blob: 4ca610d9e692fccc983052fcbfb881a98dc21625 [file] [log] [blame]
Roman Zippel80daa562008-01-14 04:51:16 +01001config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
Roman Zippelface4372006-06-08 22:12:45 -07009config DEFCONFIG_LIST
10 string
Paolo 'Blaisorblade' Giarrussob2670eac2006-10-19 23:28:23 -070011 depends on !UML
Roman Zippelface4372006-06-08 22:12:45 -070012 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
Sam Ravnborg73531902008-05-25 23:03:18 +020016 default "$ARCH_DEFCONFIG"
Roman Zippelface4372006-06-08 22:12:45 -070017 default "arch/$ARCH/defconfig"
18
Peter Oberparleiterb99b87f2009-06-17 16:28:03 -070019config CONSTRUCTORS
20 bool
21 depends on !UML
Peter Oberparleiterb99b87f2009-06-17 16:28:03 -070022
Peter Zijlstrae360adb2010-10-14 14:01:34 +080023config IRQ_WORK
24 bool
Peter Zijlstrae360adb2010-10-14 14:01:34 +080025
David Daney1dbdc6f2012-04-19 14:59:57 -070026config BUILDTIME_EXTABLE_SORT
27 bool
28
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070029config THREAD_INFO_IN_TASK
30 bool
31 help
32 Select this to move thread_info off the stack into task_struct. To
33 make this work, an arch will need to remove all thread_info fields
34 except flags and fix any runtime bugs.
35
Andy Lutomirskic6c314a2016-09-15 22:45:43 -070036 One subtle change that will be needed is to use try_get_task_stack()
37 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
38
Al Boldiff0cfc62007-07-31 00:39:23 -070039menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
Linus Torvalds1da177e2005-04-16 15:20:36 -070041config BROKEN
42 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44config BROKEN_ON_SMP
45 bool
46 depends on BROKEN || !SMP
47 default y
48
Linus Torvalds1da177e2005-04-16 15:20:36 -070049config INIT_ENV_ARG_LIMIT
50 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -070051 default 32 if !UML
52 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 help
Randy Dunlap34ad92c2005-10-30 15:01:46 -080054 Maximum of each of the number of arguments and environment
55 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
Linus Torvalds1da177e2005-04-16 15:20:36 -070057
Roland McGrath84336462009-12-21 16:24:06 -080058config CROSS_COMPILE
59 string "Cross-compiler tool prefix"
60 help
61 Same as running 'make CROSS_COMPILE=prefix-' but stored for
62 default make runs in this kernel build directory. You don't
63 need to set this unless you want the configured kernel build
64 directory to select the cross-compiler automatically.
65
Jiri Slaby4bb16672013-05-22 10:56:24 +020066config COMPILE_TEST
67 bool "Compile also drivers which will not load"
Richard Weinbergerbc083a62016-08-02 14:03:27 -070068 depends on !UML
Jiri Slaby4bb16672013-05-22 10:56:24 +020069 default n
70 help
71 Some drivers can be compiled on a different platform than they are
72 intended to be run on. Despite they cannot be loaded there (or even
73 when they load they cannot be used due to missing HW support),
74 developers still, opposing to distributors, might want to build such
75 drivers to compile-test them.
76
77 If you are a developer and want to build everything available, say Y
78 here. If you are a user/distributor, say N here to exclude useless
79 drivers to be distributed.
80
Linus Torvalds1da177e2005-04-16 15:20:36 -070081config LOCALVERSION
82 string "Local version - append to kernel release"
83 help
84 Append an extra string to the end of your kernel version.
85 This will show up when you type uname, for example.
86 The string you set here will be appended after the contents of
87 any files with a filename matching localversion* in your
88 object and source tree, in that order. Your total string can
89 be a maximum of 64 characters.
90
Ryan Andersonaaebf432005-07-31 04:57:49 -040091config LOCALVERSION_AUTO
92 bool "Automatically append version information to the version string"
93 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -070094 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -040095 help
96 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020097 release tree by looking for git tags that belong to the current
98 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -040099
100 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200101 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400102 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200103 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400104
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200105 (The actual string used here is the first eight characters produced
106 by running the command:
107
108 $ git rev-parse --verify HEAD
109
110 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400111
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800112config HAVE_KERNEL_GZIP
113 bool
114
115config HAVE_KERNEL_BZIP2
116 bool
117
118config HAVE_KERNEL_LZMA
119 bool
120
Lasse Collin3ebe1242011-01-12 17:01:23 -0800121config HAVE_KERNEL_XZ
122 bool
123
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800124config HAVE_KERNEL_LZO
125 bool
126
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700127config HAVE_KERNEL_LZ4
128 bool
129
Alain Knaff30d65db2009-01-04 22:46:17 +0100130choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800131 prompt "Kernel compression mode"
132 default KERNEL_GZIP
H. Peter Anvin2d3c6272013-11-14 21:43:47 -0800133 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800134 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100135 The linux kernel is a kind of self-extracting executable.
136 Several compression algorithms are available, which differ
137 in efficiency, compression and decompression speed.
138 Compression speed is only relevant when building a kernel.
139 Decompression speed is relevant at each boot.
140
141 If you have any problems with bzip2 or lzma compressed
142 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
143 version of this functionality (bzip2 only), for 2.4, was
144 supplied by Christian Ludwig)
145
146 High compression options are mostly useful for users, who
147 are low on disk space (embedded systems), but for whom ram
148 size matters less.
149
150 If in doubt, select 'gzip'
151
152config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800153 bool "Gzip"
154 depends on HAVE_KERNEL_GZIP
155 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800156 The old and tried gzip compression. It provides a good balance
157 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100158
159config KERNEL_BZIP2
160 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800161 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100162 help
163 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700164 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800165 size is about 10% smaller with bzip2, in comparison to gzip.
166 Bzip2 uses a large amount of memory. For modern kernels you
167 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100168
169config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800170 bool "LZMA"
171 depends on HAVE_KERNEL_LZMA
172 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700173 This compression algorithm's ratio is best. Decompression speed
174 is between gzip and bzip2. Compression is slowest.
175 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100176
Lasse Collin3ebe1242011-01-12 17:01:23 -0800177config KERNEL_XZ
178 bool "XZ"
179 depends on HAVE_KERNEL_XZ
180 help
181 XZ uses the LZMA2 algorithm and instruction set specific
182 BCJ filters which can improve compression ratio of executable
183 code. The size of the kernel is about 30% smaller with XZ in
184 comparison to gzip. On architectures for which there is a BCJ
185 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
186 will create a few percent smaller kernel than plain LZMA.
187
188 The speed is about the same as with LZMA: The decompression
189 speed of XZ is better than that of bzip2 but worse than gzip
190 and LZO. Compression is slow.
191
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800192config KERNEL_LZO
193 bool "LZO"
194 depends on HAVE_KERNEL_LZO
195 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700196 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200197 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800198 (both compression and decompression) is the fastest.
199
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700200config KERNEL_LZ4
201 bool "LZ4"
202 depends on HAVE_KERNEL_LZ4
203 help
204 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
205 A preliminary version of LZ4 de/compression tool is available at
206 <https://code.google.com/p/lz4/>.
207
208 Its compression ratio is worse than LZO. The size of the kernel
209 is about 8% bigger than LZO. But the decompression speed is
210 faster than LZO.
211
Alain Knaff30d65db2009-01-04 22:46:17 +0100212endchoice
213
Josh Triplettbd5dc172011-06-15 15:08:28 -0700214config DEFAULT_HOSTNAME
215 string "Default hostname"
216 default "(none)"
217 help
218 This option determines the default system hostname before userspace
219 calls sethostname(2). The kernel traditionally uses "(none)" here,
220 but you may wish to use a different default here to make a minimal
221 system more usable with less configuration.
222
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223config SWAP
224 bool "Support for paging of anonymous memory (swap)"
David Howells93614012006-09-30 20:45:40 +0200225 depends on MMU && BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 default y
227 help
228 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100229 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 used to provide more virtual memory than the actual RAM present
231 in your computer. If unsure say Y.
232
233config SYSVIPC
234 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 ---help---
236 Inter Process Communication is a suite of library functions and
237 system calls which let processes (running programs) synchronize and
238 exchange information. It is generally considered to be a good thing,
239 and some programs won't run unless you say Y here. In particular, if
240 you want to run the DOS emulator dosemu under Linux (read the
241 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
242 you'll need to say Y here.
243
244 You can find documentation about IPC with "info ipc" and also in
245 section 6.4 of the Linux Programmer's Guide, available from
246 <http://www.tldp.org/guides.html>.
247
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800248config SYSVIPC_SYSCTL
249 bool
250 depends on SYSVIPC
251 depends on SYSCTL
252 default y
253
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254config POSIX_MQUEUE
255 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700256 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 ---help---
258 POSIX variant of message queues is a part of IPC. In POSIX message
259 queues every message has a priority which decides about succession
260 of receiving it by a process. If you want to compile and run
261 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200262 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
264 POSIX message queues are visible as a filesystem called 'mqueue'
265 and can be mounted somewhere if you want to do filesystem
266 operations on message queues.
267
268 If unsure, say Y.
269
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700270config POSIX_MQUEUE_SYSCTL
271 bool
272 depends on POSIX_MQUEUE
273 depends on SYSCTL
274 default y
275
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700276config CROSS_MEMORY_ATTACH
277 bool "Enable process_vm_readv/writev syscalls"
278 depends on MMU
279 default y
280 help
281 Enabling this option adds the system calls process_vm_readv and
282 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700283 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700284 See the man page for more details.
285
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530286config FHANDLE
Andi Kleenf76be612016-04-01 14:31:40 -0700287 bool "open by fhandle syscalls" if EXPERT
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530288 select EXPORTFS
Andi Kleenf76be612016-04-01 14:31:40 -0700289 default y
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530290 help
291 If you say Y here, a user level program will be able to map
292 file names to handle and then later use the handle for
293 different file system operations. This is useful in implementing
294 userspace file servers, which now track files using handles instead
295 of names. The handle would remain the same even if file names
296 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
297 syscalls.
298
Josh Triplett69369a72014-04-03 14:48:27 -0700299config USELIB
300 bool "uselib syscall"
Riku Voipiob2113a42016-01-15 16:58:13 -0800301 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
Josh Triplett69369a72014-04-03 14:48:27 -0700302 help
303 This option enables the uselib syscall, a system call used in the
304 dynamic linker from libc5 and earlier. glibc does not use this
305 system call. If you intend to run programs built on libc5 or
306 earlier, you may need to enable this syscall. Current systems
307 running glibc can safely disable this.
