here is the first eight characters produced
113 by running the command:
114
115 $ git rev-parse --verify HEAD
116
117 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400118
Laura Abbott9afb7192018-07-05 17:49:37 -0700119config BUILD_SALT
120 string "Build ID Salt"
121 default ""
122 help
123 The build ID is used to link binaries and their debug info. Setting
124 this option will use the value in the calculation of the build id.
125 This is mostly useful for distributions which want to ensure the
126 build is unique between builds. It's safe to leave the default.
127
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800128config HAVE_KERNEL_GZIP
129 bool
130
131config HAVE_KERNEL_BZIP2
132 bool
133
134config HAVE_KERNEL_LZMA
135 bool
136
Lasse Collin3ebe1242011-01-12 17:01:23 -0800137config HAVE_KERNEL_XZ
138 bool
139
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800140config HAVE_KERNEL_LZO
141 bool
142
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700143config HAVE_KERNEL_LZ4
144 bool
145
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200146config HAVE_KERNEL_UNCOMPRESSED
147 bool
148
Alain Knaff30d65db2009-01-04 22:46:17 +0100149choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800150 prompt "Kernel compression mode"
151 default KERNEL_GZIP
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200152 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 -0800153 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100154 The linux kernel is a kind of self-extracting executable.
155 Several compression algorithms are available, which differ
156 in efficiency, compression and decompression speed.
157 Compression speed is only relevant when building a kernel.
158 Decompression speed is relevant at each boot.
159
160 If you have any problems with bzip2 or lzma compressed
161 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
162 version of this functionality (bzip2 only), for 2.4, was
163 supplied by Christian Ludwig)
164
165 High compression options are mostly useful for users, who
166 are low on disk space (embedded systems), but for whom ram
167 size matters less.
168
169 If in doubt, select 'gzip'
170
171config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800172 bool "Gzip"
173 depends on HAVE_KERNEL_GZIP
174 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800175 The old and tried gzip compression. It provides a good balance
176 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100177
178config KERNEL_BZIP2
179 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800180 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100181 help
182 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700183 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800184 size is about 10% smaller with bzip2, in comparison to gzip.
185 Bzip2 uses a large amount of memory. For modern kernels you
186 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100187
188config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800189 bool "LZMA"
190 depends on HAVE_KERNEL_LZMA
191 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700192 This compression algorithm's ratio is best. Decompression speed
193 is between gzip and bzip2. Compression is slowest.
194 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100195
Lasse Collin3ebe1242011-01-12 17:01:23 -0800196config KERNEL_XZ
197 bool "XZ"
198 depends on HAVE_KERNEL_XZ
199 help
200 XZ uses the LZMA2 algorithm and instruction set specific
201 BCJ filters which can improve compression ratio of executable
202 code. The size of the kernel is about 30% smaller with XZ in
203 comparison to gzip. On architectures for which there is a BCJ
204 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
205 will create a few percent smaller kernel than plain LZMA.
206
207 The speed is about the same as with LZMA: The decompression
208 speed of XZ is better than that of bzip2 but worse than gzip
209 and LZO. Compression is slow.
210
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800211config KERNEL_LZO
212 bool "LZO"
213 depends on HAVE_KERNEL_LZO
214 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700215 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200216 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800217 (both compression and decompression) is the fastest.
218
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700219config KERNEL_LZ4
220 bool "LZ4"
221 depends on HAVE_KERNEL_LZ4
222 help
223 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
224 A preliminary version of LZ4 de/compression tool is available at
225 <https://code.google.com/p/lz4/>.
226
227 Its compression ratio is worse than LZO. The size of the kernel
228 is about 8% bigger than LZO. But the decompression speed is
229 faster than LZO.
230
Vasily Gorbikf16466a2018-06-12 21:26:35 +0200231config KERNEL_UNCOMPRESSED
232 bool "None"
233 depends on HAVE_KERNEL_UNCOMPRESSED
234 help
235 Produce uncompressed kernel image. This option is usually not what
236 you want. It is useful for debugging the kernel in slow simulation
237 environments, where decompressing and moving the kernel is awfully
238 slow. This option allows early boot code to skip the decompressor
239 and jump right at uncompressed kernel image.
240
Alain Knaff30d65db2009-01-04 22:46:17 +0100241endchoice
242
Josh Triplettbd5dc172011-06-15 15:08:28 -0700243config DEFAULT_HOSTNAME
244 string "Default hostname"
245 default "(none)"
246 help
247 This option determines the default system hostname before userspace
248 calls sethostname(2). The kernel traditionally uses "(none)" here,
249 but you may wish to use a different default here to make a minimal
250 system more usable with less configuration.
251
Christoph Hellwig17c46a62018-07-31 13:39:29 +0200252#
253# For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
254# add proper SWAP support to them, in which case this can be remove.
255#
256config ARCH_NO_SWAP
257 bool
258
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259config SWAP
260 bool "Support for paging of anonymous memory (swap)"
Christoph Hellwig17c46a62018-07-31 13:39:29 +0200261 depends on MMU && BLOCK && !ARCH_NO_SWAP
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 default y
263 help
264 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100265 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 used to provide more virtual memory than the actual RAM present
267 in your computer. If unsure say Y.
268
269config SYSVIPC
270 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 ---help---
272 Inter Process Communication is a suite of library functions and
273 system calls which let processes (running programs) synchronize and
274 exchange information. It is generally considered to be a good thing,
275 and some programs won't run unless you say Y here. In particular, if
276 you want to run the DOS emulator dosemu under Linux (read the
277 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
278 you'll need to say Y here.
279
280 You can find documentation about IPC with "info ipc" and also in
281 section 6.4 of the Linux Programmer's Guide, available from
282 <http://www.tldp.org/guides.html>.
283
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800284config SYSVIPC_SYSCTL
285 bool
286 depends on SYSVIPC
287 depends on SYSCTL
288 default y
289
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290config POSIX_MQUEUE
291 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700292 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 ---help---
294 POSIX variant of message queues is a part of IPC. In POSIX message
295 queues every message has a priority which decides about succession
296 of receiving it by a process. If you want to compile and run
297 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200298 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299
300 POSIX message queues are visible as a filesystem called 'mqueue'
301 and can be mounted somewhere if you want to do filesystem
302 operations on message queues.
303
304 If unsure, say Y.
305
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700306config POSIX_MQUEUE_SYSCTL
307 bool
308 depends on POSIX_MQUEUE
309 depends on SYSCTL
310 default y
311
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700312config CROSS_MEMORY_ATTACH
313 bool "Enable process_vm_readv/writev syscalls"
314 depends on MMU
315 default y
316 help
317 Enabling this option adds the system calls process_vm_readv and
318 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700319 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700320 See the man page for more details.
321
Josh Triplett69369a72014-04-03 14:48:27 -0700322config USELIB
323 bool "uselib syscall"
Riku Voipiob2113a42016-01-15 16:58:13 -0800324 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
Josh Triplett69369a72014-04-03 14:48:27 -0700325 help
326 This option enables the uselib syscall, a system call used in the
327 dynamic linker from libc5 and earlier. glibc does not use this
328 system call. If you intend to run programs built on libc5 or
329 earlier, you may need to enable this syscall. Current systems
330 running glibc can safely disable this.
331
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332config AUDIT
333 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100334 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 help
336 Enable auditing infrastructure that can be used with another
337 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500338 logging of avc messages output). System call auditing is included
339 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900341config HAVE_ARCH_AUDITSYSCALL
342 bool
343
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500345 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900346 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347
Eric Paris939a67f2009-12-17 20:12:06 -0500348config AUDIT_WATCH
349 def_bool y
350 depends on AUDITSYSCALL
351 select FSNOTIFY
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352
Al Viro74c3cbe2007-07-22 08:04:18 -0400353config AUDIT_TREE
354 def_bool y
Eric Paris63c882a2009-05-21 17:02:01 -0400355 depends on AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500356 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400357
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000358source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200359source "kernel/time/Kconfig"
Christoph Hellwig87a4c372018-07-31 13:39:32 +0200360source "kernel/Kconfig.preempt"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000361
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200362menu "CPU/Task time and stats accounting"
363
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200364config VIRT_CPU_ACCOUNTING
365 bool
366
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200367choice
368 prompt "Cputime accounting"
369 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100370 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200371
372# Kind of a stub config for the pure tick based cputime accounting
373config TICK_CPU_ACCOUNTING
374 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200375 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200376 help
377 This is the basic tick based cputime accounting that maintains
378 statistics about user, system and idle time spent on per jiffies
379 granularity.
380
381 If unsure, say Y.
382
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200383config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200384 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200385 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200386 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200387 help
388 Select this option to enable more accurate task and CPU time
389 accounting. This is done by reading a CPU counter on each
390 kernel entry and exit and on transitions within the kernel
391 between system, softirq and hardirq state, so there is a
392 small performance impact. In the case of s390 or IBM POWER > 5,
393 this also enables accounting of stolen time on logically-partitioned
394 systems.
