blob: e3929edde2c0b782e10bf1cc2573d2efd793afc1 [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
Channagoud Kadabi820ebd22017-03-13 11:42:49 -0700315 logging of avc messages output). Does not do system-call
316 auditing without CONFIG_AUDITSYSCALL.
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
Channagoud Kadabi820ebd22017-03-13 11:42:49 -0700322 bool "Enable system-call auditing support"
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900323 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Channagoud Kadabi820ebd22017-03-13 11:42:49 -0700324 default y if SECURITY_SELINUX
325 help
326 Enable low-overhead system-call auditing infrastructure that
327 can be used independently or with another kernel subsystem,
328 such as SELinux.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329
Eric Paris939a67f2009-12-17 20:12:06 -0500330config AUDIT_WATCH
331 def_bool y
332 depends on AUDITSYSCALL
333 select FSNOTIFY
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
Al Viro74c3cbe2007-07-22 08:04:18 -0400335config AUDIT_TREE
336 def_bool y
Eric Paris63c882a2009-05-21 17:02:01 -0400337 depends on AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500338 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400339
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000340source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200341source "kernel/time/Kconfig"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000342
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200343menu "CPU/Task time and stats accounting"
344
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200345config VIRT_CPU_ACCOUNTING
346 bool
347
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200348choice
349 prompt "Cputime accounting"
350 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100351 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200352
353# Kind of a stub config for the pure tick based cputime accounting
354config TICK_CPU_ACCOUNTING
355 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200356 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200357 help
358 This is the basic tick based cputime accounting that maintains
359 statistics about user, system and idle time spent on per jiffies
360 granularity.
361
362 If unsure, say Y.
363
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200364config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200365 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200366 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200367 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200368 help
369 Select this option to enable more accurate task and CPU time
370 accounting. This is done by reading a CPU counter on each
371 kernel entry and exit and on transitions within the kernel
372 between system, softirq and hardirq state, so there is a
373 small performance impact. In the case of s390 or IBM POWER > 5,
374 this also enables accounting of stolen time on logically-partitioned
375 systems.
376
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200377config VIRT_CPU_ACCOUNTING_GEN
378 bool "Full dynticks CPU time accounting"
Kevin Hilmanff3fb252013-09-16 15:28:19 -0700379 depends on HAVE_CONTEXT_TRACKING
Kevin Hilman554b0002013-09-16 15:28:21 -0700380 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200381 select VIRT_CPU_ACCOUNTING
382 select CONTEXT_TRACKING
383 help
384 Select this option to enable task and CPU time accounting on full
385 dynticks systems. This accounting is implemented by watching every
386 kernel-user boundaries using the context tracking subsystem.
387 The accounting is thus performed at the expense of some significant
388 overhead.
389
390 For now this is only useful if you are working on the full
391 dynticks subsystem development.
392
393 If unsure, say N.
394
Rik van Rielb58c3582016-07-13 16:50:02 +0200395endchoice
396
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200397config IRQ_TIME_ACCOUNTING
398 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200399 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200400 help
401 Select this option to enable fine granularity task irq time
402 accounting. This is done by reading a timestamp on each
403 transitions between softirq and hardirq state, so there can be a
404 small performance impact.
405
406 If in doubt, say N here.
407
Srivatsa Vaddagiri26c21542016-05-31 09:08:38 -0700408config SCHED_WALT
409 bool "Support window based load tracking"
410 depends on SMP
411 help
412 This feature will allow the scheduler to maintain a tunable window
413 based set of metrics for tasks and runqueues. These metrics can be
414 used to guide task placement as well as task frequency requirements
415 for cpufreq governors.
416
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200417config BSD_PROCESS_ACCT
418 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700419 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200420 help
421 If you say Y here, a user level program will be able to instruct the
422 kernel (via a special system call) to write process accounting
423 information to a file: whenever a process exits, information about
424 that process will be appended to the file by the kernel. The
425 information includes things such as creation time, owning user,
426 command name, memory usage, controlling terminal etc. (the complete
427 list is in the struct acct in <file:include/linux/acct.h>). It is
428 up to the user level program to do useful things with this
429 information. This is generally a good idea, so say Y.
430
431config BSD_PROCESS_ACCT_V3
432 bool "BSD Process Accounting version 3 file format"
433 depends on BSD_PROCESS_ACCT
434 default n
435 help
436 If you say Y here, the process accounting information is written
437 in a new file format that also logs the process IDs of each
438 process and it's parent. Note that this file format is incompatible
439 with previous v0/v1/v2 file formats, so you will need updated tools
440 for processing it. A preliminary version of these tools is available
441 at <http://www.gnu.org/software/acct/>.
442
443config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700444 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200445 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700446 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200447 default n
448 help
449 Export selected statistics for tasks/processes through the
450 generic netlink interface. Unlike BSD process accounting, the
451 statistics are available during the lifetime of tasks/processes as
452 responses to commands. Like BSD accounting, they are sent to user
453 space on task exit.
454
455 Say N if unsure.
456
457config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700458 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200459 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530460 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200461 help
462 Collect information on time spent by a task waiting for system
463 resources like cpu, synchronous block I/O completion and swapping
464 in pages. Such statistics can help in setting a task's priorities
465 relative to other tasks for cpu, io, rss limits etc.
466
467 Say N if unsure.
468
469config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700470 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200471 depends on TASKSTATS
472 help
473 Collect extended task accounting data and send the data
474 to userland for processing over the taskstats interface.
475
476 Say N if unsure.
477
478config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700479 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200480 depends on TASK_XACCT
481 help
482 Collect information on the number of bytes of storage I/O which this
483 task has caused.
484
485 Say N if unsure.
486
487endmenu # "CPU/Task time and stats accounting"
488
Mike Travisc903ff82009-01-15 12:28:29 -0800489menu "RCU Subsystem"
490
Mike Travisc903ff82009-01-15 12:28:29 -0800491config TREE_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400492 bool
493 default y if !PREEMPT && SMP
Mike Travisc903ff82009-01-15 12:28:29 -0800494 help
495 This option selects the RCU implementation that is
496 designed for very large SMP system with hundreds or
Paul E. McKenneyc17ef452009-06-23 17:12:47 -0700497 thousands of CPUs. It also scales down nicely to
498 smaller systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800499
Pranith Kumar28f65692014-09-22 14:00:48 -0400500config PREEMPT_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400501 bool
502 default y if PREEMPT
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700503 help
504 This option selects the RCU implementation that is
505 designed for very large SMP systems with hundreds or
506 thousands of CPUs, but for which real-time response
Paul E. McKenneybbe3eae2009-09-13 09:15:08 -0700507 is also required. It also scales down nicely to
508 smaller systems.
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700509
Paul E. McKenney9fc52d82013-01-08 15:48:33 -0800510 Select this option if you are unsure.
511
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700512config TINY_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400513 bool
514 default y if !PREEMPT && !SMP
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700515 help
516 This option selects the RCU implementation that is
517 designed for UP systems from which real-time response
518 is not required. This option greatly reduces the
519 memory footprint of RCU.
520
Paul E. McKenney78cae102015-04-20 12:19:45 -0700521config RCU_EXPERT
522 bool "Make expert-level adjustments to RCU configuration"
523 default n
524 help
525 This option needs to be enabled if you wish to make
526 expert-level adjustments to RCU configuration. By default,
527 no such adjustments can be made, which has the often-beneficial
528 side-effect of preventing "make oldconfig" from asking you all
529 sorts of detailed questions about how you would like numerous
530 obscure RCU options to be set up.
531
532 Say Y if you need to make expert-level adjustments to RCU.
533
534 Say N if you are unsure.
535
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500536config SRCU
537 bool
538 help
539 This option selects the sleepable version of RCU. This version
540 permits arbitrary sleeping or blocking within RCU read-side critical
541 sections.
542
Paul E. McKenney8315f422014-06-27 13:42:20 -0700543config TASKS_RCU
Paul E. McKenney82d0f4c2015-04-20 05:42:50 -0700544 bool
Paul E. McKenney8315f422014-06-27 13:42:20 -0700545 default n
Paul E. McKenney570dd3c2016-06-15 08:56:53 -0700546 depends on !UML
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500547 select SRCU
Paul E. McKenney8315f422014-06-27 13:42:20 -0700548 help
549 This option enables a task-based RCU implementation that uses
550 only voluntary context switch (not preemption!), idle, and
551 user-mode execution as quiescent states.
552
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700553config RCU_STALL_COMMON
Pranith Kumar28f65692014-09-22 14:00:48 -0400554 def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700555 help
556 This option enables RCU CPU stall code that is common between
557 the TINY and TREE variants of RCU. The purpose is to allow
558 the tiny variants to disable RCU CPU stall warnings, while
559 making these warnings mandatory for the tree variants.
560
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100561config CONTEXT_TRACKING
562 bool
563
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100564config CONTEXT_TRACKING_FORCE
565 bool "Force context tracking"
566 depends on CONTEXT_TRACKING
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200567 default y if !NO_HZ_FULL
Frederic Weisbecker1fd2b442012-07-11 20:26:40 +0200568 help
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200569 The major pre-requirement for full dynticks to work is to
570 support the context tracking subsystem. But there are also
571 other dependencies to provide in order to make the full
572 dynticks working.
573
574 This option stands for testing when an arch implements the
575 context tracking backend but doesn't yet fullfill all the
576 requirements to make the full dynticks feature working.