308
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309config AUDIT
310 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100311 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 help
313 Enable auditing infrastructure that can be used with another
314 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500315 logging of avc messages output). System call auditing is included
316 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900318config HAVE_ARCH_AUDITSYSCALL
319 bool
320
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500322 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900323 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324
Eric Paris939a67f2009-12-17 20:12:06 -0500325config AUDIT_WATCH
326 def_bool y
327 depends on AUDITSYSCALL
328 select FSNOTIFY
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329
Al Viro74c3cbe2007-07-22 08:04:18 -0400330config AUDIT_TREE
331 def_bool y
Eric Paris63c882a2009-05-21 17:02:01 -0400332 depends on AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500333 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400334
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000335source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200336source "kernel/time/Kconfig"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000337
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200338menu "CPU/Task time and stats accounting"
339
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200340config VIRT_CPU_ACCOUNTING
341 bool
342
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200343choice
344 prompt "Cputime accounting"
345 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100346 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200347
348# Kind of a stub config for the pure tick based cputime accounting
349config TICK_CPU_ACCOUNTING
350 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200351 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200352 help
353 This is the basic tick based cputime accounting that maintains
354 statistics about user, system and idle time spent on per jiffies
355 granularity.
356
357 If unsure, say Y.
358
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200359config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200360 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200361 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200362 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200363 help
364 Select this option to enable more accurate task and CPU time
365 accounting. This is done by reading a CPU counter on each
366 kernel entry and exit and on transitions within the kernel
367 between system, softirq and hardirq state, so there is a
368 small performance impact. In the case of s390 or IBM POWER > 5,
369 this also enables accounting of stolen time on logically-partitioned
370 systems.
371
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200372config VIRT_CPU_ACCOUNTING_GEN
373 bool "Full dynticks CPU time accounting"
Kevin Hilmanff3fb252013-09-16 15:28:19 -0700374 depends on HAVE_CONTEXT_TRACKING
Kevin Hilman554b0002013-09-16 15:28:21 -0700375 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200376 select VIRT_CPU_ACCOUNTING
377 select CONTEXT_TRACKING
378 help
379 Select this option to enable task and CPU time accounting on full
380 dynticks systems. This accounting is implemented by watching every
381 kernel-user boundaries using the context tracking subsystem.
382 The accounting is thus performed at the expense of some significant
383 overhead.
384
385 For now this is only useful if you are working on the full
386 dynticks subsystem development.
387
388 If unsure, say N.
389
Rik van Rielb58c3582016-07-13 16:50:02 +0200390endchoice
391
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200392config IRQ_TIME_ACCOUNTING
393 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200394 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200395 help
396 Select this option to enable fine granularity task irq time
397 accounting. This is done by reading a timestamp on each
398 transitions between softirq and hardirq state, so there can be a
399 small performance impact.
400
401 If in doubt, say N here.
402
Srivatsa Vaddagiri26c21542016-05-31 09:08:38 -0700403config SCHED_WALT
404 bool "Support window based load tracking"
405 depends on SMP
406 help
407 This feature will allow the scheduler to maintain a tunable window
408 based set of metrics for tasks and runqueues. These metrics can be
409 used to guide task placement as well as task frequency requirements
410 for cpufreq governors.
411
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200412config BSD_PROCESS_ACCT
413 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700414 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200415 help
416 If you say Y here, a user level program will be able to instruct the
417 kernel (via a special system call) to write process accounting
418 information to a file: whenever a process exits, information about
419 that process will be appended to the file by the kernel. The
420 information includes things such as creation time, owning user,
421 command name, memory usage, controlling terminal etc. (the complete
422 list is in the struct acct in <file:include/linux/acct.h>). It is
423 up to the user level program to do useful things with this
424 information. This is generally a good idea, so say Y.
425
426config BSD_PROCESS_ACCT_V3
427 bool "BSD Process Accounting version 3 file format"
428 depends on BSD_PROCESS_ACCT
429 default n
430 help
431 If you say Y here, the process accounting information is written
432 in a new file format that also logs the process IDs of each
433 process and it's parent. Note that this file format is incompatible
434 with previous v0/v1/v2 file formats, so you will need updated tools
435 for processing it. A preliminary version of these tools is available
436 at <http://www.gnu.org/software/acct/>.
437
438config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700439 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200440 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700441 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200442 default n
443 help
444 Export selected statistics for tasks/processes through the
445 generic netlink interface. Unlike BSD process accounting, the
446 statistics are available during the lifetime of tasks/processes as
447 responses to commands. Like BSD accounting, they are sent to user
448 space on task exit.
449
450 Say N if unsure.
451
452config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700453 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200454 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530455 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200456 help
457 Collect information on time spent by a task waiting for system
458 resources like cpu, synchronous block I/O completion and swapping
459 in pages. Such statistics can help in setting a task's priorities
460 relative to other tasks for cpu, io, rss limits etc.
461
462 Say N if unsure.
463
464config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700465 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200466 depends on TASKSTATS
467 help
468 Collect extended task accounting data and send the data
469 to userland for processing over the taskstats interface.
470
471 Say N if unsure.
472
473config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700474 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200475 depends on TASK_XACCT
476 help
477 Collect information on the number of bytes of storage I/O which this
478 task has caused.
479
480 Say N if unsure.
481
482endmenu # "CPU/Task time and stats accounting"
483
Mike Travisc903ff82009-01-15 12:28:29 -0800484menu "RCU Subsystem"
485
Mike Travisc903ff82009-01-15 12:28:29 -0800486config TREE_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400487 bool
488 default y if !PREEMPT && SMP
Mike Travisc903ff82009-01-15 12:28:29 -0800489 help
490 This option selects the RCU implementation that is
491 designed for very large SMP system with hundreds or
Paul E. McKenneyc17ef452009-06-23 17:12:47 -0700492 thousands of CPUs. It also scales down nicely to
493 smaller systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800494
Pranith Kumar28f65692014-09-22 14:00:48 -0400495config PREEMPT_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400496 bool
497 default y if PREEMPT
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700498 help
499 This option selects the RCU implementation that is
500 designed for very large SMP systems with hundreds or
501 thousands of CPUs, but for which real-time response
Paul E. McKenneybbe3eae2009-09-13 09:15:08 -0700502 is also required. It also scales down nicely to
503 smaller systems.
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700504
Paul E. McKenney9fc52d82013-01-08 15:48:33 -0800505 Select this option if you are unsure.
506
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700507config TINY_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400508 bool
509 default y if !PREEMPT && !SMP
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700510 help
511 This option selects the RCU implementation that is
512 designed for UP systems from which real-time response
513 is not required. This option greatly reduces the
514 memory footprint of RCU.
515
Paul E. McKenney78cae102015-04-20 12:19:45 -0700516config RCU_EXPERT
517 bool "Make expert-level adjustments to RCU configuration"
518 default n
519 help
520 This option needs to be enabled if you wish to make
521 expert-level adjustments to RCU configuration. By default,
522 no such adjustments can be made, which has the often-beneficial
523 side-effect of preventing "make oldconfig" from asking you all
524 sorts of detailed questions about how you would like numerous
525 obscure RCU options to be set up.
526
527 Say Y if you need to make expert-level adjustments to RCU.
528
529 Say N if you are unsure.
530
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500531config SRCU
532 bool
533 help
534 This option selects the sleepable version of RCU. This version
535 permits arbitrary sleeping or blocking within RCU read-side critical
536 sections.
537
Paul E. McKenney8315f422014-06-27 13:42:20 -0700538config TASKS_RCU
Paul E. McKenney82d0f4c2015-04-20 05:42:50 -0700539 bool
Paul E. McKenney8315f422014-06-27 13:42:20 -0700540 default n
Paul E. McKenney570dd3c2016-06-15 08:56:53 -0700541 depends on !UML
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500542 select SRCU
Paul E. McKenney8315f422014-06-27 13:42:20 -0700543 help
544 This option enables a task-based RCU implementation that uses
545 only voluntary context switch (not preemption!), idle, and
546 user-mode execution as quiescent states.
547
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700548config RCU_STALL_COMMON
Pranith Kumar28f65692014-09-22 14:00:48 -0400549 def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700550 help
551 This option enables RCU CPU stall code that is common between
552 the TINY and TREE variants of RCU. The purpose is to allow
553 the tiny variants to disable RCU CPU stall warnings, while
554 making these warnings mandatory for the tree variants.
555
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100556config CONTEXT_TRACKING
557 bool
558
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100559config CONTEXT_TRACKING_FORCE
560 bool "Force context tracking"
561 depends on CONTEXT_TRACKING
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200562 default y if !NO_HZ_FULL
Frederic Weisbecker1fd2b442012-07-11 20:26:40 +0200563 help
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200564 The major pre-requirement for full dynticks to work is to
565 support the context tracking subsystem. But there are also
566 other dependencies to provide in order to make the full
567 dynticks working.
568
569 This option stands for testing when an arch implements the
570 context tracking backend but doesn't yet fullfill all the
571 requirements to make the full dynticks feature working.
572 Without the full dynticks, there is no way to test the support
573 for context tracking and the subsystems that rely on it: RCU
574 userspace extended quiescent state and tickless cputime
575 accounting. This option copes with the absence of the full
576 dynticks subsystem by forcing the context tracking on all
577 CPUs in the system.
578
Paul Gortmaker99c8b1e2013-10-24 10:07:47 -0400579 Say Y only if you're working on the development of an
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200580 architecture backend for the context tracking.
581
582 Say N otherwise, this option brings an overhead that you
583 don't want in production.
584
Frederic Weisbeckerd6771242012-10-11 01:48:28 +0200585
Mike Travisc903ff82009-01-15 12:28:29 -0800586config RCU_FANOUT
587 int "Tree-based hierarchical RCU fanout value"
588 range 2 64 if 64BIT
589 range 2 32 if !64BIT
Paul E. McKenney05c5df32015-04-20 14:27:43 -0700590 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Mike Travisc903ff82009-01-15 12:28:29 -0800591 default 64 if 64BIT
592 default 32 if !64BIT
593 help
594 This option controls the fanout of hierarchical implementations
595 of RCU, allowing RCU to work efficiently on machines with
Paul E. McKenney4d87ffa2010-08-04 17:31:12 -0700596 large numbers of CPUs. This value must be at least the fourth
597 root of NR_CPUS, which allows NR_CPUS to be insanely large.