395
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200396config VIRT_CPU_ACCOUNTING_GEN
397 bool "Full dynticks CPU time accounting"
Kevin Hilmanff3fb252013-09-16 15:28:19 -0700398 depends on HAVE_CONTEXT_TRACKING
Kevin Hilman554b0002013-09-16 15:28:21 -0700399 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200400 select VIRT_CPU_ACCOUNTING
401 select CONTEXT_TRACKING
402 help
403 Select this option to enable task and CPU time accounting on full
404 dynticks systems. This accounting is implemented by watching every
405 kernel-user boundaries using the context tracking subsystem.
406 The accounting is thus performed at the expense of some significant
407 overhead.
408
409 For now this is only useful if you are working on the full
410 dynticks subsystem development.
411
412 If unsure, say N.
413
Rik van Rielb58c3582016-07-13 16:50:02 +0200414endchoice
415
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200416config IRQ_TIME_ACCOUNTING
417 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200418 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200419 help
420 Select this option to enable fine granularity task irq time
421 accounting. This is done by reading a timestamp on each
422 transitions between softirq and hardirq state, so there can be a
423 small performance impact.
424
425 If in doubt, say N here.
426
Vincent Guittotdc535072018-12-14 23:10:06 +0100427config HAVE_SCHED_AVG_IRQ
428 def_bool y
429 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
430 depends on SMP
431
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200432config BSD_PROCESS_ACCT
433 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700434 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200435 help
436 If you say Y here, a user level program will be able to instruct the
437 kernel (via a special system call) to write process accounting
438 information to a file: whenever a process exits, information about
439 that process will be appended to the file by the kernel. The
440 information includes things such as creation time, owning user,
441 command name, memory usage, controlling terminal etc. (the complete
442 list is in the struct acct in <file:include/linux/acct.h>). It is
443 up to the user level program to do useful things with this
444 information. This is generally a good idea, so say Y.
445
446config BSD_PROCESS_ACCT_V3
447 bool "BSD Process Accounting version 3 file format"
448 depends on BSD_PROCESS_ACCT
449 default n
450 help
451 If you say Y here, the process accounting information is written
452 in a new file format that also logs the process IDs of each
Randy Dunlap3903bf92018-08-21 21:58:34 -0700453 process and its parent. Note that this file format is incompatible
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200454 with previous v0/v1/v2 file formats, so you will need updated tools
455 for processing it. A preliminary version of these tools is available
456 at <http://www.gnu.org/software/acct/>.
457
458config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700459 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200460 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700461 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200462 default n
463 help
464 Export selected statistics for tasks/processes through the
465 generic netlink interface. Unlike BSD process accounting, the
466 statistics are available during the lifetime of tasks/processes as
467 responses to commands. Like BSD accounting, they are sent to user
468 space on task exit.
469
470 Say N if unsure.
471
472config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700473 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200474 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530475 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200476 help
477 Collect information on time spent by a task waiting for system
478 resources like cpu, synchronous block I/O completion and swapping
479 in pages. Such statistics can help in setting a task's priorities
480 relative to other tasks for cpu, io, rss limits etc.
481
482 Say N if unsure.
483
484config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700485 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200486 depends on TASKSTATS
487 help
488 Collect extended task accounting data and send the data
489 to userland for processing over the taskstats interface.
490
491 Say N if unsure.
492
493config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700494 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200495 depends on TASK_XACCT
496 help
497 Collect information on the number of bytes of storage I/O which this
498 task has caused.
499
500 Say N if unsure.
501
Johannes Weinere550f942018-10-26 15:06:27 -0700502config PSI
503 bool "Pressure stall information tracking"
504 help
505 Collect metrics that indicate how overcommitted the CPU, memory,
506 and IO capacity are in the system.
507
508 If you say Y here, the kernel will create /proc/pressure/ with the
509 pressure statistics files cpu, memory, and io. These will indicate
510 the share of walltime in which some or all tasks in the system are
511 delayed due to contention of the respective resource.
512
Johannes Weinerdc9cd292018-10-26 15:06:31 -0700513 In kernels with cgroup support, cgroups (cgroup2 only) will
514 have cpu.pressure, memory.pressure, and io.pressure files,
515 which aggregate pressure stalls for the grouped tasks only.
516
Johannes Weinere550f942018-10-26 15:06:27 -0700517 For more details see Documentation/accounting/psi.txt.
518
519 Say N if unsure.
520
Johannes Weiner3bbcbc82018-11-30 14:09:58 -0800521config PSI_DEFAULT_DISABLED
522 bool "Require boot parameter to enable pressure stall information tracking"
523 default n
524 depends on PSI
525 help
526 If set, pressure stall information tracking will be disabled
Baruch Siach072a1032018-12-14 14:17:03 -0800527 per default but can be enabled through passing psi=1 on the
528 kernel commandline during boot.
Johannes Weiner3bbcbc82018-11-30 14:09:58 -0800529
Johannes Weiner9e041392019-02-01 14:21:15 -0800530 This feature adds some code to the task wakeup and sleep
531 paths of the scheduler. The overhead is too low to affect
532 common scheduling-intense workloads in practice (such as
533 webservers, memcache), but it does show up in artificial
534 scheduler stress tests, such as hackbench.
535
536 If you are paranoid and not sure what the kernel will be
537 used for, say Y.
538
539 Say N if unsure.
540
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200541endmenu # "CPU/Task time and stats accounting"
542
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200543config CPU_ISOLATION
544 bool "CPU isolation"
Geert Uytterhoeven414a2dc2018-01-02 12:13:10 +0100545 depends on SMP || COMPILE_TEST
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100546 default y
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200547 help
548 Make sure that CPUs running critical tasks are not disturbed by
549 any source of "noise" such as unbound workqueues, timers, kthreads...
Frederic Weisbecker2c438382017-12-14 19:18:26 +0100550 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
551 the "isolcpus=" boot parameter.
552
553 Say Y if unsure.
Frederic Weisbecker5c4991e2017-10-27 04:42:34 +0200554
Paul E. McKenney0af92d42017-05-17 08:43:40 -0700555source "kernel/rcu/Kconfig"
Mike Travisc903ff82009-01-15 12:28:29 -0800556
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700557config BUILD_BIN2C
558 bool
559 default n
560
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700562 tristate "Kernel .config support"
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700563 select BUILD_BIN2C
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 ---help---
565 This option enables the complete Linux kernel ".config" file
566 contents to be saved in the kernel. It provides documentation
567 of which kernel options are used in a running kernel or in an
568 on-disk kernel. This information can be extracted from the kernel
569 image file with the script scripts/extract-ikconfig and used as
570 input to rebuild the current kernel or to build another kernel.
571 It can also be extracted from a running kernel by reading
572 /proc/config.gz if enabled (below).
573
574config IKCONFIG_PROC
575 bool "Enable access to .config through /proc/config.gz"
576 depends on IKCONFIG && PROC_FS
577 ---help---
578 This option enables access to the kernel configuration file
579 through /proc/config.gz.
580
Joel Fernandes (Google)b727e0a2019-05-15 17:35:51 -0400581config IKHEADERS
582 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
583 depends on SYSFS
Joel Fernandes (Google)3e6be4f2019-04-26 15:04:29 -0400584 help
Joel Fernandes (Google)b727e0a2019-05-15 17:35:51 -0400585 This option enables access to the in-kernel headers that are generated during
586 the build process. These can be used to build eBPF tracing programs,
587 or similar programs. If you build the headers as a module, a module called
588 kheaders.ko is built which can be loaded on-demand to get access to headers.
Joel Fernandes (Google)3e6be4f2019-04-26 15:04:29 -0400589
Alistair John Strachan794543a2007-05-08 00:31:15 -0700590config LOG_BUF_SHIFT
591 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Ingo Molnarfb39f982015-07-01 10:19:11 +0200592 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700593 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700594 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700595 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700596 Select the minimal kernel log buffer size as a power of 2.
597 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
598 parameter, see below. Any higher size also might be forced
599 by "log_buf_len" boot parameter.
600
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700601 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700602 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700603 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700604 15 => 32 KB
605 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700606 13 => 8 KB
607 12 => 4 KB
608
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700609config LOG_CPU_MAX_BUF_SHIFT
610 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700611 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700612 range 0 21
613 default 12 if !BASE_SMALL
614 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700615 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700616 help
617 This option allows to increase the default ring buffer size
618 according to the number of CPUs. The value defines the contribution
619 of each CPU as a power of 2. The used space is typically only few
620 lines however it might be much more when problems are reported,
621 e.g. backtraces.
622
623 The increased size means that a new buffer has to be allocated and
624 the original static one is unused. It makes sense only on systems
625 with more CPUs. Therefore this value is used only when the sum of
626 contributions is greater than the half of the default kernel ring
627 buffer as defined by LOG_BUF_SHIFT. The default values are set
628 so that more than 64 CPUs are needed to trigger the allocation.
629
630 Also this option is ignored when "log_buf_len" kernel parameter is
631 used as it forces an exact (power of two) size of the ring buffer.