577 Without the full dynticks, there is no way to test the support
578 for context tracking and the subsystems that rely on it: RCU
579 userspace extended quiescent state and tickless cputime
580 accounting. This option copes with the absence of the full
581 dynticks subsystem by forcing the context tracking on all
582 CPUs in the system.
583
Paul Gortmaker99c8b1e2013-10-24 10:07:47 -0400584 Say Y only if you're working on the development of an
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200585 architecture backend for the context tracking.
586
587 Say N otherwise, this option brings an overhead that you
588 don't want in production.
589
Frederic Weisbeckerd6771242012-10-11 01:48:28 +0200590
Mike Travisc903ff82009-01-15 12:28:29 -0800591config RCU_FANOUT
592 int "Tree-based hierarchical RCU fanout value"
593 range 2 64 if 64BIT
594 range 2 32 if !64BIT
Paul E. McKenney05c5df32015-04-20 14:27:43 -0700595 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Mike Travisc903ff82009-01-15 12:28:29 -0800596 default 64 if 64BIT
597 default 32 if !64BIT
598 help
599 This option controls the fanout of hierarchical implementations
600 of RCU, allowing RCU to work efficiently on machines with
Paul E. McKenney4d87ffa2010-08-04 17:31:12 -0700601 large numbers of CPUs. This value must be at least the fourth
602 root of NR_CPUS, which allows NR_CPUS to be insanely large.
603 The default value of RCU_FANOUT should be used for production
604 systems, but if you are stress-testing the RCU implementation
605 itself, small RCU_FANOUT values allow you to test large-system
606 code paths on small(er) systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800607
608 Select a specific number if testing RCU itself.
609 Take the default if unsure.
610
Paul E. McKenney8932a632012-04-19 12:20:14 -0700611config RCU_FANOUT_LEAF
612 int "Tree-based hierarchical RCU leaf-level fanout value"
Paul E. McKenney8739c5c2015-04-20 18:27:54 -0700613 range 2 64 if 64BIT
614 range 2 32 if !64BIT
Paul E. McKenney47d631a2015-04-21 09:12:13 -0700615 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Paul E. McKenney8932a632012-04-19 12:20:14 -0700616 default 16
617 help
618 This option controls the leaf-level fanout of hierarchical
619 implementations of RCU, and allows trading off cache misses
620 against lock contention. Systems that synchronize their
621 scheduling-clock interrupts for energy-efficiency reasons will
622 want the default because the smaller leaf-level fanout keeps
623 lock contention levels acceptably low. Very large systems
624 (hundreds or thousands of CPUs) will instead want to set this
625 value to the maximum value possible in order to reduce the
626 number of cache misses incurred during RCU's grace-period
627 initialization. These systems tend to run CPU-bound, and thus
628 are not helped by synchronized interrupts, and thus tend to
629 skew them, which reduces lock contention enough that large
630 leaf-level fanouts work well.
631
632 Select a specific number if testing RCU itself.
633
634 Select the maximum permissible value for large systems.
635
636 Take the default if unsure.
637
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800638config RCU_FAST_NO_HZ
639 bool "Accelerate last non-dyntick-idle CPU's grace periods"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700640 depends on NO_HZ_COMMON && SMP && RCU_EXPERT
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800641 default n
642 help
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800643 This option permits CPUs to enter dynticks-idle state even if
644 they have RCU callbacks queued, and prevents RCU from waking
645 these CPUs up more than roughly once every four jiffies (by
646 default, you can adjust this using the rcutree.rcu_idle_gp_delay
647 parameter), thus improving energy efficiency. On the other
648 hand, this option increases the duration of RCU grace periods,
649 for example, slowing down synchronize_rcu().
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800650
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800651 Say Y if energy efficiency is critically important, and you
652 don't care about increased grace-period durations.
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800653
654 Say N if you are unsure.
655
Mike Travisc903ff82009-01-15 12:28:29 -0800656config TREE_RCU_TRACE
Pranith Kumar28f65692014-09-22 14:00:48 -0400657 def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU )
Mike Travisc903ff82009-01-15 12:28:29 -0800658 select DEBUG_FS
659 help
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700660 This option provides tracing for the TREE_RCU and
Pranith Kumar28f65692014-09-22 14:00:48 -0400661 PREEMPT_RCU implementations, permitting Makefile to
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700662 trivially select kernel/rcutree_trace.c.
Mike Travisc903ff82009-01-15 12:28:29 -0800663
Paul E. McKenney24278d12010-09-27 17:25:23 -0700664config RCU_BOOST
665 bool "Enable RCU priority boosting"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700666 depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700667 default n
668 help
669 This option boosts the priority of preempted RCU readers that
670 block the current preemptible RCU grace period for too long.
671 This option also prevents heavy loads from blocking RCU
672 callback invocation for all flavors of RCU.
673
674 Say Y here if you are working with real-time apps or heavy loads
675 Say N here if you are unsure.
676
Clark Williams21871d72014-09-12 21:21:09 -0500677config RCU_KTHREAD_PRIO
678 int "Real-time priority to use for RCU worker threads"
Paul E. McKenneya94844b2014-12-12 07:37:48 -0800679 range 1 99 if RCU_BOOST
680 range 0 99 if !RCU_BOOST
681 default 1 if RCU_BOOST
682 default 0 if !RCU_BOOST
Paul E. McKenney26730f52015-04-21 09:22:14 -0700683 depends on RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700684 help
Clark Williams21871d72014-09-12 21:21:09 -0500685 This option specifies the SCHED_FIFO priority value that will be
686 assigned to the rcuc/n and rcub/n threads and is also the value
687 used for RCU_BOOST (if enabled). If you are working with a
688 real-time application that has one or more CPU-bound threads
689 running at a real-time priority level, you should set
690 RCU_KTHREAD_PRIO to a priority higher than the highest-priority
691 real-time CPU-bound application thread. The default RCU_KTHREAD_PRIO
692 value of 1 is appropriate in the common case, which is real-time
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700693 applications that do not have any CPU-bound threads.
694
695 Some real-time applications might not have a single real-time
696 thread that saturates a given CPU, but instead might have
697 multiple real-time threads that, taken together, fully utilize
Clark Williams21871d72014-09-12 21:21:09 -0500698 that CPU. In this case, you should set RCU_KTHREAD_PRIO to
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700699 a priority higher than the lowest-priority thread that is
700 conspiring to prevent the CPU from running any non-real-time
701 tasks. For example, if one thread at priority 10 and another
702 thread at priority 5 are between themselves fully consuming
Clark Williams21871d72014-09-12 21:21:09 -0500703 the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700704 set to priority 6 or higher.
Paul E. McKenney24278d12010-09-27 17:25:23 -0700705
706 Specify the real-time priority, or take the default if unsure.
707
708config RCU_BOOST_DELAY
709 int "Milliseconds to delay boosting after RCU grace-period start"
710 range 0 3000
711 depends on RCU_BOOST
712 default 500
713 help
714 This option specifies the time to wait after the beginning of
715 a given grace period before priority-boosting preempted RCU
716 readers blocking that grace period. Note that any RCU reader
717 blocking an expedited RCU grace period is boosted immediately.
718
719 Accept the default if unsure.
720
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700721config RCU_NOCB_CPU
Paul E. McKenney9a5739d2013-03-28 20:48:36 -0700722 bool "Offload RCU callback processing from boot-selected CPUs"
Pranith Kumar28f65692014-09-22 14:00:48 -0400723 depends on TREE_RCU || PREEMPT_RCU
Paul E. McKenneybe55fa22015-06-02 05:29:18 -0700724 depends on RCU_EXPERT || NO_HZ_FULL
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700725 default n
726 help
727 Use this option to reduce OS jitter for aggressive HPC or
728 real-time workloads. It can also be used to offload RCU
729 callback invocation to energy-efficient CPUs in battery-powered
730 asymmetric multiprocessors.
731
732 This option offloads callback invocation from the set of
733 CPUs specified at boot time by the rcu_nocbs parameter.
Paul E. McKenneya4889852012-12-03 08:16:28 -0800734 For each such CPU, a kthread ("rcuox/N") will be created to
735 invoke callbacks, where the "N" is the CPU being offloaded,
736 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
737 "s" for RCU-sched. Nothing prevents this kthread from running
738 on the specified CPUs, but (1) the kthreads may be preempted
739 between each callback, and (2) affinity or cgroups can be used
740 to force the kthreads to run on whatever set of CPUs is desired.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700741
Paul E. McKenney34ed62462013-01-07 13:37:42 -0800742 Say Y here if you want to help to debug reduced OS jitter.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700743 Say N here if you are unsure.
744
Paul E. McKenney911af502013-02-11 10:23:27 -0800745choice
746 prompt "Build-forced no-CBs CPUs"
747 default RCU_NOCB_CPU_NONE
Stefan Hengelein45687792014-09-02 19:55:11 +0200748 depends on RCU_NOCB_CPU
Paul E. McKenney911af502013-02-11 10:23:27 -0800749 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700750 This option allows no-CBs CPUs (whose RCU callbacks are invoked
751 from kthreads rather than from softirq context) to be specified
752 at build time. Additional no-CBs CPUs may be specified by
753 the rcu_nocbs= boot parameter.
Paul E. McKenney911af502013-02-11 10:23:27 -0800754
755config RCU_NOCB_CPU_NONE
756 bool "No build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800757 help
758 This option does not force any of the CPUs to be no-CBs CPUs.
759 Only CPUs designated by the rcu_nocbs= boot parameter will be
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700760 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
761 kthreads whose names begin with "rcuo". All other CPUs will
762 invoke their own RCU callbacks in softirq context.