598 The default value of RCU_FANOUT should be used for production
599 systems, but if you are stress-testing the RCU implementation
600 itself, small RCU_FANOUT values allow you to test large-system
601 code paths on small(er) systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800602
603 Select a specific number if testing RCU itself.
604 Take the default if unsure.
605
Paul E. McKenney8932a632012-04-19 12:20:14 -0700606config RCU_FANOUT_LEAF
607 int "Tree-based hierarchical RCU leaf-level fanout value"
Paul E. McKenney8739c5c2015-04-20 18:27:54 -0700608 range 2 64 if 64BIT
609 range 2 32 if !64BIT
Paul E. McKenney47d631a2015-04-21 09:12:13 -0700610 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Paul E. McKenney8932a632012-04-19 12:20:14 -0700611 default 16
612 help
613 This option controls the leaf-level fanout of hierarchical
614 implementations of RCU, and allows trading off cache misses
615 against lock contention. Systems that synchronize their
616 scheduling-clock interrupts for energy-efficiency reasons will
617 want the default because the smaller leaf-level fanout keeps
618 lock contention levels acceptably low. Very large systems
619 (hundreds or thousands of CPUs) will instead want to set this
620 value to the maximum value possible in order to reduce the
621 number of cache misses incurred during RCU's grace-period
622 initialization. These systems tend to run CPU-bound, and thus
623 are not helped by synchronized interrupts, and thus tend to
624 skew them, which reduces lock contention enough that large
625 leaf-level fanouts work well.
626
627 Select a specific number if testing RCU itself.
628
629 Select the maximum permissible value for large systems.
630
631 Take the default if unsure.
632
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800633config RCU_FAST_NO_HZ
634 bool "Accelerate last non-dyntick-idle CPU's grace periods"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700635 depends on NO_HZ_COMMON && SMP && RCU_EXPERT
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800636 default n
637 help
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800638 This option permits CPUs to enter dynticks-idle state even if
639 they have RCU callbacks queued, and prevents RCU from waking
640 these CPUs up more than roughly once every four jiffies (by
641 default, you can adjust this using the rcutree.rcu_idle_gp_delay
642 parameter), thus improving energy efficiency. On the other
643 hand, this option increases the duration of RCU grace periods,
644 for example, slowing down synchronize_rcu().
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800645
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800646 Say Y if energy efficiency is critically important, and you
647 don't care about increased grace-period durations.
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800648
649 Say N if you are unsure.
650
Mike Travisc903ff82009-01-15 12:28:29 -0800651config TREE_RCU_TRACE
Pranith Kumar28f65692014-09-22 14:00:48 -0400652 def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU )
Mike Travisc903ff82009-01-15 12:28:29 -0800653 select DEBUG_FS
654 help
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700655 This option provides tracing for the TREE_RCU and
Pranith Kumar28f65692014-09-22 14:00:48 -0400656 PREEMPT_RCU implementations, permitting Makefile to
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700657 trivially select kernel/rcutree_trace.c.
Mike Travisc903ff82009-01-15 12:28:29 -0800658
Paul E. McKenney24278d12010-09-27 17:25:23 -0700659config RCU_BOOST
660 bool "Enable RCU priority boosting"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700661 depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700662 default n
663 help
664 This option boosts the priority of preempted RCU readers that
665 block the current preemptible RCU grace period for too long.
666 This option also prevents heavy loads from blocking RCU
667 callback invocation for all flavors of RCU.
668
669 Say Y here if you are working with real-time apps or heavy loads
670 Say N here if you are unsure.
671
Clark Williams21871d72014-09-12 21:21:09 -0500672config RCU_KTHREAD_PRIO
673 int "Real-time priority to use for RCU worker threads"
Paul E. McKenneya94844b2014-12-12 07:37:48 -0800674 range 1 99 if RCU_BOOST
675 range 0 99 if !RCU_BOOST
676 default 1 if RCU_BOOST
677 default 0 if !RCU_BOOST
Paul E. McKenney26730f52015-04-21 09:22:14 -0700678 depends on RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700679 help
Clark Williams21871d72014-09-12 21:21:09 -0500680 This option specifies the SCHED_FIFO priority value that will be
681 assigned to the rcuc/n and rcub/n threads and is also the value
682 used for RCU_BOOST (if enabled). If you are working with a
683 real-time application that has one or more CPU-bound threads
684 running at a real-time priority level, you should set
685 RCU_KTHREAD_PRIO to a priority higher than the highest-priority
686 real-time CPU-bound application thread. The default RCU_KTHREAD_PRIO
687 value of 1 is appropriate in the common case, which is real-time
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700688 applications that do not have any CPU-bound threads.
689
690 Some real-time applications might not have a single real-time
691 thread that saturates a given CPU, but instead might have
692 multiple real-time threads that, taken together, fully utilize
Clark Williams21871d72014-09-12 21:21:09 -0500693 that CPU. In this case, you should set RCU_KTHREAD_PRIO to
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700694 a priority higher than the lowest-priority thread that is
695 conspiring to prevent the CPU from running any non-real-time
696 tasks. For example, if one thread at priority 10 and another
697 thread at priority 5 are between themselves fully consuming
Clark Williams21871d72014-09-12 21:21:09 -0500698 the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700699 set to priority 6 or higher.
Paul E. McKenney24278d12010-09-27 17:25:23 -0700700
701 Specify the real-time priority, or take the default if unsure.
702
703config RCU_BOOST_DELAY
704 int "Milliseconds to delay boosting after RCU grace-period start"
705 range 0 3000
706 depends on RCU_BOOST
707 default 500
708 help
709 This option specifies the time to wait after the beginning of
710 a given grace period before priority-boosting preempted RCU
711 readers blocking that grace period. Note that any RCU reader
712 blocking an expedited RCU grace period is boosted immediately.
713
714 Accept the default if unsure.
715
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700716config RCU_NOCB_CPU
Paul E. McKenney9a5739d2013-03-28 20:48:36 -0700717 bool "Offload RCU callback processing from boot-selected CPUs"
Pranith Kumar28f65692014-09-22 14:00:48 -0400718 depends on TREE_RCU || PREEMPT_RCU
Paul E. McKenneybe55fa22015-06-02 05:29:18 -0700719 depends on RCU_EXPERT || NO_HZ_FULL
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700720 default n
721 help
722 Use this option to reduce OS jitter for aggressive HPC or
723 real-time workloads. It can also be used to offload RCU
724 callback invocation to energy-efficient CPUs in battery-powered
725 asymmetric multiprocessors.
726
727 This option offloads callback invocation from the set of
728 CPUs specified at boot time by the rcu_nocbs parameter.
Paul E. McKenneya4889852012-12-03 08:16:28 -0800729 For each such CPU, a kthread ("rcuox/N") will be created to
730 invoke callbacks, where the "N" is the CPU being offloaded,
731 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
732 "s" for RCU-sched. Nothing prevents this kthread from running
733 on the specified CPUs, but (1) the kthreads may be preempted
734 between each callback, and (2) affinity or cgroups can be used
735 to force the kthreads to run on whatever set of CPUs is desired.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700736
Paul E. McKenney34ed62462013-01-07 13:37:42 -0800737 Say Y here if you want to help to debug reduced OS jitter.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700738 Say N here if you are unsure.
739
Paul E. McKenney911af502013-02-11 10:23:27 -0800740choice
741 prompt "Build-forced no-CBs CPUs"
742 default RCU_NOCB_CPU_NONE
Stefan Hengelein45687792014-09-02 19:55:11 +0200743 depends on RCU_NOCB_CPU
Paul E. McKenney911af502013-02-11 10:23:27 -0800744 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700745 This option allows no-CBs CPUs (whose RCU callbacks are invoked
746 from kthreads rather than from softirq context) to be specified
747 at build time. Additional no-CBs CPUs may be specified by
748 the rcu_nocbs= boot parameter.
Paul E. McKenney911af502013-02-11 10:23:27 -0800749
750config RCU_NOCB_CPU_NONE
751 bool "No build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800752 help
753 This option does not force any of the CPUs to be no-CBs CPUs.
754 Only CPUs designated by the rcu_nocbs= boot parameter will be
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700755 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
756 kthreads whose names begin with "rcuo". All other CPUs will
757 invoke their own RCU callbacks in softirq context.
758
759 Select this option if you want to choose no-CBs CPUs at
760 boot time, for example, to allow testing of different no-CBs
761 configurations without having to rebuild the kernel each time.
Paul E. McKenney911af502013-02-11 10:23:27 -0800762
763config RCU_NOCB_CPU_ZERO
764 bool "CPU 0 is a build_forced no-CBs CPU"
Paul E. McKenney911af502013-02-11 10:23:27 -0800765 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700766 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
767 callbacks are invoked by a per-CPU kthread whose name begins
768 with "rcuo". Additional CPUs may be designated as no-CBs
769 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
770 All other CPUs will invoke their own RCU callbacks in softirq
771 context.
Paul E. McKenney911af502013-02-11 10:23:27 -0800772
773 Select this if CPU 0 needs to be a no-CBs CPU for real-time
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700774 or energy-efficiency reasons, but the real reason it exists
775 is to ensure that randconfig testing covers mixed systems.
Paul E. McKenney911af502013-02-11 10:23:27 -0800776
777config RCU_NOCB_CPU_ALL
778 bool "All CPUs are build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800779 help
780 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700781 boot parameter will be ignored. All CPUs' RCU callbacks will
782 be executed in the context of per-CPU rcuo kthreads created for
783 this purpose. Assuming that the kthreads whose names start with
784 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
785 on the remaining CPUs, but might decrease memory locality during
786 RCU-callback invocation, thus potentially degrading throughput.
Paul E. McKenney911af502013-02-11 10:23:27 -0800787
788 Select this if all CPUs need to be no-CBs CPUs for real-time
789 or energy-efficiency reasons.
790
791endchoice
792
Paul E. McKenneyee425712015-02-19 10:51:32 -0800793config RCU_EXPEDITE_BOOT
794 bool
795 default n
796 help
797 This option enables expedited grace periods at boot time,
798 as if rcu_expedite_gp() had been invoked early in boot.
799 The corresponding rcu_unexpedite_gp() is invoked from
800 rcu_end_inkernel_boot(), which is intended to be invoked
801 at the end of the kernel-only boot sequence, just before
802 init is exec'ed.
803
804 Accept the default if unsure.
805
Mike Travisc903ff82009-01-15 12:28:29 -0800806endmenu # "RCU Subsystem"
807
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700808config BUILD_BIN2C
809 bool
810 default n
811
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700813 tristate "Kernel .config support"
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700814 select BUILD_BIN2C
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 ---help---
816 This option enables the complete Linux kernel ".config" file
817 contents to be saved in the kernel. It provides documentation
818 of which kernel options are used in a running kernel or in an
819 on-disk kernel. This information can be extracted from the kernel
820 image file with the script scripts/extract-ikconfig and used as
821 input to rebuild the current kernel or to build another kernel.
822 It can also be extracted from a running kernel by reading
823 /proc/config.gz if enabled (below).