632
633 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200634 hotplugging making the computation optimal for the worst case
635 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700636
637 Examples shift values and their meaning:
638 17 => 128 KB for each CPU
639 16 => 64 KB for each CPU
640 15 => 32 KB for each CPU
641 14 => 16 KB for each CPU
642 13 => 8 KB for each CPU
643 12 => 4 KB for each CPU
644
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900645config PRINTK_SAFE_LOG_BUF_SHIFT
646 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
Petr Mladek427934b2016-05-20 17:00:39 -0700647 range 10 21
648 default 13
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900649 depends on PRINTK
Petr Mladek427934b2016-05-20 17:00:39 -0700650 help
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900651 Select the size of an alternate printk per-CPU buffer where messages
652 printed from usafe contexts are temporary stored. One example would
653 be NMI messages, another one - printk recursion. The messages are
654 copied to the main log buffer in a safe context to avoid a deadlock.
655 The value defines the size as a power of 2.
Petr Mladek427934b2016-05-20 17:00:39 -0700656
Sergey Senozhatskyf92bac32016-12-27 23:16:05 +0900657 Those messages are rare and limited. The largest one is when
Petr Mladek427934b2016-05-20 17:00:39 -0700658 a backtrace is printed. It usually fits into 4KB. Select
659 8KB if you want to be on the safe side.
660
661 Examples:
662 17 => 128 KB for each CPU
663 16 => 64 KB for each CPU
664 15 => 32 KB for each CPU
665 14 => 16 KB for each CPU
666 13 => 8 KB for each CPU
667 12 => 4 KB for each CPU
668
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800669#
670# Architectures with an unreliable sched_clock() should select this:
671#
672config HAVE_UNSTABLE_SCHED_CLOCK
673 bool
674
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700675config GENERIC_SCHED_CLOCK
676 bool
677
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200678#
679# For architectures that want to enable the support for NUMA-affine scheduler
680# balancing logic:
681#
682config ARCH_SUPPORTS_NUMA_BALANCING
683 bool
684
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100685#
Mel Gorman72b252a2015-09-04 15:47:32 -0700686# For architectures that prefer to flush all TLBs after a number of pages
687# are unmapped instead of sending one IPI per page to flush. The architecture
688# must provide guarantees on what happens if a clean TLB cache entry is
689# written after the unmap. Details are in mm/rmap.c near the check for
690# should_defer_flush. The architecture should also consider if the full flush
691# and the refill costs are offset by the savings of sending fewer IPIs.
692config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
693 bool
694
695#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100696# For architectures that know their GCC __int128 support is sound
697#
698config ARCH_SUPPORTS_INT128
699 bool
700
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200701# For architectures that (ab)use NUMA to represent different memory regions
702# all cpu-local but of different latencies, such as SuperH.
703#
704config ARCH_WANT_NUMA_VARIABLE_LOCALITY
705 bool
706
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200707config NUMA_BALANCING
708 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200709 depends on ARCH_SUPPORTS_NUMA_BALANCING
710 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
711 depends on SMP && NUMA && MIGRATION
712 help
713 This option adds support for automatic NUMA aware memory/task placement.
714 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400715 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200716
717 This system will be inactive on UMA systems.
718
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800719config NUMA_BALANCING_DEFAULT_ENABLED
720 bool "Automatically enable NUMA aware memory/task placement"
721 default y
722 depends on NUMA_BALANCING
723 help
724 If set, automatic NUMA balancing will be enabled if running on a NUMA
725 machine.
726
Li Zefan23964d22009-01-15 13:50:58 -0800727menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500728 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500729 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700730 help
Li Zefan23964d22009-01-15 13:50:58 -0800731 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800732 use with process control subsystems such as Cpusets, CFS, memory
733 controls or device isolation.
734 See
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800735 - Documentation/scheduler/sched-design-CFS.txt (CFS)
seokhoon.yoon9991a9c2016-08-02 14:03:13 -0700736 - Documentation/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800737 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700738
739 Say N if unsure.
740
Li Zefan23964d22009-01-15 13:50:58 -0800741if CGROUPS
742
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800743config PAGE_COUNTER
744 bool
745
Andrew Mortonc255a452012-07-31 16:43:02 -0700746config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500747 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800748 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500749 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -0800750 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500751 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800752
Andrew Mortonc255a452012-07-31 16:43:02 -0700753config MEMCG_SWAP
Johannes Weinera0166ec2015-12-17 17:19:56 -0500754 bool "Swap controller"
Andrew Mortonc255a452012-07-31 16:43:02 -0700755 depends on MEMCG && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800756 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500757 Provides control over the swap space consumed by tasks in a cgroup.
758
Andrew Mortonc255a452012-07-31 16:43:02 -0700759config MEMCG_SWAP_ENABLED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500760 bool "Swap controller enabled by default"
Andrew Mortonc255a452012-07-31 16:43:02 -0700761 depends on MEMCG_SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -0800762 default y
763 help
764 Memory Resource Controller Swap Extension comes with its price in
765 a bigger memory consumption. General purpose distribution kernels
Jim Cromie43d547f2010-12-17 14:32:36 -0700766 which want to enable the feature but keep it disabled by default
Michal Hocko07555ac2013-08-22 16:35:46 -0700767 and let the user enable it by swapaccount=1 boot command line
Michal Hockoa42c3902010-11-24 12:57:08 -0800768 parameter should have this option unselected.
769 For those who want to have the feature enabled by default should
770 select this option (if, for some reason, they need to disable it
WANG Cong00a66d22011-07-25 17:12:12 -0700771 then swapaccount=0 does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800772
Kirill Tkhai84c07d12018-08-17 15:47:25 -0700773config MEMCG_KMEM
774 bool
775 depends on MEMCG && !SLOB
776 default y
777
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500778config BLK_CGROUP
779 bool "IO controller"
780 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700781 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500782 ---help---
783 Generic block IO controller cgroup interface. This is the common
784 cgroup interface which should be used by various IO controlling
785 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700786
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500787 Currently, CFQ IO scheduler uses it to recognize task groups and
788 control disk bandwidth allocation (proportional time slice allocation)
789 to such task groups. It is also used by bio throttling logic in
790 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +0200791
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500792 This option only enables generic Block IO controller infrastructure.
793 One needs to also enable actual IO controlling logic/policy. For
794 enabling proportional weight division of disk bandwidth in CFQ, set
795 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
796 CONFIG_BLK_DEV_THROTTLING=y.
797
seokhoon.yoon9991a9c2016-08-02 14:03:13 -0700798 See Documentation/cgroup-v1/blkio-controller.txt for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500799
800config DEBUG_BLK_CGROUP
801 bool "IO controller debugging"
802 depends on BLK_CGROUP
803 default n
804 ---help---
805 Enable some debugging help. Currently it exports additional stat
806 files in a cgroup which can be useful for debugging.
807
808config CGROUP_WRITEBACK
809 bool
810 depends on MEMCG && BLK_CGROUP
811 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +0200812
Dhaval Giani7c941432010-01-20 13:26:18 +0100813menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500814 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +0100815 default n
816 help
817 This feature lets CPU scheduler recognize task groups and control CPU
818 bandwidth allocation to such task groups. It uses cgroups to group
819 tasks.
820
821if CGROUP_SCHED
822config FAIR_GROUP_SCHED
823 bool "Group scheduling for SCHED_OTHER"
824 depends on CGROUP_SCHED
825 default CGROUP_SCHED
826
Paul Turnerab84d312011-07-21 09:43:28 -0700827config CFS_BANDWIDTH
828 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -0700829 depends on FAIR_GROUP_SCHED
830 default n
831 help
832 This option allows users to define CPU bandwidth rates (limits) for
833 tasks running within the fair group scheduler. Groups with no limit
834 set are considered to be unconstrained and will run with no
835 restriction.
Sebastian Andrzej Siewiorcd33d882018-05-15 18:53:28 +0200836 See Documentation/scheduler/sched-bwc.txt for more information.
Paul Turnerab84d312011-07-21 09:43:28 -0700837
Dhaval Giani7c941432010-01-20 13:26:18 +0100838config RT_GROUP_SCHED
839 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +0100840 depends on CGROUP_SCHED
841 default n
842 help
843 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +0800844 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +0100845 schedule realtime tasks for non-root users until you allocate
846 realtime bandwidth for them.
847 See Documentation/scheduler/sched-rt-group.txt for more information.
848
849endif #CGROUP_SCHED
850
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500851config CGROUP_PIDS
852 bool "PIDs controller"
853 help
854 Provides enforcement of process number limits in the scope of a
855 cgroup. Any attempt to fork more processes than is allowed in the
856 cgroup will fail. PIDs are fundamentally a global resource because it
857 is fairly trivial to reach PID exhaustion before you reach even a
858 conservative kmemcg limit. As a result, it is possible to grind a
859 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +0530860 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500861
862 It should be noted that organisational operations (such as attaching
Parav Pandit6cc578d2016-03-05 11:30:56 +0530863 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500864 since the PIDs limit only affects a process's ability to fork, not to
865 attach to a cgroup.
866
Parav Pandit39d3e752017-01-10 00:02:13 +0000867config CGROUP_RDMA
868 bool "RDMA controller"
869 help
870 Provides enforcement of RDMA resources defined by IB stack.
871 It is fairly easy for consumers to exhaust RDMA resources, which
872 can result into resource unavailability to other consumers.