763
764 Select this option if you want to choose no-CBs CPUs at
765 boot time, for example, to allow testing of different no-CBs
766 configurations without having to rebuild the kernel each time.
Paul E. McKenney911af502013-02-11 10:23:27 -0800767
768config RCU_NOCB_CPU_ZERO
769 bool "CPU 0 is a build_forced no-CBs CPU"
Paul E. McKenney911af502013-02-11 10:23:27 -0800770 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700771 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
772 callbacks are invoked by a per-CPU kthread whose name begins
773 with "rcuo". Additional CPUs may be designated as no-CBs
774 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
775 All other CPUs will invoke their own RCU callbacks in softirq
776 context.
Paul E. McKenney911af502013-02-11 10:23:27 -0800777
778 Select this if CPU 0 needs to be a no-CBs CPU for real-time
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700779 or energy-efficiency reasons, but the real reason it exists
780 is to ensure that randconfig testing covers mixed systems.
Paul E. McKenney911af502013-02-11 10:23:27 -0800781
782config RCU_NOCB_CPU_ALL
783 bool "All CPUs are build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800784 help
785 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700786 boot parameter will be ignored. All CPUs' RCU callbacks will
787 be executed in the context of per-CPU rcuo kthreads created for
788 this purpose. Assuming that the kthreads whose names start with
789 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
790 on the remaining CPUs, but might decrease memory locality during
791 RCU-callback invocation, thus potentially degrading throughput.
Paul E. McKenney911af502013-02-11 10:23:27 -0800792
793 Select this if all CPUs need to be no-CBs CPUs for real-time
794 or energy-efficiency reasons.
795
796endchoice
797
Mike Travisc903ff82009-01-15 12:28:29 -0800798endmenu # "RCU Subsystem"
799
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700800config BUILD_BIN2C
801 bool
802 default n
803
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700805 tristate "Kernel .config support"
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700806 select BUILD_BIN2C
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 ---help---
808 This option enables the complete Linux kernel ".config" file
809 contents to be saved in the kernel. It provides documentation
810 of which kernel options are used in a running kernel or in an
811 on-disk kernel. This information can be extracted from the kernel
812 image file with the script scripts/extract-ikconfig and used as
813 input to rebuild the current kernel or to build another kernel.
814 It can also be extracted from a running kernel by reading
815 /proc/config.gz if enabled (below).
816
817config IKCONFIG_PROC
818 bool "Enable access to .config through /proc/config.gz"
819 depends on IKCONFIG && PROC_FS
820 ---help---
821 This option enables access to the kernel configuration file
822 through /proc/config.gz.
823
Alistair John Strachan794543a2007-05-08 00:31:15 -0700824config LOG_BUF_SHIFT
825 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Ingo Molnarfb39f982015-07-01 10:19:11 +0200826 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700827 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700828 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700829 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700830 Select the minimal kernel log buffer size as a power of 2.
831 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
832 parameter, see below. Any higher size also might be forced
833 by "log_buf_len" boot parameter.
834
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700835 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700836 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700837 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700838 15 => 32 KB
839 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700840 13 => 8 KB
841 12 => 4 KB
842
Mohammed Khajapashaafaee362015-09-04 20:33:31 +0530843config CONSOLE_FLUSH_ON_HOTPLUG
844 bool "Enable console flush configurable in hot plug code path"
845 depends on HOTPLUG_CPU
846 def_bool n
847 help
848 In cpu hot plug path console lock acquire and release causes the
849 console to flush. If console lock is not free hot plug latency
850 increases. So make console flush configurable in hot plug path
851 and default disabled to help in cpu hot plug latencies.
852
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700853config LOG_CPU_MAX_BUF_SHIFT
854 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700855 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700856 range 0 21
857 default 12 if !BASE_SMALL
858 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700859 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700860 help
861 This option allows to increase the default ring buffer size
862 according to the number of CPUs. The value defines the contribution
863 of each CPU as a power of 2. The used space is typically only few
864 lines however it might be much more when problems are reported,
865 e.g. backtraces.
866
867 The increased size means that a new buffer has to be allocated and
868 the original static one is unused. It makes sense only on systems
869 with more CPUs. Therefore this value is used only when the sum of
870 contributions is greater than the half of the default kernel ring
871 buffer as defined by LOG_BUF_SHIFT. The default values are set
872 so that more than 64 CPUs are needed to trigger the allocation.
873
874 Also this option is ignored when "log_buf_len" kernel parameter is
875 used as it forces an exact (power of two) size of the ring buffer.
876
877 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200878 hotplugging making the computation optimal for the worst case
879 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700880
881 Examples shift values and their meaning:
882 17 => 128 KB for each CPU
883 16 => 64 KB for each CPU
884 15 => 32 KB for each CPU
885 14 => 16 KB for each CPU
886 13 => 8 KB for each CPU
887 12 => 4 KB for each CPU
888
Petr Mladek427934b2016-05-20 17:00:39 -0700889config NMI_LOG_BUF_SHIFT
890 int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
891 range 10 21
892 default 13
893 depends on PRINTK_NMI
894 help
895 Select the size of a per-CPU buffer where NMI messages are temporary
896 stored. They are copied to the main log buffer in a safe context
897 to avoid a deadlock. The value defines the size as a power of 2.
898
899 NMI messages are rare and limited. The largest one is when
900 a backtrace is printed. It usually fits into 4KB. Select
901 8KB if you want to be on the safe side.
902
903 Examples:
904 17 => 128 KB for each CPU
905 16 => 64 KB for each CPU
906 15 => 32 KB for each CPU
907 14 => 16 KB for each CPU
908 13 => 8 KB for each CPU
909 12 => 4 KB for each CPU
910
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800911#
912# Architectures with an unreliable sched_clock() should select this:
913#
914config HAVE_UNSTABLE_SCHED_CLOCK
915 bool
916
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700917config GENERIC_SCHED_CLOCK
918 bool
919
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200920#
921# For architectures that want to enable the support for NUMA-affine scheduler
922# balancing logic:
923#
924config ARCH_SUPPORTS_NUMA_BALANCING
925 bool
926
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100927#
Mel Gorman72b252a2015-09-04 15:47:32 -0700928# For architectures that prefer to flush all TLBs after a number of pages
929# are unmapped instead of sending one IPI per page to flush. The architecture
930# must provide guarantees on what happens if a clean TLB cache entry is
931# written after the unmap. Details are in mm/rmap.c near the check for
932# should_defer_flush. The architecture should also consider if the full flush
933# and the refill costs are offset by the savings of sending fewer IPIs.
934config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
935 bool
936
937#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100938# For architectures that know their GCC __int128 support is sound
939#
940config ARCH_SUPPORTS_INT128
941 bool
942
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200943# For architectures that (ab)use NUMA to represent different memory regions
944# all cpu-local but of different latencies, such as SuperH.
945#
946config ARCH_WANT_NUMA_VARIABLE_LOCALITY
947 bool
948
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200949config NUMA_BALANCING
950 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200951 depends on ARCH_SUPPORTS_NUMA_BALANCING
952 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
953 depends on SMP && NUMA && MIGRATION
954 help
955 This option adds support for automatic NUMA aware memory/task placement.
956 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400957 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200958
959 This system will be inactive on UMA systems.
960
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800961config NUMA_BALANCING_DEFAULT_ENABLED
962 bool "Automatically enable NUMA aware memory/task placement"
963 default y
964 depends on NUMA_BALANCING
965 help
966 If set, automatic NUMA balancing will be enabled if running on a NUMA
967 machine.
968
Li Zefan23964d22009-01-15 13:50:58 -0800969menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500970 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500971 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700972 help
Li Zefan23964d22009-01-15 13:50:58 -0800973 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800974 use with process control subsystems such as Cpusets, CFS, memory
975 controls or device isolation.
976 See
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800977 - Documentation/scheduler/sched-design-CFS.txt (CFS)
seokhoon.yoon9991a9c2016-08-02 14:03:13 -0700978 - Documentation/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800979 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700980
981 Say N if unsure.
982
Li Zefan23964d22009-01-15 13:50:58 -0800983if CGROUPS
984
Patrick Bellasiae710302015-06-23 09:17:54 +0100985config CGROUP_DEBUG
986 bool "Example debug cgroup subsystem"
987 default n
988 help
989 This option enables a simple cgroup subsystem that
990 exports useful debugging information about the cgroups
991 framework.
992
993 Say N if unsure.
994
995config CGROUP_FREEZER
996 bool "Freezer cgroup subsystem"
997 help
998 Provides a way to freeze and unfreeze all tasks in a
999 cgroup.
1000
1001config CGROUP_PIDS
1002 bool "PIDs cgroup subsystem"
1003 help
1004 Provides enforcement of process number limits in the scope of a
1005 cgroup. Any attempt to fork more processes than is allowed in the
1006 cgroup will fail. PIDs are fundamentally a global resource because it
1007 is fairly trivial to reach PID exhaustion before you reach even a
1008 conservative kmemcg limit. As a result, it is possible to grind a
1009 system to halt without being limited by other cgroup policies. The
1010 PIDs cgroup subsystem is designed to stop this from happening.
1011
1012 It should be noted that organisational operations (such as attaching
1013 to a cgroup hierarchy will *not* be blocked by the PIDs subsystem),
1014 since the PIDs limit only affects a process's ability to fork, not to
1015 attach to a cgroup.