824
825config IKCONFIG_PROC
826 bool "Enable access to .config through /proc/config.gz"
827 depends on IKCONFIG && PROC_FS
828 ---help---
829 This option enables access to the kernel configuration file
830 through /proc/config.gz.
831
Alistair John Strachan794543a2007-05-08 00:31:15 -0700832config LOG_BUF_SHIFT
833 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Ingo Molnarfb39f982015-07-01 10:19:11 +0200834 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700835 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700836 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700837 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700838 Select the minimal kernel log buffer size as a power of 2.
839 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
840 parameter, see below. Any higher size also might be forced
841 by "log_buf_len" boot parameter.
842
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700843 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700844 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700845 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700846 15 => 32 KB
847 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700848 13 => 8 KB
849 12 => 4 KB
850
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700851config LOG_CPU_MAX_BUF_SHIFT
852 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700853 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700854 range 0 21
855 default 12 if !BASE_SMALL
856 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700857 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700858 help
859 This option allows to increase the default ring buffer size
860 according to the number of CPUs. The value defines the contribution
861 of each CPU as a power of 2. The used space is typically only few
862 lines however it might be much more when problems are reported,
863 e.g. backtraces.
864
865 The increased size means that a new buffer has to be allocated and
866 the original static one is unused. It makes sense only on systems
867 with more CPUs. Therefore this value is used only when the sum of
868 contributions is greater than the half of the default kernel ring
869 buffer as defined by LOG_BUF_SHIFT. The default values are set
870 so that more than 64 CPUs are needed to trigger the allocation.
871
872 Also this option is ignored when "log_buf_len" kernel parameter is
873 used as it forces an exact (power of two) size of the ring buffer.
874
875 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200876 hotplugging making the computation optimal for the worst case
877 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700878
879 Examples shift values and their meaning:
880 17 => 128 KB for each CPU
881 16 => 64 KB for each CPU
882 15 => 32 KB for each CPU
883 14 => 16 KB for each CPU
884 13 => 8 KB for each CPU
885 12 => 4 KB for each CPU
886
Petr Mladek427934b2016-05-20 17:00:39 -0700887config NMI_LOG_BUF_SHIFT
888 int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
889 range 10 21
890 default 13
891 depends on PRINTK_NMI
892 help
893 Select the size of a per-CPU buffer where NMI messages are temporary
894 stored. They are copied to the main log buffer in a safe context
895 to avoid a deadlock. The value defines the size as a power of 2.
896
897 NMI messages are rare and limited. The largest one is when
898 a backtrace is printed. It usually fits into 4KB. Select
899 8KB if you want to be on the safe side.
900
901 Examples:
902 17 => 128 KB for each CPU
903 16 => 64 KB for each CPU
904 15 => 32 KB for each CPU
905 14 => 16 KB for each CPU
906 13 => 8 KB for each CPU
907 12 => 4 KB for each CPU
908
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800909#
910# Architectures with an unreliable sched_clock() should select this:
911#
912config HAVE_UNSTABLE_SCHED_CLOCK
913 bool
914
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700915config GENERIC_SCHED_CLOCK
916 bool
917
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200918#
919# For architectures that want to enable the support for NUMA-affine scheduler
920# balancing logic:
921#
922config ARCH_SUPPORTS_NUMA_BALANCING
923 bool
924
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100925#
Mel Gorman72b252a2015-09-04 15:47:32 -0700926# For architectures that prefer to flush all TLBs after a number of pages
927# are unmapped instead of sending one IPI per page to flush. The architecture
928# must provide guarantees on what happens if a clean TLB cache entry is
929# written after the unmap. Details are in mm/rmap.c near the check for
930# should_defer_flush. The architecture should also consider if the full flush
931# and the refill costs are offset by the savings of sending fewer IPIs.
932config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
933 bool
934
935#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100936# For architectures that know their GCC __int128 support is sound
937#
938config ARCH_SUPPORTS_INT128
939 bool
940
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200941# For architectures that (ab)use NUMA to represent different memory regions
942# all cpu-local but of different latencies, such as SuperH.
943#
944config ARCH_WANT_NUMA_VARIABLE_LOCALITY
945 bool
946
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200947config NUMA_BALANCING
948 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200949 depends on ARCH_SUPPORTS_NUMA_BALANCING
950 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
951 depends on SMP && NUMA && MIGRATION
952 help
953 This option adds support for automatic NUMA aware memory/task placement.
954 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400955 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200956
957 This system will be inactive on UMA systems.
958
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800959config NUMA_BALANCING_DEFAULT_ENABLED
960 bool "Automatically enable NUMA aware memory/task placement"
961 default y
962 depends on NUMA_BALANCING
963 help
964 If set, automatic NUMA balancing will be enabled if running on a NUMA
965 machine.
966
Li Zefan23964d22009-01-15 13:50:58 -0800967menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500968 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500969 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700970 help
Li Zefan23964d22009-01-15 13:50:58 -0800971 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800972 use with process control subsystems such as Cpusets, CFS, memory
973 controls or device isolation.
974 See
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800975 - Documentation/scheduler/sched-design-CFS.txt (CFS)
seokhoon.yoon9991a9c2016-08-02 14:03:13 -0700976 - Documentation/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800977 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700978
979 Say N if unsure.
980
Li Zefan23964d22009-01-15 13:50:58 -0800981if CGROUPS
982
Patrick Bellasiae710302015-06-23 09:17:54 +0100983config CGROUP_DEBUG
984 bool "Example debug cgroup subsystem"
985 default n
986 help
987 This option enables a simple cgroup subsystem that
988 exports useful debugging information about the cgroups
989 framework.
990
991 Say N if unsure.
992
993config CGROUP_FREEZER
994 bool "Freezer cgroup subsystem"
995 help
996 Provides a way to freeze and unfreeze all tasks in a
997 cgroup.
998
999config CGROUP_PIDS
1000 bool "PIDs cgroup subsystem"
1001 help
1002 Provides enforcement of process number limits in the scope of a
1003 cgroup. Any attempt to fork more processes than is allowed in the
1004 cgroup will fail. PIDs are fundamentally a global resource because it
1005 is fairly trivial to reach PID exhaustion before you reach even a
1006 conservative kmemcg limit. As a result, it is possible to grind a
1007 system to halt without being limited by other cgroup policies. The
1008 PIDs cgroup subsystem is designed to stop this from happening.
1009
1010 It should be noted that organisational operations (such as attaching
1011 to a cgroup hierarchy will *not* be blocked by the PIDs subsystem),
1012 since the PIDs limit only affects a process's ability to fork, not to
1013 attach to a cgroup.
1014
1015config CGROUP_DEVICE
1016 bool "Device controller for cgroups"
1017 help
1018 Provides a cgroup implementing whitelists for devices which
1019 a process in the cgroup can mknod or open.
1020
1021config CPUSETS
1022 bool "Cpuset support"
1023 help
1024 This option will let you create and manage CPUSETs which
1025 allow dynamically partitioning a system into sets of CPUs and
1026 Memory Nodes and assigning tasks to run only within those sets.
1027 This is primarily useful on large SMP or NUMA systems.
1028
1029 Say N if unsure.
1030
1031config PROC_PID_CPUSET
1032 bool "Include legacy /proc/<pid>/cpuset file"
1033 depends on CPUSETS
1034 default y
1035
1036config CGROUP_CPUACCT
1037 bool "Simple CPU accounting cgroup subsystem"
1038 help
1039 Provides a simple Resource Controller for monitoring the
1040 total CPU consumed by the tasks in a cgroup.
1041
1042config CGROUP_SCHEDTUNE
1043 bool "CFS tasks boosting cgroup subsystem (EXPERIMENTAL)"
1044 depends on SCHED_TUNE
1045 help
1046 This option provides the "schedtune" controller which improves the
1047 flexibility of the task boosting mechanism by introducing the support
1048 to define "per task" boost values.
1049
1050 This new controller:
1051 1. allows only a two layers hierarchy, where the root defines the
1052 system-wide boost value and its direct childrens define each one a
1053 different "class of tasks" to be boosted with a different value
1054 2. supports up to 16 different task classes, each one which could be
1055 configured with a different boost value
1056
1057 Say N if unsure.
1058
Johannes Weiner3e32cb22014-12-10 15:42:31 -08001059config PAGE_COUNTER
1060 bool
1061
Andrew Mortonc255a452012-07-31 16:43:02 -07001062config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -05001063 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -08001064 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -05001065 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -08001066 help
Johannes Weinera0166ec2015-12-17 17:19:56 -05001067 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -08001068
Andrew Mortonc255a452012-07-31 16:43:02 -07001069config MEMCG_SWAP
Johannes Weinera0166ec2015-12-17 17:19:56 -05001070 bool "Swap controller"
Andrew Mortonc255a452012-07-31 16:43:02 -07001071 depends on MEMCG && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001072 help
Johannes Weinera0166ec2015-12-17 17:19:56 -05001073 Provides control over the swap space consumed by tasks in a cgroup.
1074
Andrew Mortonc255a452012-07-31 16:43:02 -07001075config MEMCG_SWAP_ENABLED
Johannes Weinera0166ec2015-12-17 17:19:56 -05001076 bool "Swap controller enabled by default"
Andrew Mortonc255a452012-07-31 16:43:02 -07001077 depends on MEMCG_SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -08001078 default y
1079 help
1080 Memory Resource Controller Swap Extension comes with its price in
1081 a bigger memory consumption. General purpose distribution kernels
Jim Cromie43d547f2010-12-17 14:32:36 -07001082 which want to enable the feature but keep it disabled by default
Michal Hocko07555ac2013-08-22 16:35:46 -07001083 and let the user enable it by swapaccount=1 boot command line
Michal Hockoa42c3902010-11-24 12:57:08 -08001084 parameter should have this option unselected.
1085 For those who want to have the feature enabled by default should
1086 select this option (if, for some reason, they need to disable it
WANG Cong00a66d22011-07-25 17:12:12 -07001087 then swapaccount=0 does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001088
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001089config BLK_CGROUP
1090 bool "IO controller"
1091 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -07001092 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001093 ---help---
1094 Generic block IO controller cgroup interface. This is the common
1095 cgroup interface which should be used by various IO controlling
1096 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -07001097
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001098 Currently, CFQ IO scheduler uses it to recognize task groups and
1099 control disk bandwidth allocation (proportional time slice allocation)
1100 to such task groups. It is also used by bio throttling logic in
1101 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +02001102
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001103 This option only enables generic Block IO controller infrastructure.
1104 One needs to also enable actual IO controlling logic/policy. For
1105 enabling proportional weight division of disk bandwidth in CFQ, set
1106 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1107 CONFIG_BLK_DEV_THROTTLING=y.