873 RDMA controller is designed to stop this from happening.
874 Attaching processes with active RDMA resources to the cgroup
875 hierarchy is allowed even if can cross the hierarchy's limit.
876
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500877config CGROUP_FREEZER
878 bool "Freezer controller"
879 help
880 Provides a way to freeze and unfreeze all tasks in a
881 cgroup.
882
Johannes Weiner489c2a22016-01-20 15:02:41 -0800883 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
884 controller includes important in-kernel memory consumers per default.
885
886 If you're using cgroup2, say N.
887
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500888config CGROUP_HUGETLB
889 bool "HugeTLB controller"
890 depends on HUGETLB_PAGE
891 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +0200892 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500893 help
894 Provides a cgroup controller for HugeTLB pages.
895 When you enable this, you can put a per cgroup limit on HugeTLB usage.
896 The limit is enforced during page fault. Since HugeTLB doesn't
897 support page reclaim, enforcing the limit at page fault time implies
898 that, the application will get SIGBUS signal if it tries to access
899 HugeTLB pages beyond its limit. This requires the application to know
900 beforehand how much HugeTLB pages it would require for its use. The
901 control group is tracked in the third page lru pointer. This means
902 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200903
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500904config CPUSETS
905 bool "Cpuset controller"
Nicolas Pitree1d4eee2017-06-14 13:19:23 -0400906 depends on SMP
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500907 help
908 This option will let you create and manage CPUSETs which
909 allow dynamically partitioning a system into sets of CPUs and
910 Memory Nodes and assigning tasks to run only within those sets.
911 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200912
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500913 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +0200914
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500915config PROC_PID_CPUSET
916 bool "Include legacy /proc/<pid>/cpuset file"
917 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -0400918 default y
919
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500920config CGROUP_DEVICE
921 bool "Device controller"
922 help
923 Provides a cgroup controller implementing whitelists for
924 devices which a process in the cgroup can mknod or open.
925
926config CGROUP_CPUACCT
927 bool "Simple CPU accounting controller"
928 help
929 Provides a simple controller for monitoring the
930 total CPU consumed by the tasks in a cgroup.
931
932config CGROUP_PERF
933 bool "Perf controller"
934 depends on PERF_EVENTS
935 help
936 This option extends the perf per-cpu mode to restrict monitoring
937 to threads which belong to the cgroup specified and run on the
938 designated cpu.
939
940 Say N if unsure.
941
Daniel Mack30070982016-11-23 16:52:26 +0100942config CGROUP_BPF
943 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirski483c4932016-12-16 08:33:45 -0800944 depends on BPF_SYSCALL
945 select SOCK_CGROUP_DATA
Daniel Mack30070982016-11-23 16:52:26 +0100946 help
947 Allow attaching eBPF programs to a cgroup using the bpf(2)
948 syscall command BPF_PROG_ATTACH.
949
950 In which context these programs are accessed depends on the type
951 of attachment. For instance, programs that are attached using
952 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
953 inet sockets.
954
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500955config CGROUP_DEBUG
Waiman Long23b0be42017-06-13 17:18:03 -0400956 bool "Debug controller"
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500957 default n
Waiman Long23b0be42017-06-13 17:18:03 -0400958 depends on DEBUG_KERNEL
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500959 help
960 This option enables a simple controller that exports
Waiman Long23b0be42017-06-13 17:18:03 -0400961 debugging information about the cgroups framework. This
962 controller is for control cgroup debugging only. Its
963 interfaces are not stable.
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500964
965 Say N.
966
Arnd Bergmann73b35142017-01-10 13:08:06 +0100967config SOCK_CGROUP_DATA
968 bool
969 default n
970
Li Zefan23964d22009-01-15 13:50:58 -0800971endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800972
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700973menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -0800974 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -0700975 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -0800976 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -0800977 help
978 Provides the way to make tasks work with different objects using
979 the same id. For example same IPC id may refer to different objects
980 or same user id or pid may refer to different tasks when used in
981 different namespaces.
982
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700983if NAMESPACES
984
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800985config UTS_NS
986 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700987 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -0800988 help
989 In this namespace tasks see different info provided with the
990 uname() system call
991
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800992config IPC_NS
993 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -0700994 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -0700995 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800996 help
997 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -0700998 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800999
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001000config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001001 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001002 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001003 help
1004 This allows containers, i.e. vservers, to use user namespaces
1005 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001006
1007 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001008 recommended that the MEMCG option also be enabled and that
1009 user-space use the memory control groups to limit the amount
1010 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001011
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001012 If unsure, say N.
1013
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001014config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001015 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001016 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001017 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001018 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001019 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001020 pid namespaces. This is a building block of containers.
1021
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001022config NET_NS
1023 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001024 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001025 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001026 help
1027 Allow user space to create what appear to be multiple instances
1028 of the network stack.
1029
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001030endif # NAMESPACES
1031
Adrian Reber5cb366b2018-08-21 22:01:17 -07001032config CHECKPOINT_RESTORE
1033 bool "Checkpoint/restore support"
1034 select PROC_CHILDREN
1035 default n
1036 help
1037 Enables additional kernel features in a sake of checkpoint/restore.
1038 In particular it adds auxiliary prctl codes to setup process text,
1039 data and heap segment sizes, and a few additional /proc filesystem
1040 entries.
1041
1042 If unsure, say N here.
1043
Mike Galbraith5091faa2010-11-30 14:18:03 +01001044config SCHED_AUTOGROUP
1045 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001046 select CGROUPS
1047 select CGROUP_SCHED
1048 select FAIR_GROUP_SCHED
1049 help
1050 This option optimizes the scheduler for common desktop workloads by
1051 automatically creating and populating task groups. This separation
1052 of workloads isolates aggressive CPU burners (like build jobs) from
1053 desktop applications. Task group autogeneration is currently based
1054 upon task session.
1055
Patrick Bellasi68dbff92017-10-21 18:07:35 +01001056config SCHED_TUNE
1057 bool "Boosting for CFS tasks (EXPERIMENTAL)"
1058 depends on SMP
1059 help
1060 This option enables support for task classification using a new
1061 cgroup controller, schedtune. Schedtune allows tasks to be given
1062 a boost value and marked as latency-sensitive or not. This option
1063 provides the "schedtune" controller.
1064
1065 This new controller:
1066 1. allows only a two layers hierarchy, where the root defines the
1067 system-wide boost value and its direct childrens define each one a
1068 different "class of tasks" to be boosted with a different value
1069 2. supports up to 16 different task classes, each one which could be
1070 configured with a different boost value
1071
1072 Latency-sensitive tasks are not subject to energy-aware wakeup
1073 task placement. The boost value assigned to tasks is used to
1074 influence task placement and CPU frequency selection (if
1075 utilization-driven frequency selection is in use).
1076
1077 If unsure, say N.
1078
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001079config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001080 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001081 depends on SYSFS
1082 default n
1083 help
1084 This option adds code that switches the layout of the "block" class
1085 devices, to not show up in /sys/class/block/, but only in
1086 /sys/block/.
1087
1088 This switch is only active when the sysfs.deprecated=1 boot option is
1089 passed or the SYSFS_DEPRECATED_V2 option is set.
1090
1091 This option allows new kernels to run on old distributions and tools,
1092 which might get confused by /sys/class/block/. Since 2007/2008 all
1093 major distributions and tools handle this just fine.
1094
1095 Recent distributions and userspace tools after 2009/2010 depend on
1096 the existence of /sys/class/block/, and will not work with this
1097 option enabled.
1098
1099 Only if you are using a new kernel on an old distribution, you might
1100 need to say Y here.
1101
1102config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001103 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001104 default n
1105 depends on SYSFS
1106 depends on SYSFS_DEPRECATED
1107 help
1108 Enable deprecated sysfs by default.
1109
1110 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1111 option.
1112
1113 Only if you are using a new kernel on an old distribution, you might
1114 need to say Y here. Even then, odds are you would not need it
1115 enabled, you can always pass the boot option if absolutely necessary.
1116
1117config RELAY
1118 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001119 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001120 help
1121 This option enables support for relay interface support in
1122 certain file systems (such as debugfs).
1123 It is designed to provide an efficient mechanism for tools and
1124 facilities to relay large amounts of data from kernel space to
1125 user space.
1126
1127 If unsure, say N.
1128
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001129config BLK_DEV_INITRD
1130 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001131 help
1132 The initial RAM filesystem is a ramfs which is loaded by the
1133 boot loader (loadlin or lilo) and that is mounted as root
1134 before the normal boot procedure. It is typically used to
1135 load modules needed to mount the "real" root file system,
Mauro Carvalho Chehab8c27ceff32016-10-18 10:12:27 -02001136 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001137
1138 If RAM disk support (BLK_DEV_RAM) is also included, this
1139 also enables initial RAM disk (initrd) support and adds
1140 15 Kbytes (more on some other architectures) to the kernel size.