1016
1017config CGROUP_DEVICE
1018 bool "Device controller for cgroups"
1019 help
1020 Provides a cgroup implementing whitelists for devices which
1021 a process in the cgroup can mknod or open.
1022
1023config CPUSETS
1024 bool "Cpuset support"
1025 help
1026 This option will let you create and manage CPUSETs which
1027 allow dynamically partitioning a system into sets of CPUs and
1028 Memory Nodes and assigning tasks to run only within those sets.
1029 This is primarily useful on large SMP or NUMA systems.
1030
1031 Say N if unsure.
1032
1033config PROC_PID_CPUSET
1034 bool "Include legacy /proc/<pid>/cpuset file"
1035 depends on CPUSETS
1036 default y
1037
1038config CGROUP_CPUACCT
1039 bool "Simple CPU accounting cgroup subsystem"
1040 help
1041 Provides a simple Resource Controller for monitoring the
1042 total CPU consumed by the tasks in a cgroup.
1043
1044config CGROUP_SCHEDTUNE
1045 bool "CFS tasks boosting cgroup subsystem (EXPERIMENTAL)"
1046 depends on SCHED_TUNE
1047 help
1048 This option provides the "schedtune" controller which improves the
1049 flexibility of the task boosting mechanism by introducing the support
1050 to define "per task" boost values.
1051
1052 This new controller:
1053 1. allows only a two layers hierarchy, where the root defines the
1054 system-wide boost value and its direct childrens define each one a
1055 different "class of tasks" to be boosted with a different value
1056 2. supports up to 16 different task classes, each one which could be
1057 configured with a different boost value
1058
1059 Say N if unsure.
1060
Johannes Weiner3e32cb22014-12-10 15:42:31 -08001061config PAGE_COUNTER
1062 bool
1063
Andrew Mortonc255a452012-07-31 16:43:02 -07001064config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -05001065 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -08001066 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -05001067 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -08001068 help
Johannes Weinera0166ec2015-12-17 17:19:56 -05001069 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -08001070
Andrew Mortonc255a452012-07-31 16:43:02 -07001071config MEMCG_SWAP
Johannes Weinera0166ec2015-12-17 17:19:56 -05001072 bool "Swap controller"
Andrew Mortonc255a452012-07-31 16:43:02 -07001073 depends on MEMCG && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001074 help
Johannes Weinera0166ec2015-12-17 17:19:56 -05001075 Provides control over the swap space consumed by tasks in a cgroup.
1076
Andrew Mortonc255a452012-07-31 16:43:02 -07001077config MEMCG_SWAP_ENABLED
Johannes Weinera0166ec2015-12-17 17:19:56 -05001078 bool "Swap controller enabled by default"
Andrew Mortonc255a452012-07-31 16:43:02 -07001079 depends on MEMCG_SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -08001080 default y
1081 help
1082 Memory Resource Controller Swap Extension comes with its price in
1083 a bigger memory consumption. General purpose distribution kernels
Jim Cromie43d547f2010-12-17 14:32:36 -07001084 which want to enable the feature but keep it disabled by default
Michal Hocko07555ac2013-08-22 16:35:46 -07001085 and let the user enable it by swapaccount=1 boot command line
Michal Hockoa42c3902010-11-24 12:57:08 -08001086 parameter should have this option unselected.
1087 For those who want to have the feature enabled by default should
1088 select this option (if, for some reason, they need to disable it
WANG Cong00a66d22011-07-25 17:12:12 -07001089 then swapaccount=0 does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001090
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001091config BLK_CGROUP
1092 bool "IO controller"
1093 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -07001094 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001095 ---help---
1096 Generic block IO controller cgroup interface. This is the common
1097 cgroup interface which should be used by various IO controlling
1098 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -07001099
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001100 Currently, CFQ IO scheduler uses it to recognize task groups and
1101 control disk bandwidth allocation (proportional time slice allocation)
1102 to such task groups. It is also used by bio throttling logic in
1103 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +02001104
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001105 This option only enables generic Block IO controller infrastructure.
1106 One needs to also enable actual IO controlling logic/policy. For
1107 enabling proportional weight division of disk bandwidth in CFQ, set
1108 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1109 CONFIG_BLK_DEV_THROTTLING=y.
1110
seokhoon.yoon9991a9c2016-08-02 14:03:13 -07001111 See Documentation/cgroup-v1/blkio-controller.txt for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001112
1113config DEBUG_BLK_CGROUP
1114 bool "IO controller debugging"
1115 depends on BLK_CGROUP
1116 default n
1117 ---help---
1118 Enable some debugging help. Currently it exports additional stat
1119 files in a cgroup which can be useful for debugging.
1120
1121config CGROUP_WRITEBACK
1122 bool
1123 depends on MEMCG && BLK_CGROUP
1124 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +02001125
Dhaval Giani7c941432010-01-20 13:26:18 +01001126menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -05001127 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +01001128 default n
1129 help
1130 This feature lets CPU scheduler recognize task groups and control CPU
1131 bandwidth allocation to such task groups. It uses cgroups to group
1132 tasks.
1133
1134if CGROUP_SCHED
1135config FAIR_GROUP_SCHED
1136 bool "Group scheduling for SCHED_OTHER"
1137 depends on CGROUP_SCHED
1138 default CGROUP_SCHED
1139
Paul Turnerab84d312011-07-21 09:43:28 -07001140config CFS_BANDWIDTH
1141 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -07001142 depends on FAIR_GROUP_SCHED
1143 default n
1144 help
1145 This option allows users to define CPU bandwidth rates (limits) for
1146 tasks running within the fair group scheduler. Groups with no limit
1147 set are considered to be unconstrained and will run with no
1148 restriction.
1149 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1150
Dhaval Giani7c941432010-01-20 13:26:18 +01001151config RT_GROUP_SCHED
1152 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +01001153 depends on CGROUP_SCHED
1154 default n
1155 help
1156 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +08001157 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +01001158 schedule realtime tasks for non-root users until you allocate
1159 realtime bandwidth for them.
1160 See Documentation/scheduler/sched-rt-group.txt for more information.
1161
1162endif #CGROUP_SCHED
1163
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001164config CGROUP_PIDS
1165 bool "PIDs controller"
1166 help
1167 Provides enforcement of process number limits in the scope of a
1168 cgroup. Any attempt to fork more processes than is allowed in the
1169 cgroup will fail. PIDs are fundamentally a global resource because it
1170 is fairly trivial to reach PID exhaustion before you reach even a
1171 conservative kmemcg limit. As a result, it is possible to grind a
1172 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +05301173 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001174
1175 It should be noted that organisational operations (such as attaching
Parav Pandit6cc578d2016-03-05 11:30:56 +05301176 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001177 since the PIDs limit only affects a process's ability to fork, not to
1178 attach to a cgroup.
1179
1180config CGROUP_FREEZER
1181 bool "Freezer controller"
1182 help
1183 Provides a way to freeze and unfreeze all tasks in a
1184 cgroup.
1185
Johannes Weiner489c2a22016-01-20 15:02:41 -08001186 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1187 controller includes important in-kernel memory consumers per default.
1188
1189 If you're using cgroup2, say N.
1190
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001191config CGROUP_HUGETLB
1192 bool "HugeTLB controller"
1193 depends on HUGETLB_PAGE
1194 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +02001195 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001196 help
1197 Provides a cgroup controller for HugeTLB pages.
1198 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1199 The limit is enforced during page fault. Since HugeTLB doesn't
1200 support page reclaim, enforcing the limit at page fault time implies
1201 that, the application will get SIGBUS signal if it tries to access
1202 HugeTLB pages beyond its limit. This requires the application to know
1203 beforehand how much HugeTLB pages it would require for its use. The
1204 control group is tracked in the third page lru pointer. This means
1205 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001206
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001207config CPUSETS
1208 bool "Cpuset controller"
1209 help
1210 This option will let you create and manage CPUSETs which
1211 allow dynamically partitioning a system into sets of CPUs and
1212 Memory Nodes and assigning tasks to run only within those sets.
1213 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001214
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001215 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001216
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001217config PROC_PID_CPUSET
1218 bool "Include legacy /proc/<pid>/cpuset file"
1219 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001220 default y
1221
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001222config CGROUP_DEVICE
1223 bool "Device controller"
1224 help
1225 Provides a cgroup controller implementing whitelists for
1226 devices which a process in the cgroup can mknod or open.
1227
1228config CGROUP_CPUACCT
1229 bool "Simple CPU accounting controller"
1230 help
1231 Provides a simple controller for monitoring the
1232 total CPU consumed by the tasks in a cgroup.
1233
1234config CGROUP_PERF
1235 bool "Perf controller"
1236 depends on PERF_EVENTS
1237 help
1238 This option extends the perf per-cpu mode to restrict monitoring
1239 to threads which belong to the cgroup specified and run on the
1240 designated cpu.
1241
1242 Say N if unsure.
1243
Daniel Mackf791c422016-11-23 16:52:26 +01001244config CGROUP_BPF
1245 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirskicde30d12016-12-16 08:33:45 -08001246 depends on BPF_SYSCALL
1247 select SOCK_CGROUP_DATA
Daniel Mackf791c422016-11-23 16:52:26 +01001248 help
1249 Allow attaching eBPF programs to a cgroup using the bpf(2)
1250 syscall command BPF_PROG_ATTACH.
1251
1252 In which context these programs are accessed depends on the type
1253 of attachment. For instance, programs that are attached using
1254 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1255 inet sockets.