1108
seokhoon.yoon9991a9c2016-08-02 14:03:13 -07001109 See Documentation/cgroup-v1/blkio-controller.txt for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001110
1111config DEBUG_BLK_CGROUP
1112 bool "IO controller debugging"
1113 depends on BLK_CGROUP
1114 default n
1115 ---help---
1116 Enable some debugging help. Currently it exports additional stat
1117 files in a cgroup which can be useful for debugging.
1118
1119config CGROUP_WRITEBACK
1120 bool
1121 depends on MEMCG && BLK_CGROUP
1122 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +02001123
Dhaval Giani7c941432010-01-20 13:26:18 +01001124menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -05001125 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +01001126 default n
1127 help
1128 This feature lets CPU scheduler recognize task groups and control CPU
1129 bandwidth allocation to such task groups. It uses cgroups to group
1130 tasks.
1131
1132if CGROUP_SCHED
1133config FAIR_GROUP_SCHED
1134 bool "Group scheduling for SCHED_OTHER"
1135 depends on CGROUP_SCHED
1136 default CGROUP_SCHED
1137
Paul Turnerab84d312011-07-21 09:43:28 -07001138config CFS_BANDWIDTH
1139 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -07001140 depends on FAIR_GROUP_SCHED
1141 default n
1142 help
1143 This option allows users to define CPU bandwidth rates (limits) for
1144 tasks running within the fair group scheduler. Groups with no limit
1145 set are considered to be unconstrained and will run with no
1146 restriction.
1147 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1148
Dhaval Giani7c941432010-01-20 13:26:18 +01001149config RT_GROUP_SCHED
1150 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +01001151 depends on CGROUP_SCHED
1152 default n
1153 help
1154 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +08001155 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +01001156 schedule realtime tasks for non-root users until you allocate
1157 realtime bandwidth for them.
1158 See Documentation/scheduler/sched-rt-group.txt for more information.
1159
1160endif #CGROUP_SCHED
1161
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001162config CGROUP_PIDS
1163 bool "PIDs controller"
1164 help
1165 Provides enforcement of process number limits in the scope of a
1166 cgroup. Any attempt to fork more processes than is allowed in the
1167 cgroup will fail. PIDs are fundamentally a global resource because it
1168 is fairly trivial to reach PID exhaustion before you reach even a
1169 conservative kmemcg limit. As a result, it is possible to grind a
1170 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +05301171 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001172
1173 It should be noted that organisational operations (such as attaching
Parav Pandit6cc578d2016-03-05 11:30:56 +05301174 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001175 since the PIDs limit only affects a process's ability to fork, not to
1176 attach to a cgroup.
1177
1178config CGROUP_FREEZER
1179 bool "Freezer controller"
1180 help
1181 Provides a way to freeze and unfreeze all tasks in a
1182 cgroup.
1183
Johannes Weiner489c2a22016-01-20 15:02:41 -08001184 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1185 controller includes important in-kernel memory consumers per default.
1186
1187 If you're using cgroup2, say N.
1188
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001189config CGROUP_HUGETLB
1190 bool "HugeTLB controller"
1191 depends on HUGETLB_PAGE
1192 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +02001193 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001194 help
1195 Provides a cgroup controller for HugeTLB pages.
1196 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1197 The limit is enforced during page fault. Since HugeTLB doesn't
1198 support page reclaim, enforcing the limit at page fault time implies
1199 that, the application will get SIGBUS signal if it tries to access
1200 HugeTLB pages beyond its limit. This requires the application to know
1201 beforehand how much HugeTLB pages it would require for its use. The
1202 control group is tracked in the third page lru pointer. This means
1203 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001204
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001205config CPUSETS
1206 bool "Cpuset controller"
1207 help
1208 This option will let you create and manage CPUSETs which
1209 allow dynamically partitioning a system into sets of CPUs and
1210 Memory Nodes and assigning tasks to run only within those sets.
1211 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001212
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001213 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001214
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001215config PROC_PID_CPUSET
1216 bool "Include legacy /proc/<pid>/cpuset file"
1217 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001218 default y
1219
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001220config CGROUP_DEVICE
1221 bool "Device controller"
1222 help
1223 Provides a cgroup controller implementing whitelists for
1224 devices which a process in the cgroup can mknod or open.
1225
1226config CGROUP_CPUACCT
1227 bool "Simple CPU accounting controller"
1228 help
1229 Provides a simple controller for monitoring the
1230 total CPU consumed by the tasks in a cgroup.
1231
1232config CGROUP_PERF
1233 bool "Perf controller"
1234 depends on PERF_EVENTS
1235 help
1236 This option extends the perf per-cpu mode to restrict monitoring
1237 to threads which belong to the cgroup specified and run on the
1238 designated cpu.
1239
1240 Say N if unsure.
1241
Daniel Mackf791c422016-11-23 16:52:26 +01001242config CGROUP_BPF
1243 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirskicde30d12016-12-16 08:33:45 -08001244 depends on BPF_SYSCALL
1245 select SOCK_CGROUP_DATA
Daniel Mackf791c422016-11-23 16:52:26 +01001246 help
1247 Allow attaching eBPF programs to a cgroup using the bpf(2)
1248 syscall command BPF_PROG_ATTACH.
1249
1250 In which context these programs are accessed depends on the type
1251 of attachment. For instance, programs that are attached using
1252 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1253 inet sockets.
1254
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001255config CGROUP_DEBUG
1256 bool "Example controller"
1257 default n
1258 help
1259 This option enables a simple controller that exports
1260 debugging information about the cgroups framework.
1261
1262 Say N.
1263
Arnd Bergmanna2adc7c2017-01-10 13:08:06 +01001264config SOCK_CGROUP_DATA
1265 bool
1266 default n
1267
Li Zefan23964d22009-01-15 13:50:58 -08001268endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001269
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001270config CHECKPOINT_RESTORE
1271 bool "Checkpoint/restore support" if EXPERT
Iago López Galeiras2e13ba52015-06-25 15:00:57 -07001272 select PROC_CHILDREN
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001273 default n
1274 help
1275 Enables additional kernel features in a sake of checkpoint/restore.
1276 In particular it adds auxiliary prctl codes to setup process text,
1277 data and heap segment sizes, and a few additional /proc filesystem
1278 entries.
1279
1280 If unsure, say N here.
1281
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001282menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001283 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001284 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001285 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001286 help
1287 Provides the way to make tasks work with different objects using
1288 the same id. For example same IPC id may refer to different objects
1289 or same user id or pid may refer to different tasks when used in
1290 different namespaces.
1291
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001292if NAMESPACES
1293
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001294config UTS_NS
1295 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001296 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001297 help
1298 In this namespace tasks see different info provided with the
1299 uname() system call
1300
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001301config IPC_NS
1302 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001303 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001304 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001305 help
1306 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001307 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001308
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001309config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001310 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001311 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001312 help
1313 This allows containers, i.e. vservers, to use user namespaces
1314 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001315
1316 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001317 recommended that the MEMCG option also be enabled and that
1318 user-space use the memory control groups to limit the amount
1319 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001320
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001321 If unsure, say N.
1322
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001323config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001324 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001325 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001326 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001327 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001328 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001329 pid namespaces. This is a building block of containers.
1330
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001331config NET_NS
1332 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001333 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001334 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001335 help
1336 Allow user space to create what appear to be multiple instances
1337 of the network stack.
1338
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001339endif # NAMESPACES
1340
Mike Galbraith5091faa2010-11-30 14:18:03 +01001341config SCHED_AUTOGROUP
1342 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001343 select CGROUPS
1344 select CGROUP_SCHED
1345 select FAIR_GROUP_SCHED
1346 help
1347 This option optimizes the scheduler for common desktop workloads by
1348 automatically creating and populating task groups. This separation
1349 of workloads isolates aggressive CPU burners (like build jobs) from
1350 desktop applications. Task group autogeneration is currently based
1351 upon task session.
1352
Patrick Bellasi69fa4c72015-06-22 18:11:44 +01001353config SCHED_TUNE
1354 bool "Boosting for CFS tasks (EXPERIMENTAL)"
Patrick Bellasi2178e842016-07-22 11:35:59 +01001355 depends on SMP
Patrick Bellasi69fa4c72015-06-22 18:11:44 +01001356 help
1357 This option enables the system-wide support for task boosting.
1358 When this support is enabled a new sysctl interface is exposed to
1359 userspace via:
1360 /proc/sys/kernel/sched_cfs_boost
1361 which allows to set a system-wide boost value in range [0..100].
1362
1363 The currently boosting strategy is implemented in such a way that:
1364 - a 0% boost value requires to operate in "standard" mode by
1365 scheduling all tasks at the minimum capacities required by their
1366 workload demand
1367 - a 100% boost value requires to push at maximum the task
1368 performances, "regardless" of the incurred energy consumption
1369
1370 A boost value in between these two boundaries is used to bias the
1371 power/performance trade-off, the higher the boost value the more the
1372 scheduler is biased toward performance boosting instead of energy
1373 efficiency.
1374
1375 Since this support exposes a single system-wide knob, the specified
1376 boost value is applied to all (CFS) tasks in the system.
1377
1378 If unsure, say N.
1379
John Stultzac82d162016-09-20 18:42:22 -07001380config DEFAULT_USE_ENERGY_AWARE
1381 bool "Default to enabling the Energy Aware Scheduler feature"
1382 default n
1383 help
1384 This option defaults the ENERGY_AWARE scheduling feature to true,
1385 as without SCHED_DEBUG set this feature can't be enabled or disabled
1386 via sysctl.
1387
1388 Say N if unsure.
1389
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001390config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001391 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001392 depends on SYSFS
1393 default n
1394 help
1395 This option adds code that switches the layout of the "block" class
1396 devices, to not show up in /sys/class/block/, but only in
1397 /sys/block/.
1398
1399 This switch is only active when the sysfs.deprecated=1 boot option is
1400 passed or the SYSFS_DEPRECATED_V2 option is set.
1401
1402 This option allows new kernels to run on old distributions and tools,
1403 which might get confused by /sys/class/block/. Since 2007/2008 all
1404 major distributions and tools handle this just fine.
1405
1406 Recent distributions and userspace tools after 2009/2010 depend on
1407 the existence of /sys/class/block/, and will not work with this
1408 option enabled.
1409
1410 Only if you are using a new kernel on an old distribution, you might
1411 need to say Y here.
1412
1413config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001414 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001415 default n
1416 depends on SYSFS
1417 depends on SYSFS_DEPRECATED
1418 help
1419 Enable deprecated sysfs by default.
1420
1421 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1422 option.
1423
1424 Only if you are using a new kernel on an old distribution, you might
1425 need to say Y here. Even then, odds are you would not need it
1426 enabled, you can always pass the boot option if absolutely necessary.