1141
1142 If unsure say Y.
1143
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001144if BLK_DEV_INITRD
1145
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001146source "usr/Kconfig"
1147
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001148endif
1149
Arnd Bergmann877417e2016-04-25 17:35:27 +02001150choice
1151 prompt "Compiler optimization level"
Ulf Magnusson2cc3ce22017-10-04 01:53:26 +02001152 default CC_OPTIMIZE_FOR_PERFORMANCE
Arnd Bergmann877417e2016-04-25 17:35:27 +02001153
1154config CC_OPTIMIZE_FOR_PERFORMANCE
1155 bool "Optimize for performance"
1156 help
1157 This is the default optimization level for the kernel, building
1158 with the "-O2" compiler flag for best performance and most
1159 helpful compile-time warnings.
1160
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001161config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +02001162 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001163 help
Masahiro Yamada31a4af72014-08-05 14:43:07 +09001164 Enabling this option will pass "-Os" instead of "-O2" to
1165 your compiler resulting in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001166
Kirill Smelkov3a55fb02012-11-02 15:41:01 +04001167 If unsure, say N.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001168
Arnd Bergmann877417e2016-04-25 17:35:27 +02001169endchoice
1170
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001171config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1172 bool
1173 help
1174 This requires that the arch annotates or otherwise protects
1175 its external entry points from being discarded. Linker scripts
1176 must also merge .text.*, .data.*, and .bss.* correctly into
1177 output sections. Care must be taken not to pull in unrelated
1178 sections (e.g., '.text.init'). Typically '.' in section names
1179 is used to distinguish them from label names / C identifiers.
1180
1181config LD_DEAD_CODE_DATA_ELIMINATION
1182 bool "Dead code and data elimination (EXPERIMENTAL)"
1183 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1184 depends on EXPERT
Paul Burton0098f2e2019-01-11 19:06:44 +00001185 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
Masahiro Yamadae85d1d62018-08-22 22:51:09 +09001186 depends on $(cc-option,-ffunction-sections -fdata-sections)
1187 depends on $(ld-option,--gc-sections)
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001188 help
Masahiro Yamada8b9d2712018-06-24 01:41:51 +09001189 Enable this if you want to do dead code and data elimination with
1190 the linker by compiling with -ffunction-sections -fdata-sections,
1191 and linking with --gc-sections.
Nicholas Piggin5d20ee32018-05-09 23:00:00 +10001192
1193 This can reduce on disk and in-memory size of the kernel
1194 code and static data, particularly for small configs and
1195 on small systems. This has the possibility of introducing
1196 silently broken kernel if the required annotations are not
1197 present. This option is not well tested yet, so use at your
1198 own risk.
1199
Randy Dunlap08470622006-09-30 23:28:13 -07001200config SYSCTL
1201 bool
1202
Mike Frysinger657a5202013-04-30 15:28:45 -07001203config HAVE_UID16
1204 bool
1205
1206config SYSCTL_EXCEPTION_TRACE
1207 bool
1208 help
1209 Enable support for /proc/sys/debug/exception-trace.
1210
1211config SYSCTL_ARCH_UNALIGN_NO_WARN
1212 bool
1213 help
1214 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1215 Allows arch to define/use @no_unaligned_warning to possibly warn
1216 about unaligned access emulation going on under the hood.
1217
1218config SYSCTL_ARCH_UNALIGN_ALLOW
1219 bool
1220 help
1221 Enable support for /proc/sys/kernel/unaligned-trap
1222 Allows arches to define/use @unaligned_enabled to runtime toggle
1223 the unaligned access emulation.
1224 see arch/parisc/kernel/unaligned.c for reference
1225
Mike Frysinger657a5202013-04-30 15:28:45 -07001226config HAVE_PCSPKR_PLATFORM
1227 bool
1228
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001229# interpreter that classic socket filters depend on
1230config BPF
1231 bool
1232
David Rientjes6a108a12011-01-20 14:44:16 -08001233menuconfig EXPERT
1234 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001235 # Unhide debug options, to make the on-by-default options visible
1236 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237 help
1238 This option allows certain base kernel options and settings
1239 to be disabled or tweaked. This is for specialized
1240 environments which can tolerate a "non-standard" kernel.
1241 Only use this if you really know what you are doing.
1242
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001243config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001244 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001245 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001246 default y
1247 help
1248 This enables the legacy 16-bit UID syscall wrappers.
1249
Iulia Manda28138932015-04-15 16:16:41 -07001250config MULTIUSER
1251 bool "Multiple users, groups and capabilities support" if EXPERT
1252 default y
1253 help
1254 This option enables support for non-root users, groups and
1255 capabilities.
1256
1257 If you say N here, all processes will run with UID 0, GID 0, and all
1258 possible capabilities. Saying N here also compiles out support for
1259 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1260 setgid, and capset.
1261
1262 If unsure, say Y here.
1263
Fabian Frederickf6187762014-06-04 16:11:12 -07001264config SGETMASK_SYSCALL
1265 bool "sgetmask/ssetmask syscalls support" if EXPERT
Arnd Bergmanna687a532018-03-07 23:30:54 +01001266 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
Fabian Frederickf6187762014-06-04 16:11:12 -07001267 ---help---
1268 sys_sgetmask and sys_ssetmask are obsolete system calls
1269 no longer supported in libc but still enabled by default in some
1270 architectures.
1271
1272 If unsure, leave the default option here.
1273
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001274config SYSFS_SYSCALL
1275 bool "Sysfs syscall support" if EXPERT
1276 default y
1277 ---help---
1278 sys_sysfs is an obsolete system call no longer supported in libc.
1279 Note that disabling this option is more secure but might break
1280 compatibility with some systems.
1281
1282 If unsure say Y here.
1283
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001284config SYSCTL_SYSCALL
David Rientjes6a108a12011-01-20 14:44:16 -08001285 bool "Sysctl syscall support" if EXPERT
Eric W. Biederman26a70342009-11-05 05:26:41 -08001286 depends on PROC_SYSCTL
WANG Congc736de62011-11-02 13:39:25 -07001287 default n
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001288 select SYSCTL
1289 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001290 sys_sysctl uses binary paths that have been found challenging
1291 to properly maintain and use. The interface in /proc/sys
1292 using paths with ascii names is now the primary path to this
1293 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001294
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001295 Almost nothing using the binary sysctl interface so if you are
1296 trying to save some space it is probably safe to disable this,
1297 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001298
WANG Congc736de62011-11-02 13:39:25 -07001299 If unsure say N here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001300
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001301config FHANDLE
1302 bool "open by fhandle syscalls" if EXPERT
1303 select EXPORTFS
1304 default y
1305 help
1306 If you say Y here, a user level program will be able to map
1307 file names to handle and then later use the handle for
1308 different file system operations. This is useful in implementing
1309 userspace file servers, which now track files using handles instead
1310 of names. The handle would remain the same even if file names
1311 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1312 syscalls.
1313
Nicolas Pitrebaa73d92016-11-11 00:10:10 -05001314config POSIX_TIMERS
1315 bool "Posix Clocks & timers" if EXPERT
1316 default y
1317 help
1318 This includes native support for POSIX timers to the kernel.
1319 Some embedded systems have no use for them and therefore they
1320 can be configured out to reduce the size of the kernel image.
1321
1322 When this option is disabled, the following syscalls won't be
1323 available: timer_create, timer_gettime: timer_getoverrun,
1324 timer_settime, timer_delete, clock_adjtime, getitimer,
1325 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1326 clock_getres and clock_nanosleep syscalls will be limited to
1327 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1328
1329 If unsure say y.
1330
Matt Mackalld59745c2005-05-01 08:59:02 -07001331config PRINTK
1332 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001333 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001334 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001335 help
1336 This option enables normal printk support. Removing it
1337 eliminates most of the message strings from the kernel image
1338 and makes the kernel more or less silent. As this makes it
1339 very difficult to diagnose system problems, saying N here is
1340 strongly discouraged.
1341
Petr Mladek42a0bb32016-05-20 17:00:33 -07001342config PRINTK_NMI
1343 def_bool y
1344 depends on PRINTK
1345 depends on HAVE_NMI
1346
Matt Mackallc8538a72005-05-01 08:59:01 -07001347config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001348 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001349 default y
1350 help
1351 Disabling this option eliminates support for BUG and WARN, reducing
1352 the size of your kernel image and potentially quietly ignoring
1353 numerous fatal conditions. You should only consider disabling this
1354 option for embedded systems with no facilities for reporting errors.
1355 Just say Y.
1356
Matt Mackall708e9a72006-01-08 01:05:25 -08001357config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001358 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001359 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001360 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001361 help
1362 Enable support for generating core dumps. Disabling saves about 4k.
1363
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001364
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001365config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001366 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001367 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001368 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001369 default y
1370 help
1371 This option allows to disable the internal PC-Speaker
1372 support, saving some memory.
1373
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374config BASE_FULL
1375 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001376 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 help
1378 Disabling this option reduces the size of miscellaneous core
1379 kernel data structures. This saves memory on small machines,
1380 but may reduce performance.
1381
1382config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001383 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 default y
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001385 imply RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 help
1387 Disabling this option will cause the kernel to be built without
1388 support for "fast userspace mutexes". The resulting kernel may not
1389 run glibc-based applications correctly.