1256
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001257config CGROUP_DEBUG
1258 bool "Example controller"
1259 default n
1260 help
1261 This option enables a simple controller that exports
1262 debugging information about the cgroups framework.
1263
1264 Say N.
1265
Arnd Bergmanna2adc7c2017-01-10 13:08:06 +01001266config SOCK_CGROUP_DATA
1267 bool
1268 default n
1269
Li Zefan23964d22009-01-15 13:50:58 -08001270endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001271
Olav Haugan9306c802016-08-18 17:22:44 -07001272config SCHED_CORE_CTL
1273 bool "QTI Core Control"
1274 depends on SMP
1275 help
1276 This options enables the core control functionality in
1277 the scheduler. Core control automatically offline and
1278 online cores based on cpu load and utilization.
1279
1280 If unsure, say N here.
1281
Joonwoo Parkbf785702017-09-26 17:24:22 -07001282config SCHED_CORE_ROTATE
1283 bool "Scheduler core rotation"
1284 depends on SMP
1285 help
1286 This options enables the core rotation functionality in
1287 the scheduler. Scheduler with core rotation aims to utilize
1288 CPUs evenly.
1289
1290 If unsure, say N here.
1291
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001292config CHECKPOINT_RESTORE
1293 bool "Checkpoint/restore support" if EXPERT
Iago López Galeiras2e13ba52015-06-25 15:00:57 -07001294 select PROC_CHILDREN
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001295 default n
1296 help
1297 Enables additional kernel features in a sake of checkpoint/restore.
1298 In particular it adds auxiliary prctl codes to setup process text,
1299 data and heap segment sizes, and a few additional /proc filesystem
1300 entries.
1301
1302 If unsure, say N here.
1303
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001304menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001305 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001306 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001307 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001308 help
1309 Provides the way to make tasks work with different objects using
1310 the same id. For example same IPC id may refer to different objects
1311 or same user id or pid may refer to different tasks when used in
1312 different namespaces.
1313
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001314if NAMESPACES
1315
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001316config UTS_NS
1317 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001318 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001319 help
1320 In this namespace tasks see different info provided with the
1321 uname() system call
1322
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001323config IPC_NS
1324 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001325 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001326 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001327 help
1328 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001329 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001330
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001331config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001332 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001333 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001334 help
1335 This allows containers, i.e. vservers, to use user namespaces
1336 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001337
1338 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001339 recommended that the MEMCG option also be enabled and that
1340 user-space use the memory control groups to limit the amount
1341 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001342
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001343 If unsure, say N.
1344
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001345config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001346 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001347 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001348 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001349 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001350 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001351 pid namespaces. This is a building block of containers.
1352
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001353config NET_NS
1354 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001355 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001356 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001357 help
1358 Allow user space to create what appear to be multiple instances
1359 of the network stack.
1360
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001361endif # NAMESPACES
1362
Mike Galbraith5091faa2010-11-30 14:18:03 +01001363config SCHED_AUTOGROUP
1364 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001365 select CGROUPS
1366 select CGROUP_SCHED
1367 select FAIR_GROUP_SCHED
1368 help
1369 This option optimizes the scheduler for common desktop workloads by
1370 automatically creating and populating task groups. This separation
1371 of workloads isolates aggressive CPU burners (like build jobs) from
1372 desktop applications. Task group autogeneration is currently based
1373 upon task session.
1374
Patrick Bellasi62c1c062015-06-22 18:11:44 +01001375config SCHED_TUNE
1376 bool "Boosting for CFS tasks (EXPERIMENTAL)"
Patrick Bellasi2178e842016-07-22 11:35:59 +01001377 depends on SMP
Patrick Bellasi62c1c062015-06-22 18:11:44 +01001378 help
1379 This option enables the system-wide support for task boosting.
1380 When this support is enabled a new sysctl interface is exposed to
1381 userspace via:
1382 /proc/sys/kernel/sched_cfs_boost
1383 which allows to set a system-wide boost value in range [0..100].
1384
1385 The currently boosting strategy is implemented in such a way that:
1386 - a 0% boost value requires to operate in "standard" mode by
1387 scheduling all tasks at the minimum capacities required by their
1388 workload demand
1389 - a 100% boost value requires to push at maximum the task
1390 performances, "regardless" of the incurred energy consumption
1391
1392 A boost value in between these two boundaries is used to bias the
1393 power/performance trade-off, the higher the boost value the more the
1394 scheduler is biased toward performance boosting instead of energy
1395 efficiency.
1396
1397 Since this support exposes a single system-wide knob, the specified
1398 boost value is applied to all (CFS) tasks in the system.
1399
1400 If unsure, say N.
1401
John Stultzac82d162016-09-20 18:42:22 -07001402config DEFAULT_USE_ENERGY_AWARE
1403 bool "Default to enabling the Energy Aware Scheduler feature"
1404 default n
1405 help
1406 This option defaults the ENERGY_AWARE scheduling feature to true,
1407 as without SCHED_DEBUG set this feature can't be enabled or disabled
1408 via sysctl.
1409
1410 Say N if unsure.
1411
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001412config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001413 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001414 depends on SYSFS
1415 default n
1416 help
1417 This option adds code that switches the layout of the "block" class
1418 devices, to not show up in /sys/class/block/, but only in
1419 /sys/block/.
1420
1421 This switch is only active when the sysfs.deprecated=1 boot option is
1422 passed or the SYSFS_DEPRECATED_V2 option is set.
1423
1424 This option allows new kernels to run on old distributions and tools,
1425 which might get confused by /sys/class/block/. Since 2007/2008 all
1426 major distributions and tools handle this just fine.
1427
1428 Recent distributions and userspace tools after 2009/2010 depend on
1429 the existence of /sys/class/block/, and will not work with this
1430 option enabled.
1431
1432 Only if you are using a new kernel on an old distribution, you might
1433 need to say Y here.
1434
1435config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001436 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001437 default n
1438 depends on SYSFS
1439 depends on SYSFS_DEPRECATED
1440 help
1441 Enable deprecated sysfs by default.
1442
1443 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1444 option.
1445
1446 Only if you are using a new kernel on an old distribution, you might
1447 need to say Y here. Even then, odds are you would not need it
1448 enabled, you can always pass the boot option if absolutely necessary.
1449
1450config RELAY
1451 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001452 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001453 help
1454 This option enables support for relay interface support in
1455 certain file systems (such as debugfs).
1456 It is designed to provide an efficient mechanism for tools and
1457 facilities to relay large amounts of data from kernel space to
1458 user space.
1459
1460 If unsure, say N.
1461
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001462config BLK_DEV_INITRD
1463 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1464 depends on BROKEN || !FRV
1465 help
1466 The initial RAM filesystem is a ramfs which is loaded by the
1467 boot loader (loadlin or lilo) and that is mounted as root
1468 before the normal boot procedure. It is typically used to
1469 load modules needed to mount the "real" root file system,
1470 etc. See <file:Documentation/initrd.txt> for details.
1471
1472 If RAM disk support (BLK_DEV_RAM) is also included, this
1473 also enables initial RAM disk (initrd) support and adds
1474 15 Kbytes (more on some other architectures) to the kernel size.
1475
1476 If unsure say Y.
1477
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001478if BLK_DEV_INITRD
1479
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001480source "usr/Kconfig"
1481
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001482endif
1483
Arnd Bergmann877417e2016-04-25 17:35:27 +02001484choice
1485 prompt "Compiler optimization level"
1486 default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
1487
1488config CC_OPTIMIZE_FOR_PERFORMANCE
1489 bool "Optimize for performance"
1490 help
1491 This is the default optimization level for the kernel, building
1492 with the "-O2" compiler flag for best performance and most
1493 helpful compile-time warnings.
1494
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001495config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +02001496 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001497 help
Masahiro Yamada31a4af72014-08-05 14:43:07 +09001498 Enabling this option will pass "-Os" instead of "-O2" to
1499 your compiler resulting in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001500
Kirill Smelkov3a55fb02012-11-02 15:41:01 +04001501 If unsure, say N.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001502
Arnd Bergmann877417e2016-04-25 17:35:27 +02001503endchoice
1504
Randy Dunlap08470622006-09-30 23:28:13 -07001505config SYSCTL
1506 bool
1507
Randy Dunlapb943c462009-03-10 12:55:46 -07001508config ANON_INODES
1509 bool
1510
Mike Frysinger657a5202013-04-30 15:28:45 -07001511config HAVE_UID16
1512 bool
1513
1514config SYSCTL_EXCEPTION_TRACE
1515 bool
1516 help
1517 Enable support for /proc/sys/debug/exception-trace.
1518
1519config SYSCTL_ARCH_UNALIGN_NO_WARN
1520 bool
1521 help
1522 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1523 Allows arch to define/use @no_unaligned_warning to possibly warn
1524 about unaligned access emulation going on under the hood.
1525
1526config SYSCTL_ARCH_UNALIGN_ALLOW
1527 bool
1528 help
1529 Enable support for /proc/sys/kernel/unaligned-trap
1530 Allows arches to define/use @unaligned_enabled to runtime toggle
1531 the unaligned access emulation.