1427
1428config RELAY
1429 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001430 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001431 help
1432 This option enables support for relay interface support in
1433 certain file systems (such as debugfs).
1434 It is designed to provide an efficient mechanism for tools and
1435 facilities to relay large amounts of data from kernel space to
1436 user space.
1437
1438 If unsure, say N.
1439
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001440config BLK_DEV_INITRD
1441 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1442 depends on BROKEN || !FRV
1443 help
1444 The initial RAM filesystem is a ramfs which is loaded by the
1445 boot loader (loadlin or lilo) and that is mounted as root
1446 before the normal boot procedure. It is typically used to
1447 load modules needed to mount the "real" root file system,
1448 etc. See <file:Documentation/initrd.txt> for details.
1449
1450 If RAM disk support (BLK_DEV_RAM) is also included, this
1451 also enables initial RAM disk (initrd) support and adds
1452 15 Kbytes (more on some other architectures) to the kernel size.
1453
1454 If unsure say Y.
1455
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001456if BLK_DEV_INITRD
1457
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001458source "usr/Kconfig"
1459
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001460endif
1461
Arnd Bergmann877417e2016-04-25 17:35:27 +02001462choice
1463 prompt "Compiler optimization level"
1464 default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
1465
1466config CC_OPTIMIZE_FOR_PERFORMANCE
1467 bool "Optimize for performance"
1468 help
1469 This is the default optimization level for the kernel, building
1470 with the "-O2" compiler flag for best performance and most
1471 helpful compile-time warnings.
1472
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001473config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +02001474 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001475 help
Masahiro Yamada31a4af72014-08-05 14:43:07 +09001476 Enabling this option will pass "-Os" instead of "-O2" to
1477 your compiler resulting in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001478
Kirill Smelkov3a55fb02012-11-02 15:41:01 +04001479 If unsure, say N.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001480
Arnd Bergmann877417e2016-04-25 17:35:27 +02001481endchoice
1482
Randy Dunlap08470622006-09-30 23:28:13 -07001483config SYSCTL
1484 bool
1485
Randy Dunlapb943c462009-03-10 12:55:46 -07001486config ANON_INODES
1487 bool
1488
Mike Frysinger657a5202013-04-30 15:28:45 -07001489config HAVE_UID16
1490 bool
1491
1492config SYSCTL_EXCEPTION_TRACE
1493 bool
1494 help
1495 Enable support for /proc/sys/debug/exception-trace.
1496
1497config SYSCTL_ARCH_UNALIGN_NO_WARN
1498 bool
1499 help
1500 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1501 Allows arch to define/use @no_unaligned_warning to possibly warn
1502 about unaligned access emulation going on under the hood.
1503
1504config SYSCTL_ARCH_UNALIGN_ALLOW
1505 bool
1506 help
1507 Enable support for /proc/sys/kernel/unaligned-trap
1508 Allows arches to define/use @unaligned_enabled to runtime toggle
1509 the unaligned access emulation.
1510 see arch/parisc/kernel/unaligned.c for reference
1511
Mike Frysinger657a5202013-04-30 15:28:45 -07001512config HAVE_PCSPKR_PLATFORM
1513 bool
1514
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001515# interpreter that classic socket filters depend on
1516config BPF
1517 bool
1518
David Rientjes6a108a12011-01-20 14:44:16 -08001519menuconfig EXPERT
1520 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001521 # Unhide debug options, to make the on-by-default options visible
1522 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523 help
1524 This option allows certain base kernel options and settings
1525 to be disabled or tweaked. This is for specialized
1526 environments which can tolerate a "non-standard" kernel.
1527 Only use this if you really know what you are doing.
1528
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001529config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001530 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001531 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001532 default y
1533 help
1534 This enables the legacy 16-bit UID syscall wrappers.
1535
Iulia Manda28138932015-04-15 16:16:41 -07001536config MULTIUSER
1537 bool "Multiple users, groups and capabilities support" if EXPERT
1538 default y
1539 help
1540 This option enables support for non-root users, groups and
1541 capabilities.
1542
1543 If you say N here, all processes will run with UID 0, GID 0, and all
1544 possible capabilities. Saying N here also compiles out support for
1545 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1546 setgid, and capset.
1547
1548 If unsure, say Y here.
1549
Fabian Frederickf6187762014-06-04 16:11:12 -07001550config SGETMASK_SYSCALL
1551 bool "sgetmask/ssetmask syscalls support" if EXPERT
1552 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1553 ---help---
1554 sys_sgetmask and sys_ssetmask are obsolete system calls
1555 no longer supported in libc but still enabled by default in some
1556 architectures.
1557
1558 If unsure, leave the default option here.
1559
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001560config SYSFS_SYSCALL
1561 bool "Sysfs syscall support" if EXPERT
1562 default y
1563 ---help---
1564 sys_sysfs is an obsolete system call no longer supported in libc.
1565 Note that disabling this option is more secure but might break
1566 compatibility with some systems.
1567
1568 If unsure say Y here.
1569
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001570config SYSCTL_SYSCALL
David Rientjes6a108a12011-01-20 14:44:16 -08001571 bool "Sysctl syscall support" if EXPERT
Eric W. Biederman26a70342009-11-05 05:26:41 -08001572 depends on PROC_SYSCTL
WANG Congc736de62011-11-02 13:39:25 -07001573 default n
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001574 select SYSCTL
1575 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001576 sys_sysctl uses binary paths that have been found challenging
1577 to properly maintain and use. The interface in /proc/sys
1578 using paths with ascii names is now the primary path to this
1579 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001580
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001581 Almost nothing using the binary sysctl interface so if you are
1582 trying to save some space it is probably safe to disable this,
1583 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001584
WANG Congc736de62011-11-02 13:39:25 -07001585 If unsure say N here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001586
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587config KALLSYMS
David Rientjes6a108a12011-01-20 14:44:16 -08001588 bool "Load all symbols for debugging/ksymoops" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589 default y
1590 help
1591 Say Y here to let the kernel print out symbolic crash information and
1592 symbolic stack backtraces. This increases the size of the kernel
1593 somewhat, as all symbols have to be loaded into the kernel image.
1594
1595config KALLSYMS_ALL
1596 bool "Include all symbols in kallsyms"
1597 depends on DEBUG_KERNEL && KALLSYMS
1598 help
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001599 Normally kallsyms only contains the symbols of functions for nicer
1600 OOPS messages and backtraces (i.e., symbols from the text and inittext
1601 sections). This is sufficient for most cases. And only in very rare
1602 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1603 names of variables from the data sections, etc).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001605 This option makes sure that all symbols are loaded into the kernel
1606 image (i.e., symbols from all sections) in cost of increased kernel
1607 size (depending on the kernel configuration, it may be 300KiB or
1608 something like this).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001610 Say N unless you really need all symbols.
Matt Mackalld59745c2005-05-01 08:59:02 -07001611
Ard Biesheuvel4d5d5662016-03-15 14:58:12 -07001612config KALLSYMS_ABSOLUTE_PERCPU
1613 bool
Randy Dunlap076501f2016-07-06 16:06:53 -07001614 depends on KALLSYMS
Ard Biesheuvel4d5d5662016-03-15 14:58:12 -07001615 default X86_64 && SMP
1616
Ard Biesheuvel2213e9a2016-03-15 14:58:19 -07001617config KALLSYMS_BASE_RELATIVE
1618 bool
1619 depends on KALLSYMS
1620 default !IA64 && !(TILE && 64BIT)
1621 help
1622 Instead of emitting them as absolute values in the native word size,
1623 emit the symbol references in the kallsyms table as 32-bit entries,
1624 each containing a relative value in the range [base, base + U32_MAX]
1625 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1626 an absolute value in the range [0, S32_MAX] or a relative value in the
1627 range [base, base + S32_MAX], where base is the lowest relative symbol
1628 address encountered in the image.
1629
1630 On 64-bit builds, this reduces the size of the address table by 50%,
1631 but more importantly, it results in entries whose values are build
1632 time constants, and no relocation pass is required at runtime to fix
1633 up the entries based on the runtime load address of the kernel.
1634
Matt Mackalld59745c2005-05-01 08:59:02 -07001635config PRINTK
1636 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001637 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001638 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001639 help
1640 This option enables normal printk support. Removing it
1641 eliminates most of the message strings from the kernel image
1642 and makes the kernel more or less silent. As this makes it
1643 very difficult to diagnose system problems, saying N here is
1644 strongly discouraged.
1645
Petr Mladek42a0bb32016-05-20 17:00:33 -07001646config PRINTK_NMI
1647 def_bool y
1648 depends on PRINTK
1649 depends on HAVE_NMI
1650
Matt Mackallc8538a72005-05-01 08:59:01 -07001651config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001652 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001653 default y
1654 help
1655 Disabling this option eliminates support for BUG and WARN, reducing
1656 the size of your kernel image and potentially quietly ignoring
1657 numerous fatal conditions. You should only consider disabling this
1658 option for embedded systems with no facilities for reporting errors.
1659 Just say Y.
1660
Matt Mackall708e9a72006-01-08 01:05:25 -08001661config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001662 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001663 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001664 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001665 help
1666 Enable support for generating core dumps. Disabling saves about 4k.
1667
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001668
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001669config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001670 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001671 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001672 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001673 default y
1674 help
1675 This option allows to disable the internal PC-Speaker
1676 support, saving some memory.
1677
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678config BASE_FULL
1679 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001680 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681 help
1682 Disabling this option reduces the size of miscellaneous core
1683 kernel data structures. This saves memory on small machines,
1684 but may reduce performance.
1685
1686config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001687 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688 default y
Ingo Molnar23f78d4a2006-06-27 02:54:53 -07001689 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 help
1691 Disabling this option will cause the kernel to be built without
1692 support for "fast userspace mutexes". The resulting kernel may not
1693 run glibc-based applications correctly.
1694
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001695config HAVE_FUTEX_CMPXCHG
1696 bool
Josh Triplett62b4d202014-10-03 16:19:24 -07001697 depends on FUTEX
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001698 help
1699 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1700 is implemented and always working. This removes a couple of runtime
1701 checks.
1702
Linus Torvalds1da177e2005-04-16 15:20:36 -07001703config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001704 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001705 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001706 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707 help
1708 Disabling this option will cause the kernel to be built without
1709 support for epoll family of system calls.
1710
Davide Libenzifba2afa2007-05-10 22:23:13 -07001711config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001712 bool "Enable signalfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001713 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -07001714 default y
1715 help
1716 Enable the signalfd() system call that allows to receive signals
1717 on a file descriptor.