1390
Nicolas Pitrebc2eecd2017-08-01 00:31:32 -04001391config FUTEX_PI
1392 bool
1393 depends on FUTEX && RT_MUTEXES
1394 default y
1395
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001396config HAVE_FUTEX_CMPXCHG
1397 bool
Josh Triplett62b4d202014-10-03 16:19:24 -07001398 depends on FUTEX
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001399 help
1400 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1401 is implemented and always working. This removes a couple of runtime
1402 checks.
1403
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001405 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406 default y
1407 help
1408 Disabling this option will cause the kernel to be built without
1409 support for epoll family of system calls.
1410
Davide Libenzifba2afa2007-05-10 22:23:13 -07001411config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001412 bool "Enable signalfd() system call" if EXPERT
Davide Libenzifba2afa2007-05-10 22:23:13 -07001413 default y
1414 help
1415 Enable the signalfd() system call that allows to receive signals
1416 on a file descriptor.
1417
1418 If unsure, say Y.
1419
Davide Libenzib215e282007-05-10 22:23:16 -07001420config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001421 bool "Enable timerfd() system call" if EXPERT
Davide Libenzib215e282007-05-10 22:23:16 -07001422 default y
1423 help
1424 Enable the timerfd() system call that allows to receive timer
1425 events on a file descriptor.
1426
1427 If unsure, say Y.
1428
Davide Libenzie1ad7462007-05-10 22:23:19 -07001429config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001430 bool "Enable eventfd() system call" if EXPERT
Davide Libenzie1ad7462007-05-10 22:23:19 -07001431 default y
1432 help
1433 Enable the eventfd() system call that allows to receive both
1434 kernel notification (ie. KAIO) or userspace notifications.
1435
1436 If unsure, say Y.
1437
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001439 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440 default y
1441 depends on MMU
1442 help
1443 The shmem is an internal filesystem used to manage shared memory.
1444 It is backed by swap and manages resource limits. It is also exported
1445 to userspace as tmpfs if TMPFS is enabled. Disabling this
1446 option replaces shmem and tmpfs with the much simpler ramfs code,
1447 which may be appropriate on small systems without swap.
1448
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001449config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001450 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001451 default y
1452 help
1453 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001454 by some high performance threaded applications. Disabling
1455 this option saves about 7k.
1456
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001457config ADVISE_SYSCALLS
1458 bool "Enable madvise/fadvise syscalls" if EXPERT
1459 default y
1460 help
1461 This option enables the madvise and fadvise syscalls, used by
1462 applications to advise the kernel about their future memory or file
1463 usage, improving performance. If building an embedded system where no
1464 applications use these syscalls, you can disable this option to save
1465 space.
1466
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001467config MEMBARRIER
1468 bool "Enable membarrier() system call" if EXPERT
1469 default y
1470 help
1471 Enable the membarrier() system call that allows issuing memory
1472 barriers across all running threads, which can be used to distribute
1473 the cost of user-space memory barriers asymmetrically by transforming
1474 pairs of memory barriers into pairs consisting of membarrier() and a
1475 compiler barrier.
1476
1477 If unsure, say Y.
1478
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001479config KALLSYMS
1480 bool "Load all symbols for debugging/ksymoops" if EXPERT
1481 default y
1482 help
1483 Say Y here to let the kernel print out symbolic crash information and
1484 symbolic stack backtraces. This increases the size of the kernel
1485 somewhat, as all symbols have to be loaded into the kernel image.
1486
1487config KALLSYMS_ALL
1488 bool "Include all symbols in kallsyms"
1489 depends on DEBUG_KERNEL && KALLSYMS
1490 help
1491 Normally kallsyms only contains the symbols of functions for nicer
1492 OOPS messages and backtraces (i.e., symbols from the text and inittext
1493 sections). This is sufficient for most cases. And only in very rare
1494 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1495 names of variables from the data sections, etc).
1496
1497 This option makes sure that all symbols are loaded into the kernel
1498 image (i.e., symbols from all sections) in cost of increased kernel
1499 size (depending on the kernel configuration, it may be 300KiB or
1500 something like this).
1501
1502 Say N unless you really need all symbols.
1503
1504config KALLSYMS_ABSOLUTE_PERCPU
1505 bool
1506 depends on KALLSYMS
1507 default X86_64 && SMP
1508
1509config KALLSYMS_BASE_RELATIVE
1510 bool
1511 depends on KALLSYMS
Arnd Bergmanna687a532018-03-07 23:30:54 +01001512 default !IA64
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001513 help
1514 Instead of emitting them as absolute values in the native word size,
1515 emit the symbol references in the kallsyms table as 32-bit entries,
1516 each containing a relative value in the range [base, base + U32_MAX]
1517 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1518 an absolute value in the range [0, S32_MAX] or a relative value in the
1519 range [base, base + S32_MAX], where base is the lowest relative symbol
1520 address encountered in the image.
1521
1522 On 64-bit builds, this reduces the size of the address table by 50%,
1523 but more importantly, it results in entries whose values are build
1524 time constants, and no relocation pass is required at runtime to fix
1525 up the entries based on the runtime load address of the kernel.
1526
1527# end of the "standard kernel features (expert users)" menu
1528
1529# syscall, maps, verifier
1530config BPF_SYSCALL
1531 bool "Enable bpf() system call"
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001532 select BPF
Song Liubae77c52018-05-07 10:50:48 -07001533 select IRQ_WORK
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001534 default n
1535 help
1536 Enable the bpf() system call that allows to manipulate eBPF
1537 programs and maps via file descriptors.
1538
Alexei Starovoitov290af862018-01-09 10:04:29 -08001539config BPF_JIT_ALWAYS_ON
1540 bool "Permanently enable BPF JIT and remove BPF interpreter"
1541 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1542 help
1543 Enables BPF JIT and removes BPF interpreter to avoid
1544 speculative execution of BPF instructions by the interpreter
1545
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001546config USERFAULTFD
1547 bool "Enable userfaultfd() system call"
Randy Dunlapd1b069f2017-11-17 15:31:47 -08001548 depends on MMU
1549 help
1550 Enable the userfaultfd() system call that allows to intercept and
1551 handle page faults in userland.
1552
Mathieu Desnoyers3ccfebe2018-01-29 15:20:11 -05001553config ARCH_HAS_MEMBARRIER_CALLBACKS
1554 bool
1555
Mathieu Desnoyers70216e12018-01-29 15:20:17 -05001556config ARCH_HAS_MEMBARRIER_SYNC_CORE
1557 bool
1558
Mathieu Desnoyersd7822b12018-06-02 08:43:54 -04001559config RSEQ
1560 bool "Enable rseq() system call" if EXPERT
1561 default y
1562 depends on HAVE_RSEQ
1563 select MEMBARRIER
1564 help
1565 Enable the restartable sequences system call. It provides a
1566 user-space cache for the current CPU number value, which
1567 speeds up getting the current CPU number from user-space,
1568 as well as an ABI to speed up user-space operations on
1569 per-CPU data.
1570
1571 If unsure, say Y.
1572
1573config DEBUG_RSEQ
1574 default n
1575 bool "Enabled debugging of rseq() system call" if EXPERT
1576 depends on RSEQ && DEBUG_KERNEL
1577 help
1578 Enable extra debugging checks for the rseq system call.
1579
1580 If unsure, say N.
1581
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001582config EMBEDDED
1583 bool "Embedded system"
Josh Triplett5d2acfc2014-04-07 15:39:09 -07001584 option allnoconfig_y
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001585 select EXPERT
1586 help
1587 This option should be enabled if compiling the kernel for
1588 an embedded system so certain expert options are available
1589 for configuration.
1590
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001591config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001592 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001593 help
1594 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001595
Peter Zijlstra906010b2009-09-21 16:08:49 +02001596config PERF_USE_VMALLOC
1597 bool
1598 help
1599 See tools/perf/design.txt for details
1600
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001601config PC104
William Breathitt Gray424529f2017-12-29 15:14:59 -05001602 bool "PC/104 support" if EXPERT
William Breathitt Grayad90a3d2017-01-10 13:50:54 -05001603 help
1604 Expose PC/104 form factor device drivers and options available for
1605 selection and configuration. Enable this option if your target
1606 machine has a PC/104 bus.
1607
Ingo Molnar57c0c152009-09-21 12:20:38 +02001608menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001609
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001610config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001611 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001612 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001613 depends on HAVE_PERF_EVENTS
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001614 select IRQ_WORK
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001615 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001616 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001617 Enable kernel support for various performance events provided
1618 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001619
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001620 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001621 use of generic tracepoints.
1622
1623 Most modern CPUs support performance events via performance
1624 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001625 types of hw events: such as instructions executed, cachemisses
1626 suffered, or branches mis-predicted - without slowing down the
1627 kernel or applications. These registers can also trigger interrupts
1628 when a threshold number of events have passed - and can thus be
1629 used to profile the code that runs on that CPU.
1630
Ingo Molnar57c0c152009-09-21 12:20:38 +02001631 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001632 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001633 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001634 provides per task and per CPU counters, and it provides event
1635 capabilities on top of those.