1532 see arch/parisc/kernel/unaligned.c for reference
1533
Mike Frysinger657a5202013-04-30 15:28:45 -07001534config HAVE_PCSPKR_PLATFORM
1535 bool
1536
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001537# interpreter that classic socket filters depend on
1538config BPF
1539 bool
1540
David Rientjes6a108a12011-01-20 14:44:16 -08001541menuconfig EXPERT
1542 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001543 # Unhide debug options, to make the on-by-default options visible
1544 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 help
1546 This option allows certain base kernel options and settings
1547 to be disabled or tweaked. This is for specialized
1548 environments which can tolerate a "non-standard" kernel.
1549 Only use this if you really know what you are doing.
1550
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001551config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001552 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001553 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001554 default y
1555 help
1556 This enables the legacy 16-bit UID syscall wrappers.
1557
Iulia Manda28138932015-04-15 16:16:41 -07001558config MULTIUSER
1559 bool "Multiple users, groups and capabilities support" if EXPERT
1560 default y
1561 help
1562 This option enables support for non-root users, groups and
1563 capabilities.
1564
1565 If you say N here, all processes will run with UID 0, GID 0, and all
1566 possible capabilities. Saying N here also compiles out support for
1567 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1568 setgid, and capset.
1569
1570 If unsure, say Y here.
1571
Fabian Frederickf6187762014-06-04 16:11:12 -07001572config SGETMASK_SYSCALL
1573 bool "sgetmask/ssetmask syscalls support" if EXPERT
1574 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1575 ---help---
1576 sys_sgetmask and sys_ssetmask are obsolete system calls
1577 no longer supported in libc but still enabled by default in some
1578 architectures.
1579
1580 If unsure, leave the default option here.
1581
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001582config SYSFS_SYSCALL
1583 bool "Sysfs syscall support" if EXPERT
1584 default y
1585 ---help---
1586 sys_sysfs is an obsolete system call no longer supported in libc.
1587 Note that disabling this option is more secure but might break
1588 compatibility with some systems.
1589
1590 If unsure say Y here.
1591
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001592config SYSCTL_SYSCALL
David Rientjes6a108a12011-01-20 14:44:16 -08001593 bool "Sysctl syscall support" if EXPERT
Eric W. Biederman26a70342009-11-05 05:26:41 -08001594 depends on PROC_SYSCTL
WANG Congc736de62011-11-02 13:39:25 -07001595 default n
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001596 select SYSCTL
1597 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001598 sys_sysctl uses binary paths that have been found challenging
1599 to properly maintain and use. The interface in /proc/sys
1600 using paths with ascii names is now the primary path to this
1601 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001602
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001603 Almost nothing using the binary sysctl interface so if you are
1604 trying to save some space it is probably safe to disable this,
1605 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001606
WANG Congc736de62011-11-02 13:39:25 -07001607 If unsure say N here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001608
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609config KALLSYMS
David Rientjes6a108a12011-01-20 14:44:16 -08001610 bool "Load all symbols for debugging/ksymoops" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611 default y
1612 help
1613 Say Y here to let the kernel print out symbolic crash information and
1614 symbolic stack backtraces. This increases the size of the kernel
1615 somewhat, as all symbols have to be loaded into the kernel image.
1616
1617config KALLSYMS_ALL
1618 bool "Include all symbols in kallsyms"
1619 depends on DEBUG_KERNEL && KALLSYMS
1620 help
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001621 Normally kallsyms only contains the symbols of functions for nicer
1622 OOPS messages and backtraces (i.e., symbols from the text and inittext
1623 sections). This is sufficient for most cases. And only in very rare
1624 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1625 names of variables from the data sections, etc).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001627 This option makes sure that all symbols are loaded into the kernel
1628 image (i.e., symbols from all sections) in cost of increased kernel
1629 size (depending on the kernel configuration, it may be 300KiB or
1630 something like this).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001632 Say N unless you really need all symbols.
Matt Mackalld59745c2005-05-01 08:59:02 -07001633
Ard Biesheuvel4d5d5662016-03-15 14:58:12 -07001634config KALLSYMS_ABSOLUTE_PERCPU
1635 bool
Randy Dunlap076501f2016-07-06 16:06:53 -07001636 depends on KALLSYMS
Ard Biesheuvel4d5d5662016-03-15 14:58:12 -07001637 default X86_64 && SMP
1638
Ard Biesheuvel2213e9a2016-03-15 14:58:19 -07001639config KALLSYMS_BASE_RELATIVE
1640 bool
1641 depends on KALLSYMS
1642 default !IA64 && !(TILE && 64BIT)
1643 help
1644 Instead of emitting them as absolute values in the native word size,
1645 emit the symbol references in the kallsyms table as 32-bit entries,
1646 each containing a relative value in the range [base, base + U32_MAX]
1647 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1648 an absolute value in the range [0, S32_MAX] or a relative value in the
1649 range [base, base + S32_MAX], where base is the lowest relative symbol
1650 address encountered in the image.
1651
1652 On 64-bit builds, this reduces the size of the address table by 50%,
1653 but more importantly, it results in entries whose values are build
1654 time constants, and no relocation pass is required at runtime to fix
1655 up the entries based on the runtime load address of the kernel.
1656
Matt Mackalld59745c2005-05-01 08:59:02 -07001657config PRINTK
1658 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001659 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001660 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001661 help
1662 This option enables normal printk support. Removing it
1663 eliminates most of the message strings from the kernel image
1664 and makes the kernel more or less silent. As this makes it
1665 very difficult to diagnose system problems, saying N here is
1666 strongly discouraged.
1667
Petr Mladek42a0bb32016-05-20 17:00:33 -07001668config PRINTK_NMI
1669 def_bool y
1670 depends on PRINTK
1671 depends on HAVE_NMI
1672
Matt Mackallc8538a72005-05-01 08:59:01 -07001673config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001674 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001675 default y
1676 help
1677 Disabling this option eliminates support for BUG and WARN, reducing
1678 the size of your kernel image and potentially quietly ignoring
1679 numerous fatal conditions. You should only consider disabling this
1680 option for embedded systems with no facilities for reporting errors.
1681 Just say Y.
1682
Matt Mackall708e9a72006-01-08 01:05:25 -08001683config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001684 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001685 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001686 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001687 help
1688 Enable support for generating core dumps. Disabling saves about 4k.
1689
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001690
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001691config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001692 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001693 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001694 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001695 default y
1696 help
1697 This option allows to disable the internal PC-Speaker
1698 support, saving some memory.
1699
Linus Torvalds1da177e2005-04-16 15:20:36 -07001700config BASE_FULL
1701 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001702 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001703 help
1704 Disabling this option reduces the size of miscellaneous core
1705 kernel data structures. This saves memory on small machines,
1706 but may reduce performance.
1707
1708config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001709 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001710 default y
Ingo Molnar23f78d4a2006-06-27 02:54:53 -07001711 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712 help
1713 Disabling this option will cause the kernel to be built without
1714 support for "fast userspace mutexes". The resulting kernel may not
1715 run glibc-based applications correctly.
1716
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001717config HAVE_FUTEX_CMPXCHG
1718 bool
Josh Triplett62b4d202014-10-03 16:19:24 -07001719 depends on FUTEX
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001720 help
1721 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1722 is implemented and always working. This removes a couple of runtime
1723 checks.
1724
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001726 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001728 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729 help
1730 Disabling this option will cause the kernel to be built without
1731 support for epoll family of system calls.
1732
Davide Libenzifba2afa2007-05-10 22:23:13 -07001733config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001734 bool "Enable signalfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001735 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -07001736 default y
1737 help
1738 Enable the signalfd() system call that allows to receive signals
1739 on a file descriptor.
1740
1741 If unsure, say Y.
1742
Davide Libenzib215e282007-05-10 22:23:16 -07001743config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001744 bool "Enable timerfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001745 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -07001746 default y
1747 help
1748 Enable the timerfd() system call that allows to receive timer
1749 events on a file descriptor.
1750
1751 If unsure, say Y.
1752
Davide Libenzie1ad7462007-05-10 22:23:19 -07001753config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001754 bool "Enable eventfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001755 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -07001756 default y
1757 help
1758 Enable the eventfd() system call that allows to receive both
1759 kernel notification (ie. KAIO) or userspace notifications.
1760
1761 If unsure, say Y.
1762
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001763# syscall, maps, verifier
1764config BPF_SYSCALL
Ingo Molnare1abf2c2015-04-02 15:51:39 +02001765 bool "Enable bpf() system call"
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001766 select ANON_INODES
1767 select BPF
1768 default n
1769 help
1770 Enable the bpf() system call that allows to manipulate eBPF
1771 programs and maps via file descriptors.
1772
Alexei Starovoitova3d6dd62018-01-29 02:48:56 +01001773config BPF_JIT_ALWAYS_ON
1774 bool "Permanently enable BPF JIT and remove BPF interpreter"
1775 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1776 help
1777 Enables BPF JIT and removes BPF interpreter to avoid
1778 speculative execution of BPF instructions by the interpreter
1779
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001781 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001782 default y
1783 depends on MMU
1784 help
1785 The shmem is an internal filesystem used to manage shared memory.
1786 It is backed by swap and manages resource limits. It is also exported
1787 to userspace as tmpfs if TMPFS is enabled. Disabling this
1788 option replaces shmem and tmpfs with the much simpler ramfs code,
1789 which may be appropriate on small systems without swap.
1790
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001791config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001792 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001793 default y
1794 help
1795 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001796 by some high performance threaded applications. Disabling
1797 this option saves about 7k.