1718
1719 If unsure, say Y.
1720
Davide Libenzib215e282007-05-10 22:23:16 -07001721config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001722 bool "Enable timerfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001723 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -07001724 default y
1725 help
1726 Enable the timerfd() system call that allows to receive timer
1727 events on a file descriptor.
1728
1729 If unsure, say Y.
1730
Davide Libenzie1ad7462007-05-10 22:23:19 -07001731config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001732 bool "Enable eventfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001733 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -07001734 default y
1735 help
1736 Enable the eventfd() system call that allows to receive both
1737 kernel notification (ie. KAIO) or userspace notifications.
1738
1739 If unsure, say Y.
1740
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001741# syscall, maps, verifier
1742config BPF_SYSCALL
Ingo Molnare1abf2c2015-04-02 15:51:39 +02001743 bool "Enable bpf() system call"
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001744 select ANON_INODES
1745 select BPF
1746 default n
1747 help
1748 Enable the bpf() system call that allows to manipulate eBPF
1749 programs and maps via file descriptors.
1750
Alexei Starovoitova3d6dd62018-01-29 02:48:56 +01001751config BPF_JIT_ALWAYS_ON
1752 bool "Permanently enable BPF JIT and remove BPF interpreter"
1753 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1754 help
1755 Enables BPF JIT and removes BPF interpreter to avoid
1756 speculative execution of BPF instructions by the interpreter
1757
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001759 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 default y
1761 depends on MMU
1762 help
1763 The shmem is an internal filesystem used to manage shared memory.
1764 It is backed by swap and manages resource limits. It is also exported
1765 to userspace as tmpfs if TMPFS is enabled. Disabling this
1766 option replaces shmem and tmpfs with the much simpler ramfs code,
1767 which may be appropriate on small systems without swap.
1768
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001769config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001770 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001771 default y
1772 help
1773 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001774 by some high performance threaded applications. Disabling
1775 this option saves about 7k.
1776
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001777config ADVISE_SYSCALLS
1778 bool "Enable madvise/fadvise syscalls" if EXPERT
1779 default y
1780 help
1781 This option enables the madvise and fadvise syscalls, used by
1782 applications to advise the kernel about their future memory or file
1783 usage, improving performance. If building an embedded system where no
1784 applications use these syscalls, you can disable this option to save
1785 space.
1786
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001787config USERFAULTFD
1788 bool "Enable userfaultfd() system call"
1789 select ANON_INODES
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001790 depends on MMU
1791 help
1792 Enable the userfaultfd() system call that allows to intercept and
1793 handle page faults in userland.
1794
Mike Frysinger657a5202013-04-30 15:28:45 -07001795config PCI_QUIRKS
1796 default y
1797 bool "Enable PCI quirk workarounds" if EXPERT
1798 depends on PCI
1799 help
1800 This enables workarounds for various PCI chipset
1801 bugs/quirks. Disable this only if your target machine is
1802 unaffected by PCI quirks.
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001803
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001804config MEMBARRIER
1805 bool "Enable membarrier() system call" if EXPERT
1806 default y
1807 help
1808 Enable the membarrier() system call that allows issuing memory
1809 barriers across all running threads, which can be used to distribute
1810 the cost of user-space memory barriers asymmetrically by transforming
1811 pairs of memory barriers into pairs consisting of membarrier() and a
1812 compiler barrier.
1813
1814 If unsure, say Y.
1815
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001816config EMBEDDED
1817 bool "Embedded system"
Josh Triplett5d2acfc2014-04-07 15:39:09 -07001818 option allnoconfig_y
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001819 select EXPERT
1820 help
1821 This option should be enabled if compiling the kernel for
1822 an embedded system so certain expert options are available
1823 for configuration.
1824
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001825config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001826 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001827 help
1828 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001829
Peter Zijlstra906010b2009-09-21 16:08:49 +02001830config PERF_USE_VMALLOC
1831 bool
1832 help
1833 See tools/perf/design.txt for details
1834
Ingo Molnar57c0c152009-09-21 12:20:38 +02001835menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001836
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001837config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001838 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001839 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001840 depends on HAVE_PERF_EVENTS
Ingo Molnar4c59e462008-12-08 19:38:33 +01001841 select ANON_INODES
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001842 select IRQ_WORK
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001843 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001844 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001845 Enable kernel support for various performance events provided
1846 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001847
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001848 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001849 use of generic tracepoints.
1850
1851 Most modern CPUs support performance events via performance
1852 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001853 types of hw events: such as instructions executed, cachemisses
1854 suffered, or branches mis-predicted - without slowing down the
1855 kernel or applications. These registers can also trigger interrupts
1856 when a threshold number of events have passed - and can thus be
1857 used to profile the code that runs on that CPU.
1858
Ingo Molnar57c0c152009-09-21 12:20:38 +02001859 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001860 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001861 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001862 provides per task and per CPU counters, and it provides event
1863 capabilities on top of those.
1864
1865 Say Y if unsure.
1866
Peter Zijlstra906010b2009-09-21 16:08:49 +02001867config DEBUG_PERF_USE_VMALLOC
1868 default n
1869 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb307112015-05-04 16:26:39 +10001870 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001871 select PERF_USE_VMALLOC
1872 help
1873 Use vmalloc memory to back perf mmap() buffers.
1874
1875 Mostly useful for debugging the vmalloc code on platforms
1876 that don't require it.
1877
1878 Say N if unsure.
1879
Thomas Gleixner0793a612008-12-04 20:12:29 +01001880endmenu
1881
Christoph Lameterf8891e52006-06-30 01:55:45 -07001882config VM_EVENT_COUNTERS
1883 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001884 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001885 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001886 VM event counters are needed for event counts to be shown.
1887 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001888 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001889 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001890
Christoph Lameter41ecc552007-05-09 02:32:44 -07001891config SLUB_DEBUG
1892 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001893 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001894 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001895 help
1896 SLUB has extensive debug support features. Disabling these can
1897 result in significant savings in code size. This also disables
1898 SLUB sysfs support. /sys/slab will not exist and there will be
1899 no support for cache validation etc.
1900
Tejun Heoa4ffb672018-08-24 13:22:21 +09001901config SLUB_MEMCG_SYSFS_ON
1902 default n
1903 bool "Enable memcg SLUB sysfs support by default" if EXPERT
1904 depends on SLUB && SYSFS && MEMCG
1905 help
1906 SLUB creates a directory under /sys/kernel/slab for each
1907 allocation cache to host info and debug files. If memory
1908 cgroup is enabled, each cache can have per memory cgroup
1909 caches. SLUB can create the same sysfs directories for these
1910 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1911 to a very high number of debug files being created. This is
1912 controlled by slub_memcg_sysfs boot parameter and this
1913 config option determines the parameter's default value.
1914
Randy Dunlapb943c462009-03-10 12:55:46 -07001915config COMPAT_BRK
1916 bool "Disable heap randomization"
1917 default y
1918 help
1919 Randomizing heap placement makes heap exploits harder, but it
1920 also breaks ancient binaries (including anything libc5 based).
1921 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001922 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001923 /proc/sys/kernel/randomize_va_space to 2.
1924
1925 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1926
Christoph Lameter81819f02007-05-06 14:49:36 -07001927choice
1928 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001929 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001930 help
1931 This option allows to select a slab allocator.
1932
1933config SLAB
1934 bool "SLAB"
Kees Cook04385fc2016-06-23 15:20:59 -07001935 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001936 help
1937 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001938 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001939 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001940
1941config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001942 bool "SLUB (Unqueued Allocator)"
Kees Cooked18adc2016-06-23 15:24:05 -07001943 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001944 help
1945 SLUB is a slab allocator that minimizes cache line usage
1946 instead of managing queues of cached objects (SLAB approach).
1947 Per cpu caching is realized using slabs of objects instead
1948 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001949 and has enhanced diagnostics. SLUB is the default choice for
1950 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001951
1952config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001953 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001954 bool "SLOB (Simple Allocator)"
1955 help
Matt Mackall37291452008-02-04 22:29:38 -08001956 SLOB replaces the stock allocator with a drastically simpler
1957 allocator. SLOB is generally more space efficient but
1958 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001959
1960endchoice
1961
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001962config SLAB_FREELIST_RANDOM
1963 default n
Thomas Garnier210e7a42016-07-26 15:21:59 -07001964 depends on SLAB || SLUB
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001965 bool "SLAB freelist randomization"
1966 help
Thomas Garnier210e7a42016-07-26 15:21:59 -07001967 Randomizes the freelist order used on creating new pages. This
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001968 security feature reduces the predictability of the kernel slab
1969 allocator against heap overflows.
1970
Joonsoo Kim345c9052013-06-19 14:05:52 +09001971config SLUB_CPU_PARTIAL
1972 default y
Uwe Kleine-Königb39ffbf2013-07-17 16:54:59 +02001973 depends on SLUB && SMP
Joonsoo Kim345c9052013-06-19 14:05:52 +09001974 bool "SLUB per cpu partial cache"
1975 help
1976 Per cpu partial caches accellerate objects allocation and freeing
1977 that is local to a processor at the price of more indeterminism
1978 in the latency of the free. On overflow these caches will be cleared
1979 which requires the taking of locks that may cause latency spikes.
1980 Typically one would choose no for a realtime system.
1981
Jie Zhangea637632009-12-14 18:00:02 -08001982config MMAP_ALLOW_UNINITIALIZED
1983 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08001984 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08001985 default n
1986 help
1987 Normally, and according to the Linux spec, anonymous memory obtained
1988 from mmap() has it's contents cleared before it is passed to
1989 userspace. Enabling this config option allows you to request that
1990 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1991 providing a huge performance boost. If this option is not enabled,
1992 then the flag will be ignored.
1993
1994 This is taken advantage of by uClibc's malloc(), and also by
1995 ELF-FDPIC binfmt's brk and stack allocator.
1996
1997 Because of the obvious security issues, this option should only be
1998 enabled on embedded devices where you control what is run in
1999 userspace. Since that isn't generally a problem on no-MMU systems,
2000 it is normally safe to say Y here.
2001
2002 See Documentation/nommu-mmap.txt for more information.
2003
David Howells091f6e22015-07-20 21:16:28 +01002004config SYSTEM_DATA_VERIFICATION
2005 def_bool n
2006 select SYSTEM_TRUSTED_KEYRING
2007 select KEYS
2008 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00002009 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01002010 select ASYMMETRIC_KEY_TYPE
2011 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01002012 select ASN1
2013 select OID_REGISTRY
2014 select X509_CERTIFICATE_PARSER
2015 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07002016 help
David Howells091f6e22015-07-20 21:16:28 +01002017 Provide PKCS#7 message verification using the contents of the system
2018 trusted keyring to provide public keys. This then can be used for
2019 module verification, kexec image verification and firmware blob
2020 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07002021
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05002022config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01002023 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05002024 help
2025 Say Y here to enable the extended profiling support mechanisms used
2026 by profilers such as OProfile.