1636
1637 Say Y if unsure.
1638
Peter Zijlstra906010b2009-09-21 16:08:49 +02001639config DEBUG_PERF_USE_VMALLOC
1640 default n
1641 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb307112015-05-04 16:26:39 +10001642 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001643 select PERF_USE_VMALLOC
1644 help
1645 Use vmalloc memory to back perf mmap() buffers.
1646
1647 Mostly useful for debugging the vmalloc code on platforms
1648 that don't require it.
1649
1650 Say N if unsure.
1651
Thomas Gleixner0793a612008-12-04 20:12:29 +01001652endmenu
1653
Christoph Lameterf8891e52006-06-30 01:55:45 -07001654config VM_EVENT_COUNTERS
1655 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001656 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001657 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001658 VM event counters are needed for event counts to be shown.
1659 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001660 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001661 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001662
Christoph Lameter41ecc552007-05-09 02:32:44 -07001663config SLUB_DEBUG
1664 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001665 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001666 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001667 help
1668 SLUB has extensive debug support features. Disabling these can
1669 result in significant savings in code size. This also disables
1670 SLUB sysfs support. /sys/slab will not exist and there will be
1671 no support for cache validation etc.
1672
Tejun Heo1663f262017-02-22 15:41:39 -08001673config SLUB_MEMCG_SYSFS_ON
1674 default n
1675 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1676 depends on SLUB && SYSFS && MEMCG
1677 help
1678 SLUB creates a directory under /sys/kernel/slab for each
1679 allocation cache to host info and debug files. If memory
1680 cgroup is enabled, each cache can have per memory cgroup
1681 caches. SLUB can create the same sysfs directories for these
1682 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1683 to a very high number of debug files being created. This is
1684 controlled by slub_memcg_sysfs boot parameter and this
1685 config option determines the parameter's default value.
1686
Randy Dunlapb943c462009-03-10 12:55:46 -07001687config COMPAT_BRK
1688 bool "Disable heap randomization"
1689 default y
1690 help
1691 Randomizing heap placement makes heap exploits harder, but it
1692 also breaks ancient binaries (including anything libc5 based).
1693 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001694 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001695 /proc/sys/kernel/randomize_va_space to 2.
1696
1697 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1698
Christoph Lameter81819f02007-05-06 14:49:36 -07001699choice
1700 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001701 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001702 help
1703 This option allows to select a slab allocator.
1704
1705config SLAB
1706 bool "SLAB"
Kees Cook04385fc2016-06-23 15:20:59 -07001707 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001708 help
1709 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001710 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001711 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001712
1713config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001714 bool "SLUB (Unqueued Allocator)"
Kees Cooked18adc2016-06-23 15:24:05 -07001715 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001716 help
1717 SLUB is a slab allocator that minimizes cache line usage
1718 instead of managing queues of cached objects (SLAB approach).
1719 Per cpu caching is realized using slabs of objects instead
1720 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001721 and has enhanced diagnostics. SLUB is the default choice for
1722 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001723
1724config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001725 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001726 bool "SLOB (Simple Allocator)"
1727 help
Matt Mackall37291452008-02-04 22:29:38 -08001728 SLOB replaces the stock allocator with a drastically simpler
1729 allocator. SLOB is generally more space efficient but
1730 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001731
1732endchoice
1733
Kees Cook7660a6f2017-07-06 15:36:40 -07001734config SLAB_MERGE_DEFAULT
1735 bool "Allow slab caches to be merged"
1736 default y
1737 help
1738 For reduced kernel memory fragmentation, slab caches can be
1739 merged when they share the same size and other characteristics.
1740 This carries a risk of kernel heap overflows being able to
1741 overwrite objects from merged caches (and more easily control
1742 cache layout), which makes such heap attacks easier to exploit
1743 by attackers. By keeping caches unmerged, these kinds of exploits
1744 can usually only damage objects in the same cache. To disable
1745 merging at runtime, "slab_nomerge" can be passed on the kernel
1746 command line.
1747
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001748config SLAB_FREELIST_RANDOM
1749 default n
Thomas Garnier210e7a42016-07-26 15:21:59 -07001750 depends on SLAB || SLUB
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001751 bool "SLAB freelist randomization"
1752 help
Thomas Garnier210e7a42016-07-26 15:21:59 -07001753 Randomizes the freelist order used on creating new pages. This
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001754 security feature reduces the predictability of the kernel slab
1755 allocator against heap overflows.
1756
Kees Cook2482dde2017-09-06 16:19:18 -07001757config SLAB_FREELIST_HARDENED
1758 bool "Harden slab freelist metadata"
1759 depends on SLUB
1760 help
1761 Many kernel heap attacks try to target slab cache metadata and
1762 other infrastructure. This options makes minor performance
1763 sacrifies to harden the kernel slab allocator against common
1764 freelist exploit methods.
1765
Joonsoo Kim345c9052013-06-19 14:05:52 +09001766config SLUB_CPU_PARTIAL
1767 default y
Uwe Kleine-Königb39ffbf2013-07-17 16:54:59 +02001768 depends on SLUB && SMP
Joonsoo Kim345c9052013-06-19 14:05:52 +09001769 bool "SLUB per cpu partial cache"
1770 help
1771 Per cpu partial caches accellerate objects allocation and freeing
1772 that is local to a processor at the price of more indeterminism
1773 in the latency of the free. On overflow these caches will be cleared
1774 which requires the taking of locks that may cause latency spikes.
1775 Typically one would choose no for a realtime system.
1776
Jie Zhangea637632009-12-14 18:00:02 -08001777config MMAP_ALLOW_UNINITIALIZED
1778 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08001779 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08001780 default n
1781 help
1782 Normally, and according to the Linux spec, anonymous memory obtained
Randy Dunlap3903bf92018-08-21 21:58:34 -07001783 from mmap() has its contents cleared before it is passed to
Jie Zhangea637632009-12-14 18:00:02 -08001784 userspace. Enabling this config option allows you to request that
1785 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1786 providing a huge performance boost. If this option is not enabled,
1787 then the flag will be ignored.
1788
1789 This is taken advantage of by uClibc's malloc(), and also by
1790 ELF-FDPIC binfmt's brk and stack allocator.
1791
1792 Because of the obvious security issues, this option should only be
1793 enabled on embedded devices where you control what is run in
1794 userspace. Since that isn't generally a problem on no-MMU systems,
1795 it is normally safe to say Y here.
1796
1797 See Documentation/nommu-mmap.txt for more information.
1798
David Howells091f6e22015-07-20 21:16:28 +01001799config SYSTEM_DATA_VERIFICATION
1800 def_bool n
1801 select SYSTEM_TRUSTED_KEYRING
1802 select KEYS
1803 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00001804 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01001805 select ASYMMETRIC_KEY_TYPE
1806 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01001807 select ASN1
1808 select OID_REGISTRY
1809 select X509_CERTIFICATE_PARSER
1810 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07001811 help
David Howells091f6e22015-07-20 21:16:28 +01001812 Provide PKCS#7 message verification using the contents of the system
1813 trusted keyring to provide public keys. This then can be used for
1814 module verification, kexec image verification and firmware blob
1815 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07001816
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001817config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001818 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001819 help
1820 Say Y here to enable the extended profiling support mechanisms used
1821 by profilers such as OProfile.
1822
Ingo Molnar5f87f112008-07-23 14:15:22 +02001823#
1824# Place an empty function call at each tracepoint site. Can be
1825# dynamically changed for a probe function.
1826#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001827config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001828 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001829
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830endmenu # General setup
1831
Christoph Hellwig15724972018-07-31 13:39:30 +02001832source "arch/Kconfig"
1833
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001834config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05001835 bool
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001836
Linus Torvalds1da177e2005-04-16 15:20:36 -07001837config BASE_SMALL
1838 int
1839 default 0 if BASE_FULL
1840 default 1 if !BASE_FULL
1841
Jan Engelhardt66da5732007-07-15 23:39:29 -07001842menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843 bool "Enable loadable module support"
Yann E. MORIN11097a02013-08-11 16:07:50 +02001844 option modules
Linus Torvalds1da177e2005-04-16 15:20:36 -07001845 help
1846 Kernel modules are small pieces of compiled code which can
1847 be inserted in the running kernel, rather than being
1848 permanently built into the kernel. You use the "modprobe"
1849 tool to add (and sometimes remove) them. If you say Y here,
1850 many parts of the kernel can be built as modules (by
1851 answering M instead of Y where indicated): this is most
1852 useful for infrequently used options which are not required
1853 for booting. For more information, see the man pages for
1854 modprobe, lsmod, modinfo, insmod and rmmod.
1855
1856 If you say Y here, you will need to run "make
1857 modules_install" to put the modules under /lib/modules/
1858 where modprobe can find them (you may need to be root to do
1859 this).
1860
1861 If unsure, say Y.
1862
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001863if MODULES
1864
Linus Torvalds826e4502008-05-04 17:04:16 -07001865config MODULE_FORCE_LOAD
1866 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07001867 default n
1868 help
Rusty Russell91e37a72008-05-09 16:25:28 +10001869 Allow loading of modules without version information (ie. modprobe
1870 --force). Forced module loading sets the 'F' (forced) taint flag and
1871 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07001872
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873config MODULE_UNLOAD
1874 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875 help
1876 Without this option you will not be able to unload any
1877 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05001878 anyway), which makes your kernel smaller, faster
1879 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880
1881config MODULE_FORCE_UNLOAD
1882 bool "Forced module unloading"
Kees Cook19c92392012-10-02 11:19:29 -07001883 depends on MODULE_UNLOAD
Linus Torvalds1da177e2005-04-16 15:20:36 -07001884 help
1885 This option allows you to force a module to unload, even if the
1886 kernel believes it is unsafe: the kernel will remove the module
1887 without waiting for anyone to stop using it (using the -f option to
1888 rmmod). This is mainly for kernel developers and desperate users.