1798
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001799config ADVISE_SYSCALLS
1800 bool "Enable madvise/fadvise syscalls" if EXPERT
1801 default y
1802 help
1803 This option enables the madvise and fadvise syscalls, used by
1804 applications to advise the kernel about their future memory or file
1805 usage, improving performance. If building an embedded system where no
1806 applications use these syscalls, you can disable this option to save
1807 space.
1808
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001809config USERFAULTFD
1810 bool "Enable userfaultfd() system call"
1811 select ANON_INODES
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001812 depends on MMU
1813 help
1814 Enable the userfaultfd() system call that allows to intercept and
1815 handle page faults in userland.
1816
Mike Frysinger657a5202013-04-30 15:28:45 -07001817config PCI_QUIRKS
1818 default y
1819 bool "Enable PCI quirk workarounds" if EXPERT
1820 depends on PCI
1821 help
1822 This enables workarounds for various PCI chipset
1823 bugs/quirks. Disable this only if your target machine is
1824 unaffected by PCI quirks.
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001825
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001826config MEMBARRIER
1827 bool "Enable membarrier() system call" if EXPERT
1828 default y
1829 help
1830 Enable the membarrier() system call that allows issuing memory
1831 barriers across all running threads, which can be used to distribute
1832 the cost of user-space memory barriers asymmetrically by transforming
1833 pairs of memory barriers into pairs consisting of membarrier() and a
1834 compiler barrier.
1835
1836 If unsure, say Y.
1837
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001838config EMBEDDED
1839 bool "Embedded system"
Josh Triplett5d2acfc2014-04-07 15:39:09 -07001840 option allnoconfig_y
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001841 select EXPERT
1842 help
1843 This option should be enabled if compiling the kernel for
1844 an embedded system so certain expert options are available
1845 for configuration.
1846
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001847config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001848 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001849 help
1850 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001851
Peter Zijlstra906010b2009-09-21 16:08:49 +02001852config PERF_USE_VMALLOC
1853 bool
1854 help
1855 See tools/perf/design.txt for details
1856
Ingo Molnar57c0c152009-09-21 12:20:38 +02001857menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001858
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001859config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001860 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001861 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001862 depends on HAVE_PERF_EVENTS
Ingo Molnar4c59e462008-12-08 19:38:33 +01001863 select ANON_INODES
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001864 select IRQ_WORK
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001865 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001866 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001867 Enable kernel support for various performance events provided
1868 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001869
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001870 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001871 use of generic tracepoints.
1872
1873 Most modern CPUs support performance events via performance
1874 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001875 types of hw events: such as instructions executed, cachemisses
1876 suffered, or branches mis-predicted - without slowing down the
1877 kernel or applications. These registers can also trigger interrupts
1878 when a threshold number of events have passed - and can thus be
1879 used to profile the code that runs on that CPU.
1880
Ingo Molnar57c0c152009-09-21 12:20:38 +02001881 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001882 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001883 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001884 provides per task and per CPU counters, and it provides event
1885 capabilities on top of those.
1886
1887 Say Y if unsure.
1888
Raghavendra Rao Ananta459740a2017-09-20 12:40:34 -07001889config PERF_USER_SHARE
1890 bool "Perf event sharing with user-space"
1891 help
1892 Say yes here to enable the user-space sharing of events. The events
1893 can be shared among other user-space events or with kernel created
1894 events that has the same config and type event attributes.
1895
1896 Say N if unsure.
1897
1898
Peter Zijlstra906010b2009-09-21 16:08:49 +02001899config DEBUG_PERF_USE_VMALLOC
1900 default n
1901 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb307112015-05-04 16:26:39 +10001902 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001903 select PERF_USE_VMALLOC
1904 help
1905 Use vmalloc memory to back perf mmap() buffers.
1906
1907 Mostly useful for debugging the vmalloc code on platforms
1908 that don't require it.
1909
1910 Say N if unsure.
1911
Thomas Gleixner0793a612008-12-04 20:12:29 +01001912endmenu
1913
Christoph Lameterf8891e52006-06-30 01:55:45 -07001914config VM_EVENT_COUNTERS
1915 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001916 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001917 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001918 VM event counters are needed for event counts to be shown.
1919 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001920 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001921 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001922
Christoph Lameter41ecc552007-05-09 02:32:44 -07001923config SLUB_DEBUG
1924 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001925 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001926 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001927 help
1928 SLUB has extensive debug support features. Disabling these can
1929 result in significant savings in code size. This also disables
1930 SLUB sysfs support. /sys/slab will not exist and there will be
1931 no support for cache validation etc.
1932
Randy Dunlapb943c462009-03-10 12:55:46 -07001933config COMPAT_BRK
1934 bool "Disable heap randomization"
1935 default y
1936 help
1937 Randomizing heap placement makes heap exploits harder, but it
1938 also breaks ancient binaries (including anything libc5 based).
1939 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001940 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001941 /proc/sys/kernel/randomize_va_space to 2.
1942
1943 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1944
Christoph Lameter81819f02007-05-06 14:49:36 -07001945choice
1946 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001947 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001948 help
1949 This option allows to select a slab allocator.
1950
1951config SLAB
1952 bool "SLAB"
Kees Cook04385fc2016-06-23 15:20:59 -07001953 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001954 help
1955 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001956 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001957 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001958
1959config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001960 bool "SLUB (Unqueued Allocator)"
Kees Cooked18adc2016-06-23 15:24:05 -07001961 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001962 help
1963 SLUB is a slab allocator that minimizes cache line usage
1964 instead of managing queues of cached objects (SLAB approach).
1965 Per cpu caching is realized using slabs of objects instead
1966 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001967 and has enhanced diagnostics. SLUB is the default choice for
1968 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001969
1970config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001971 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001972 bool "SLOB (Simple Allocator)"
1973 help
Matt Mackall37291452008-02-04 22:29:38 -08001974 SLOB replaces the stock allocator with a drastically simpler
1975 allocator. SLOB is generally more space efficient but
1976 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001977
1978endchoice
1979
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001980config SLAB_FREELIST_RANDOM
1981 default n
Thomas Garnier210e7a42016-07-26 15:21:59 -07001982 depends on SLAB || SLUB
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001983 bool "SLAB freelist randomization"
1984 help
Thomas Garnier210e7a42016-07-26 15:21:59 -07001985 Randomizes the freelist order used on creating new pages. This
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001986 security feature reduces the predictability of the kernel slab
1987 allocator against heap overflows.
1988
Joonsoo Kim345c9052013-06-19 14:05:52 +09001989config SLUB_CPU_PARTIAL
1990 default y
Uwe Kleine-Königb39ffbf2013-07-17 16:54:59 +02001991 depends on SLUB && SMP
Joonsoo Kim345c9052013-06-19 14:05:52 +09001992 bool "SLUB per cpu partial cache"
1993 help
1994 Per cpu partial caches accellerate objects allocation and freeing
1995 that is local to a processor at the price of more indeterminism
1996 in the latency of the free. On overflow these caches will be cleared
1997 which requires the taking of locks that may cause latency spikes.
1998 Typically one would choose no for a realtime system.
1999
Jie Zhangea637632009-12-14 18:00:02 -08002000config MMAP_ALLOW_UNINITIALIZED
2001 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08002002 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08002003 default n
2004 help
2005 Normally, and according to the Linux spec, anonymous memory obtained
2006 from mmap() has it's contents cleared before it is passed to
2007 userspace. Enabling this config option allows you to request that
2008 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
2009 providing a huge performance boost. If this option is not enabled,
2010 then the flag will be ignored.
2011
2012 This is taken advantage of by uClibc's malloc(), and also by
2013 ELF-FDPIC binfmt's brk and stack allocator.
2014
2015 Because of the obvious security issues, this option should only be
2016 enabled on embedded devices where you control what is run in
2017 userspace. Since that isn't generally a problem on no-MMU systems,
2018 it is normally safe to say Y here.
2019
2020 See Documentation/nommu-mmap.txt for more information.
2021
David Howells091f6e22015-07-20 21:16:28 +01002022config SYSTEM_DATA_VERIFICATION
2023 def_bool n
2024 select SYSTEM_TRUSTED_KEYRING
2025 select KEYS
2026 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00002027 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01002028 select ASYMMETRIC_KEY_TYPE
2029 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01002030 select ASN1
2031 select OID_REGISTRY
2032 select X509_CERTIFICATE_PARSER
2033 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07002034 help
David Howells091f6e22015-07-20 21:16:28 +01002035 Provide PKCS#7 message verification using the contents of the system
2036 trusted keyring to provide public keys. This then can be used for
2037 module verification, kexec image verification and firmware blob
2038 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07002039
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05002040config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01002041 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05002042 help
2043 Say Y here to enable the extended profiling support mechanisms used
2044 by profilers such as OProfile.
2045
Ingo Molnar5f87f112008-07-23 14:15:22 +02002046#
2047# Place an empty function call at each tracepoint site. Can be
2048# dynamically changed for a probe function.
2049#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04002050config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02002051 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04002052
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05002053source "arch/Kconfig"
2054
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055endmenu # General setup
2056
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +04002057config HAVE_GENERIC_DMA_COHERENT
2058 bool
2059 default n
2060
Linus Torvalds158a9622008-01-02 13:04:48 -08002061config SLABINFO
2062 bool
2063 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +03002064 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -08002065 default y
2066
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07002067config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05002068 bool
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07002069
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070config BASE_SMALL
2071 int
2072 default 0 if BASE_FULL
2073 default 1 if !BASE_FULL
2074
Jan Engelhardt66da5732007-07-15 23:39:29 -07002075menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07002076 bool "Enable loadable module support"
Yann E. MORIN11097a02013-08-11 16:07:50 +02002077 option modules
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078 help
2079 Kernel modules are small pieces of compiled code which can
2080 be inserted in the running kernel, rather than being
2081 permanently built into the kernel. You use the "modprobe"
2082 tool to add (and sometimes remove) them. If you say Y here,
2083 many parts of the kernel can be built as modules (by
2084 answering M instead of Y where indicated): this is most
2085 useful for infrequently used options which are not required
2086 for booting. For more information, see the man pages for
2087 modprobe, lsmod, modinfo, insmod and rmmod.