2027
Ingo Molnar5f87f112008-07-23 14:15:22 +02002028#
2029# Place an empty function call at each tracepoint site. Can be
2030# dynamically changed for a probe function.
2031#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04002032config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02002033 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04002034
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05002035source "arch/Kconfig"
2036
Linus Torvalds1da177e2005-04-16 15:20:36 -07002037endmenu # General setup
2038
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +04002039config HAVE_GENERIC_DMA_COHERENT
2040 bool
2041 default n
2042
Linus Torvalds158a9622008-01-02 13:04:48 -08002043config SLABINFO
2044 bool
2045 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +03002046 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -08002047 default y
2048
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07002049config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05002050 bool
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07002051
Linus Torvalds1da177e2005-04-16 15:20:36 -07002052config BASE_SMALL
2053 int
2054 default 0 if BASE_FULL
2055 default 1 if !BASE_FULL
2056
Jan Engelhardt66da5732007-07-15 23:39:29 -07002057menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058 bool "Enable loadable module support"
Yann E. MORIN11097a02013-08-11 16:07:50 +02002059 option modules
Linus Torvalds1da177e2005-04-16 15:20:36 -07002060 help
2061 Kernel modules are small pieces of compiled code which can
2062 be inserted in the running kernel, rather than being
2063 permanently built into the kernel. You use the "modprobe"
2064 tool to add (and sometimes remove) them. If you say Y here,
2065 many parts of the kernel can be built as modules (by
2066 answering M instead of Y where indicated): this is most
2067 useful for infrequently used options which are not required
2068 for booting. For more information, see the man pages for
2069 modprobe, lsmod, modinfo, insmod and rmmod.
2070
2071 If you say Y here, you will need to run "make
2072 modules_install" to put the modules under /lib/modules/
2073 where modprobe can find them (you may need to be root to do
2074 this).
2075
2076 If unsure, say Y.
2077
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002078if MODULES
2079
Linus Torvalds826e4502008-05-04 17:04:16 -07002080config MODULE_FORCE_LOAD
2081 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07002082 default n
2083 help
Rusty Russell91e37a72008-05-09 16:25:28 +10002084 Allow loading of modules without version information (ie. modprobe
2085 --force). Forced module loading sets the 'F' (forced) taint flag and
2086 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07002087
Linus Torvalds1da177e2005-04-16 15:20:36 -07002088config MODULE_UNLOAD
2089 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002090 help
2091 Without this option you will not be able to unload any
2092 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05002093 anyway), which makes your kernel smaller, faster
2094 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002095
2096config MODULE_FORCE_UNLOAD
2097 bool "Forced module unloading"
Kees Cook19c92392012-10-02 11:19:29 -07002098 depends on MODULE_UNLOAD
Linus Torvalds1da177e2005-04-16 15:20:36 -07002099 help
2100 This option allows you to force a module to unload, even if the
2101 kernel believes it is unsafe: the kernel will remove the module
2102 without waiting for anyone to stop using it (using the -f option to
2103 rmmod). This is mainly for kernel developers and desperate users.
2104 If unsure, say N.
2105
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01002107 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002108 help
2109 Usually, you have to use modules compiled with your kernel.
2110 Saying Y here makes it sometimes possible to use modules
2111 compiled for different kernels, by adding enough information
2112 to the modules to (hopefully) spot any changes which would
2113 make them incompatible with the kernel you are running. If
2114 unsure, say N.
2115
2116config MODULE_SRCVERSION_ALL
2117 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002118 help
2119 Modules which contain a MODULE_VERSION get an extra "srcversion"
2120 field inserted into their modinfo section, which contains a
2121 sum of the source files which made it. This helps maintainers
2122 see exactly which source was used to build a module (since
2123 others sometimes change the module source without updating
2124 the version). With this option, such a "srcversion" field
2125 will be created for all modules. If unsure, say N.
2126
Rusty Russell106a4ee2012-09-26 10:09:40 +01002127config MODULE_SIG
2128 bool "Module signature verification"
2129 depends on MODULES
David Howells091f6e22015-07-20 21:16:28 +01002130 select SYSTEM_DATA_VERIFICATION
Rusty Russell106a4ee2012-09-26 10:09:40 +01002131 help
2132 Check modules for valid signatures upon load: the signature
2133 is simply appended to the module. For more information see
2134 Documentation/module-signing.txt.
2135
David Howells228c37f2015-08-11 12:38:54 +01002136 Note that this option adds the OpenSSL development packages as a
2137 kernel build dependency so that the signing tool can use its crypto
2138 library.
2139
David Howellsea0b6dc2012-09-26 10:09:50 +01002140 !!!WARNING!!! If you enable this option, you MUST make sure that the
2141 module DOES NOT get stripped after being signed. This includes the
2142 debuginfo strip done by some packagers (such as rpmbuild) and
2143 inclusion into an initramfs that wants the module size reduced.
2144
Rusty Russell106a4ee2012-09-26 10:09:40 +01002145config MODULE_SIG_FORCE
2146 bool "Require modules to be validly signed"
2147 depends on MODULE_SIG
2148 help
2149 Reject unsigned modules or signed modules for which we don't have a
2150 key. Without this, such modules will simply taint the kernel.
David Howellsea0b6dc2012-09-26 10:09:50 +01002151
Michal Marekd9d8d7e2013-01-25 13:41:31 +10302152config MODULE_SIG_ALL
2153 bool "Automatically sign all modules"
2154 default y
2155 depends on MODULE_SIG
2156 help
2157 Sign all modules during make modules_install. Without this option,
2158 modules must be signed manually, using the scripts/sign-file tool.
2159
2160comment "Do not forget to sign required modules with scripts/sign-file"
2161 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
2162
David Howellsea0b6dc2012-09-26 10:09:50 +01002163choice
2164 prompt "Which hash algorithm should modules be signed with?"
2165 depends on MODULE_SIG
2166 help
2167 This determines which sort of hashing algorithm will be used during
2168 signature generation. This algorithm _must_ be built into the kernel
2169 directly so that signature verification can take place. It is not
2170 possible to load a signed module containing the algorithm to check
2171 the signature on that module.
2172
2173config MODULE_SIG_SHA1
2174 bool "Sign modules with SHA-1"
2175 select CRYPTO_SHA1
2176
2177config MODULE_SIG_SHA224
2178 bool "Sign modules with SHA-224"
2179 select CRYPTO_SHA256
2180
2181config MODULE_SIG_SHA256
2182 bool "Sign modules with SHA-256"
2183 select CRYPTO_SHA256
2184
2185config MODULE_SIG_SHA384
2186 bool "Sign modules with SHA-384"
2187 select CRYPTO_SHA512
2188
2189config MODULE_SIG_SHA512
2190 bool "Sign modules with SHA-512"
2191 select CRYPTO_SHA512
2192
2193endchoice
2194
Michal Marek22753672013-01-25 13:41:00 +10302195config MODULE_SIG_HASH
2196 string
2197 depends on MODULE_SIG
2198 default "sha1" if MODULE_SIG_SHA1
2199 default "sha224" if MODULE_SIG_SHA224
2200 default "sha256" if MODULE_SIG_SHA256
2201 default "sha384" if MODULE_SIG_SHA384
2202 default "sha512" if MODULE_SIG_SHA512
2203
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302204config MODULE_COMPRESS
2205 bool "Compress modules on installation"
2206 depends on MODULES
2207 help
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302208
Rusty Russellb6c09b52015-06-16 12:16:22 +09302209 Compresses kernel modules when 'make modules_install' is run; gzip or
2210 xz depending on "Compression algorithm" below.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302211
Rusty Russellb6c09b52015-06-16 12:16:22 +09302212 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302213
Rusty Russellb6c09b52015-06-16 12:16:22 +09302214 Out-of-tree kernel modules installed using Kbuild will also be
2215 compressed upon installation.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302216
Rusty Russellb6c09b52015-06-16 12:16:22 +09302217 Note: for modules inside an initrd or initramfs, it's more efficient
2218 to compress the whole initrd or initramfs instead.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302219
Rusty Russellb6c09b52015-06-16 12:16:22 +09302220 Note: This is fully compatible with signed modules.
2221
2222 If in doubt, say N.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302223
2224choice
2225 prompt "Compression algorithm"
2226 depends on MODULE_COMPRESS
2227 default MODULE_COMPRESS_GZIP
2228 help
2229 This determines which sort of compression will be used during
2230 'make modules_install'.
2231
2232 GZIP (default) and XZ are supported.
2233
2234config MODULE_COMPRESS_GZIP
2235 bool "GZIP"
2236
2237config MODULE_COMPRESS_XZ
2238 bool "XZ"
2239
2240endchoice
2241
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002242config TRIM_UNUSED_KSYMS
2243 bool "Trim unused exported kernel symbols"
2244 depends on MODULES && !UNUSED_SYMBOLS
2245 help
2246 The kernel and some modules make many symbols available for
2247 other modules to use via EXPORT_SYMBOL() and variants. Depending
2248 on the set of modules being selected in your kernel configuration,
2249 many of those exported symbols might never be used.
2250
2251 This option allows for unused exported symbols to be dropped from
2252 the build. In turn, this provides the compiler more opportunities
2253 (especially when using LTO) for optimizing the code and reducing
2254 binary size. This might have some security advantages as well.
2255
Valdis Kletnieksf1cb6372016-08-02 14:07:27 -07002256 If unsure, or if you need to build out-of-tree modules, say N.
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002257
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002258endif # MODULES
2259
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302260config MODULES_TREE_LOOKUP
2261 def_bool y
Sami Tolvanen00a195e2017-05-11 15:03:36 -07002262 depends on PERF_EVENTS || TRACING || CFI_CLANG
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302263
Rusty Russell98a79d62008-12-13 21:19:41 +10302264config INIT_ALL_POSSIBLE
2265 bool
2266 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302267 Back when each arch used to define their own cpu_online_mask and
2268 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302269 with all 1s, and others with all 0s. When they were centralised,
2270 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002271 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302272
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002273source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002274
2275config PREEMPT_NOTIFIERS
2276 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002277
Steffen Klassert16295be2010-01-06 19:47:10 +11002278config PADATA
2279 depends on SMP
2280 bool
2281
David Howells4520c6a2012-09-21 23:31:13 +01002282config ASN1
2283 tristate
2284 help
2285 Build a simple ASN.1 grammar compiler that produces a bytecode output
2286 that can be interpreted by the ASN.1 stream decoder and used to
2287 inform it as to what tags are to be expected in a stream and what
2288 functions to call on what tags.
2289
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002290source "kernel/Kconfig.locks"