1889 If unsure, say N.
1890
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01001892 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893 help
1894 Usually, you have to use modules compiled with your kernel.
1895 Saying Y here makes it sometimes possible to use modules
1896 compiled for different kernels, by adding enough information
1897 to the modules to (hopefully) spot any changes which would
1898 make them incompatible with the kernel you are running. If
1899 unsure, say N.
1900
Ard Biesheuvel56067812017-02-03 09:54:05 +00001901config MODULE_REL_CRCS
1902 bool
1903 depends on MODVERSIONS
1904
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905config MODULE_SRCVERSION_ALL
1906 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907 help
1908 Modules which contain a MODULE_VERSION get an extra "srcversion"
1909 field inserted into their modinfo section, which contains a
1910 sum of the source files which made it. This helps maintainers
1911 see exactly which source was used to build a module (since
1912 others sometimes change the module source without updating
1913 the version). With this option, such a "srcversion" field
1914 will be created for all modules. If unsure, say N.
1915
Rusty Russell106a4ee2012-09-26 10:09:40 +01001916config MODULE_SIG
1917 bool "Module signature verification"
1918 depends on MODULES
David Howells091f6e22015-07-20 21:16:28 +01001919 select SYSTEM_DATA_VERIFICATION
Rusty Russell106a4ee2012-09-26 10:09:40 +01001920 help
1921 Check modules for valid signatures upon load: the signature
1922 is simply appended to the module. For more information see
Nathan Chancellorcbdc8212017-09-10 02:48:29 -07001923 <file:Documentation/admin-guide/module-signing.rst>.
Rusty Russell106a4ee2012-09-26 10:09:40 +01001924
David Howells228c37f2015-08-11 12:38:54 +01001925 Note that this option adds the OpenSSL development packages as a
1926 kernel build dependency so that the signing tool can use its crypto
1927 library.
1928
David Howellsea0b6dc2012-09-26 10:09:50 +01001929 !!!WARNING!!! If you enable this option, you MUST make sure that the
1930 module DOES NOT get stripped after being signed. This includes the
1931 debuginfo strip done by some packagers (such as rpmbuild) and
1932 inclusion into an initramfs that wants the module size reduced.
1933
Rusty Russell106a4ee2012-09-26 10:09:40 +01001934config MODULE_SIG_FORCE
1935 bool "Require modules to be validly signed"
1936 depends on MODULE_SIG
1937 help
1938 Reject unsigned modules or signed modules for which we don't have a
1939 key. Without this, such modules will simply taint the kernel.
David Howellsea0b6dc2012-09-26 10:09:50 +01001940
Michal Marekd9d8d7e2013-01-25 13:41:31 +10301941config MODULE_SIG_ALL
1942 bool "Automatically sign all modules"
1943 default y
1944 depends on MODULE_SIG
1945 help
1946 Sign all modules during make modules_install. Without this option,
1947 modules must be signed manually, using the scripts/sign-file tool.
1948
1949comment "Do not forget to sign required modules with scripts/sign-file"
1950 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1951
David Howellsea0b6dc2012-09-26 10:09:50 +01001952choice
1953 prompt "Which hash algorithm should modules be signed with?"
1954 depends on MODULE_SIG
1955 help
1956 This determines which sort of hashing algorithm will be used during
1957 signature generation. This algorithm _must_ be built into the kernel
1958 directly so that signature verification can take place. It is not
1959 possible to load a signed module containing the algorithm to check
1960 the signature on that module.
1961
1962config MODULE_SIG_SHA1
1963 bool "Sign modules with SHA-1"
1964 select CRYPTO_SHA1
1965
1966config MODULE_SIG_SHA224
1967 bool "Sign modules with SHA-224"
1968 select CRYPTO_SHA256
1969
1970config MODULE_SIG_SHA256
1971 bool "Sign modules with SHA-256"
1972 select CRYPTO_SHA256
1973
1974config MODULE_SIG_SHA384
1975 bool "Sign modules with SHA-384"
1976 select CRYPTO_SHA512
1977
1978config MODULE_SIG_SHA512
1979 bool "Sign modules with SHA-512"
1980 select CRYPTO_SHA512
1981
1982endchoice
1983
Michal Marek22753672013-01-25 13:41:00 +10301984config MODULE_SIG_HASH
1985 string
1986 depends on MODULE_SIG
1987 default "sha1" if MODULE_SIG_SHA1
1988 default "sha224" if MODULE_SIG_SHA224
1989 default "sha256" if MODULE_SIG_SHA256
1990 default "sha384" if MODULE_SIG_SHA384
1991 default "sha512" if MODULE_SIG_SHA512
1992
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09301993config MODULE_COMPRESS
1994 bool "Compress modules on installation"
1995 depends on MODULES
1996 help
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09301997
Rusty Russellb6c09b52015-06-16 12:16:22 +09301998 Compresses kernel modules when 'make modules_install' is run; gzip or
1999 xz depending on "Compression algorithm" below.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302000
Rusty Russellb6c09b52015-06-16 12:16:22 +09302001 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302002
Rusty Russellb6c09b52015-06-16 12:16:22 +09302003 Out-of-tree kernel modules installed using Kbuild will also be
2004 compressed upon installation.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302005
Rusty Russellb6c09b52015-06-16 12:16:22 +09302006 Note: for modules inside an initrd or initramfs, it's more efficient
2007 to compress the whole initrd or initramfs instead.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302008
Rusty Russellb6c09b52015-06-16 12:16:22 +09302009 Note: This is fully compatible with signed modules.
2010
2011 If in doubt, say N.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302012
2013choice
2014 prompt "Compression algorithm"
2015 depends on MODULE_COMPRESS
2016 default MODULE_COMPRESS_GZIP
2017 help
2018 This determines which sort of compression will be used during
2019 'make modules_install'.
2020
2021 GZIP (default) and XZ are supported.
2022
2023config MODULE_COMPRESS_GZIP
2024 bool "GZIP"
2025
2026config MODULE_COMPRESS_XZ
2027 bool "XZ"
2028
2029endchoice
2030
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002031config TRIM_UNUSED_KSYMS
2032 bool "Trim unused exported kernel symbols"
2033 depends on MODULES && !UNUSED_SYMBOLS
2034 help
2035 The kernel and some modules make many symbols available for
2036 other modules to use via EXPORT_SYMBOL() and variants. Depending
2037 on the set of modules being selected in your kernel configuration,
2038 many of those exported symbols might never be used.
2039
2040 This option allows for unused exported symbols to be dropped from
2041 the build. In turn, this provides the compiler more opportunities
2042 (especially when using LTO) for optimizing the code and reducing
2043 binary size. This might have some security advantages as well.
2044
Valdis Kletnieksf1cb6372016-08-02 14:07:27 -07002045 If unsure, or if you need to build out-of-tree modules, say N.
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002046
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002047endif # MODULES
2048
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302049config MODULES_TREE_LOOKUP
2050 def_bool y
Sami Tolvanen4976b0d2019-04-25 16:09:05 -07002051 depends on PERF_EVENTS || TRACING || CFI_CLANG
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302052
Rusty Russell98a79d62008-12-13 21:19:41 +10302053config INIT_ALL_POSSIBLE
2054 bool
2055 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302056 Back when each arch used to define their own cpu_online_mask and
2057 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302058 with all 1s, and others with all 0s. When they were centralised,
2059 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002060 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302061
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002062source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002063
2064config PREEMPT_NOTIFIERS
2065 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002066
Steffen Klassert16295be2010-01-06 19:47:10 +11002067config PADATA
2068 depends on SMP
2069 bool
2070
David Howells4520c6a2012-09-21 23:31:13 +01002071config ASN1
2072 tristate
2073 help
2074 Build a simple ASN.1 grammar compiler that produces a bytecode output
2075 that can be interpreted by the ASN.1 stream decoder and used to
2076 inform it as to what tags are to be expected in a stream and what
2077 functions to call on what tags.
2078
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002079source "kernel/Kconfig.locks"
Mathieu Desnoyerse61938a2018-01-29 15:20:15 -05002080
2081config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2082 bool
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002083
2084# It may be useful for an architecture to override the definitions of the
Dominik Brodowski7303e302018-04-05 11:53:03 +02002085# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2086# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2087# different calling convention for syscalls. They can also override the
2088# macros for not-implemented syscalls in kernel/sys_ni.c and
2089# kernel/time/posix-stubs.c. All these overrides need to be available in
2090# <asm/syscall_wrapper.h>.
Dominik Brodowski1bd21c62018-04-05 11:53:01 +02002091config ARCH_HAS_SYSCALL_WRAPPER
2092 def_bool n