2088
2089 If you say Y here, you will need to run "make
2090 modules_install" to put the modules under /lib/modules/
2091 where modprobe can find them (you may need to be root to do
2092 this).
2093
2094 If unsure, say Y.
2095
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002096if MODULES
2097
Linus Torvalds826e4502008-05-04 17:04:16 -07002098config MODULE_FORCE_LOAD
2099 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07002100 default n
2101 help
Rusty Russell91e37a72008-05-09 16:25:28 +10002102 Allow loading of modules without version information (ie. modprobe
2103 --force). Forced module loading sets the 'F' (forced) taint flag and
2104 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07002105
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106config MODULE_UNLOAD
2107 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002108 help
2109 Without this option you will not be able to unload any
2110 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05002111 anyway), which makes your kernel smaller, faster
2112 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113
2114config MODULE_FORCE_UNLOAD
2115 bool "Forced module unloading"
Kees Cook19c92392012-10-02 11:19:29 -07002116 depends on MODULE_UNLOAD
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117 help
2118 This option allows you to force a module to unload, even if the
2119 kernel believes it is unsafe: the kernel will remove the module
2120 without waiting for anyone to stop using it (using the -f option to
2121 rmmod). This is mainly for kernel developers and desperate users.
2122 If unsure, say N.
2123
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01002125 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002126 help
2127 Usually, you have to use modules compiled with your kernel.
2128 Saying Y here makes it sometimes possible to use modules
2129 compiled for different kernels, by adding enough information
2130 to the modules to (hopefully) spot any changes which would
2131 make them incompatible with the kernel you are running. If
2132 unsure, say N.
2133
2134config MODULE_SRCVERSION_ALL
2135 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07002136 help
2137 Modules which contain a MODULE_VERSION get an extra "srcversion"
2138 field inserted into their modinfo section, which contains a
2139 sum of the source files which made it. This helps maintainers
2140 see exactly which source was used to build a module (since
2141 others sometimes change the module source without updating
2142 the version). With this option, such a "srcversion" field
2143 will be created for all modules. If unsure, say N.
2144
Rusty Russell106a4ee2012-09-26 10:09:40 +01002145config MODULE_SIG
2146 bool "Module signature verification"
2147 depends on MODULES
David Howells091f6e22015-07-20 21:16:28 +01002148 select SYSTEM_DATA_VERIFICATION
Rusty Russell106a4ee2012-09-26 10:09:40 +01002149 help
2150 Check modules for valid signatures upon load: the signature
2151 is simply appended to the module. For more information see
2152 Documentation/module-signing.txt.
2153
David Howells228c37f2015-08-11 12:38:54 +01002154 Note that this option adds the OpenSSL development packages as a
2155 kernel build dependency so that the signing tool can use its crypto
2156 library.
2157
David Howellsea0b6dc2012-09-26 10:09:50 +01002158 !!!WARNING!!! If you enable this option, you MUST make sure that the
2159 module DOES NOT get stripped after being signed. This includes the
2160 debuginfo strip done by some packagers (such as rpmbuild) and
2161 inclusion into an initramfs that wants the module size reduced.
2162
Rusty Russell106a4ee2012-09-26 10:09:40 +01002163config MODULE_SIG_FORCE
2164 bool "Require modules to be validly signed"
2165 depends on MODULE_SIG
2166 help
2167 Reject unsigned modules or signed modules for which we don't have a
2168 key. Without this, such modules will simply taint the kernel.
David Howellsea0b6dc2012-09-26 10:09:50 +01002169
Michal Marekd9d8d7e2013-01-25 13:41:31 +10302170config MODULE_SIG_ALL
2171 bool "Automatically sign all modules"
2172 default y
2173 depends on MODULE_SIG
2174 help
2175 Sign all modules during make modules_install. Without this option,
2176 modules must be signed manually, using the scripts/sign-file tool.
2177
2178comment "Do not forget to sign required modules with scripts/sign-file"
2179 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
2180
David Howellsea0b6dc2012-09-26 10:09:50 +01002181choice
2182 prompt "Which hash algorithm should modules be signed with?"
2183 depends on MODULE_SIG
2184 help
2185 This determines which sort of hashing algorithm will be used during
2186 signature generation. This algorithm _must_ be built into the kernel
2187 directly so that signature verification can take place. It is not
2188 possible to load a signed module containing the algorithm to check
2189 the signature on that module.
2190
2191config MODULE_SIG_SHA1
2192 bool "Sign modules with SHA-1"
2193 select CRYPTO_SHA1
2194
2195config MODULE_SIG_SHA224
2196 bool "Sign modules with SHA-224"
2197 select CRYPTO_SHA256
2198
2199config MODULE_SIG_SHA256
2200 bool "Sign modules with SHA-256"
2201 select CRYPTO_SHA256
2202
2203config MODULE_SIG_SHA384
2204 bool "Sign modules with SHA-384"
2205 select CRYPTO_SHA512
2206
2207config MODULE_SIG_SHA512
2208 bool "Sign modules with SHA-512"
2209 select CRYPTO_SHA512
2210
2211endchoice
2212
Michal Marek22753672013-01-25 13:41:00 +10302213config MODULE_SIG_HASH
2214 string
2215 depends on MODULE_SIG
2216 default "sha1" if MODULE_SIG_SHA1
2217 default "sha224" if MODULE_SIG_SHA224
2218 default "sha256" if MODULE_SIG_SHA256
2219 default "sha384" if MODULE_SIG_SHA384
2220 default "sha512" if MODULE_SIG_SHA512
2221
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302222config MODULE_COMPRESS
2223 bool "Compress modules on installation"
2224 depends on MODULES
2225 help
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302226
Rusty Russellb6c09b52015-06-16 12:16:22 +09302227 Compresses kernel modules when 'make modules_install' is run; gzip or
2228 xz depending on "Compression algorithm" below.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302229
Rusty Russellb6c09b52015-06-16 12:16:22 +09302230 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302231
Rusty Russellb6c09b52015-06-16 12:16:22 +09302232 Out-of-tree kernel modules installed using Kbuild will also be
2233 compressed upon installation.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302234
Rusty Russellb6c09b52015-06-16 12:16:22 +09302235 Note: for modules inside an initrd or initramfs, it's more efficient
2236 to compress the whole initrd or initramfs instead.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302237
Rusty Russellb6c09b52015-06-16 12:16:22 +09302238 Note: This is fully compatible with signed modules.
2239
2240 If in doubt, say N.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302241
2242choice
2243 prompt "Compression algorithm"
2244 depends on MODULE_COMPRESS
2245 default MODULE_COMPRESS_GZIP
2246 help
2247 This determines which sort of compression will be used during
2248 'make modules_install'.
2249
2250 GZIP (default) and XZ are supported.
2251
2252config MODULE_COMPRESS_GZIP
2253 bool "GZIP"
2254
2255config MODULE_COMPRESS_XZ
2256 bool "XZ"
2257
2258endchoice
2259
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002260config TRIM_UNUSED_KSYMS
2261 bool "Trim unused exported kernel symbols"
2262 depends on MODULES && !UNUSED_SYMBOLS
2263 help
2264 The kernel and some modules make many symbols available for
2265 other modules to use via EXPORT_SYMBOL() and variants. Depending
2266 on the set of modules being selected in your kernel configuration,
2267 many of those exported symbols might never be used.
2268
2269 This option allows for unused exported symbols to be dropped from
2270 the build. In turn, this provides the compiler more opportunities
2271 (especially when using LTO) for optimizing the code and reducing
2272 binary size. This might have some security advantages as well.
2273
Valdis Kletnieksf1cb6372016-08-02 14:07:27 -07002274 If unsure, or if you need to build out-of-tree modules, say N.
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002275
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002276endif # MODULES
2277
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302278config MODULES_TREE_LOOKUP
2279 def_bool y
Sami Tolvanen00a195e2017-05-11 15:03:36 -07002280 depends on PERF_EVENTS || TRACING || CFI_CLANG
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302281
Rusty Russell98a79d62008-12-13 21:19:41 +10302282config INIT_ALL_POSSIBLE
2283 bool
2284 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302285 Back when each arch used to define their own cpu_online_mask and
2286 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302287 with all 1s, and others with all 0s. When they were centralised,
2288 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002289 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302290
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002291source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002292
2293config PREEMPT_NOTIFIERS
2294 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002295
Steffen Klassert16295be2010-01-06 19:47:10 +11002296config PADATA
2297 depends on SMP
2298 bool
2299
David Howells4520c6a2012-09-21 23:31:13 +01002300config ASN1
2301 tristate
2302 help
2303 Build a simple ASN.1 grammar compiler that produces a bytecode output
2304 that can be interpreted by the ASN.1 stream decoder and used to
2305 inform it as to what tags are to be expected in a stream and what
2306 functions to call on what tags.
2307
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002308source "kernel/Kconfig.locks"